WO2021230800A1

WO2021230800A1 - Reduced overhead radio bearer

Info

Publication number: WO2021230800A1
Application number: PCT/SE2021/050451
Authority: WO
Inventors: Olof Liberg; Andreas HÖGLUND; Yi-Pin Eric Wang; Tuomas TIRRONEN; Johan Bergman
Original assignee: Telefonaktiebolaget LM Ericsson AB
Current assignee: Telefonaktiebolaget LM Ericsson AB
Priority date: 2020-05-13
Filing date: 2021-05-11
Publication date: 2021-11-18
Anticipated expiration: 2022-11-13

Abstract

Systems and methods are disclosed herein that relate to a reduced overhead radio bearer. In one embodiment, a method performed by a first radio node for data transmission in a radio access network of a cellular communications system comprises transmitting a reduced overhead radio bearer to a second radio node, where the reduced overhead radio bearer is a radio bearer in which: (a) a PHY layer CRC is excluded, (b) all or part of a MAC header is excluded, (c) all or part of a RLC header is excluded, (d) all or part of a PDCP header is excluded, (e) all or part of a SDAP header is excluded, or (f) a combination of any two or more of (a) – (e). In this manner, the radio bearer overhead can be reduced for small (e.g., single block, e.g., single transport block or single PDCP/RLC/MAC PDU) data transmissions.

Description

REDUCED OVERHEAD RADIO BEARER

Related Applications

This application claims the benefit of provisional patent application serial number 62/704,497, filed May 13, 2020, and provisional patent application serial number 63/025,232, filed May 15, 2020, the disclosures of which are hereby incorporated herein by reference in their entireties.

Technical Field

The present disclosure relates to transmission and reception of a radio bearer in a cellular communications system.

Background

In the Third Generation Partnership Project (3GPP) Release 8, the Evolved Packet System (EPS) was specified. EPS is based on the Long-Term Evolution (LTE) radio network and the Evolved Packet Core (EPC). It was originally intended to provide voice and Mobile Broadband (MBB) services but has continuously evolved to broaden its functionality. Since Release 13, Narrowband Internet of Things (NB-IoT) and LTE for Machine Type Communication (LTE-M) are part of the LTE specifications and provide connectivity to massive Machine Type Communications (mMTC) services.

In 3GPP Release 15, the first release of the 5G System (5GS) was specified. This is a new generation's radio access technology intended to serve use cases such as enhanced Mobile Broadband (eMBB), Ultra-Reliable and Low Latency Communication (URLLC), and mMTC. The 5GS includes the New Radio (NR) access stratum interface and the 5G Core Network (5GC). The NR physical and higher layers reuse parts of the LTE specification, and to that add needed components when motivated by new use cases. One such component is the introduction of a sophisticated framework for beam forming and beam management to extend the support of the 3GPP technologies to a frequency range going beyond 6 Gigahertz (GHz).

A new NR Release 17 Work Item RP-193252 'New Work Item on NR small data transmissions in INACTIVE state' has been approved in 3GPP with the focus of optimizing the transmission for small data payloads by reducing the signaling overhead. In parallel, LTE-M and NB-IoT continue to evolve their support for mMTC services and applications.

The LTE and NR Radio Access Network (RAN) protocol stack supports a control plane (CP) and a user plane (UP). The UP controls transmission of Internet Protocol (IP) based application payload received from a Packet Data Network (PDN). The LTE protocol stack comprises:

• Packet Data Convergence Protocol (PDCP) Layer: The PDCP layer e.g., supports ciphering, integrity protection, and IP header compression. A PDCP entity receives data in terms of Service Data Units (SDUs) on Data or Signaling Radio Bearers (DRBs, SRBs) from higher layers. The PDCP entity maps the SDUs to Protocol Data Units (PDUs) including a header and, for SRBs, a Message Authentication Code for Integrity protection (MAC-I). The header contains a sequence number (SN) which is up to 18 bits long. The MAC-I is 4 bytes.

• Radio Link Control (RLC) Layer: The RLC layer supports three modes: Acknowledged Mode (AM), Unacknowledged Mode (UM), and Transparent Mode (TM). RLC AM support e.g., Automatic Repeat Request (ARQ) retransmissions, concatenation, and segmentation. RLC UM does not, in comparison, support ARQ, while RLC TM is merely forwarding the packets between the upper and lower layers. A RLC entity receives SDUs on a RLC channel and forwards PDUs to the Medium Access Control (MAC) layer over a logical channel. For RLC AM and RLC UM, a header is added to the RLC data PDUs which e.g., contains:

- a SN that is up to 16 bits long;

- a 2 bit indicator informing the receiver if segmentation was performed and if so what part of the segmented SDU is included in the PDU;

- if segmentation is performed, and it is not the first segment that is included in the PDU, a 16 bit Segment Offset (SO) which indicates the position of the SDU segment in original SDU;

- if concatenation is performed, one or more length indicators, each of up to 15 bits, indicating the length of the concatenated data fields.

For RLC TM, no header is appended to the RLC PDUs. For RLC AM, control PDUs are supported which provide ARQ feedback to received data PDUs.

• Medium Access Control (MAC) Layer: The MAC layer multiplexes logical channels from different RLC engines and performs Hybrid ARQ (HARQ) retransmissions when needed. A MAC PDU may contain multiple MAC SDUs, and also MAC Control Elements (CEs). A MAC sub-header is appended to each SDU or CE. The sub-header contains e.g., a Logical Channel Identifier (LCID), a length indicator, and an indicator for the format of the length indicator.

• Physical Layer (PHY): The PHY layer is a layer in which a Cyclic Redundancy Check (CRC) is added for error detection. The CRC has a size of 24 bits in LTE. Figure 1 illustrates the LTE user plane protocol stack for the transmission of a DRB with RLC configured to operate in RLC AM (a header is added to the RLC PDU).

The RLC layer is performing segmentation of the second RLC SDU, and concatenation of the first and second RLC SDUs into the first RLC PDU.

The LTE and NR protocol stacks are similar, but with some noticeable differences. On top of PDCP, there is for NR a Service Data Application Protocol (SDAP) which is responsible for mapping Quality of Service (QoS) bearers to radio bearers. The SDAP contains an optional header including a 6 bit Quality Flow Indicator (QFI). The PDCP layer for NR has integrity protection for DRBs, which is not supported in LTE. For reduced latency, NR RLC does not support in-sequence delivery and concatenation as done in LTE. The NR PHY layer CRC is 24 or 16 bits depending on the size of the transport block.

There currently exist certain challenge(s). For devices focused on providing small data transmissions, the overheads mentioned above may pose a significant overhead compared to the actual useful data being transmitted.

Summary

Systems and methods are disclosed herein that relate to a reduced overhead radio bearer. In one embodiment, a method performed by a first radio node for data transmission in a radio access network of a cellular communications system comprises transmitting a reduced overhead radio bearer to a second radio node, where the reduced overhead radio bearer is a radio bearer in which: (a) a physical (PHY) layer cyclic redundancy check (CRC) is excluded, (b) all or part of a Medium Access Control (MAC) header is excluded, (c) all or part of a Radio Link Control (RLC) header is excluded, (d) all or part of a Packet Data Convergence Protocol (PDCP) header is excluded, (e) all or part of a Service Data Application Protocol (SDAP) header is excluded, or (f) a combination of any two or more of (a) - (e). In this manner, the radio bearer overhead can be reduced for small (e.g., single block, e.g., single transport block or single PDCP/RLC/MAC PDU) data transmissions.

In one embodiment, the reduced overhead radio bearer is a radio bearer in which: (i) all or part of RLC header is excluded from the radio bearer, and the all or part of the RLC header is static for: a respective connection between the first radio node and the second radio node, the first radio node, or the second radio node; (ii) all or part of a PDCP header is excluded from the radio bearer, and the all or part of the PDCP header is static for: a respective connection between the first radio node and the second radio node, the first radio node, or the second radio node; (iii) all or part of a SDAP header is excluded from the radio bearer, and the all or part of the SDAP header is static for: a respective connection between the first radio node and the second radio node, the first radio node, or the second radio node; or (iv) a combination of any two or more of (i) - (iii).

In one embodiment, the PHY layer CRC is excluded from the reduced overhead radio bearer, and the reduced overhead radio bearer supports error correction and integrity protection at a higher layer.

In one embodiment, the PHY layer CRC is excluded from the reduced overhead radio bearer, and the reduced overhead radio bearer supports integrity protection, including bit error detection, at a PDCP layer.

In one embodiment, a logical channel identity (LCID) is excluded from the reduced overhead radio bearer at the MAC layer, where the LCID is a static LCID. In one embodiment, the LCID excluded from the reduced overhead radio bearer at the MAC layer is a static LCID used for a particular transmission type of the reduced overhead radio bearer. In one embodiment, different static LCIDs are predefined or preconfigured for different transmission types (e.g., at both the first radio node and the second radio node).

In one embodiment, a static transport block size is used for the reduced overhead radio bearer, and either or both of a MAC length indicator and a length format indicator are excluded from the reduced overhead radio bearer at the MAC layer. In one embodiment, the either or both of the MAC length indicator and the length format indicator is/are predefined or preconfigured.

In one embodiment, the reduced overhead radio bearer comprises a single RLC Acknowledgment Mode (AM) data Protocol Data Unit (PDU) transmission or a single RLC Unacknowledged Mode (UM) data PDU transmission, and a RLC Sequence Number (SN) is excluded from the reduced overhead radio bearer at the RLC layer. In one embodiment, an implicit RLC SN is associated to the signal RLC AM data PDU transmission or the single RLC UM data PDU transmission.

In one embodiment, RLC AM functionality, concatenation at the RLC layer, segmentation at the RLC layer, reassembly at the RLC layer, reordering at the RLC layer, and/or duplicate detection and discard functionality at the RLC layer is/are disabled for the reduced overhead radio bearer, and associated information is excluded from the reduced overhead radio bearer at the RLC layer.

In one embodiment, RLC AM functionality, concatenation at the RLC layer, segmentation at the RLC layer, reassembly at the RLC layer, reordering at the RLC layer, and duplicate detection and discard functionality at the RLC layer are disabled for the reduced overhead radio bearer, and associated information is excluded from the reduced overhead radio bearer at the RLC layer. In one embodiment, the RLC AM header of the reduced overhead radio bearer comprises only a first data/control bit that indicates whether an associated PDU is a control or data PDU and a polling bit that indicates whether a RLC status report is requested.

In one embodiment, the reduced overhead radio bearer comprises a single PDCP PDU transmission, and a PDCP SN is excluded from the reduced overhead radio bearer at the PDCP layer. In one embodiment, the reduced overhead radio bearer is associated to an implicit PDCP SN.

In one embodiment, a fixed Quality of Service (QoS) to radio bearer mapping applicable to the reduced overhead radio bearer is configured and stored at both the first radio node and the second radio node, and all or a part of the SDAP header is excluded from the reduced overhead radio bearer.

In one embodiment, a QoS Flow Indicator, QFI, applicable to the reduced overhead radio bearer is configured and stored at both the first radio node and the second radio node, and the QFI is excluded from the reduced overhead radio bearer at the SDAP layer.

In one embodiment, the method further comprises configuring or receiving a configuration of the reduced overhead radio bearer.

In one embodiment, the first radio node is a wireless communication device, and the method further comprising requesting permission to use a reduced overhead radio bearer. In one embodiment, requesting permission to use a reduced overhead radio bearer comprises requesting permission to use a reduced overhead radio bearer during a random access procedure or during a connection establishment procedure. In another embodiment, requesting permission to use a reduced overhead radio bearer comprises transmitting a random access preamble from a dedicated set of random access preambles for requesting permission to use a reduced overhead radio bearer. In another embodiment, requesting permission to use a reduced overhead radio bearer comprises, during a random access procedure, transmitting a Msg3 comprising an indication of a request to use a reduced overhead radio bearer.

In one embodiment, use of a reduced overhead radio bearer is configured by the radio access network for mobile terminated data transfers. In one embodiment, the first radio node is a radio access node, and the method further comprising transmitting, to the second radio node, an indication that a reduced overhead radio bearer is to be used, during a connection establishment procedure or in an associated uplink grant.

In one embodiment, either the first radio node or the second radio node is a User Equipment (UE), and use of a reduced overhead radio bearer is stored as part of a UE context of the UE.

In one embodiment, use of the reduced overhead radio bearer is indicated by inclusion of a reserved LCID or enhanced LCID (eLCID) value in the reduced overhead radio bearer at the MAC layer.

In one embodiment, use of the reduced overhead radio bearer is indicated by inclusion of a reserved LCID or eLCID value in the reduced overhead radio bearer at the MAC layer, the reserved LCID or eLCID value being one of two or more reserved LCID or eLCID values mapped to different fixed headers or configurations.

In one embodiment, one or more restrictions associated with use of a reduced overhead radio bearer are predefined or preconfigured, and the reduced overhead radio bearer is transmitted in accordance with the one or more restrictions.

In one embodiment, whether a PHY CRC is included in the reduced overhead radio bearer and/or a size of the PHY CRC for the reduced overhead radio bearer is dynamically controlled.

