US20180184415A1

US20180184415A1 - Method and system for performing network slicing in a radio access network

Info

Publication number: US20180184415A1
Application number: US15/905,477
Authority: US
Inventors: Lu Rong; Jianglei Ma; Peiying Zhu; Wen Tong; Kelvin Kar Kin Au
Original assignee: Huawei Technologies Co Ltd
Current assignee: Huawei Technologies Co Ltd
Priority date: 2015-12-08
Filing date: 2018-02-26
Publication date: 2018-06-28
Also published as: EP3378197A1; EP3378197A4; CN112333001A; CN108353008A; EP3378263A1; EP3378251A4; CN108370587B; US10536946B2; KR102113018B1; BR112018011546A2; WO2017098441A1; CN108370587A; CN108370530B; US20180176900A1; EP3378263A4; CN112333001B; JP6626204B2; EP3378197B1; EP3381236A4; JP2018538751A

Abstract

Systems and methods of performing handover for a user equipment between hyper cells are provided. Handover is done on a per service basis. In some cases, a handover of one service from a source cell to target cell is performed while continuing to use the source cell, the target cell, or another cell for another service. In some cases the handover for a user equipment is from a source cell to a target cell in respect of one of uplink and downlink communications, and the user equipment continues to use the source cell for the other of uplink and downlink communications.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of PCT Application No. PCT/CN2016/109050, filed Dec. 8, 2016, which claims priority to U.S. patent application Ser. No. 15/356,124 filed Nov. 18, 2016 and to U.S. Provisional Patent Application No. 62/264,629 filed Dec. 8, 2015, all of which applications are hereby incorporated herein by reference.

TECHNICAL FIELD

The present invention relates to systems and method for performing handover of a mobile device between hyper cells in a wireless network.

BACKGROUND

In designing mobile networks, an architecture has arisen in which the network can be divided into a Core Network (CN) and a Radio Access Network (RAN). The RAN provides wireless communication channels to User Equipment (UE), while the CN is typically comprises of nodes and functions making use of fixed links. In the RAN, fronthaul and backhaul connections often rely on wired connections, although some wireless connections (typically between fixed points) are present. The RAN has different requirements and issues to address than the CN.
With planning for next generation networks, and researching techniques that can enable such networks, network slicing has drawn attention for the benefits that it can provide in the CN. When combined with such techniques as Network Function Virtualization (NFV) and Software Defined Networking (SDN), network slicing can allow for the creation of Virtual Networks (VNs) atop a general pool of compute, storage and communications resources. These VNs can be designed with control over in-network topology, and can be designed with traffic and resource isolation so that traffic and processing within one slice is isolated from traffic and processing demands in another slice. By creating network slices, isolated networks can be created with characteristics and parameters specifically suited to the needs of the traffic flows intended for the slice. This allows for a single pool of resources to be divided up to service very specific and disparate needs, without requiring that each slice be able to support the demands of the services and devices supported by other slices. Those skilled in the art will appreciate that a CN that has been sliced, may appear to the RAN as a plurality of core networks, or there may be a common interface, with each slice identified by a slice identifier. It should also be understood that while a slice may be tailored to the traffic patterns of the flows that it is intended to carry, there may be multiple services (typically with similar requirements) carried within each slice. Each of these services is typically differentiated by a service identifier.
In creating a sliced core network, it should be understood that typically the resource pool that is being drawn upon for slice resources is somewhat static. The compute resources of a data center are not considered to be dynamic on a short term basis. The bandwidth provided by a communications link between two data centers, or between two functions instantiated within a single data center does not typically have dynamic characteristics.
The topic of slicing within a Radio Access Network has arisen in some discussions. RAN slicing poses problems not encountered with slicing in the CN. Issues associated with dynamic channel quality on the radio link to the UE, provision of isolation for transmissions over a common broadcast transmission medium, and how RAN and CN slices interact, have to be addressed to usefully enable Ran slicing in mobile wireless networks.
In Third Generation and Fourth Generation (3G/4G) network architecture, a base station, base transceiver station, NodeB, and evolved NodeB (eNodeB) have been the terms used to refer to the wireless interface to the network. In the following, a generic Access Point is used to denote the wireless edge node of the network. An Access Point will be understood to be any of a Transmission Point (TP), a Receive Point (RP) and a Transmit/Receive Point (TRP). It will be understood that the term AP can be understood to include the above mentioned nodes, as well as their successor nodes, but is not necessarily restricted to them.
Through the use of SDN and NFV, functional nodes can be created at various points in the network and access to the functional nodes can be restricted to sets of devices, such as UEs. This allows what has been referred to as Network Slicing in which a series of virtual network slices can be created to serve the needs of different virtual networks. Traffic carried by the different slices can be isolated from the traffic of other slices, which allows for both data security and easing of network planning decisions.
Slicing has been a used in core networks due to the ease with which virtualized resources can be allocated, and the manner in which traffic can be isolated. In a Radio Access Network, all traffic is transmitted over a common resource which has made traffic isolation effectively impossible. The benefits of network slicing in the Radio Access Network are numerous, but the technical obstacles to designing and implementing an architecture have resulted in a lack of network slicing at the radio edge.
Conventionally, a cell is associated with a TRP (e.g. an eNB in LTE). Very often, a cell is the geographic area provided coverage by a TRP. Cells are arranged so that a mobile device, such as a User Equipment (UE) can remain connected to a serving cell as it moves. In the ideal, as the strength of coverage from a first cell decreases, the UE will be able to connect to a second cell. Very often there are regions at the edge of cells in which a UE can “see” more than one cell. This results in some problems such as poor cell-edge throughput, frequent handover, etc. To solve these problems, in some proposed next generation mobile network proposals a cell may be no longer associated to a fixed TRP. Instead, a hyper cell may be associated with a set of TRPs and certain frequency bands which can provide certain services for the user equipment (UE). Services that are supported by a network operator can fall within a range of categories, including for example: enhanced mobile broadband (eMBB) communications such as bi-directional voice and video communications; messaging; streaming media content delivery; ultra-reliable and low latency communications (URLLC); and massive Machine Type Communications (mMTC). Each of these categories could include multiple types of services—for example intelligent traffic systems and eHealth services could both be categorized as types of URLL services. Existing handover procedures, for example those shown in 3GPP TS 36.300 V12.0.0, section 10.1.2.1.1: Intra-mobility management entity (MME)/Serving Gateway Handover (SGW) handover (HO), are not suitable for handing off between hyper cells.