Corresponding embodiments of a first radio node are also disclosed. In one embodiment, a first radio node for data transmission in a radio access network of a cellular communications system is adapted to transmit a reduced overhead radio bearer to a second radio node, the reduced overhead radio bearer being a radio bearer in which: (a) a PHY layer CRC is excluded, (b) all or part of a MAC header is excluded, (c) all or part of a RLC header is excluded, (d) all or part of a PDCP header is excluded, (e) all or part of a SDAP header is excluded, (f) a combination of any two or more of (a) - (e).

In one embodiment, a first radio node for data transmission in a radio access network of a cellular communications system comprising processing circuitry configured to cause the first radio node to transmit a reduced overhead radio bearer to a second radio node, the reduced overhead radio bearer being a radio bearer in which: (a) a PHY layer CRC is excluded, (b) all or part of a MAC header is excluded, (c) all or part of a RLC header is excluded, (d) all or part of a PDCP header is excluded, (e) all or part of a SDAP header is excluded, (f) a combination of any two or more of (a) - (e).

Embodiments of a method performed by a second radio node are also disclosed herein. In one embodiment, a method performed by a second radio node for data reception in a radio access network of a cellular communications system comprises receiving a reduced overhead radio bearer from a first radio node (300), the reduced overhead radio bearer being a radio bearer in which: (a) a PHY layer CRC is excluded, (b) all or part of a MAC header is excluded, (c) all or part of a RLC header is excluded, (d) all or part of a PDCP header is excluded, (e) all or part of a SDAP header is excluded, (f) a combination of any two or more of (a) - (e).

In one embodiment, the reduced overhead radio bearer is a radio bearer in which: (i) all or part of RLC header is excluded from the radio bearer, and the all or part of the RLC header is static for: a respective connection between the first radio node and the second radio node, the first radio node, or the second radio node; (ii) all or part of a PDCP header is excluded from the radio bearer, and the all or part of the PDCP header is static for: a respective connection between the first radio node and the second radio node, the first radio node, or the second radio node; (iii) all or part of a SDAP header is excluded from the radio bearer, and the all or part of the SDAP header is static for: a respective connection between the first radio node and the second radio node, the first radio node, or the second radio node; or (iv) a combination of any two or more of (i) - (iii). In one embodiment, the PHY layer CRC is excluded from the reduced overhead radio bearer, and the reduced overhead radio bearer supports error correction and integrity protection at a higher layer.

In one embodiment, a LCID is excluded from the reduced overhead radio bearer at the MAC layer, where the LCID is a static LCID. In one embodiment, the LCID excluded from the reduced overhead radio bearer at the MAC layer is a static LCID used for a particular transmission type of the reduced overhead radio bearer. In one embodiment, different static LCIDs are predefined or preconfigured for different transmission types (e.g., at both the first radio node and the second radio node).

In one embodiment, the reduced overhead radio bearer comprises a single RLC AM PDU transmission or a single RLC UM data PDU transmission, and a RLC SN is excluded from the reduced overhead radio bearer at the RLC layer. In one embodiment, an implicit RLC SN is associated to the signal RLC AM data PDU transmission or the single RLC UM data PDU transmission.

In one embodiment, a fixed QoS to radio bearer mapping applicable to the reduced overhead radio bearer is configured and stored at both the first radio node and the second radio node, and all or a part of the SDAP header is excluded from the reduced overhead radio bearer.

In one embodiment, the first radio node is a wireless communication device, and the method further comprising receiving a request from the first radio node for permission to use a reduced overhead radio bearer, and granting the first radio node permission to use a reduced overhead radio bearer. In one embodiment, receiving the request for permission to use a reduced overhead radio bearer comprises receiving the request for permission to use a reduced overhead radio bearer during a random access procedure or during a connection establishment procedure. In another embodiment, receiving the request for permission to use a reduced overhead radio bearer comprises receiving a random access preamble from a dedicated set of random access preambles for requesting permission to use a reduced overhead radio bearer. In another embodiment, receiving the request for permission to use a reduced overhead radio bearer comprises, during a random access procedure, receiving a Msg3 comprising an indication of a request to use a reduced overhead radio bearer.

In one embodiment, use of a reduced overhead radio bearer is configured by the radio access network for mobile terminated data transfers.

In one embodiment, either the first radio node or the second radio node is a UE, and use of a reduced overhead radio bearer is stored as part of a UE context of the UE. In one embodiment, use of the reduced overhead radio bearer is indicated by inclusion of a reserved LCID or eLCID value in the reduced overhead radio bearer the MAC layer.

In one embodiment, use of the reduced overhead radio bearer is indicated by inclusion of a reserved LCID or eLCID value in the reduced overhead radio bearer the MAC layer, the reserved LCID or eLCID value being one of two or more reserved LCID or eLCID values mapped to different fixed headers or configurations.

In one embodiment, a PHY CRC is included in the reduced overhead radio bearer and/or a size of the PHY CRC for the reduced overhead radio bearer is dynamically controlled.

Corresponding embodiments of a second radio node are also disclosed. In one embodiment, a second radio node for data reception in a radio access network of a cellular communications system is adapted to receive a reduced overhead radio bearer from a first radio node, the reduced overhead radio bearer being a radio bearer in which: (a) a PHY layer CRC is excluded, (b) all or part of a MAC header is excluded, (c) all or part of a RLC header is excluded, (d) all or part of a PDCP header is excluded, (e) all or part of a SDAP header is excluded, (f) a combination of any two or more of (a) - (e).

In one embodiment, a second radio node for data reception in a radio access network of a cellular communications system comprising processing circuitry configured to cause the second radio node to receive a reduced overhead radio bearer from a first radio node, the reduced overhead radio bearer being a radio bearer in which: (a) a PHY layer CRC is excluded, (b) all or part of a MAC header is excluded, (c) all or part of a RLC header is excluded, (d) all or part of a PDCP header is excluded, (e) all or part of a SDAP header is excluded, (f) a combination of any two or more of (a) - (e).

The accompanying drawing figures incorporated in and forming a part of this specification illustrate several aspects of the disclosure, and together with the description serve to explain the principles of the disclosure. Figure 1 illustrates the Long Term Evolution (LTE) user plane protocol stack for the transmission of a Data Radio Bearer (DRB) with Radio Link Control (RLC) configured to operate in RLC Acknowledgement Mode (AM);

Figure 2 illustrates one example of a cellular communications system in which embodiments of the present disclosure may be implemented;

Figure 3 illustrates the operation of a transmitting radio node and a receiving radio node to transmit and receive a reduced overhead radio bearer (RORB) in accordance with embodiments of the present disclosure;

Figure 4 illustrates a legacy data transmission with full header in part (a) of the figure and a data transmission (on a RORB) having no or reduced header overhead by using stored headers or configuration in accordance with some embodiments of the present disclosure in part (b) of the figure;

Figures 5, 6, and 7 are schematic block diagrams of example embodiments of a radio access node;

Figures 8 and 9 are schematic block diagrams of example embodiments of a wireless communication device or User Equipment (UE);

Figure 10 illustrates an example embodiment of a communication system in which embodiments of the present disclosure may be implemented;

Figure 11 illustrates example embodiments of the host computer, base station, and UE of Figure 10; and

Figures 12, 13, 14, and 15 are flow charts that illustrate example embodiments of methods implemented in a communication system such as that of Figure 10.

The embodiments set forth below represent information to enable those skilled in the art to practice the embodiments and illustrate the best mode of practicing the embodiments. Upon reading the following description in light of the accompanying drawing figures, those skilled in the art will understand the concepts of the disclosure and will recognize applications of these concepts not particularly addressed herein. It should be understood that these concepts and applications fall within the scope of the disclosure.

Some of the embodiments contemplated herein will now be described more fully with reference to the accompanying drawings. Other embodiments, however, are contained within the scope of the subject matter disclosed herein, the disclosed subject matter should not be construed as limited to only the embodiments set forth herein; rather, these embodiments are provided by way of example to convey the scope of the subject matter to those skilled in the art.

Generally, all terms used herein are to be interpreted according to their ordinary meaning in the relevant technical field, unless a different meaning is clearly given and/or is implied from the context in which it is used. All references to a/an/the element, apparatus, component, means, step, etc. are to be interpreted openly as referring to at least one instance of the element, apparatus, component, means, step, etc., unless explicitly stated otherwise. The steps of any methods disclosed herein do not have to be performed in the exact order disclosed, unless a step is explicitly described as following or preceding another step and/or where it is implicit that a step must follow or precede another step. Any feature of any of the embodiments disclosed herein may be applied to any other embodiment, wherever appropriate. Likewise, any advantage of any of the embodiments may apply to any other embodiments, and vice versa. Other objectives, features, and advantages of the enclosed embodiments will be apparent from the following description.

Radio Node: As used herein, a "radio node" is either a radio access node or a wireless communication device.

Radio Access Node: As used herein, a "radio access node" or "radio network node" or "radio access network node" is any node in a Radio Access Network (RAN) of a cellular communications network that operates to wirelessly transmit and/or receive signals. Some examples of a radio access node include, but are not limited to, a base station (e.g., a New Radio (NR) base station (gNB) in a Third Generation Partnership Project (3GPP) Fifth Generation (5G) NR network or an enhanced or evolved Node B (eNB) in a 3GPP Long Term Evolution (LTE) network), a high-power or macro base station, a low-power base station (e.g., a micro base station, a pico base station, a home eNB, or the like), a relay node, a network node that implements part of the functionality of a base station (e.g., a network node that implements a gNB Central Unit (gNB-CU) or a network node that implements a gNB Distributed Unit (gNB-DU)) or a network node that implements part of the functionality of some other type of radio access node. Core Network Node: As used herein, a "core network node" is any type of node in a core network or any node that implements a core network function. Some examples of a core network node include, e.g., a Mobility Management Entity (MME), a Packet Data Network Gateway (P-GW), a Service Capability Exposure Function (SCEF), a Flome Subscriber Server (HSS), or the like. Some other examples of a core network node include a node implementing an Access and Mobility Management Function (AMF), a User Plane Function (UPF), a Session Management Function (SMF), an Authentication Server Function (AUSF), a Network Slice Selection Function (NSSF), a Network Exposure Function (NEF), a Network Function (NF) Repository Function (NRF), a Policy Control Function (PCF), a Unified Data Management (UDM), or the like.

Communication Device: As used herein, a "communication device" is any type of device that has access to an access network. Some examples of a communication device include, but are not limited to: mobile phone, smart phone, sensor device, meter, vehicle, household appliance, medical appliance, media player, camera, or any type of consumer electronic, for instance, but not limited to, a television, radio, lighting arrangement, tablet computer, laptop, or Personal Computer (PC). The communication device may be a portable, hand-held, computer-comprised, or vehicle- mounted mobile device, enabled to communicate voice and/or data via a wireless or wireline connection.

Wireless Communication Device: One type of communication device is a wireless communication device, which may be any type of wireless device that has access to (i.e., is served by) a wireless network (e.g., a cellular network). Some examples of a wireless communication device include, but are not limited to: a User Equipment device (UE) in a 3GPP network, a Machine Type Communication (MTC) device, and an Internet of Things (IoT) device. Such wireless communication devices may be, or may be integrated into, a mobile phone, smart phone, sensor device, meter, vehicle, household appliance, medical appliance, media player, camera, or any type of consumer electronic, for instance, but not limited to, a television, radio, lighting arrangement, tablet computer, laptop, or PC. The wireless communication device may be a portable, hand-held, computer-comprised, or vehicle-mounted mobile device, enabled to communicate voice and/or data via a wireless connection.

Network Node: As used herein, a "network node" is any node that is either part of the RAN or the core network of a cellular communications network/ system. Note that the description given herein focuses on a 3GPP cellular communications system and, as such, 3GPP terminology or terminology similar to 3GPP terminology is oftentimes used. However, the concepts disclosed herein are not limited to a 3GPP system.

Note that, in the description herein, reference may be made to the term "cell"; however, particularly with respect to 5G NR concepts, beams may be used instead of cells and, as such, it is important to note that the concepts described herein are equally applicable to both cells and beams.

As discussed above, there currently exist certain challenge(s) with respect to small data transmissions, e.g., in LTE and NR. For devices focused on providing small data transmissions, the overhead described above with respect to the LTE and NR protocol stacks may pose a significant overhead compared to the actual useful data being transmitted.

Certain aspects of the present disclosure and their embodiments may provide solutions to the aforementioned or other challenges. Systems and methods are disclosed herein for introducing a Reduced Overhead Radio Bearer (RORB) which is optimized for delivery of a small data packet and for which the radio bearer overhead (e.g., header overhead) is reduced, e.g., Packet Data Convergence Protocol (PDCP) Sequence Number (SN) and Radio Link Control (RLC) SN are excluded from the PDCP and RLC headers.

Certain embodiments may provide one or more of the following technical advantage(s). Embodiments disclosed herein reduce the radio bearer overhead for small (e.g., single block, e.g., single transport block or single PDCP/RLC/MAC PDU) data transmissions. In some embodiments, compared to e.g., RLC TM mode, the RORB disclosed herein also supports RLC ARQ.