SUMMARY

Systems and methods of performing handover for a user equipment between hyper cells are provided. Handover is done on a per service basis. In some cases, a handover of one service from a source cell to target cell is performed while continuing to use the source cell, the target cell, or another cell for another service. In some cases the handover for a user equipment is from a source cell to a target cell in respect of one of uplink and downlink communications, and the user equipment continues to use the source cell for the other of uplink and downlink communications.
A first broad aspect of the invention provides a method in a UE comprising communicating with at least one first serving cell to send or receive each of a plurality of packet streams. For each of at least one service, uplink communications for the service comprises one of said plurality of packet streams or downlink communications for the service comprises one of said plurality of packet streams or uplink communications for the service comprises one of said plurality of packet streams and downlink communications for the service comprises one of said plurality of packet streams. The method includes transmitting at least one measurement report or transmitting a reference signal. In response to instructions, a handover is completed from one of the at least one serving cell to a target serving cell in respect of at least one of the plurality of packet streams. After the handover, the UE continues to communicate with one of the at least one first serving cell to send or receive one of the plurality of packet streams.
In some embodiments, the handover can be completed without performing a synchronization in the second cell in respect of the second service. In other embodiments the handover can be completed by performing a synchronization in the second cell in respect of the second service. In embodiments, the handovers can be either intra-MME/SGW handovers or inter-MME/SGW handovers. In other embodiments the method can further comprise, while in an inactive state, the UE transmitting a signal to let the network determine that the UE is moving into a new cell, and the UE receiving a message indicating a cell ID of a new cell.
According to a second broad aspect, the invention provides a method in an access network comprising a plurality of cells, each cell comprising at least one access point. The method includes communicating with a UE using at least one first serving cell of said plurality of cells to send or receive each of a plurality of packet streams, wherein for each of at least one service, uplink communications for the service comprises one of said plurality of packet streams or downlink communications for the service comprises one of said plurality of packet streams or uplink communications for the service comprises one of said plurality of packet streams and downlink communications for the service comprises one of said plurality of packet streams. The method continues with receiving at least one measurement report or receiving a reference signal. Instructions are transmitted to the UE to complete a handover from one of the at least one serving cell to a target serving cell of said plurality of cells in respect of at least one of the plurality of packet streams. After the handover, the method involves continuing to communicate with the UE with one of the at least one first serving cell to send or receive one of the plurality of packet streams.
In some embodiments, the handover in either aspect referred to above is from a source cell to a target cell for a first service while continuing to use another cell for a second service. In other embodiments, the handover in either aspect referred to above is from a source cell to a target cell for a first service while continuing to use the target cell for a second service. In other embodiments, the handover in either aspect referred to above is from a source cell to a target cell for uplink communications for a service while continuing to use the source cell for downlink communications for the service. In some embodiments, the handover in either aspect referred to above is from a source cell to a target cell for downlink communications for a service while continuing to use the source cell for uplink communications for the service. Further embodiments provide a user equipment configured to perform one of the methods summarized above or disclosed herein. Further embodiments provide an access network configured to perform one of the methods summarized above or disclosed herein.
Those skilled in the art will appreciate that these embodiments may be combined with other listed embodiments, or may be implemented alone as a variation of the aspects.

BRIEF DESCRIPTION OF THE DRAWINGS

For a more complete understanding of the present invention, and the advantages thereof, reference is now made to the following descriptions taken in conjunction with the accompanying drawing, in which:

FIG. 1 is a schematic diagram of an example communications system suitable for implementing various examples described in the present disclosure;

FIG. 2 is a schematic diagram illustrating an example set of parameters that are defined by a RAN slice manager for a service specific RAN slice instance according to example embodiments;

FIG. 3 is a schematic diagram illustrating an example of slice based service isolation in a RAN;

FIG. 4 is a schematic diagram illustrating dynamic slice allocations for different services on a common carrier according to example embodiments;

FIG. 5 is a schematic diagram illustrating a further example of slice based service isolation in a RAN;

FIG. 6 is a schematic diagram illustrating a UE connecting to multiple slices over different access technologies;

FIG. 7 is a schematic diagram, illustrating service customized virtual networks implemented using slices according to example embodiments;

FIG. 8 is a schematic diagram of an example processing system suitable for implementing various examples described in the present disclosure;

FIG. 9 is an illustration of an architecture for routing traffic from a Core Network Slice to a RAN slice in accordance with disclosed embodiments;

FIG. 10 is a flow chart illustrating a method for routing downlink traffic received from a core network slice to an AP in accordance with disclosed embodiments;

FIG. 11 is a flow chart illustrating a method for execution by an access point in accordance with disclosed embodiments;

FIG. 12 is an illustration of an architecture, similar to that of FIG. 9, for routing traffic from a core network slice to a RAN slice in accordance with disclosed embodiments;

FIG. 13 is a flow chart illustrating a method for execution by a network controller in accordance with disclosed embodiments;

FIG. 14A is a diagram illustrating a radio access system based on hyper cells;

FIG. 14B is diagram of the network of FIG. 1A in which the TRPs are arranged in two hyper cells;

FIG. 14C is diagram of the network of FIG. 1A in which some of the TRPs are arranged in a third hyper cell;

FIG. 14D is a flowchart of a method of performing a handover provided by an embodiment of the invention from the perspective of a UE;

FIG. 14E is a flowchart of a method of performing a handover provided by an embodiment of the invention from the perspective of the network;

FIG. 15 shows an example of handover of a service from a source hyper cell to a target cell, while maintaining use of other serving hyper cells for another service;

FIG. 16 shows an example of handover of a service from a source hyper cell to a target cell, while maintaining use of the source hyper cell for another service;

FIG. 17 shows an example of handover of a service from a source hyper cell to a target hyper cell, where the UE was already using the target hyper cell for another service;

FIG. 18 shows an example of handover of a service from a source hyper cell to a target cell for uplink communications only, while maintaining use of the source hyper cell for downlink communications;

FIG. 19 shows an example of handover of a service from a source hyper cell to a target cell for downlink communications only, while maintaining use of the source hyper cell for uplink communications; and

FIG. 20 is a flowchart illustrating a method for execution at a UE.