Figure 2 illustrates one example of a cellular communications system 200 in which embodiments of the present disclosure may be implemented. In the embodiments described herein, the cellular communications system 200 is a 5G System (5GS) including a Next Generation RAN (NG-RAN) and a 5G Core (5GC). In this example, the RAN includes base stations 202-1 and 202-2, which in the 5GS include NR base stations (gNBs) and optionally next generation eNBs (ng-eNBs) (i.e., LTE RAN nodes connected to the 5GC), controlling corresponding (macro) cells 204-1 and 204-2. The base stations 202-1 and 202-2 are generally referred to herein collectively as base stations 202 and individually as base station 202. Likewise, the (macro) cells 204-1 and 204-2 are generally referred to herein collectively as (macro) cells 204 and individually as (macro) cell 204. The RAN may also include a number of low power nodes 206-1 through 206-4 controlling corresponding small cells 208-1 through 208-4. The low power nodes 206-1 through 206-4 can be small base stations (such as pico or femto base stations) or Remote Radio Heads (RRHs), or the like. Notably, while not illustrated, one or more of the small cells 208-1 through 208-4 may alternatively be provided by the base stations 202. The low power nodes 206-1 through 206-4 are generally referred to herein collectively as low power nodes 206 and individually as low power node 206. Likewise, the small cells 208-1 through 208-4 are generally referred to herein collectively as small cells 208 and individually as small cell 208. The cellular communications system 200 also includes a core network 210, which in the 5GS is referred to as the 5G Core (5GC). The base stations 202 (and optionally the low power nodes 206) are connected to the core network 210.

The base stations 202 and the low power nodes 206 provide service to wireless communication devices 212-1 through 212-5 in the corresponding cells 204 and 208. The wireless communication devices 212-1 through 212-5 are generally referred to herein collectively as wireless communication devices 212 and individually as wireless communication device 212. In the following description, the wireless communication devices 212 are oftentimes UEs and as such sometimes referred to herein as UEs 212, but the present disclosure is not limited thereto.

Now, a description of details of embodiments of the present disclosure will be provided. In this regard, Figure 3 illustrates the operation of a transmitting radio node 300 and a receiving radio node 302 to transmit and receive a reduced overhead radio bearer (RORB) in accordance with embodiments of the present disclosure. Optional steps are represented by dashed lines/boxes. Note that, in one embodiment, the transmitting radio node 300 is a radio access node (e.g., a base station 202 or low power node 206) and the receiving radio node 302 is a UE 212. In another embodiment, the transmitting radio node 300 is a UE 212 and the receiving radio node 302 is a radio access node (e.g., a base station 202 or low power node 206).

As illustrated, optionally, a RORB is configured (step 304). While details of the configuration of the RORB are provided below, in one embodiment, the receiving radio node 302 is a UE 212, and the UE 212 requests permission to use a RORB, e.g., during a random access procedure or during a connection (re-)establishment procedure (step 304A). The transmitting radio node 300 (i.e., a radio access node such as, e.g., a base station 202 or low power node 206 in this example) grants the request to use the RORB (step 304B). In another embodiment, the use of a RORB is configured for mobile terminated data transfers. In some embodiments, the physical layer (PHY) Cyclic Redundancy Check (CRC) is excluded in the RORB. In this case, the exclusion of the PHY CRC may be configured (e.g., activated) during step 304 (step 304C). In some embodiments, the RORB is a radio bearer in which parts or all of the Medium Access Control (MAC) header and/or the RLC header and/or the PDCP header, and/or the Service Data Application Protocol (SDAP) header are excluded. In this case, the excluded header field(s) are, in some embodiments, configured at both the transmitting radio node 300 and the receiving radio node 302 during the configuration of step 304 (step 304D), as described below in detail. Note that, in some cases, the entire header is excluded. However, in other cases, a header is not excluded, but one or more fields within the header are excluded.

The transmitting radio node 300 transmits, and the receiving radio node 302 receives, the RORB (step 306). Transmission of the RORB by the transmitting radio node 300 and reception (e.g., decoding) of the RORB by the receiving radio node 302 is performed in accordance with knowledge of the exclusion of the PHY CRC and/or the exclusion of parts or all of the MAC header and/or the RLC header and/or the PDCP header, and/or the SDAP header, from the RORB.

While the details are provided below, some example embodiments of the present disclosure are as follows. In one embodiment, the RORB is a radio bearer in which:

(a) a PHY layer CRC is excluded,

(b) all or part of a MAC header is excluded,

(c) all or part of a RLC header is excluded,

(d) all or part of a PDCP header is excluded,

(e) all or part of a SDAP header is excluded, or

(f) a combination of any two or more of (a) - (e).

In one embodiment, the RORB is a radio bearer in which:

(i) all or part of RLC header is excluded from the radio bearer, and the all or part of the RLC header is static for: a respective connection, the first radio node 300, or the second radio node 302 (e.g., static for a respective connection including the first radio node 300 and the second radio node 302),

(ii) all or part of a PDCP header is excluded from the radio bearer, and the all or part of the PDCP header is static for: a respective connection, the first radio node 300, or the second radio node 302 (e.g., static for a respective connection including the first radio node 300 and the second radio node 302),

(iii) all or part of a SDAP header is excluded from the radio bearer, and the all or part of the SDAP header is static for: a respective connection, the first radio node 300, or the second radio node 302 (e.g., static for a respective connection including the first radio node 300 and the second radio node 302), or

(iv) a combination of any two or more of (i) - (iii).

In one embodiment, the PHY layer CRC is excluded from the RORB, and the RORB support integrity protection at a layer other than the PHY layer.

In one embodiment, the PHY layer CRC is excluded from the RORB, and the RORB supports integrity protection at a PDCP layer.

In one embodiment, a logical channel identity (LCID) is excluded from the RORB at the MAC layer, the LCID being a static LCID. In one embodiment, the static LCID is a static LCID used for a particular transmission type of the RORB. In one embodiment, different static LCIDs are predefined or preconfigured for different transmission types (e.g., at both the first radio node 300 and the second radio node 302).

In one embodiment, a static transport block size is used for the RORB, and a MAC length indicator and/or a length format indicator are excluded from the RORB at the MAC layer. In one embodiment, the MAC length indicator and/or the length format indicator are predefined or preconfigured (e.g., at both the first radio node 300 and the second radio node 302).

In one embodiment, the RORB comprises a single RLC Acknowledgment Mode (AM) data Protocol Data Unit (PDU) transmission or a single RLC Unacknowledged Mode (UM) data PDU transmission, and a RLC Sequence Number (SN) is excluded from the RORB at the RLC layer.

In one embodiment, RLC AM functionality, concatenation at the RLC layer, segmentation at the RLC layer, reassembly at the RLC layer, reordering at the RLC layer, and/or duplicate detection and discard functionality at the RLC layer is/are disabled for the RORB, and associated information is excluded from the RORB at the RLC layer.

In one embodiment, RLC AM functionality, concatenation at the RLC layer, segmentation at the RLC layer, reassembly at the RLC layer, reordering at the RLC layer, and duplicate detection and discard functionality at the RLC layer are disabled for the RORB, and associated information is excluded from the RORB at the RLC layer. In one embodiment, the RLC AM header of the RORB comprises only a first data/control bit that indicates whether an associated PDU is a control or data PDU and a polling bit that indicates whether a RLC status report is requested.

In one embodiment, the RORB comprises a single PDCP PDU transmission, and a PDCP SN is excluded from the RORB at the PDCP layer.

In one embodiment, a fixed Quality of Service (QoS) to radio bearer mapping applicable to the RORB is configured and stored at both the first radio node 302 and the second radio node 304, and all or a part of the SDAP header is excluded from the RORB.

In one embodiment, a QoS Flow Indicator (QFI) applicable to the RORB is configured and stored at both the first radio node 302 and the second radio node 304, and the QFI is excluded from the RORB at the SDAP layer.

In one embodiment, the first radio node 300 is a wireless communication device 212, and the wireless communication device 212 requests permission to use a RORB (step 304A). In one embodiment, the wireless communications device 212 requests permission to use a RORB during a random access procedure or during a connection establishment procedure. In another embodiment, the wireless communications device 212 requests permission to use a RORB by transmitting a random access preamble from a dedicated set of random access preambles for requesting permission to use a RORB.

In another embodiment, the wireless communications device 212 requests permission to use a RORB by, during a random access procedure, transmitting a Msg3 comprising an indication of a request to use a RORB.

In one embodiment, use of a RORB is configured by the radio access network for mobile terminated data transfers. In one embodiment, the first radio node 300 is a radio access node, and the first radio node 300 transmits, to the second radio node, an indication that a RORB is to be used, during a connection establishment procedure (e.g., in a random access response or in a RRC connection setup message) or in an associated uplink grant.

In one embodiment, either the first radio node 300 or the second radio node 302 is a UE 212, and use of a RORB is stored as part of a UE context of the UE 212.

In one embodiment, use of the RORB is indicated by inclusion of a reserved LCID or eLCID value in the RORB the MAC layer.

In one embodiment, use of the RORB is indicated by inclusion of a reserved LCID or eLCID value in the RORB the MAC layer, the reserved LCID or eLCID value being one of two or more reserved LCID or eLCID values mapped to different fixed headers or configurations (e.g., stored in an associated UE context).

In one embodiment, one or more restrictions associated with use of a RORB (e.g., for uplink transmission) are predefined or preconfigured, and the RORB is transmitted in accordance with the one or more restrictions.

In one embodiment, whether a PHY CRC is included in the RORB and/or a size of the PHY CRC for the RORB is dynamically controlled (e.g., via DCI or random access response).

Figure 4 illustrates a legacy data transmission with full header in part (a) of the figure and a data transmission (on a RORB) having no or reduced header overhead by using stored headers or configuration in accordance with some embodiments of the present disclosure in part (b) of the figure.

Now, some example embodiments of different aspects of the procedure of Figure 3 will be described in detail.

General Methods for Reducing Radio Bearer Overhead

In one embodiment, parts or all of, MAC and/or RLC and/or PDCP and/or SDAP headers are configured to be static for a connection or a UE (possibly differently for SRBs and DRBs). The configuration may be performed, e.g., during steps 304 of Figure 3. After the configuration, only headers with reduced content, or no headers, are used in transmission between a UE and the network (e.g., between two radio nodes, where the node that is transmitting is the transmitting radio node 300 and the node that is receiving is the receiving radio node 302). Thus, in step 306 of Figure 3, the receiving radio node 302 receives (e.g., decodes) the RORB transmission based on the static MAC and/or RLC and/or PDCP and/or SDAP header(s) or the static part(s) of the MAC and/or RLC and/or PDCP and/or SDAP header(s), where the static header(s) or static header part(s) may be configured, e.g., during step 304 and therefore known to the receiving radio node 302.

PHY Methods for Reducing Radio Bearer Overhead As discussed above, in some embodiments, the RORB excludes the PHY CRC. In this regard, in one embodiment, for a DRB supporting integrity protection, the PHY CRC is not calculated and appended to the transport block (TB). In other words, the RORB transmitted from the transmitting radio node 300 to the receiving radio node 302 includes a DRB that supports integrity protection, and the PHY CRC is not calculated and appended to the TB (i.e., the PHY CRC is excluded from the RORB). Bit errors introduced during a transmission are consequently not detected in the PHY-layer at the receiving radio node 302. The PDCP MAC-I check at the receiving radio node 302 is instead expected to detect bit errors, and trigger retransmission of a PDCP packet when needed.

MAC Methods for Reducing Radio Bearer Overhead As discussed above, in some embodiments, the RORB transmitted from the transmitting radio node 300 to the receiving radio node 302 excludes all or part of the MAC header. In this regard, in one embodiment for MAC, a static Logical Channel Identity (LCID) is used for a determined transmission type. Since the 6 bit LCID is static, in one embodiment, the LCID is eliminated from the MAC sub header. Instead, the LCID is determined based on predefined or preconfigured information (e.g., information in a technical specification (e.g., a 3GPP TS)) for a respective transmission type (i.e., the transmission type of the corresponding transmission). Alternatively, the LCID is determined based on an initial configuration that is stored in the transmitting and receiving nodes. This initial configuration may be performed, e.g., during step 304 of Figure 3. Thus, in step 306 of Figure 3, the receiving radio node 302 receives (e.g., decodes) the RORB transmission based on knowledge of the excluded MAC header or excluded part(s) of the MAC header. The excluded MAC header or excluded part(s) of the MAC header (e.g., LCID) may be determined by the receiving radio node 302 based on predefined or preconfigured information or determined based on an initial configuration that is stored in the transmitting and receiving radio nodes 300 and 302. In another embodiment, a static transport block size is used for a determined transmission. Since the MAC length indicator and length indicator format indicator are static, the MAC length indicator and/or the length format indicator is/are eliminated from the MAC sub header of the RORB. Instead, the MAC length and/or MAC length indicator is/are determined based on, e.g., an initial configuration that is stored in the transmitting and receiving radio nodes 300 and 302 (e.g., configured and stored in step 304 of Figure 3). Thus, in step 306 of Figure 3, the receiving radio node 302 receives (e.g., decodes) the RORB transmission based on the static MAC length indicator and/or the static length format indicator, which is/are not included in the MAC sub header of the RORB. This static information may be configured, e.g., during step 304 and therefore known to the receiving radio node 302.

These methods would e.g., be applicable to a pre-configured periodic transmission opportunity supporting the transmission of a single uplink data block per transmission opportunity using a Dedicated Traffic Channel (DTCFI). A technical specification can determine that e.g., a DTCFI associated with PUSCFI transmissions from Radio Resource Control (RRC) inactive mode is using a fixed LCID. Optionally the LCID can be preconfigured for mentioned DTCFI using one of the RRC, MAC, or PFIY protocol layer.

These methods can also be generalized to support a sequence of transmissions using e.g., a sequence of configured LCIDs.

RLC Methods for Reducing Radio Bearer Overhead

As discussed above, in some embodiments, the RORB transmitted from the transmitting radio node 300 to the receiving radio node 302 excludes all or part of the RLC header. In one embodiment, for a DRB comprising a single RLC AM or UM data PDU transmission, the RLC SN is not included in the RLC data PDU. The DRB transmission is associated with an implicit RLC SN = 0. In other words, the RORB transmitted from the transmitting radio node 300 to the receiving radio node 302 includes a DRB comprising a single RLC AM or UM data PDU transmission, and the RLC SN is not included in the RLC data PDU. Thus, in step 306 of Figure 3, the receiving radio node 302 receives (e.g., decodes) the RORB transmission based on the known excluded part of the RLC header such as, e.g., an implicit SN that is not included in the RLC header. In another embodiment applicable to RLC AM, concatenation, segmentation, reassembly, reordering, and duplicate detection and discard functions, or a subset of these functions, are disabled for a DRB. Information associated with the disabled functionality is excluded from the RLC header (i.e., the data PDU header). If all of the aforementioned functionalities are disabled, the data PDU header can consequently be reduced to only comprise two signaling bits, namely:

- a first data/control (D/C) bit indicating if the PDU is a control or data PDU, and

- a second polling (P) bit indicating if a RLC status report is requested.

PDCP Methods for Reducing Radio Bearer Overhead As discussed above, in some embodiments, the RORB transmitted from the transmitting radio node 300 to the receiving radio node 302 excludes all or part of the PDCP header. In this regard, for a DRB comprising a single PDCP PDU transmission, the PDCP SN is not included in the PDCP PDU. The DRB transmission is associated with an implicit PDCP SN = 0. Thus, in step 306 of Figure 3, the receiving radio node 302 receives (e.g., decodes) the RORB transmission based on the known excluded part of the PDCP header such as, e.g., an implicit PDCP SN that is not included in the PDCP header.

In one embodiment, SN is information that is kept in the protocol headers, but only either in RLC or PDCP layer and not in both. This makes it possible e.g., to retain some of the functionality, like duplication detection and discard (in either RLC or PDCP layer).

SDAP Methods for Reducing Radio Bearer Overhead As discussed above, in some embodiments, the RORB transmitted from the transmitting radio node 300 to the receiving radio node 302 excludes all or part of the SDAP header. In this regard, for SDAP, a fixed Quality of Service (QoS) to radio bearer mapping can be configured and stored and applied until later reconfiguration. For example, the SDAP header including the 6 bit QoS Flow Indicator (QFI) can be stored at both ends (e.g., stored during the configuration of step 304 of Figure 3) but not transmitted explicitly within the RORB. The stored SDAP header is assumed to be applicable for any data transmitted until reconfiguration including storing of another SDAP header. This is similar to header compression but not requiring any header to be included at all since there is only one candidate SDAP header at a time. The difference to turning off SDAP to remove the SDAP headers is that SDAP functionality is still used, but it is constant over time until the stored SDAP header is reconfigured.

Methods for Configuring a RORB

In one embodiment, the transmitting radio node 300 is a UE 212, and the UE 212 requests permission to use a RORB during the random access procedure, or the connection establishment procedure (see, e.g., step 304A of Figure 3). A dedicated set of Physical Random Access Channel (PRACH) preambles, or a signaling indication in Msg3 (e.g., RRCConnectionSetupRequest ) can be used to convey this request. After granted permission to make use of a RORB (see, e.g., step 304B of Figure 3), the UE 212 will, based on the grant, reduce at least one of PHY, MAC, RLC, PDCP, and SDAP overheads as described in the previous sections.

In one embodiment, a network node configures the use of a RORB for mobile terminated data transfers (see, e.g., step 304C of Figure 3). The configuration can e.g., be sent as an indication during the connection establishment procedure e.g., in the random access response (RAR), or in RRCConnectionSetup in Msg4. The configuration can alternatively be sent as part of a configured grant. After being configured to receive transmission over a RORB, the UE 212 will expect the base station 202 to reduce at least one of PHY, MAC, RLC, PDCP, and SDAP overheads as described in previous sections.

In another embodiment, a RORB configuration is associated with a DRB (or SRB) and stored with the UE context when the UE 212 moves to the RRC_INACTIVE state. Later upon RRC bearer resumption, when the UE 212 is moved back to RRC_CON NECTED, the RORB configuration is also resumed.

In another embodiment, reserved LCID or enhanced LCID (eLCID) values (see bits 35-39 in Table 6.2.1-2 in TS 38.321 vl6.0.0) are used to point out that a static and previously configured header is being used (or part of it is being used). In other words, a reserved LCID value or eLCID value is included in the MAC header of the RORB, and the receiving node sees this reserved value and, based on it, will know that a certain header(s) or certain header field(s) are excluded from the RORB (and that some previously used or predefined/preconfigured header(s) or header field(s) are used instead). In one embodiment, several fixed headers/configurations could be stored and differentiated by using more than one of the reserved values. Further, the set of reserved LCID values is limited and therefore, in one embodiment, a definition of the use of the reserved values is made part of a dedicated UE configuration and stored as part of the UE context. In this way, the use of the reserved values would not need to be hard-coded in a specification and still free to use for any other feature.

In another embodiment, some LCID or eLCID values are reserved to indicate specific configurations of the RORB. These configurations can be either defined in the specification or some value can be reserved for dynamic configuration, where details of how to reduce PHY, MAC, RLC, PDCP, and SDAP headers are signaled either in a grant or configured with RRC protocol. In an alternative, a specific LCID or eLCID value indicates use of "small data transmission" feature and RORB.

In another embodiment, a network node signals a set of restrictions associated with the use of a RORB for uplink transmissions. The network node may choose to permit uplink RORB transmissions for PDCP and/or RLC SDUs of size less than a signaled threshold.

In another embodiment, the application or size of the PHY CRC is controlled dynamically through the downlink control information (DCI) or random access response (RAR). This configuration can be made, e.g., during step 304 of Figure 3. In one embodiment, one bit in the DCI or RAR can control whether PHY CRC is applied or not to the PHY data transmission. In another embodiment, the size of the PHY CRC is controlled by a field in DCI or RAR. In an example of the latter embodiment, a transport block size (TBS) field or modulation and coding scheme (MCS) field in a DCI or RAR is extended (or repurposed) so that at least some values of the field correspond to transmission with a reduced PHY CRC size (or with a completely omitted PHY CRC).

This will allow the base station to reduce or eliminate the overhead from PHY CRC e.g., when a PHY data transmission with a small TBS is scheduled.

Additional Description

Figure 5 is a schematic block diagram of a radio access node 500 according to some embodiments of the present disclosure. Optional features are represented by dashed boxes. The radio access node 500 may be, for example, a base station 202 or 206 or a network node that implements all or part of the functionality of the base station 202 or gNB described herein. As illustrated, the radio access node 500 includes a control system 502 that includes one or more processors 504 (e.g., Central Processing Units (CPUs), Application Specific Integrated Circuits (ASICs), Field Programmable Gate Arrays (FPGAs), and/or the like), memory 506, and a network interface 508. The one or more processors 504 are also referred to herein as processing circuitry. In addition, the radio access node 500 may include one or more radio units 510 that each includes one or more transmitters 512 and one or more receivers 514 coupled to one or more antennas 516. The radio units 510 may be referred to or be part of radio interface circuitry. In some embodiments, the radio unit(s) 510 is external to the control system 502 and connected to the control system 502 via, e.g., a wired connection (e.g., an optical cable). Flowever, in some other embodiments, the radio unit(s) 510 and potentially the antenna(s) 516 are integrated together with the control system 502.

The one or more processors 504 operate to provide one or more functions of a radio access node 500 as described herein (e.g., one or more functions of the transmitting radio node 300, one or more functions of a receiving radio node 302, or one or more functions of a base station or other radio access node, as described herein). In some embodiments, the function(s) are implemented in software that is stored, e.g., in the memory 506 and executed by the one or more processors 504.

Figure 6 is a schematic block diagram that illustrates a virtualized embodiment of the radio access node 500 according to some embodiments of the present disclosure. This discussion is equally applicable to other types of network nodes. Further, other types of network nodes may have similar virtualized architectures. Again, optional features are represented by dashed boxes.

As used herein, a "virtualized" radio access node is an implementation of the radio access node 500 in which at least a portion of the functionality of the radio access node 500 is implemented as a virtual component(s) (e.g., via a virtual machine(s) executing on a physical processing node(s) in a network(s)). As illustrated, in this example, the radio access node 500 may include the control system 502 and/or the one or more radio units 510, as described above. The control system 502 may be connected to the radio unit(s) 510 via, for example, an optical cable or the like. The radio access node 500 includes one or more processing nodes 600 coupled to or included as part of a network(s) 602. If present, the control system 502 or the radio unit(s) are connected to the processing node(s) 600 via the network 602. Each processing node 600 includes one or more processors 604 (e.g., CPUs, ASICs, FPGAs, and/or the like), memory 606, and a network interface 608.

In this example, functions 610 of the radio access node 500 described herein (e.g., one or more functions of the transmitting radio node 300, one or more functions of a receiving radio node 302, or one or more functions of a base station or other radio access node, as described herein) are implemented at the one or more processing nodes 600 or distributed across the one or more processing nodes 600 and the control system 502 and/or the radio unit(s) 510 in any desired manner. In some particular embodiments, some or all of the functions 610 of the radio access node 500 described herein are implemented as virtual components executed by one or more virtual machines implemented in a virtual environ ment(s) hosted by the processing node(s)

600. As will be appreciated by one of ordinary skill in the art, additional signaling or communication between the processing node(s) 600 and the control system 502 is used in order to carry out at least some of the desired functions 610. Notably, in some embodiments, the control system 502 may not be included, in which case the radio unit(s) 510 communicate directly with the processing node(s) 600 via an appropriate network interface(s).

In some embodiments, a computer program including instructions which, when executed by at least one processor, causes the at least one processor to carry out the functionality of the radio access node 500 or a node (e.g., a processing node 600) implementing one or more of the functions 610 of the radio access node 500 in a virtual environment according to any of the embodiments described herein is provided. In some embodiments, a carrier comprising the aforementioned computer program product is provided. The carrier is one of an electronic signal, an optical signal, a radio signal, or a computer readable storage medium (e.g., a non-transitory computer readable medium such as memory).

Figure 7 is a schematic block diagram of the radio access node 500 according to some other embodiments of the present disclosure. The radio access node 500 includes one or more modules 700, each of which is implemented in software. The module(s) 700 provide the functionality of the radio access node 500 described herein (e.g., one or more functions of the transmitting radio node 300, one or more functions of a receiving radio node 302, or one or more functions of a base station or other radio access node, as described herein). This discussion is equally applicable to the processing node 600 of Figure 6 where the modules 700 may be implemented at one of the processing nodes 600 or distributed across multiple processing nodes 600 and/or distributed across the processing node(s) 600 and the control system 502.

Figure 8 is a schematic block diagram of a wireless communication device 800 according to some embodiments of the present disclosure. As illustrated, the wireless communication device 800 includes one or more processors 802 (e.g., CPUs, ASICs, FPGAs, and/or the like), memory 804, and one or more transceivers 806 each including one or more transmitters 808 and one or more receivers 810 coupled to one or more antennas 812. The transceiver(s) 806 includes radio-front end circuitry connected to the antenna(s) 812 that is configured to condition signals communicated between the antenna(s) 812 and the processor(s) 802, as will be appreciated by on of ordinary skill in the art. The processors 802 are also referred to herein as processing circuitry. The transceivers 806 are also referred to herein as radio circuitry. In some embodiments, the functionality of the wireless communication device 800 described above (e.g., one or more functions of the transmitting radio node 300, one or more functions of a receiving radio node 302, or one or more functions of a UE, as described herein) may be fully or partially implemented in software that is, e.g., stored in the memory 804 and executed by the processor(s) 802. Note that the wireless communication device 800 may include additional components not illustrated in Figure 8 such as, e.g., one or more user interface components (e.g., an input/output interface including a display, buttons, a touch screen, a microphone, a speaker(s), and/or the like and/or any other components for allowing input of information into the wireless communication device 800 and/or allowing output of information from the wireless communication device 800), a power supply (e.g., a battery and associated power circuitry), etc.