DETAILED DESCRIPTION OF ILLUSTRATIVE EMBODIMENTS

Software Defined Networking (SDN) and Network Function Virtualization (NFV) have been used to enable network slicing in a physical core network. Network slicing involves allocating resources, such as compute, storage, and connectivity resources, to create otherwise isolated virtual networks. From the perspective of a network entity inside a slice, the slice is a distinct and contained network. Traffic carried on a first slice is invisible to a second slice, as are any processing demands within the first slice. In addition to isolating networks from each other, slicing allows for each slice to be created with a different network configuration. Thus, a first slice can be created with network functions that can respond with very low latency, while a second slice can be created with very high throughput. These two slices can have different characteristics, allowing for the creation of different slices to service the needs of specific services. A network slice is a dedicated logical (also referred to as virtual) network with service specific functionalities, and can be hosted on a common infrastructure with other slices. The service specific functionalities associated with a network slice can, for example, govern geographical coverage areas, capacity, speed, latency, robustness, security and availability. Traditionally, network slicing has been limited to the core network, in view of the difficulties in implementing slicing in a Radio Access Network (RAN). However example embodiments will now be described for implementing RAN slicing. In at least some examples, RAN slicing and network core slicing are coordinated to provide end-to-end slicing that can be used to provide service-specific network slices extending across the entire core network and RAN communications infrastructure.
Radio resources allocated to a RAN are typically a set of wireless network rights granted to a network operator which may include for example one or more specified radio frequency bandwidths within one or more geographic regions. A network operator typically enters into service level agreements (SLAs) with customers that specify the level of service that the network operator must provide. Services that are supported by a network operator can fall within a range of categories, including for example: basic mobile broadband (MBB) communications such as bi-directional voice and video communications; messaging; streaming media content delivery; ultra-reliable low latency (URLL) communications; micro Machine Type Communications (μMTC); and massive Machine Type Communications (mMTC). Each of these categories could include multiple types of services—for example intelligent traffic systems and eHealth services could both be categorized as types of URLL services. In some examples, a network slice may be assigned for a service for a group of customers (for example smart phone subscribers in the case of mobile broadband), and in some examples a network slice may be assigned for a single customer (for example, an organization that is providing intelligent traffic systems).
FIG. 1 is a schematic diagram of an example communications system or network 100, in which examples described in the present disclosure may be implemented. The communications network 100 is controlled by one or more organizations and includes a physical core network 130 and a Radio Access Network (RAN) 125. In some examples, the core network 130 and RAN 125 are controlled by a common network operator, however in some examples the core network 130 and RAN 125 are controlled by different organizations. In some embodiments, multiple RANs 125, at least some of which are controlled by different network operators, may be connected to a core network 130 that is controlled by one or more of the network operators or by an independent organization. Core Network 130 is sliced, and shown having CN Slice 1 132, CN Slice 2 134, CN Slice 3 136 and CN Slice 4 138. It should also be understood, as will be discussed in more detail below, that a plurality of core networks can make use of the same RAN resources.
An interface between the core network 130 and RAN 125 is provided to allow traffic from CN 130 to be directed towards UEs 110 through access points (APs) 105, which may be base stations, such as an evolved Node B (eNB) in the Long-Term Evolution (LTE) standard, a 5G node, or any other suitable nodes or access points. APs 105, also referred to as Transmit/Receive Points (TRPs), may serve a plurality of mobile nodes, generally referred to as UEs 110. As noted above, in the present description access point (AP) is used to denote the wireless edge node of the network. Thus, the APs 105 provide the radio edge of RAN 125, which may for example be a 5G wireless communication network. The UEs 110 may receive communications from, and transmit communications to, the AP's 105. Communications from the APs 105 to the UEs 110 may be referred to as downlink (DL) communications, and communications from the UEs 110 to the APs 105 may be referred to as uplink (UL) communications.
In the simplified example shown in FIG. 1, network entities within the RAN 125 may include a resource allocation manager 115, a scheduler 120, and a RAN slice manager 150, which may in some embodiments be under the control of the network operator who controls RAN 125. The resource allocation manager 115 may perform mobility-related operations. For example, the resource allocation manager 115 may monitor the mobility status of the UEs 110, may oversee handover of a UE 110 between or within networks, and may enforce UE roaming restrictions, among other functions. The resource allocation manager 115 may also include an air interface configuration function. The scheduler 120 may manage the use of network resources and/or may schedule the timing of network communications, among other functions. RAN slice manager 150 is configured for implementing RAN slicing, as described in greater detail below. It should be understood that in some embodiments, the scheduler 120 is a slice specific scheduler and is specific to the RAN slice, and not common to the RAN. Those skilled in the art will further appreciate that in some embodiments, some slices will have a slice specific scheduler, while other slices will make use of a common RAN scheduler. A common RAN scheduler may also be used to coordinate between slice specific schedulers so that the common RAN resources are properly scheduled.
In example embodiments, the core network 130 includes a core network slice manager 140 for implementing (and optionally managing) core network slicing. As shown in FIG. 1, Core Network 130 has four illustrates slices CN Slice 1 132, CN Slice 2 134, CN Slice 3 136 and CN Slice 4 138. These slices can, in some embodiments, appear to the RAN as distinct Core Networks. The UEs 110 may include any client devices, and may also be referred to as mobile stations, mobile terminals, user devices, client devices, subscriber devices, sensor devices, and machine type devices for example.
Next generation wireless networks (e.g. fifth generation, or so-called 5G networks) are likely to support a flexible air interface in RAN 125 that allows for the use of different waveforms, and different transmission parameters of each of the waveforms (e.g. different numerology for some of the supported waveforms), different frame structures, as well as different protocols. Similarly, to take advantage of a large number of APs 105, which may take the form of both macro and pico-cell sized transmission points operating in different frequency bands, it is possible that a 5G network will group a series of APs 105 to create a virtual transmission point (vTP). The coverage area of a vTP may be referred to by some as a hyper-cell. By coordinating the transmission of signals from the APs 105 in the virtual TP, the network 125 can improve capacity and coverage. Similarly, a grouping of APs 105 can be formed to create a virtual receive point (vRP) that allows for multipoint reception. By varying the APs 105 in the virtual groups, the network 100 can allow the virtual TP and RP associated with an UE 110 to move through the network.
From the perspective of a network operator, deploying network infrastructure can be very expensive. Maximizing the utilization of the deployed infrastructure, and the wireless resources, is of importance to allow network operators to recover their investments. The following disclosure provides systems and methods for enabling network slicing at the radio edge of RAN 125, and for facilitating routing of traffic between slices of the radio edge of RAN 125 and core network 130, which may also be sliced. In some examples, this can enable an end-to-end network slice, and allows network operators to then divide the network and provide service isolation in wireless connections within a single network infrastructure.
Referring to FIG. 2, in example embodiments the RAN slice manager 150 is configured to create and manage RAN slices 152. Each of the RAN slices 152 have a unique allocation of RAN resources. The RAN resources that are available for allocation can be categorized as: RAN access resources, which include
the AP's 105 and UEs 110;
radio resources, which include:
wireless network frequency and time (f/t) resources 158, and
spatial resources based on the geographic placement of APs 105 associated with the slice and based on the directionality of transmissions if advanced antenna technologies are applied; and
radio air interface configurations 160 that specify how the radio resources and the access resources interface with each other.
For an active UE obtaining service from multiple hyper cells for different services, the UE can perform respective handovers from multiple source hyper cells to one or more target hyper cells. A handover may be initiated by a handover request message in which the UE may indicate a desired target hyper cell to the network. For example, the handover request message may contain an information element indicating the cell ID of the target hyper cell. In some embodiments, this handover request may be sent to the source hyper cell of the same type as the target hyper cell or another hyper cell of a different type that the UE is associated with.
Upon receiving a handover request from a UE, the network may first determine the source hyper cell as the one (the UE is currently associated with) of the same type as the target hyper cell, and will then transfer the context of the UE from the source hyper cell to the target hyper cell.
During and after the handover, the UE may still keep connection with the previous hyper cells of different types as the target hyper cells.
In some embodiments, a UE may perform handover in multiple types of hyper cells at a time. In this case, a list of target hyper cells may be indicated in the handover request message. The network may determine a list of source hyper cells as those of the same type as the target hyper cells in the list.
Handover from One of Multiple Serving Cells
FIG. 15 shows an example of procedure provided by an embodiment of the invention for handover from one of the hyper cells a UE is associated with to a target hyper cell. The handover from one serving hyper cell (the source hyper cell) does not affect the packet data transmission between the UE and the other serving hyper cells. For example, the UE may handover from one eMBB hyper cell to another eMBB hyper cell, while still keeping its existing connections to a mMTC hyper cell and a URLLC hyper cell.
FIG. 15 shows transmissions between a UE 1504, a serving hyper cell which is to be a source hyper cell 1506 for a handover, and a hyper cell which is to be a target hyper cell 1508 for the handover. Also shown are other serving hyper cells 1502. These are other hyper cells 1502 that the UE 1504 is associated with, but which are not being handed off as part of this procedure. The various serving hyper cells 1502, 1506 may, for example, each be associated with a different service/slice. It should be understood that the method of FIG. 15 is a very detailed example and that these specific steps do not necessarily need to be performed. Some of the steps can be modified or omitted.
In step 1, measurement control message(s) may be transmitted to the UE 1504 from some of (one of, part of, or all of) the serving hyper cells (including the source hyper cell 1506 and the other hyper cells 1502). In some embodiments, the measurement control message transmitted from one serving hyper cell control the measurement for some or all of the serving hyper cells 1502, 1506. All the while, the UE 1504 is exchanging packet data with the serving hyper cells 1502, 1506. The measurement procedures may be configured according to context information for the UE 1504 in respect of one or multiple hyper cells. For example, the context may include information regarding roaming and access restrictions that were provided at either connection establishment or at a last timing advance update.
In step 2, measurement report(s) may be sent from the UE 1504 to one or more of the serving hyper cells 1502, 1506. In some embodiments, a serving hyper cell may forward the measurement report or some measurement report information in it to some other serving hyper cells. The measurement report indicates measurement results of downlink wireless channels obtained by the UE. What to measure may be configured by the network for the UE, for example by RRC signaling.
For this and other embodiments described herein, there are many different possible conditions to trigger a measurement report. For example:
serving cell becomes better than absolute threshold;
neighbour cell becomes better than an offset relative to the serving cell; and
neighbour cell becomes better than absolute threshold.
The cells that are reported in a given measurement report can depend on the trigger. For a given handover of a service, at least the source cell or the target cell is needed in the measurement report.
Optionally, for any of the embodiments described herein, the UE may transmit multiple measurement reports, each of them addressing one type of service.
After step 2, each serving hyper cell may separately determine whether handover is needed for it based on the measurement report for it. In other embodiments, the measurement reports may be sent to a network function that may make the determination of whether a handover is needed in accordance with a more global picture of the needs of the network than can be done by an entity within a specific hyper cell. In the example shown in FIG. 2, one serving hyper cell (the source hyper cell 1506) makes a handover decision at step 3 for the UE 1504 while the other serving hyper cells 1502 decide no handover is needed for the UE 1504.
Logically, the TRPs of a hyper cell can be viewed as a set of remote antennas of one cell. These may, for example, be sending signals generated by one BBU (which as noted above may be a discrete entity, or may be a virtualized entity within a computing resource). From the UE's perspective, it is communicating with the cell, and does not need to be aware of individual TRPs. In some embodiments there is a logical entity (for example part of the handover manager of FIG. 1 described previously) associated with each hyper cell that makes handover decisions for the hyper cell. This entity may be dedicated to a single hyper cell or it may be associated with a plurality of different hyper cells as discussed above.
In step 4, a handover request message is sent from the source hyper cell 1506 to the target hyper cell 1508. This may include information that can allow the target hyper cell 1508 to prepare for the handover on the target side. In step 5, Admission Control may be performed by the target hyper cell 1508, for example dependent on received quality of service (QoS) information to increase the likelihood of a successful handover, if the resources can be granted by target hyper cell 1508. As will be understood by those skilled in the art, admission control may include interaction with other network functions to carry out an admission control process. The target hyper cell 1508 can then configure the required resources according to the received E-RAB (radio access bearer) QoS information and reserve a C-RNTI and optionally a random access channel (RACH) preamble. The AS-configuration to be used in the target cell can either be specified independently (i.e. an “establishment”), as a delta compared to the AS-configuration used in the source cell (i.e. a “reconfiguration”), or it can be specified in other manners that will be apparent to those skilled in the art.
In Step 6, the target hyper cell 1508 prepares handover with L1/L2 and sends a HANDOVER REQUEST ACKNOWLEDGE message to the source hyper cell 1506. The HANDOVER REQUEST ACKNOWLEDGE message may include a transparent container to be sent to the UE 1504 as an RRC message to perform the handover. The container can include any or all of a new C-RNTI, target hyper cell security algorithm identifiers for the selected security algorithms, as well it may include a dedicated RACH preamble, and possibly some other parameters i.e. access parameters, SIBs, etc. The HANDOVER REQUEST ACKNOWLEDGE message may also include RNL/TNL information for the forwarding tunnels, if necessary.
Data forwarding can be initiated after the source hyper cell 1506 receives the HANDOVER REQUEST ACKNOWLEDGE message, or upon transmission of the handover command in the downlink.
In step 7, a RRC connection reconfiguration message is sent from the source hyper cell 1506 to the UE 1504, and this may indicate that the UE 1504 should handover from the source hyper cell 1506 to the target hyper cell 1508. This may, for example, involve the target hyper cell 1508 generating an RRC message to perform the handover, i.e.
RRCConnectionReconfiguration message including the mobilityControlInformation, to be sent by the source hyper cell 1506 towards the UE 1504. The source hyper cell 1506 may perform the integrity protection and ciphering of the message. The UE 1504 receives the RRCConnectionReconfiguration message with parameters (i.e. new C-RNTI, target eNB security algorithm identifiers, and optionally dedicated RACH preamble, target eNB SIBs, etc.) and is instructed by the source hyper cell 1506 to perform the handover. After step 7, the UE 1504 detaches from the source hyper cell 1506 and synchronize to the target hyper cell 1508. At this time the UE 1504 does not detach from the other serving hyper cells 1502.
Additional steps to help to avoid data loss during a handover may be performed. For example, in step 8, the source hyper cell 1506 can send a SN STATUS TRANSFER message to the target hyper cell 1508 to convey the uplink packet data convergence protocol (PDCP) SN receiver status and the downlink PDCP SN transmitter status of E-RABs for which PDCP status preservation applies (i.e. for RLC AM). The uplink PDCP SN receiver status includes at least the PDCP SN of the first missing uplink service data unit (SDU) and may include a bit map of the receive status of the out of sequence uplink SDUs that the UE 1504 needs to retransmit in the target cell, if there are any such SDUs. The downlink PDCP SN transmitter status can indicate the next PDCP SN that the target hyper cell 1508 assigns to new SDUs, not yet having a PDCP SN. The source hyper cell 1506 may omit sending this message if none of the E-RABs of the UE 1504 are treated with PDCP status preservation.
In step 9, after receiving the RRCConnectionReconfiguration message including the mobilityControlInformation, UE 1504 begins the synchronization to the target hyper cell 1508. This may involve the UE 1504 accessing the target cell 1508 via RACH, following a contention-free procedure if a dedicated RACH preamble was indicated in the mobilityControlInformation, or following a contention-based procedure if no dedicated preamble was indicated. UE 1504 can derive target hyper cell 1508 specific keys and configures the selected security algorithms to be used in the target cell 1508.
In step 10, the target hyper cell 1508 responds by transmitting uplink allocation and timing advance information to UE 1504.
In step 11, when the UE 1504 has successfully accessed the target cell, the UE 1504 sends the RRCConnectionReconfigurationComplete message (C-RNTI) to the target hyper cell 1508. This message can be used to confirm the handover, and may be sent along with an uplink Buffer Status Report, to the target hyper cell 1508 to indicate that the handover procedure is completed for the UE 1504. It will be understood that the transmission of an uplink Buffer Status Report may not always occur, but it may be advantageous in some embodiments to transmit the uplink Buffer Status Report if possible. The target hyper cell 1508 can verify the C-RNTI sent in the RRCConnectionReconfigurationComplete message. The target hyper cell 1508 can now begin sending data to the UE 1504.
Handover for Some of the Services in a Cell
FIG. 16 shows an example of a procedure 1600 provided by an embodiment of the invention for handover of some of the services for a UE 1602 from a source hyper cell 1604 to a target hyper cell 1606. With this example, the UE is obtaining multiple services in the source hyper cell 1604 and is handing over some, but not all of these services to a target hyper cell 1606.
With this embodiment, the handover for one service (or service set) B being obtained through a hyper cell does not affect the packet data transmission for another service (or service set) A being obtained through the same hyper cell. For example, a UE participating in both a URLLC service and an mMTC service in a hyper cell may handover its mMTC service to a new hyper cell, while still transmitting traffic associated with the URLLC service to the old hyper cell.
In step 3, the source hyper cell 1604 decides to handover for service B to the target hyper cell 1606 and not to handover for service A. It will be understood that this may involve the participation of a network function that transmits instructions to the source hyper cell 1604 to initiate a handover.
In step 4, the source hyper cell 1604 sends a handover request message to the target hyper cell 1606. This handover request message requesting handover of traffic associated with service B.
In step 7, the source hyper cell 1604 sends a message to the UE 1602 to indicate that the UE 1602 is perform a handover of traffic associated with service B (but not for service A) to the target hyper cell 1606.
After receiving the message in step 7, the UE 1602 synchronizes to the target cell 1606 without detaching from the source cell 1604. The packet data for service A may still be transmitted in the source hyper cell 1604.
After the handover execution, the packet data for service B is transmitted through target hyper cell 1606.
In step 12, the target hyper cell 1606 sends a message to the source hyper cell 1604 to inform that the UE 1602 has changed its cell for service B. This allows source hyper cell 1604 to release the resources associate with service B.
Handover to a Serving Cell