In some embodiments, a computer program including instructions which, when executed by at least one processor, causes the at least one processor to carry out the functionality of the wireless communication device 800 according to any of the embodiments described herein (e.g., one or more functions of the transmitting radio node 300, one or more functions of a receiving radio node 302, or one or more functions of a UE, as described herein) is provided. In some embodiments, a carrier comprising the aforementioned computer program product is provided. The carrier is one of an electronic signal, an optical signal, a radio signal, or a computer readable storage medium (e.g., a non-transitory computer readable medium such as memory). Figure 9 is a schematic block diagram of the wireless communication device 800 according to some other embodiments of the present disclosure. The wireless communication device 800 includes one or more modules 900, each of which is implemented in software. The module(s) 900 provide the functionality of the wireless communication device 800 described herein (e.g., one or more functions of the transmitting radio node 300, one or more functions of a receiving radio node 302, or one or more functions of a UE, as described herein).

With reference to Figure 10, in accordance with an embodiment, a communication system includes a telecommunication network 1000, such as a 3GPP- type cellular network, which comprises an access network 1002, such as a RAN, and a core network 1004. The access network 1002 comprises a plurality of base stations 1006A, 1006B, 1006C, such as Node Bs, eNBs, gNBs, or other types of wireless Access Points (APs), each defining a corresponding coverage area 1008A, 1008B, 1008C. Each base station 1006A, 1006B, 1006C is connectable to the core network 1004 over a wired or wireless connection 1010. A first UE 1012 located in coverage area 1008C is configured to wirelessly connect to, or be paged by, the corresponding base station 1006C. A second UE 1014 in coverage area 1008A is wirelessly connectable to the corresponding base station 1006A. While a plurality of UEs 1012, 1014 are illustrated in this example, the disclosed embodiments are equally applicable to a situation where a sole UE is in the coverage area or where a sole UE is connecting to the corresponding base station 1006.

The telecommunication network 1000 is itself connected to a host computer 1016, which may be embodied in the hardware and/or software of a standalone server, a cloud-implemented server, a distributed server, or as processing resources in a server farm. The host computer 1016 may be under the ownership or control of a service provider, or may be operated by the service provider or on behalf of the service provider. Connections 1018 and 1020 between the telecommunication network 1000 and the host computer 1016 may extend directly from the core network 1004 to the host computer 1016 or may go via an optional intermediate network 1022. The intermediate network 1022 may be one of, or a combination of more than one of, a public, private, or hosted network; the intermediate network 1022, if any, may be a backbone network or the Internet; in particular, the intermediate network 1022 may comprise two or more sub-networks (not shown). The communication system of Figure 10 as a whole enables connectivity between the connected UEs 1012, 1014 and the host computer 1016. The connectivity may be described as an Over-the-Top (OTT) connection 1024. The host computer 1016 and the connected UEs 1012, 1014 are configured to communicate data and/or signaling via the OTT connection 1024, using the access network 1002, the core network 1004, any intermediate network 1022, and possible further infrastructure (not shown) as intermediaries. The OTT connection 1024 may be transparent in the sense that the participating communication devices through which the OTT connection 1024 passes are unaware of routing of uplink and downlink communications. For example, the base station 1006 may not or need not be informed about the past routing of an incoming downlink communication with data originating from the host computer 1016 to be forwarded (e.g., handed over) to a connected UE 1012. Similarly, the base station 1006 need not be aware of the future routing of an outgoing uplink communication originating from the UE 1012 towards the host computer 1016.

Example implementations, in accordance with an embodiment, of the UE, base station, and host computer discussed in the preceding paragraphs will now be described with reference to Figure 11. In a communication system 1100, a host computer 1102 comprises hardware 1104 including a communication interface 1106 configured to set up and maintain a wired or wireless connection with an interface of a different communication device of the communication system 1100. The host computer 1102 further comprises processing circuitry 1108, which may have storage and/or processing capabilities. In particular, the processing circuitry 1108 may comprise one or more programmable processors, ASICs, FPGAs, or combinations of these (not shown) adapted to execute instructions. The host computer 1102 further comprises software 1110, which is stored in or accessible by the host computer 1102 and executable by the processing circuitry 1108. The software 1110 includes a host application 1112. The host application 1112 may be operable to provide a service to a remote user, such as a UE 1114 connecting via an OTT connection 1116 terminating at the UE 1114 and the host computer 1102. In providing the service to the remote user, the host application 1112 may provide user data which is transmitted using the OTT connection 1116.

The communication system 1100 further includes a base station 1118 provided in a telecommunication system and comprising hardware 1120 enabling it to communicate with the host computer 1102 and with the UE 1114. The hardware 1120 may include a communication interface 1122 for setting up and maintaining a wired or wireless connection with an interface of a different communication device of the communication system 1100, as well as a radio interface 1124 for setting up and maintaining at least a wireless connection 1126 with the UE 1114 located in a coverage area (not shown in Figure 11) served by the base station 1118. The communication interface 1122 may be configured to facilitate a connection 1128 to the host computer 1102. The connection 1128 may be direct or it may pass through a core network (not shown in Figure 11) of the telecommunication system and/or through one or more intermediate networks outside the telecommunication system. In the embodiment shown, the hardware 1120 of the base station 1118 further includes processing circuitry 1130, which may comprise one or more programmable processors, ASICs, FPGAs, or combinations of these (not shown) adapted to execute instructions. The base station 1118 further has software 1132 stored internally or accessible via an external connection.

The communication system 1100 further includes the UE 1114 already referred to. The UE's 1114 hardware 1134 may include a radio interface 1136 configured to set up and maintain a wireless connection 1126 with a base station serving a coverage area in which the UE 1114 is currently located. The hardware 1134 of the UE 1114 further includes processing circuitry 1138, which may comprise one or more programmable processors, ASICs, FPGAs, or combinations of these (not shown) adapted to execute instructions. The UE 1114 further comprises software 1140, which is stored in or accessible by the UE 1114 and executable by the processing circuitry 1138. The software 1140 includes a client application 1142. The client application 1142 may be operable to provide a service to a human or non-human user via the UE 1114, with the support of the host computer 1102. In the host computer 1102, the executing host application 1112 may communicate with the executing client application 1142 via the OTT connection 1116 terminating at the UE 1114 and the host computer 1102. In providing the service to the user, the client application 1142 may receive request data from the host application 1112 and provide user data in response to the request data. The OTT connection 1116 may transfer both the request data and the user data. The client application 1142 may interact with the user to generate the user data that it provides.

It is noted that the host computer 1102, the base station 1118, and the UE 1114 illustrated in Figure 11 may be similar or identical to the host computer 1016, one of the base stations 1006A, 1006B, 1006C, and one of the UEs 1012, 1014 of Figure 10, respectively. This is to say, the inner workings of these entities may be as shown in Figure 11 and independently, the surrounding network topology may be that of Figure 10.

In Figure 11, the OTT connection 1116 has been drawn abstractly to illustrate the communication between the host computer 1102 and the UE 1114 via the base station 1118 without explicit reference to any intermediary devices and the precise routing of messages via these devices. The network infrastructure may determine the routing, which may be configured to hide from the UE 1114 or from the service provider operating the host computer 1102, or both. While the OTT connection 1116 is active, the network infrastructure may further take decisions by which it dynamically changes the routing (e.g., on the basis of load balancing consideration or reconfiguration of the network).

The wireless connection 1126 between the UE 1114 and the base station 1118 is in accordance with the teachings of the embodiments described throughout this disclosure. One or more of the various embodiments improve the performance of OTT services provided to the UE 1114 using the OTT connection 1116, in which the wireless connection 1126 forms the last segment. More precisely, the teachings of these embodiments may improve, e.g., power consumption and thereby provide benefits such as, e.g., extended battery lifetime.

A measurement procedure may be provided for the purpose of monitoring data rate, latency, and other factors on which the one or more embodiments improve. There may further be an optional network functionality for reconfiguring the OTT connection 1116 between the host computer 1102 and the UE 1114, in response to variations in the measurement results. The measurement procedure and/or the network functionality for reconfiguring the OTT connection 1116 may be implemented in the software 1110 and the hardware 1104 of the host computer 1102 or in the software 1140 and the hardware 1134 of the UE 1114, or both. In some embodiments, sensors (not shown) may be deployed in or in association with communication devices through which the OTT connection 1116 passes; the sensors may participate in the measurement procedure by supplying values of the monitored quantities exemplified above, or supplying values of other physical quantities from which the software 1110, 1140 may compute or estimate the monitored quantities. The reconfiguring of the OTT connection 1116 may include message format, retransmission settings, preferred routing, etc.; the reconfiguring need not affect the base station 1118, and it may be unknown or imperceptible to the base station 1118. Such procedures and functionalities may be known and practiced in the art. In certain embodiments, measurements may involve proprietary UE signaling facilitating the host computer 1102's measurements of throughput, propagation times, latency, and the like. The measurements may be implemented in that the software 1110 and 1140 causes messages to be transmitted, in particular empty or 'dummy' messages, using the OTT connection 1116 while it monitors propagation times, errors, etc.

Figure 12 is a flowchart illustrating a method implemented in a communication system, in accordance with one embodiment. The communication system includes a host computer, a base station, and a UE which may be those described with reference to Figures 10 and 11. For simplicity of the present disclosure, only drawing references to Figure 12 will be included in this section. In step 1200, the host computer provides user data. In sub-step 1202 (which may be optional) of step 1200, the host computer provides the user data by executing a host application. In step 1204, the host computer initiates a transmission carrying the user data to the UE. In step 1206 (which may be optional), the base station transmits to the UE the user data which was carried in the transmission that the host computer initiated, in accordance with the teachings of the embodiments described throughout this disclosure. In step 1208 (which may also be optional), the UE executes a client application associated with the host application executed by the host computer.

Figure 13 is a flowchart illustrating a method implemented in a communication system, in accordance with one embodiment. The communication system includes a host computer, a base station, and a UE which may be those described with reference to Figures 10 and 11. For simplicity of the present disclosure, only drawing references to Figure 13 will be included in this section. In step 1300 of the method, the host computer provides user data. In an optional sub-step (not shown) the host computer provides the user data by executing a host application. In step 1302, the host computer initiates a transmission carrying the user data to the UE. The transmission may pass via the base station, in accordance with the teachings of the embodiments described throughout this disclosure. In step 1304 (which may be optional), the UE receives the user data carried in the transmission. Figure 14 is a flowchart illustrating a method implemented in a communication system, in accordance with one embodiment. The communication system includes a host computer, a base station, and a UE which may be those described with reference to Figures 10 and 11. For simplicity of the present disclosure, only drawing references to Figure 14 will be included in this section. In step 1400 (which may be optional), the UE receives input data provided by the host computer. Additionally or alternatively, in step 1402, the UE provides user data. In sub-step 1404 (which may be optional) of step 1400, the UE provides the user data by executing a client application. In sub-step 1406 (which may be optional) of step 1402, the UE executes a client application which provides the user data in reaction to the received input data provided by the host computer. In providing the user data, the executed client application may further consider user input received from the user. Regardless of the specific manner in which the user data was provided, the UE initiates, in sub-step 1408 (which may be optional), transmission of the user data to the host computer. In step 1410 of the method, the host computer receives the user data transmitted from the UE, in accordance with the teachings of the embodiments described throughout this disclosure.

Figure 15 is a flowchart illustrating a method implemented in a communication system, in accordance with one embodiment. The communication system includes a host computer, a base station, and a UE which may be those described with reference to Figures 10 and 11. For simplicity of the present disclosure, only drawing references to Figure 15 will be included in this section. In step 1500 (which may be optional), in accordance with the teachings of the embodiments described throughout this disclosure, the base station receives user data from the UE. In step 1502 (which may be optional), the base station initiates transmission of the received user data to the host computer. In step 1504 (which may be optional), the host computer receives the user data carried in the transmission initiated by the base station.

Any appropriate steps, methods, features, functions, or benefits disclosed herein may be performed through one or more functional units or modules of one or more virtual apparatuses. Each virtual apparatus may comprise a number of these functional units. These functional units may be implemented via processing circuitry, which may include one or more microprocessor or microcontrollers, as well as other digital hardware, which may include Digital Signal Processor (DSPs), special-purpose digital logic, and the like. The processing circuitry may be configured to execute program code stored in memory, which may include one or several types of memory such as Read Only Memory (ROM), Random Access Memory (RAM), cache memory, flash memory devices, optical storage devices, etc. Program code stored in memory includes program instructions for executing one or more telecommunications and/or data communications protocols as well as instructions for carrying out one or more of the techniques described herein. In some implementations, the processing circuitry may be used to cause the respective functional unit to perform corresponding functions according one or more embodiments of the present disclosure.

While processes in the figures may show a particular order of operations performed by certain embodiments of the present disclosure, it should be understood that such order is exemplary (e.g., alternative embodiments may perform the operations in a different order, combine certain operations, overlap certain operations, etc.).

Some example embodiments of the present disclosure are as follows:

Group A Embodiments

Embodiment 1: A method performed by a first radio node (300) for data transmission in a radio access network of a cellular communications system, the method comprising transmitting (306) a reduced overhead radio bearer to a second radio node (302), the reduced overhead radio bearer being a radio bearer in which:

(a) a physical, PHY, layer cyclic redundancy check, CRC, is excluded;

(b) all or part of a Medium Access Control, MAC, header is excluded;

(c) all or part of a Radio Link Control, RLC, header is excluded;

(d) all or part of a Packet Data Convergence Protocol, PDCP, header is excluded;

(e) all or part of a Service Data Application Protocol, SDAP, header is excluded; or

(f) a combination of any two or more of (a) - (e).