FIG. 17 shows an example of a procedure 1700 provided by an embodiment of the invention for handover from one serving hyper cell to another serving hyper cell. In this case, there is a UE 1702 that is obtaining a first service (or service set) B with source hyper cell 1704, and is obtaining a second service (or service set) A with a serving hyper cell which is to be a target hyper cell 1706 for a handover in respect of the first service set B from the source hyper cell 1704. As shown in the figure, the handover for service (or service set) B does not affect the packet data transmission for service (or service set) A. For example, a UE using mMTC service in the source hyper cell and URLLC service in the target hyper cell may handover its mMTC service to the target hyper cell, thus enjoying both mMTC service and URLLC service in the target hyper cell.
In step 3, the source hyper cell 1704 decides the UE 1702 should handover (for service B) to the target hyper cell 1706.
After receiving the message in step 7, the UE 1702 may not need to do additional synchronization to the target hyper cell 1706 because it is already synchronized to the target hyper cell 1706 to use service A. However, if service B requires different synchronization from service A, then the UE 1702 may still perform synchronization.
After the execution of the handover, the packet data for both service A and service B is transmitted through the target hyper cell 1706.
In step 12, the target hyper cell 1706 can send a message to the source hyper cell 1704 to inform the source hyper cell 1704 that the UE 1702 has changed its cell for service B and thus the resources for service B in the source hyper cell can be released.
Handover in Uplink Only
FIG. 18 shows an example of a procedure 1800 provided by an embodiment for handover in the uplink from one hyper cell to another without handover in the downlink. In this case, there is a UE 1802 that is performing both uplink and downlink communications for a first service (or service set) with source hyper cell 1804, and there is a target hyper cell 1806 that is the target of a handover in respect of the uplink only for the service from the source hyper cell 1804. Also shown is a serving gateway (GW) 506. As illustrated in FIG. 18, handover of responsibility for the uplink connection does not affect the packet data transmission to the UE 1802 in the downlink direction. For example, the UE 1802 may handover its uplink mMTC service to a new hyper cell while remaining connected to the old cell for the other services (and possibly for the downlink traffic of the mMTC service).
In step 2, the UE 1802 sends downlink measurement reports and/or uplink reference signals such as sounding signals for the network to perform uplink measurement.
In step 3, the source hyper cell 1804 makes a decision that uplink handover is needed for the UE 1802 without downlink handover based on the measurement results.
In step 4, the source hyper cell 1804 sends an uplink handover request message to the target hyper cell 1806. This message may indicate that uplink handover without downlink handover is requested.
In step 7, the source hyper cell 1804 sends a message to the UE 1802 to indicate that the UE 1802 is to perform a handover of uplink traffic without a corresponding handover of downlink traffic.
After receiving the message in step 7, the UE 1802 synchronizes to the target hyper cell 1806 without detaching from the source cell.
After execution of the handover, the UE 1802 sends uplink packets to the target hyper cell 1806 and receives downlink packets from the source hyper cell 1804.
After receiving the RRC connection reconfiguration complete message from the UE 1802, the target hyper cell 1806 does not need to send a path switch request to the MME. The target hyper cell 1806 will receive uplink packets from the UE 1802 and forwards them to a gateway function such as serving GW 506.
In step 12, the target hyper cell 1806 sends a message to the source hyper cell 1804 to inform the source hyper cell 1804 that the UE 1802 has changed its uplink cell and thus the resources for uplink transmissions in the source hyper cell 1804 can be released.
Handover in Downlink Only
FIG. 19 shows an example of a procedure 1900 provided by an embodiment of the invention for handover in downlink from one hyper cell to another without handover of traffic in the uplink direction. In this example, there is a UE 1902 that is communicating both uplink and downlink traffic associated with a first service (or service set) with source hyper cell 1904. There is a target hyper cell 1906 that is the target of a handover in respect of only the downlink traffic associated with a first service or a first service set from the source hyper cell 1904. As shown in the figure, the handover in the downlink does not affect the packet data transmission to the UE 1902 in the uplink. For example, the UE 1902 may handover its downlink multimedia broadcast multicast service (MBMS) service to a new cell while, which still staying in the old cell for the other services.
In step 2, the UE 1902 sends downlink measurement reports and/or uplink reference signals such as sounding signals to the source hyper cell 1904. These reports can be used by an entity within the network to perform uplink measurement.
In step 3, the source hyper cell 1904 makes a decision (or is informed of a decision made by another network entity) that a handover of downlink for the UE 1902 without a corresponding uplink handover should be performed. This determination may have been made in accordance with the measurement results.
In step 4, the source hyper cell 1904 sends a downlink handover request message to the target hyper cell 1906. This message may indicate that downlink handover without uplink handover is requested.
In step 7, the source hyper cell 1904 sends a message to the UE 1902 instructing UE 1902 to perform a handover of downlink traffic to target hyper cell 1906 without a corresponding uplink handover.
After receiving the message in step 7, the UE 1902 begins the synchronization process to synchronize to the target hyper cell 1906 without detaching from the source hyper cell 1904. Uplink synchronization and Tracking Area (TA) adjustment may not be required in all instances as the UE 1902 does not need to send uplink packets in the target cell.
After the handover execution, the UE 1902 sends downlink packets to the target hyper cell 1906 and receives uplink packets from the source hyper cell 1904.
In step 12, the target hyper cell 1906 sends a message to the source hyper cell 1904 to inform that the UE 1902 has changed its downlink cell and thus the resources for downlink transmissions in the source hyper cell 1904 can be released.
FIGS. 15-19 illustrate the procedures suitable for intra-MME/S-GW uplink handover. In some embodiments, a MME is connected to multiple hyper cells and controls intra-MME handover and functions as the hyper cell manager of FIG. 14A. In further embodiments, these procedures are extended to cover other handover scenarios such as inter-MME uplink handover and inter-serving gateway (SGW) uplink handover without downlink handover. An SGW (not shown in FIG. 14) may be connected to multiple handover managers/MMEs. In the scenarios, the handover in some of the services does not affect the transmission of packet data for the other services.
In some embodiments, for an inactive UE, the UE may send a signal to let the network know if the UE is moving into another hyper cell. Then the network may assign it a new connection ID if needed. This connection ID may be used in grant free transmissions to identify the UE or in generation of uplink reference signals to avoid conflict or interference in the hyper cell. Two possible ways for the UE to obtain a new connection ID for the target hyper cell include:
a. Generate the connection ID according to the cell ID of the target hyper cell. E.g., the connection ID for a UE may be associated with both a UE ID and the cell ID of the hyper cell serving it. In this case, the connection ID may change naturally as the UE moves into a new hyper cell; and
b. Use a new connection ID assigned by the network for the UE in the target hyper cell. E.g., the UE may send a message to the network indicating the cell ID of the target hyper cell, and then receive a message from the network assigning a new connection ID for the UE.
In one embodiment, the UE sends an uplink reference signal for the network to detect. The network may make a decision on whether the UE should be served by another hyper cell based on the measurement results of one or more access points in a hyper cell. If the network decides to use another hyper cell to serve the UE, it may send a message to inform the UE of the target hyper cell it shall be associated with (in some embodiments this message will include an ID of the selected hyper cell). The message may contain a new connection ID for the UE to use in the target hyper cell. The message may also indicate the condition for this new connection ID to be applied. E.g., it may indicate that this new connection ID should be applied when the reference signal received power (RSRP) of the source hyper cell is below a threshold, when the reference signal received quality (RSRQ) of the target hyper cell is above a threshold, or when a timer times out, or any combination of the above. The message may also indicate the ID of the target hyper cell(s) that the new connection ID can be used in.
When the UE is served by multiple hyper cells, the message the network sent to the UE may also indicate which one out of them should no longer be used. This indication may be explicit, e.g., realized by indicating in the message the source hyper cell or the connection ID to be released. It may also be implicit, e.g., realized by sending the message from the source hyper cell to the UE.
In another embodiment, the UE sends a message to the network to request for a new connection ID or to indicate that it is moving into another hyper cell. Such a message may be triggered by a condition pre-defined or indicated by the network. It may contain the ID of the target hyper cell. The network may response with a message to indicate the connection ID that the UE can use in the target hyper cell. This new connection ID may be the current connection ID (if there is no conflict in the target hyper cell), a new connection ID derived by UE according to certain rules (e.g., as a function of the ID of the target hyper cell), or a new connection ID assigned in the message.
When the UE is served by multiple hyper cells, the message the UE sent to the network may also indicate which one out of them is the source hyper cell. This indication may be explicit, e.g., realized by indicating in the message the source hyper cell or connection ID to be released. It may also be implicit, e.g., realized by sending the message to the source hyper cell.
As noted above, FIG. 8 is a schematic diagram of an example simplified processing system 400. As discussed above, the processing system 400 can be used to implement the methods and systems disclosed herein, and the example methods described below. The UEs, access points, hyper cell managers and handover managers may be implemented using the example processing system 400, or variations of the processing system 400. The processing system 400 may be a server or a mobile device, for example, or any suitable processing system. Other processing systems suitable for implementing examples described in the present disclosure may be used, which may include components different from those discussed below. Although FIG. 7 shows a single instance of each component, there may be multiple instances of each component in the processing system 400.
The processing system 400 may include one or more processing devices 405, such as a processor, a microprocessor, an application-specific integrated circuit (ASIC), a field-programmable gate array (FPGA), a dedicated logic circuitry, or combinations thereof. The processing system 400 may also include one or more input/output (I/O) interfaces 410, which may enable interfacing with one or more appropriate input devices 435 and/or output devices 440. The processing system 400 may include one or more network interfaces 415 for wired or wireless communication with a network (e.g., an intranet, the Internet, a P2P network, a WAN and/or a LAN) or other node. The network interfaces 415 may include wired links (e.g., Ethernet cable) and/or wireless links (e.g., one or more antennas) for intra-network and/or inter-network communications. The network interfaces 415 may provide wireless communication via one or more transmitters or transmit antennas and one or more receivers or receive antennas, for example. In this example, a single antenna 445 is shown, which may serve as both transmitter and receiver. However, in other examples there may be separate antennas for transmitting and receiving. The processing system 400 may also include one or more storage units 420, which may include a mass storage unit such as a solid state drive, a hard disk drive, a magnetic disk drive and/or an optical disk drive.
The processing system 400 may include one or more memories 425, which may include a volatile or non-volatile memory (e.g., a flash memory, a random access memory (RAM), and/or a read-only memory (ROM)). The non-transitory memories 425 may store instructions for execution by the processing devices 405, such as to carry out examples described in the present disclosure. The memories 425 may include other software instructions, such as for implementing an operating system and other applications/functions. In some examples, one or more data sets and/or modules may be provided by an external memory (e.g., an external drive in wired or wireless communication with the processing system 400) or may be provided by a transitory or non-transitory computer-readable medium. Examples of non-transitory computer readable media include a RAM, a ROM, an erasable programmable ROM (EPROM), an electrically erasable programmable ROM (EEPROM), a flash memory, a CD-ROM, or other portable memory storage.
There may be a bus 430 providing communication among components of the processing system 400. The bus 430 may be any suitable bus architecture including, for example, a memory bus, a peripheral bus or a video bus. In FIG. 8, the input devices 435 (e.g., a keyboard, a mouse, a microphone, a touchscreen, and/or a keypad) and output devices 440 (e.g., a display, a speaker and/or a printer) are shown as external to the processing system 400. In other examples, one or more of the input devices 435 and/or the output devices 440 may be included as a component of the processing system 400.
In some of the embodiments of the above described method, the RAN resources can include any or all of: network access resources that connect the RAN to a physical core network; radio frequency and time resources of the RAN; and an air interface configuration specifying how the network access resources interface with the radio frequency resources of the RAN. Optionally, at least some of the RAN slices can have common allocations of network access resources and adjacent radio frequency resources, with differentiating air interface configurations being allocated to each of the at least some of the RAN slices to isolate the radio communications of the at least some of the RAN slices from each other. The air interface configurations may specify waveforms for the RAN slices and numerology to apply to the waveforms. The plurality of RAN slices can comprises first and second RAN slices for which the air interface configurations specify the same waveform but different numerologies. In this manner, a numerology can allow a degree of isolation between the slices, as a receiver associated with the first slice would not be able to properly decode data transmitted in the second slice due to the differing transmission numerology. In one such example, the common waveform can be an OFDMA waveform, and the numerologies associated with each slice can have a different combination of one or more of: sub-carrier spacing, cyclic prefix length, symbol length, a duration of a scheduled transmission duration and a number of symbols contained in a scheduled transmission duration.
In another embodiment, different network access resources and different combinations of time and radio frequency resources can be allocated to RAN slices to provide isolation.
Those skilled in the art will appreciate that this method allows for the association of RAN slices with respective core network slices (or services within the core network slices) to enable communications associated with service to use a RAN slice and its associated core slice.
In other embodiments, for at least one of the RAN slices, the network access resources comprise at least one logical transmit point for downlink communications and at least one logical receive point for uplink communications. The TP and RP can be based on different sets of physical access points. In some embodiments, there may be overlap between the membership of physical access points within the logical TP and RP. In other embodiments there may be no overlap. Even if the membership of the physical APs is identical, the assignment of different logical identifiers to a TP and RP associated with a slice create a logical distinction for a UE. It is also possible that a set of physical APs assigned to a TP or RP in one slice may differ from the set of physical APs assigned to a TP or RP in another slice. The membership of the TP or RP in any slice can be changed without informing the UE, so long as the logical TP or RP identifiers are maintained. A UE may be communicating with the same set of physical APs in two different slices without being aware of this overlap.
After the establishment of the slices, and the definition of logical TPs and RPs within each slice, traffic destined for a UE attached to more than one slice can be received and routed to the APs associated with the CN, CN slice, or service, that the traffic is associated with. The traffic can then be transmitted to the UE using the transmission parameters associated with the RAN slice. Traffic associated with a different slice may be transmitted to the UE by a different logical TP, which may or may not have the same physical APs.
When the UE has traffic to transmit, it can transmit the traffic to the RP associated with the slice associated with the respective service. Based on any or all of an identification of the UE, the RP that traffic is received over, a service identifier associated with the transmission, and a destination address, the received traffic can be routed to the appropriate core network or core network slice.
FIG. 20 is a flow chart illustrating a method 2000 for execution at a UE. It will be understood by those skilled in the art that this method 2000 may be used by a UE in interactions with hyper cell handover instructions. In step 2002, the UE communicates with a first hyper cell. This communication is used to carry traffic associated with a first service. In some embodiments both uplink and downlink traffic are transmitted through the first hyper cell, while in other embodiments only one of the two is transmitted through the first hyper cell. In step 2004, the UE communicates with a second hyper cell for transmissions associated with a second service. Again, this may be both uplink and downlink, or it may only be traffic for a single direction. In step 2006 the UE receives a handover instruction. This instruction may be the result of a decision made by a network component or function on the basis of various different inputs, which may include any or all of traffic reports from the UE, loading information from the infrastructure elements and other data that will be understood by those skilled in the art as being relevant to cell loading and handover decisions. This handover instruction, received in step 2006 instructs the UE to handover at least one of the uplink and downlink traffic associated with the first service to a third hyper cell. In instances in which only uplink, or only downlink traffic were communicated with the first hyper cell, the instruction would relate to that traffic. In instances in which both uplink and downlink traffic were communicated, either or both of uplink and downlink traffic may be associated with the instruction. In response to receipt of the instruction in 2006, the UE in step 2008 performs the instructed handover without initiation of a handover of the traffic associated with the second service.
Those skilled in the art will appreciate that in some embodiments the first and second hyper cells can be the same hyper cell, in which case communications for both services were being communicated through the same hyper cell, and following the handover traffic associated with the first service is being communicated in a different hyper cell than traffic associated with the second service. In other embodiments, the first and second hyper cells are different, but the third cell can be the same as the second cell. This has the effect of moving traffic associated with both service to the same cell.
In other embodiments, the first hyper cell may have been used to carry both uplink and downlink traffic associated with the first service in step 2002, but following the execution of step 2008, only one of the uplink and downlink traffic is transferred to the third cell. In other embodiments, the first hyper cell carried only one of the uplink and downlink traffic in step 2002, and following the execution of step 2008, both uplink and downlink traffic are carried in the third hyper cell.
It is possible for a single handover instruction to contain information about more than traffic flow, and possibly more than one service. As an example, a handover instruction may instruct a UE that was transmitting uplink and downlink traffic in a first hyper cell to handover uplink traffic to a third cell and downlink traffic to a fourth cell, while leaving traffic associated with the second service in the second hyper cell. In another embodiment, an instruction may be received to handover uplink traffic associated with both the first and second services (carried in the first and second hyper cells respectively) to the third cell, while leaving the downlink traffic in the respective hyper cells.
It should be understood that the ability network to provide a sliced RAN, can allow for the network to provide a plurality of different hyper cells in each slice. A UE that can connect to a plurality of different slices could then connect to a plurality of different hyper cells (a per-service-per-hyper cell connection model). Handover procedures can then require the UE to be able to treat the connection to each slice separately, resulting in the ability to experience handovers between different hyper cells independently. The ability to further decouple the uplink and downlink connections associated with a service allows for greater flexibility still.
While this invention has been described with reference to illustrative embodiments, this description is not intended to be construed in a limiting sense. Various modifications and combinations of the illustrative embodiments, as well as other embodiments of the invention, will be apparent to persons skilled in the art upon reference to the description. It is therefore intended that the appended claims encompass any such modifications or embodiments.