Embodiment 2: The method of embodiment 1 wherein the reduced overhead radio bearer is a radio bearer in which:

(i) all or part of RLC header is excluded from the radio bearer, and the all or part of the RLC header is static for: a respective connection, the first radio node (300), or the second radio node (302) (e.g., static for a respective connection including the first radio node (300) and the second radio node (302)); (ii) all or part of a PDCP header is excluded from the radio bearer, and the all or part of the PDCP header is static for: a respective connection, the first radio node (300), or the second radio node (302) (e.g., static for a respective connection including the first radio node (300) and the second radio node (302));

(iii)all or part of a SDAP header is excluded from the radio bearer, and the all or part of the SDAP header is static for: a respective connection, the first radio node (300), or the second radio node (302) (e.g., static for a respective connection including the first radio node (300) and the second radio node (302)); or

(iv)a combination of any two or more of (i) - (iii).

Embodiment 3: The method of embodiment 1 or 2 wherein the PHY layer CRC is excluded from the reduced overhead radio bearer, and the reduced overhead radio bearer support integrity protection at a layer other than the PHY layer.

Embodiment 4: The method of embodiment 1 or 2 wherein the PHY layer CRC is excluded from the reduced overhead radio bearer, and the reduced overhead radio bearer supports integrity protection at a PDCP layer.

Embodiment 5: The method of any one of embodiments 1 to 4 wherein a logical channel identity, LCID, is excluded from the reduced overhead radio bearer at the MAC layer, the LCID being a static LCID.

Embodiment 6: The method of embodiment 5 wherein the static LCID is a static LCID used for a particular transmission type of the reduced overhead radio bearer.

Embodiment 7: The method of embodiment 6 wherein different static LCIDs are predefined or preconfigured for different transmission types (e.g., at both the first radio node (300) and the second radio node (302)).

Embodiment 8: The method of any one of embodiments 1 to 7 wherein a static transport block size is used for the reduced overhead radio bearer, and a MAC length indicator and/or a length format indicator are excluded from the reduced overhead radio bearer at the MAC layer.

Embodiment 9: The method of embodiment 8 wherein the MAC length indicator and/or the length format indicator are predefined or preconfigured (e.g., at both the first radio node (300) and the second radio node (302)). Embodiment 10: The method of any one of embodiments 1 to 9 wherein the reduced overhead radio bearer comprises a single RLC Acknowledgment Mode, AM, data Protocol Data Unit, PDU, transmission or a single RLC Unacknowledged Mode, UM, data PDU transmission, and a RLC Sequence Number, SN, is excluded from the reduced overhead radio bearer at the RLC layer.

Embodiment 11: The method of any one of embodiments 1 to 9 wherein RLC Acknowledgment Mode, AM, functionality, concatenation at the RLC layer, segmentation at the RLC layer, reassembly at the RLC layer, reordering at the RLC layer, and/or duplicate detection and discard functionality at the RLC layer is/are disabled for the reduced overhead radio bearer, and associated information is excluded from the reduced overhead radio bearer at the RLC layer.

Embodiment 12: The method of any one of embodiments 1 to 9 wherein RLC Acknowledgment Mode, AM, functionality, concatenation at the RLC layer, segmentation at the RLC layer, reassembly at the RLC layer, reordering at the RLC layer, and duplicate detection and discard functionality at the RLC layer are disabled for the reduced overhead radio bearer, and associated information is excluded from the reduced overhead radio bearer at the RLC layer.

Embodiment 13: The method of embodiment 12 wherein the RLC AM header of the reduced overhead radio bearer comprises only a first data/control bit that indicates whether an associated PDU is a control or data PDU and a polling bit that indicates whether a RLC status report is requested.

Embodiment 14: The method of any one of embodiments 1 to 13 wherein the reduced overhead radio bearer comprises a single PDCP Protocol Data Unit, PDU, transmission, and a PDCP Sequence Number, SN, is excluded from the reduced overhead radio bearer at the PDCP layer.

Embodiment 15: The method of any one of embodiments 1 to 14 wherein a fixed Quality of Service, QoS, to radio bearer mapping applicable to the reduced overhead radio bearer is configured and stored at both the first radio node (302) and the second radio node (304), and all or a part of the SDAP header is excluded from the reduced overhead radio bearer.

Embodiment 16: The method of any one of embodiments 1 to 14 wherein QFI applicable to the reduced overhead radio bearer is configured and stored at both the first radio node (302) and the second radio node (304), and the QFI is excluded from the reduced overhead radio bearer at the SDAP layer.

Embodiment 17: The method of any one of embodiments 1 to 16 further comprising configuring (304) or receiving (304) a configuration of the reduced overhead radio bearer.

Embodiment 18: The method of any one of embodiments 1 to 17 wherein the first radio node (300) is a wireless communication device (212), and the method further comprising requesting (304A) permission to use a reduced overhead radio bearer.

Embodiment 19: The method of embodiment 18 wherein requesting (304A) permission to use a reduced overhead radio bearer comprises requesting (304A) permission to use a reduced overhead radio bearer during a random access procedure or during a connection establishment procedure.

Embodiment 20: The method of embodiment 18 wherein requesting (304A) permission to use a reduced overhead radio bearer comprises transmitting a random access preamble from a dedicated set of random access preambles for requesting permission to use a reduced overhead radio bearer.

Embodiment 21: The method of embodiment 18 wherein requesting (304A) permission to use a reduced overhead radio bearer comprises, during a random access procedure, transmitting a Msg3 comprising an indication of a request to use a reduced overhead radio bearer.

Embodiment 22: The method of any one of embodiments 1 to 21 wherein use of a reduced overhead radio bearer is configured by the radio access network for mobile terminated data transfers.

Embodiment 23: The method of embodiment 22 wherein the first radio node (300) is a radio access node (202; 206), and the method further comprising transmitting, to the second radio node (302; 212), an indication that a reduced overhead radio bearer is to be used, during a connection establishment procedure (e.g., in a random access response or in a RRC connection setup message) or in an associated uplink grant.

Embodiment 24: The method of any one of embodiments 1 to 21 wherein either the first radio node (300) or the second radio node (302) is a User Equipment, UE, (212), and use of a reduced overhead radio bearer is stored as part of a UE context of the UE (212). Embodiment 25: The method of any one of embodiments 1 to 21 wherein use of the reduced overhead radio bearer is indicated by inclusion of a reserved LCID or eLCID value in the reduced overhead radio bearer the MAC layer.

Embodiment 26: The method of any one of embodiments 1 to 21 wherein use of the reduced overhead radio bearer is indicated by inclusion of a reserved LCID or eLCID value in the reduced overhead radio bearer the MAC layer, the reserved LCID or eLCID value being one of two or more reserved LCID or eLCID values mapped to different fixed headers or configurations (e.g., stored in an associated UE context).

Embodiment 27: The method of any one of embodiments 1 to 26 wherein one or more restrictions associated with use of a reduced overhead radio bearer (e.g., for uplink transmission) are predefined or preconfigured, and the reduced overhead radio bearer is transmitted in accordance with the one or more restrictions.

Embodiment 28: The method of any one of embodiments 1 to 27 wherein whether a PHY CRC is included in the reduced overhead radio bearer and/or a size of the PHY CRC for the reduced overhead radio bearer is dynamically controlled (e.g., via downlink control information or random access response).

Embodiment 29: The method of any of the previous embodiments, further comprising: providing user data; and forwarding the user data to a host computer via the transmission to the base station.

Group B Embodiments

Embodiment 30: A method performed by a second radio node (302) for data reception in a radio access network of a cellular communications system, the method comprising receiving (306) a reduced overhead radio bearer from a first radio node (300), the reduced overhead radio bearer being a radio bearer in which:

(a) a physical, PHY, layer cyclic redundancy check, CRC, is excluded;

(b) all or part of a Medium Access Control, MAC, header is excluded;

(c) all or part of a Radio Link Control, RLC, header is excluded;

(f) a combination of any two or more of (a) - (e).

Embodiment 31: The method of embodiment 30 wherein the reduced overhead radio bearer is a radio bearer in which: (i) all or part of RLC header is excluded from the radio bearer, and the all or part of the RLC header is static for: a respective connection, the first radio node (300), or the second radio node (302) (e.g., static for a respective connection including the first radio node (300) and the second radio node (302));

(ii) all or part of a PDCP header is excluded from the radio bearer, and the all or part of the PDCP header is static for: a respective connection, the first radio node (300), or the second radio node (302) (e.g., static for a respective connection including the first radio node (300) and the second radio node (302));

(iv)a combination of any two or more of (i) - (iii).

Embodiment 32: The method of embodiment 30 or 31 wherein the PHY layer CRC is excluded from the reduced overhead radio bearer, and the reduced overhead radio bearer support integrity protection at a layer other than the PHY layer.

Embodiment 33: The method of embodiment 30 or 31 wherein the PHY layer CRC is excluded from the reduced overhead radio bearer, and the reduced overhead radio bearer supports integrity protection at a PDCP layer.

Embodiment 34: The method of any one of embodiments 30 to 33 wherein a logical channel identity, LCID, is excluded from the reduced overhead radio bearer at the MAC layer, the LCID being a static LCID.

Embodiment 35: The method of embodiment 34 wherein the static LCID is a static LCID used for a particular transmission type of the reduced overhead radio bearer.

Embodiment 36: The method of embodiment 35 wherein different static LCIDs are predefined or preconfigured for different transmission types (e.g., at both the first radio node (300) and the second radio node (302)).

Embodiment 37: The method of any one of embodiments 30 to 36 wherein a static transport block size is used for the reduced overhead radio bearer, and a MAC length indicator and/or a length format indicator are excluded from the reduced overhead radio bearer at the MAC layer.

Embodiment 38: The method of embodiment 37 wherein the MAC length indicator and/or the length format indicator are predefined or preconfigured (e.g., at both the first radio node (300) and the second radio node (302)).

Embodiment 39: The method of any one of embodiments 30 to 38 wherein the reduced overhead radio bearer comprises a single RLC Acknowledgment Mode, AM, data Protocol Data Unit, PDU, transmission or a single RLC Unacknowledged Mode, UM, data PDU transmission, and a RLC Sequence Number, SN, is excluded from the reduced overhead radio bearer at the RLC layer.

Embodiment 40: The method of any one of embodiments 30 to 38 wherein RLC Acknowledgment Mode, AM, functionality, concatenation at the RLC layer, segmentation at the RLC layer, reassembly at the RLC layer, reordering at the RLC layer, and/or duplicate detection and discard functionality at the RLC layer is/are disabled for the reduced overhead radio bearer, and associated information is excluded from the reduced overhead radio bearer at the RLC layer.

Embodiment 41: The method of any one of embodiments 30 to 38 wherein RLC Acknowledgment Mode, AM, functionality, concatenation at the RLC layer, segmentation at the RLC layer, reassembly at the RLC layer, reordering at the RLC layer, and duplicate detection and discard functionality at the RLC layer are disabled for the reduced overhead radio bearer, and associated information is excluded from the reduced overhead radio bearer at the RLC layer.

Embodiment 42: The method of embodiment 41 wherein the RLC AM header of the reduced overhead radio bearer comprises only a first data/control bit that indicates whether an associated PDU is a control or data PDU and a polling bit that indicates whether a RLC status report is requested.

Embodiment 43: The method of any one of embodiments 30 to 42 wherein the reduced overhead radio bearer comprises a single PDCP Protocol Data Unit, PDU, transmission, and a PDCP Sequence Number, SN, is excluded from the reduced overhead radio bearer at the PDCP layer.

Embodiment 44: The method of any one of embodiments 30 to 43 wherein a fixed Quality of Service, QoS, to radio bearer mapping applicable to the reduced overhead radio bearer is configured and stored at both the first radio node (302) and the second radio node (304), and all or a part of the SDAP header is excluded from the reduced overhead radio bearer.

Embodiment 45: The method of any one of embodiments 30 to 43 wherein QFI applicable to the reduced overhead radio bearer is configured and stored at both the first radio node (302) and the second radio node (304), and the QFI is excluded from the reduced overhead radio bearer at the SDAP layer.

Embodiment 46: The method of any one of embodiments 30 to 45 further comprising configuring (304) or receiving (304) a configuration of the reduced overhead radio bearer.

Embodiment 47: The method of any one of embodiments 30 to 46 wherein the first radio node (300) is a wireless communication device (212), and the method further comprising receiving (304A) a request from the first radio node (300) for permission to use a reduced overhead radio bearer, and granting (304B) the first radio node (300) permission to use a reduced overhead radio bearer.

Embodiment 48: The method of embodiment 47 wherein receiving (304A) the request for permission to use a reduced overhead radio bearer comprises receiving (304A) the request for permission to use a reduced overhead radio bearer during a random access procedure or during a connection establishment procedure.

Embodiment 49: The method of embodiment 47 wherein receiving (304A) the request for permission to use a reduced overhead radio bearer comprises receiving a random access preamble from a dedicated set of random access preambles for requesting permission to use a reduced overhead radio bearer.