Claims

What is claimed is:

1. A method in an access network comprising a plurality of cells, the method comprising:

communicating with a user equipment (UE) using at least one of the plurality of cells to send or receive each of a plurality of packet streams, the plurality of cells comprising at least one serving cell and a target cell, wherein the plurality of packet streams comprise either or both of uplink communications and downlink communications for at least one service;

receiving at least one measurement report or receiving a reference signal;

transmitting instructions to the UE to complete a handover, in respect of a first packet stream of the plurality of packet streams, from one of the at least one serving cell to the target cell; and

after the handover, continuing to communicate with the UE, in respect of a second packet stream of the plurality of packet streams, with one of the at least one serving cell and the target cell.

2. The method of claim 1 wherein:

communicating with the UE using at least one of the plurality of cells comprises, in a first serving cell of the at least one serving cell, communicating the first packet stream with the UE in respect of a first service, and in a second serving cell of the at least one serving cell, communicating the second packet stream with the UE in respect of a second service; and

receiving at least one measurement report or receiving a reference signal comprises, at the first serving cell or the second serving cell, receiving at least one measurement report in respect of at least one of the first serving cell or the target cell;

the method further comprising the first serving cell making a decision to handover to the target cell in respect of the first service;

wherein transmitting instructions comprises the first serving cell transmitting a control message indicating that the UE should handover from the first serving cell to the target cell in respect of the first service;

the method further comprising completing the handover from the first serving cell to the target cell in respect of the first service; and

wherein continuing to communicate comprises the second serving cell continuing to communicate with the UE in respect of the second service.

3. The method of claim 1 wherein:

communicating with the UE using at least one of the plurality of cells comprises, in a first serving cell of the at least one serving cell, communicating the first packet stream with the UE in respect of a first service and communicating the second packet stream with the UE in respect of a second service;

receiving at least one measurement report or receiving a reference signal comprises, at the first serving cell, receiving at least one measurement report in respect of at least one of the first serving cell or the target cell;

the method further comprising:

the first serving cell making a decision to handover to the target cell in respect of the first service but not to perform a handover in respect of the second service, wherein transmitting instructions comprises the first serving cell transmitting a control message indicating that the UE should handover from the first serving cell to the target cell in respect of the first service; and

completing the handover from the first serving cell to the target cell in respect of the first service, wherein continuing to communicate comprises the first serving cell continuing to communicate with the UE in respect of the second service.

4. The method of claim 1 wherein:

communicating with the UE using at least one of the plurality of cells comprises, in a first serving cell of the at least one serving cell, communicating the first packet stream with the UE in respect a first service and, in the target cell, communicating the second packet stream with the UE in respect of a second service; and

receiving at least one measurement report or receiving a reference signal comprises receiving at least one measurement report in respect of at least one of the first serving cell or the target cell;

the method further comprising:

the first serving cell making a decision to handover to the target cell in respect of the first service, wherein transmitting instructions comprises the first serving cell transmitting a control message indicating that the UE should handover from the first serving cell to the target cell in respect of the first service; and

completing the handover from the first serving cell to the target cell in respect of the first service, wherein continuing to communicate comprises the target cell continuing to communicate with the UE in respect of the second service.

5. The method of claim 1 wherein:

communicating with the UE using at least one of the plurality of cells comprises, in a first serving cell of the at least one serving cell, communicating the first packet stream with the UE in respect of a downlink communication, and communicating the second packet stream with the UE in respect of an uplink communication; and

the method further comprising:

the first serving cell making a decision to handover to the target cell in respect of the downlink communication but not to perform a handover in respect of the uplink communication, wherein transmitting instructions comprises the first serving cell transmitting a control message indicating that the UE should handover from the first serving cell to the target cell in respect of the downlink communication; and

completing the handover from the first serving cell to the target cell in respect of the downlink communication, wherein continuing to communicate comprises the first serving cell continuing to communicate with the UE in respect of the uplink communication.

6. The method of claim 1 wherein:

communicating with the UE using at least one of the plurality of cells comprises, in a first serving cell of the at least one serving cell, communicating the first packet stream with the UE in respect of an uplink communication, and communicating the second packet stream with the UE in respect of a downlink communication; and

the method further comprising:

the first serving cell making a decision to handover to a target cell in respect of the uplink communication but not to perform a handover in respect of the downlink communication, wherein transmitting instructions comprises the first serving cell transmitting a control message indicating that the UE should handover from the first serving cell to the target cell in respect of the uplink communication; and

completing the handover from the first serving cell to the target cell in respect of the uplink communication, wherein continuing to communicate comprises the first serving cell continuing to communicate with the UE in respect of the downlink communication.

7. An access network comprising:

a non-transitory memory storage comprising instructions; and

one or more processors in communication with the non-transitory memory storage, wherein the one or more processors execute the instructions to:

communicate with a user equipment (UE) using at least one of a plurality of cells to send or receive each of a plurality of packet streams, the plurality of cells comprising at least one serving cell and a target cell, wherein the plurality of packet streams comprise either or both of uplink communications and downlink communications for at least one service;

receive at least one measurement report or receive a reference signal;

transmit instructions to the UE to complete a handover, in respect of a first packet stream of the plurality of packet streams, from one of the at least one serving cell to the target cell; and

after the handover, continue to communicate with the UE, in respect of a second packet stream of the plurality of packet streams, with one of the at least one serving cell and the target cell.

8. The access network of claim 7 wherein:

the one or more processors executing the instructions to communicate with the UE using at least one of the plurality of cells comprises the one or more processors executing the instructions to, in a first serving cell of the at least one serving cell, communicate the first packet stream with the UE in respect of a first service, and in a second serving cell of the at least one serving cell, communicate the second packet stream with the UE in respect of a second service; and

the one or more processors executing the instructions to receive at least one measurement report or receive a reference signal comprises the one or more processors executing the instructions to, at the first serving cell or the second serving cell, receive at least one measurement report in respect of at least one of the first serving cell or the target cell;

the one or more processors further executing the instructions to, at the first serving cell, make a decision to handover the target cell in respect of the first service;

wherein the one or more processors executing the instructions to transmit instructions comprises the one or more processors executing the instructions to, at the first serving cell, transmit a control message indicating that the UE should handover from the first serving cell to the target cell in respect of the first service;

the one or more processors further executing the instructions to the handover from the first serving cell to the target cell in respect of the first service; and

wherein the one or more processors executing the instructions to continue to communicate comprises the one or more processors executing the instructions to, at the second serving cell, continue to communicate with the UE in respect of the second service.