Embodiment 50: The method of embodiment 47 wherein receiving (304A) the request for permission to use a reduced overhead radio bearer comprises, during a random access procedure, receiving a Msg3 comprising an indication of a request to use a reduced overhead radio bearer.

Embodiment 51: The method of any one of embodiments 30 to 50 wherein use of a reduced overhead radio bearer is configured by the radio access network for mobile terminated data transfers.

Embodiment 52: The method of any one of embodiments 30 to 50 wherein either the first radio node (300) or the second radio node (302) is a User Equipment,

UE, (212), and use of a reduced overhead radio bearer is stored as part of a UE context of the UE (212). Embodiment 53: The method of any one of embodiments 30 to 50 wherein use of the reduced overhead radio bearer is indicated by inclusion of a reserved LCID or eLCID value in the reduced overhead radio bearer the MAC layer.

Embodiment 54: The method of any one of embodiments 30 to 50 wherein use of the reduced overhead radio bearer is indicated by inclusion of a reserved LCID or eLCID value in the reduced overhead radio bearer the MAC layer, the reserved LCID or eLCID value being one of two or more reserved LCID or eLCID values mapped to different fixed headers or configurations (e.g., stored in an associated UE context).

Embodiment 55: The method of any one of embodiments 30 to 54 wherein one or more restrictions associated with use of a reduced overhead radio bearer (e.g., for uplink transmission) are predefined or preconfigured, and the reduced overhead radio bearer is transmitted in accordance with the one or more restrictions.

Embodiment 56: The method of any one of embodiments 30 to 55 wherein whether a PHY CRC is included in the reduced overhead radio bearer and/or a size of the PHY CRC for the reduced overhead radio bearer is dynamically controlled (e.g., via downlink control information or random access response).

Embodiment 57: The method of any of the previous embodiments, further comprising: obtaining user data; and forwarding the user data to a host computer or a wireless communication device.

Group C Embodiments

Embodiment 58: A wireless communication device, the wireless communication device comprising: processing circuitry configured to perform any of the steps of any of the Group A embodiments or any of the steps of any of the Group B embodiments; and power supply circuitry configured to supply power to the wireless communication device.

Embodiment 59: A base station comprising: processing circuitry configured to perform any of the steps of any of the Group A embodiments or any of the steps of any of the Group B embodiments; and power supply circuitry configured to supply power to the base station.

Embodiment 60: A User Equipment, UE, comprising: an antenna configured to send and receive wireless signals; radio front-end circuitry connected to the antenna and to processing circuitry, and configured to condition signals communicated between the antenna and the processing circuitry; the processing circuitry being configured to perform any of the steps of any of the Group A embodiments or any of the steps of any of the Group B embodiments; an input interface connected to the processing circuitry and configured to allow input of information into the UE to be processed by the processing circuitry; an output interface connected to the processing circuitry and configured to output information from the UE that has been processed by the processing circuitry; and a battery connected to the processing circuitry and configured to supply power to the UE.

Embodiment 61: A communication system including a host computer comprising: processing circuitry configured to provide user data; and a communication interface configured to forward the user data to a cellular network for transmission to a User Equipment, UE; wherein the cellular network comprises a base station having a radio interface and processing circuitry, the base station's processing circuitry configured to perform any of the steps of any of the Group A embodiments.

Embodiment 62: The communication system of the previous embodiment further including the base station.

Embodiment 63: The communication system of the previous 2 embodiments, further including the UE, wherein the UE is configured to communicate with the base station.

Embodiment 64: The communication system of the previous 3 embodiments, wherein: the processing circuitry of the host computer is configured to execute a host application, thereby providing the user data; and the UE comprises processing circuitry configured to execute a client application associated with the host application.

Embodiment 65: A method implemented in a communication system including a host computer, a base station, and a User Equipment, UE, the method comprising: at the host computer, providing user data; and at the host computer, initiating a transmission carrying the user data to the UE via a cellular network comprising the base station, wherein the base station performs any of the steps of any of the Group A embodiments.

Embodiment 66: The method of the previous embodiment, further comprising, at the base station, transmitting the user data.

Embodiment 67: The method of the previous 2 embodiments, wherein the user data is provided at the host computer by executing a host application, the method further comprising, at the UE, executing a client application associated with the host application.

Embodiment 68: A User Equipment, UE, configured to communicate with a base station, the UE comprising a radio interface and processing circuitry configured to perform the method of the previous 3 embodiments.

Embodiment 69: A communication system including a host computer comprising: processing circuitry configured to provide user data; and a communication interface configured to forward user data to a cellular network for transmission to a User Equipment, UE; wherein the UE comprises a radio interface and processing circuitry, the UE's components configured to perform any of the steps of any of the Group B embodiments.

Embodiment 70: The communication system of the previous embodiment, wherein the cellular network further includes a base station configured to communicate with the UE.

Embodiment 71: The communication system of the previous 2 embodiments, wherein: the processing circuitry of the host computer is configured to execute a host application, thereby providing the user data; and the UE's processing circuitry is configured to execute a client application associated with the host application.

Embodiment 72: A method implemented in a communication system including a host computer, a base station, and a User Equipment, UE, the method comprising: at the host computer, providing user data; and at the host computer, initiating a transmission carrying the user data to the UE via a cellular network comprising the base station, wherein the UE performs any of the steps of any of the Group B embodiments.

Embodiment 73: The method of the previous embodiment, further comprising at the UE, receiving the user data from the base station.

Embodiment 74: A communication system including a host computer comprising: communication interface configured to receive user data originating from a transmission from a User Equipment, UE, to a base station; wherein the UE comprises a radio interface and processing circuitry, the UE's processing circuitry configured to perform any of the steps of any of the Group A embodiments.

Embodiment 75: The communication system of the previous embodiment, further including the UE. Embodiment 76: The communication system of the previous 2 embodiments, further including the base station, wherein the base station comprises a radio interface configured to communicate with the UE and a communication interface configured to forward to the host computer the user data carried by a transmission from the UE to the base station.

Embodiment 77: The communication system of the previous 3 embodiments, wherein: the processing circuitry of the host computer is configured to execute a host application; and the UE's processing circuitry is configured to execute a client application associated with the host application, thereby providing the user data.

Embodiment 78: The communication system of the previous 4 embodiments, wherein: the processing circuitry of the host computer is configured to execute a host application, thereby providing request data; and the UE's processing circuitry is configured to execute a client application associated with the host application, thereby providing the user data in response to the request data.

Embodiment 79: A method implemented in a communication system including a host computer, a base station, and a User Equipment, UE, the method comprising: at the host computer, receiving user data transmitted to the base station from the UE, wherein the UE performs any of the steps of any of the Group A embodiments.

Embodiment 80: The method of the previous embodiment, further comprising, at the UE, providing the user data to the base station.

Embodiment 81: The method of the previous 2 embodiments, further comprising: at the UE, executing a client application, thereby providing the user data to be transmitted; and at the host computer, executing a host application associated with the client application.

Embodiment 82: The method of the previous 3 embodiments, further comprising: at the UE, executing a client application; and at the UE, receiving input data to the client application, the input data being provided at the host computer by executing a host application associated with the client application; wherein the user data to be transmitted is provided by the client application in response to the input data.

Embodiment 83: A communication system including a host computer comprising a communication interface configured to receive user data originating from a transmission from a User Equipment, UE, to a base station, wherein the base station comprises a radio interface and processing circuitry, the base station's processing circuitry configured to perform any of the steps of any of the Group B embodiments.

Embodiment 84: The communication system of the previous embodiment further including the base station.

Embodiment 85: The communication system of the previous 2 embodiments, further including the UE, wherein the UE is configured to communicate with the base station.

Embodiment 86: The communication system of the previous 3 embodiments, wherein: the processing circuitry of the host computer is configured to execute a host application; and the UE is configured to execute a client application associated with the host application, thereby providing the user data to be received by the host computer.

Embodiment 87: A method implemented in a communication system including a host computer, a base station, and a User Equipment, UE, the method comprising: at the host computer, receiving, from the base station, user data originating from a transmission which the base station has received from the UE, wherein the UE performs any of the steps of any of the Group A embodiments.

Embodiment 88: The method of the previous embodiment, further comprising at the base station, receiving the user data from the UE.

Embodiment 89: The method of the previous 2 embodiments, further comprising at the base station, initiating a transmission of the received user data to the host computer.

Those skilled in the art will recognize improvements and modifications to the embodiments of the present disclosure. All such improvements and modifications are considered within the scope of the concepts disclosed herein.

Claims

1. A method performed by a first radio node (300) for data transmission in a radio access network of a cellular communications system, the method comprising: transmitting (306) a reduced overhead radio bearer to a second radio node (302), the reduced overhead radio bearer being a radio bearer in which:

(a) a physical, PHY, layer cyclic redundancy check, CRC, is excluded;

(b) all or part of a Medium Access Control, MAC, header is excluded;

(c) all or part of a Radio Link Control, RLC, header is excluded;

(f) a combination of any two or more of (a) - (e).

2. The method of claim 1 wherein the reduced overhead radio bearer is a radio bearer in which: i) all or part of RLC header is excluded from the radio bearer, and the all or part of the RLC header is static for: a respective connection between the first radio node (300) and the second radio node (302), the first radio node (300), or the second radio node (302); ii) all or part of a PDCP header is excluded from the radio bearer, and the all or part of the PDCP header is static for: a respective connection between the first radio node (300) and the second radio node (302), the first radio node (300), or the second radio node (302); iii) all or part of a SDAP header is excluded from the radio bearer, and the all or part of the SDAP header is static for: a respective connection between the first radio node (300) and the second radio node (302), the first radio node (300), or the second radio node (302); or iv) a combination of any two or more of (i) - (iii).

3. The method of claim 1 or 2 wherein the PHY layer CRC is excluded from the reduced overhead radio bearer, and the reduced overhead radio bearer supports error correction and integrity protection at a higher layer.

4. The method of claim 1 or 2 wherein the PHY layer CRC is excluded from the reduced overhead radio bearer, and the reduced overhead radio bearer supports integrity protection, including bit error detection, at a PDCP layer.

5. The method of any one of claims 1 to 4 wherein a logical channel identity, LCID, is excluded from the reduced overhead radio bearer at the MAC layer, the LCID being a static LCID.

6. The method of claim 5 wherein the LCID excluded from the reduced overhead radio bearer at the MAC layer is a static LCID used for a particular transmission type of the reduced overhead radio bearer.

7. The method of claim 6 wherein different static LCIDs are predefined or preconfigured for different transmission types.

8. The method of any one of claims 1 to 7 wherein a static transport block size is used for the reduced overhead radio bearer, and either or both of a MAC length indicator and a length format indicator are excluded from the reduced overhead radio bearer at the MAC layer.

9. The method of claim 8 wherein the either or both of the MAC length indicator and the length format indicator is/are predefined or preconfigured.

10. The method of any one of claims 1 to 9 wherein the reduced overhead radio bearer comprises a single RLC Acknowledgment Mode, AM, data Protocol Data Unit, PDU, transmission or a single RLC Unacknowledged Mode, UM, data PDU transmission, and a RLC Sequence Number, SN, is excluded from the reduced overhead radio bearer at the RLC layer.

11. The method of claim 10 wherein an implicit RLC SN is associated to the signal RLC AM data PDU transmission or the single RLC UM data PDU transmission.

12. The method of any one of claims 1 to 9 wherein RLC Acknowledgment Mode,

AM, functionality, concatenation at the RLC layer, segmentation at the RLC layer, reassembly at the RLC layer, reordering at the RLC layer, and/or duplicate detection and discard functionality at the RLC layer is/are disabled for the reduced overhead radio bearer, and associated information is excluded from the reduced overhead radio bearer at the RLC layer.

13. The method of any one of claims 1 to 9 wherein RLC Acknowledgment Mode,

AM, functionality, concatenation at the RLC layer, segmentation at the RLC layer, reassembly at the RLC layer, reordering at the RLC layer, and duplicate detection and discard functionality at the RLC layer are disabled for the reduced overhead radio bearer, and associated information is excluded from the reduced overhead radio bearer at the RLC layer.

14. The method of claim 13 wherein the RLC AM header of the reduced overhead radio bearer comprises only a first data/control bit that indicates whether an associated Protocol Data Unit, PDU, is a control or data PDU and a polling bit that indicates whether a RLC status report is requested.

15. The method of any one of claims 1 to 14 wherein the reduced overhead radio bearer comprises a single PDCP Protocol Data Unit, PDU, transmission, and a PDCP Sequence Number, SN, is excluded from the reduced overhead radio bearer at the PDCP layer.

16. The method of claim 15 wherein the reduced overhead radio bearer is associated to an implicit PDCP SN.

17. The method of any one of claims 1 to 16 wherein a fixed Quality of Service, QoS, to radio bearer mapping applicable to the reduced overhead radio bearer is configured and stored at both the first radio node (302) and the second radio node (304), and all or a part of the SDAP header is excluded from the reduced overhead radio bearer.

18. The method of any one of claims 1 to 17 wherein a Quality of Service, QoS, Flow Indicator, QFI, applicable to the reduced overhead radio bearer is configured and stored at both the first radio node (302) and the second radio node (304), and the QFI is excluded from the reduced overhead radio bearer at the SDAP layer.

19. The method of any one of claims 1 to 18 further comprising configuring (304) or receiving (304) a configuration of the reduced overhead radio bearer.

20. The method of any one of claims 1 to 19 wherein the first radio node (300) is a wireless communication device (212), and the method further comprising requesting (304A) permission to use a reduced overhead radio bearer.

21. The method of claim 20 wherein requesting (304A) permission to use a reduced overhead radio bearer comprises requesting (304A) permission to use a reduced overhead radio bearer during a random access procedure or during a connection establishment procedure.

22. The method of claim 20 wherein requesting (304A) permission to use a reduced overhead radio bearer comprises transmitting a random access preamble from a dedicated set of random access preambles for requesting permission to use a reduced overhead radio bearer.

23. The method of claim 20 wherein requesting (304A) permission to use a reduced overhead radio bearer comprises, during a random access procedure, transmitting a Msg3 comprising an indication of a request to use a reduced overhead radio bearer.

24. The method of any one of claims 1 to 23 wherein use of a reduced overhead radio bearer is configured by the radio access network for mobile terminated data transfers.

25. The method of claim 24 wherein the first radio node (300) is a radio access node (202; 206), and the method further comprising transmitting, to the second radio node (302; 212), an indication that a reduced overhead radio bearer is to be used, during a connection establishment procedure or in an associated uplink grant.

26. The method of any one of claims 1 to 23 wherein either the first radio node (300) or the second radio node (302) is a User Equipment, UE, (212), and use of a reduced overhead radio bearer is stored as part of a UE context of the UE (212).

27. The method of any one of claims 1 to 23 wherein use of the reduced overhead radio bearer is indicated by inclusion of a reserved Logical Channel Identity, LCID, or enhanced LCID, eLCID, value in the reduced overhead radio bearer at the MAC layer.

28. The method of any one of claims 1 to 23 wherein use of the reduced overhead radio bearer is indicated by inclusion of a reserved Logical Channel Identity, LCID, or enhanced LCID, eLCID, value in the reduced overhead radio bearer at the MAC layer, the reserved LCID or eLCID value being one of two or more reserved LCID or eLCID values mapped to different fixed headers or configurations.

29. The method of any one of claims 1 to 28 wherein one or more restrictions associated with use of a reduced overhead radio bearer are predefined or preconfigured, and the reduced overhead radio bearer is transmitted in accordance with the one or more restrictions.

30. The method of any one of claims 1 to 29 wherein whether a PHY CRC is included in the reduced overhead radio bearer and/or a size of the PHY CRC for the reduced overhead radio bearer is dynamically controlled.

31. A first radio node (300) for data transmission in a radio access network of a cellular communications system, the first radio node (300) adapted to: transmit (306) a reduced overhead radio bearer to a second radio node (302), the reduced overhead radio bearer being a radio bearer in which: a) a physical, PHY, layer cyclic redundancy check, CRC, is excluded; b) all or part of a Medium Access Control, MAC, header is excluded; c) all or part of a Radio Link Control, RLC, header is excluded; d) all or part of a Packet Data Convergence Protocol, PDCP, header is excluded; e) all or part of a Service Data Application Protocol, SDAP, header is excluded; or f) a combination of any two or more of (a) - (e).

32. The first radio node (300) of claim 31 wherein the first radio node (300) is further adapted to perform the method of any one of claims 2 to 30.

33. A first radio node (300) for data transmission in a radio access network of a cellular communications system, the first radio node (300) comprising processing circuitry (504; 604; 802) configured to cause the first radio node (300) to: transmit (306) a reduced overhead radio bearer to a second radio node (302), the reduced overhead radio bearer being a radio bearer in which: a) a physical, PHY, layer cyclic redundancy check, CRC, is excluded; b) all or part of a Medium Access Control, MAC, header is excluded; c) all or part of a Radio Link Control, RLC, header is excluded; d) all or part of a Packet Data Convergence Protocol, PDCP, header is excluded; e) all or part of a Service Data Application Protocol, SDAP, header is excluded; or f) a combination of any two or more of (a) - (e).

34. The first radio node (300) of claim 33 wherein the processing circuitry (504; 604; 802) is further configured to cause the first radio node (300) to perform the method of any one of claims 2 to 30.

35. A method performed by a second radio node (302) for data reception in a radio access network of a cellular communications system, the method comprising: receiving (306) a reduced overhead radio bearer from a first radio node (300), the reduced overhead radio bearer being a radio bearer in which: a) a physical, PHY, layer cyclic redundancy check, CRC, is excluded; b) all or part of a Medium Access Control, MAC, header is excluded; c) all or part of a Radio Link Control, RLC, header is excluded; d) all or part of a Packet Data Convergence Protocol, PDCP, header is excluded; e) all or part of a Service Data Application Protocol, SDAP, header is excluded; or f) a combination of any two or more of (a) - (e).

36. The method of claim 35 wherein the reduced overhead radio bearer is a radio bearer in which: i) all or part of RLC header is excluded from the radio bearer, and the all or part of the RLC header is static for: a respective connection between the first radio node (300) and the second radio node (302), the first radio node (300), or the second radio node (302); ii) all or part of a PDCP header is excluded from the radio bearer, and the all or part of the PDCP header is static for: a respective connection between the first radio node (300) and the second radio node (302), the first radio node (300), or the second radio node (302); iii) all or part of a SDAP header is excluded from the radio bearer, and the all or part of the SDAP header is static for: a respective connection between the first radio node (300) and the second radio node (302), the first radio node (300), or the second radio node (302); or iv) a combination of any two or more of (i) - (iii).

37. The method of claim 35 or 36 wherein the PHY layer CRC is excluded from the reduced overhead radio bearer, and the reduced overhead radio bearer supports error correction and integrity protection at a higher layer.

38. The method of claim 35 or 36 wherein the PHY layer CRC is excluded from the reduced overhead radio bearer, and the reduced overhead radio bearer supports integrity protection, including bit error detection, at a PDCP layer.

39. The method of any one of claims 35 to 38 wherein a logical channel identity, LCID, is excluded from the reduced overhead radio bearer at the MAC layer, the LCID being a static LCID.

40. The method of claim 39 wherein the LCID excluded from the reduced overhead radio bearer at the MAC layer is a static LCID used for a particular transmission type of the reduced overhead radio bearer.

41. The method of claim 40 wherein different static LCIDs are predefined or preconfigured for different transmission types (e.g., at both the first radio node (300) and the second radio node (302)).

42. The method of any one of claims 35 to 41 wherein a static transport block size is used for the reduced overhead radio bearer, and either or both of a MAC length indicator and a length format indicator are excluded from the reduced overhead radio bearer at the MAC layer.

43. The method of claim 42 wherein either or both of the MAC length indicator and the length format indicator is/are predefined or preconfigured.

44. The method of any one of claims 35 to 43 wherein the reduced overhead radio bearer comprises a single RLC Acknowledgment Mode, AM, data Protocol Data Unit,

PDU, transmission or a single RLC Unacknowledged Mode, UM, data PDU transmission, and a RLC Sequence Number, SN, is excluded from the reduced overhead radio bearer at the RLC layer.

45. The method of claim 44 wherein an implicit RLC SN is associated to the signal RLC AM data PDU transmission or the single RLC UM data PDU transmission.

46. The method of any one of claims 35 to 43 wherein RLC Acknowledgment Mode, AM, functionality, concatenation at the RLC layer, segmentation at the RLC layer, reassembly at the RLC layer, reordering at the RLC layer, and/or duplicate detection and discard functionality at the RLC layer is/are disabled for the reduced overhead radio bearer, and associated information is excluded from the reduced overhead radio bearer at the RLC layer.

47. The method of any one of claims 35 to 43 wherein RLC Acknowledgment Mode, AM, functionality, concatenation at the RLC layer, segmentation at the RLC layer, reassembly at the RLC layer, reordering at the RLC layer, and duplicate detection and discard functionality at the RLC layer are disabled for the reduced overhead radio bearer, and associated information is excluded from the reduced overhead radio bearer at the RLC layer.

48. The method of claim 47 wherein the RLC AM header of the reduced overhead radio bearer comprises only a first data/control bit that indicates whether an associated Protocol Data Unit, PDU, is a control or data PDU and a polling bit that indicates whether a RLC status report is requested.

49. The method of any one of claims 35 to 48 wherein the reduced overhead radio bearer comprises a single PDCP Protocol Data Unit, PDU, transmission, and a PDCP Sequence Number, SN, is excluded from the reduced overhead radio bearer at the PDCP layer.

50. The method of claim 49 wherein the reduced overhead radio bearer is associated to an implicit PDCP SN.

51. The method of any one of claims 35 to 49 wherein a fixed Quality of Service,

QoS, to radio bearer mapping applicable to the reduced overhead radio bearer is configured and stored at both the first radio node (302) and the second radio node (304), and all or a part of the SDAP header is excluded from the reduced overhead radio bearer.

52. The method of any one of claims 35 to 49 wherein a Quality of Service, QoS,

Flow Indicator, QFI, applicable to the reduced overhead radio bearer is configured and stored at both the first radio node (302) and the second radio node (304), and the QFI is excluded from the reduced overhead radio bearer at the SDAP layer.

53. The method of any one of claims 35 to 52 further comprising configuring (304) or receiving (304) a configuration of the reduced overhead radio bearer.

54. The method of any one of claims 35 to 53 wherein the first radio node (300) is a wireless communication device (212), and the method further comprising receiving (304A) a request from the first radio node (300) for permission to use a reduced overhead radio bearer, and granting (304B) the first radio node (300) permission to use a reduced overhead radio bearer.

55. The method of claim 54 wherein receiving (304A) the request for permission to use a reduced overhead radio bearer comprises receiving (304A) the request for permission to use a reduced overhead radio bearer during a random access procedure or during a connection establishment procedure.

56. The method of claim 54 wherein receiving (304A) the request for permission to use a reduced overhead radio bearer comprises receiving a random access preamble from a dedicated set of random access preambles for requesting permission to use a reduced overhead radio bearer.

57. The method of claim 54 wherein receiving (304A) the request for permission to use a reduced overhead radio bearer comprises, during a random access procedure, receiving a Msg3 comprising an indication of a request to use a reduced overhead radio bearer.

58. The method of any one of claims 35 to 57 wherein use of a reduced overhead radio bearer is configured by the radio access network for mobile terminated data transfers.

59. The method of any one of claims 35 to 57 wherein either the first radio node (300) or the second radio node (302) is a User Equipment, UE, (212), and use of a reduced overhead radio bearer is stored as part of a UE context of the UE (212).

60. The method of any one of claims 35 to 57 wherein use of the reduced overhead radio bearer is indicated by inclusion of a reserved Logical Channel Identity, LCID, or enhanced LCID, eLCID, value in the reduced overhead radio bearer the MAC layer.

61. The method of any one of claims 35 to 57 wherein use of the reduced overhead radio bearer is indicated by inclusion of a reserved Logical Channel Identity, LCID, or enhanced LCID, eLCID, value in the reduced overhead radio bearer the MAC layer, the reserved LCID or eLCID value being one of two or more reserved LCID or eLCID values mapped to different fixed headers or configurations.

62. The method of any one of claims 35 to 61 wherein one or more restrictions associated with use of a reduced overhead radio bearer are predefined or preconfigured, and the reduced overhead radio bearer is transmitted in accordance with the one or more restrictions.

63. The method of any one of claims 35 to 62 wherein whether a PHY CRC is included in the reduced overhead radio bearer and/or a size of the PHY CRC for the reduced overhead radio bearer is dynamically controlled.

64. A second radio node (302) for data reception in a radio access network of a cellular communications system, the second radio node (302) adapted to: receive (306) a reduced overhead radio bearer from a first radio node (300), the reduced overhead radio bearer being a radio bearer in which: a) a physical, PHY, layer cyclic redundancy check, CRC, is excluded; b) all or part of a Medium Access Control, MAC, header is excluded; c) all or part of a Radio Link Control, RLC, header is excluded; d) all or part of a Packet Data Convergence Protocol, PDCP, header is excluded; e) all or part of a Service Data Application Protocol, SDAP, header is excluded; or f) a combination of any two or more of (a) - (e).

65. The second radio node (302) of claim 64 wherein the second radio node (302) is further adapted to perform the method of any of claims 36 to 63.

66. A second radio node (302) for data reception in a radio access network of a cellular communications system, the second radio node (302) comprising processing circuitry (504; 604; 802) configured to cause the second radio node (302) to: receive (306) a reduced overhead radio bearer from a first radio node (300), the reduced overhead radio bearer being a radio bearer in which: a) a physical, PHY, layer cyclic redundancy check, CRC, is excluded; b) all or part of a Medium Access Control, MAC, header is excluded; c) all or part of a Radio Link Control, RLC, header is excluded; d) all or part of a Packet Data Convergence Protocol, PDCP, header is excluded; e) all or part of a Service Data Application Protocol, SDAP, header is excluded; or f) a combination of any two or more of (a) - (e).

67. The second radio node (302) of claim 66 wherein the processing circuitry (504; 604; 802) is further configured to cause the second radio node (302) to perform the method of any of claims 36 to 63.