9. The access network of claim 7 wherein:

the one or more processors executing the instructions to communicate with the UE using at least one of the plurality of cells comprises the one or more processors executing the instructions to, in a first serving cell of the at least one serving cell, communicate the first packet stream with the UE in respect of a first service and communicating the second packet stream with the UE in respect of a second service;

the one or more processors executing the instructions to receive at least one measurement report or receive a reference signal comprises the one or more processors executing the instructions to, at the first serving cell, receive at least one measurement report in respect of at least one of the first serving cell or the target cell;

the one or more processors further executing the instructions to:

at the first serving cell, make a decision to handover to the target cell in respect of the first service but not to perform a handover in respect of the second service, wherein the one or more processors executing the instructions to transmit instructions comprises the one or more processors executing the instructions to, at the first serving cell, transmit a control message indicating that the UE should handover from the first serving cell to the target cell in respect of the first service; and

the one or more processors execute the instructions to complete the handover from the first serving cell to the target cell in respect of the first service, wherein the one or more processors executing the instructions to continue to communicate comprises the one or more processors executing the instructions to, at the first serving cell, continue to communicate with the UE in respect of the second service.

10. The access network of claim 7 wherein:

the one or more processors executing the instructions to communicate with the UE using at least one of the plurality of cells comprises the one or more processors executing the instructions to, in a first serving cell of the at least one serving cell, communicate the first packet stream with the UE in respect a first service and, in the target cell, communicate the second packet stream with the UE in respect of a second service; and

the one or more processors executing the instructions to receive at least one measurement report or receive a reference signal comprises the one or more processors executing the instructions to receive at least one measurement report in respect of at least one of the first serving cell or the target cell;

the one or more processors further executing the instructions to:

at the first serving cell, make a decision to handover to the target cell in respect of the first service, wherein the one or more processors executing the instructions to transmit instructions comprises the one or more processors executing the instructions to, at the first serving cell, transmit a control message indicating that the UE should handover from the first serving cell to the target cell in respect of the first service; and

complete the handover from the first serving cell to the target cell in respect of the first service, wherein the one or more processors executing the instructions to continue to communicate comprises the one or more processors executing the instructions to, at the target cell, continue to communicate with the UE in respect of the second service.

11. The access network of claim 7 wherein:

the one or more processors executing the instructions to communicate with the UE using at least one of the plurality of cells comprises the one or more processors executing the instructions to, in a first serving cell of the at least one serving cell, communicate the first packet stream with the UE in respect of a downlink communication, and communicate the second packet stream with the UE in respect of an uplink communication; and

the one or more processors further executing the instructions to:

at the first serving cell, make a decision to handover to the target cell in respect of the downlink communication but not to perform a handover in respect of the uplink communication, wherein the one or more processors executing the instructions to transmit instructions comprises the one or more processors executing the instructions to, at the first serving cell, transmit a control message indicating that the UE should handover from the first serving cell to the target cell in respect of the downlink communication; and

the one or more processors executing the instructions to complete the handover from the first serving cell to the target cell in respect of the downlink communication, wherein the one or more processors executing the instructions to continue to communicate comprises the one or more processors executing the instructions to, at the first serving cell, continue to communicate with the UE in respect of the uplink communication.

12. The access network of claim 7 wherein:

the one or more processors executing the instructions to communicate with the UE using at least one of the plurality of cells comprises the one or more processors executing the instructions to, in a first serving cell of the at least one serving cell, communicate the first packet stream with the UE in respect of an uplink communication, and communicate the second packet stream with the UE in respect of a downlink communication; and

the one or more processors further executing the instructions to:

at the first serving cell, make a decision to handover to a target cell in respect of the uplink communication but not to perform a handover in respect of the downlink communication, wherein the one or more processors executing the instructions to transmit instructions comprises the one or more processors executing the instructions to, at the first serving cell, transmit a control message indicating that the UE should handover from the first serving cell to the target cell in respect of the uplink communication; and

the one or more processors executing the instructions to complete the handover from the first serving cell to the target cell in respect of the uplink communication, wherein the one or more processors executing the instructions to continue to communicate comprises the one or more processors executing the instructions to, at the first serving cell, continue to communicate with the UE in respect of the downlink communication.

13. A method in a user equipment (UE) in an access network comprising a plurality of cells, the method comprising:

communicating, by the UE, with at least one of the plurality of cells to send or receive each of a plurality of packet streams, the plurality of cells comprising at least one serving cell and a target cell, wherein the plurality of packet streams comprise either or both of uplink communications and downlink communications for at least one service;

transmitting at least one measurement report or transmitting a reference signal;

receiving instructions to complete a handover, in respect of a first packet stream of the plurality of packet streams, from one of the at least one serving cell to the target cell; and

after the handover, continuing to communicate with one of the at least one serving cell and the target cell, in respect of a second packet stream of the plurality of packet streams.

14. The method of claim 13 wherein:

communicating with the at least one of the plurality of cells comprises, in respect of a first service, communicating the first packet stream with a first serving cell of the at least one serving cell and, in respect of a second service, communicating the second packet stream with a second serving cell of the at least one serving cell;

transmitting at least one measurement report or transmitting a reference signal comprises transmitting, to the first serving cell or the second serving cell, at least one measurement report in respect of at least one of the first serving cell or the target cell;

receiving instructions comprises receiving a control message from the first serving cell indicating that the UE should handover from the first serving cell to the target cell in respect of the first service; and

continuing to communicate comprises continuing to communicate with the second serving cell in respect of the second service.

15. The method of claim 13 wherein:

communicating with the at least one of the plurality of cells comprises, in respect of a first service, communicating the first packet stream with a first serving cell of the at least one serving cell and, in respect of a second service, communicating the second packet stream with the first serving cell of the at least one serving cell;

transmitting at least one measurement report or transmitting a reference signal comprises transmitting, to the first serving cell, at least one measurement report in respect of at least one of the first serving cell or the target cell;

wherein continuing to communicate comprises continuing to communicate with the first serving cell in respect of the second service.

16. The method of claim 13 wherein:

communicating with the at least one of the plurality of cells comprises, in respect a first service, communicating the first packet stream with a first serving cell of the at least one serving cell and, in respect of a second service, communicating the second packet stream with the target cell; and

transmitting at least one measurement report or transmitting a reference signal comprises transmitting at least one measurement report in respect of at least one of the first serving cell or the target cell;

wherein continuing to communicate comprises continuing to communicate with the target cell in respect of the second service.

17. The method of claim 13 wherein:

communicating with at least one of the plurality of cells comprises, in respect of a downlink communication, communicating the first packet stream with a first serving cell of the at least one serving cell and, in respect of an uplink communication, communicating the second packet stream with the first serving cell of the at least one serving cell; and

receiving instructions comprises receiving a control message from the first serving cell indicating that the UE should handover from the first serving cell to the target cell in respect of the downlink communication; and

the method further comprising completing the handover from the first serving cell to the target cell in respect of the downlink communication; and

wherein continuing to communicate comprises continuing to communicate with the first serving cell in respect of the uplink communication.

18. The method of claim 13 wherein:

communicating with the at least one of the plurality of cells comprises, in respect of an uplink communication, communicating the first packet stream with a first serving cell of the at least one serving cell and, in respect of a downlink communication, communicating the second packet stream with the first serving cell of the at least one serving cell; and

receiving instructions comprises receiving a control message from the first serving cell indicating that the UE should handover from the first serving cell to the target cell in respect of the uplink communication; and

the method further comprising completing the handover from the first serving cell to the target cell in respect of the uplink communication; and

wherein continuing to communicate comprises continuing to communicate with the first serving cell in respect of the downlink communication.

19. A user equipment (UE) comprising:

a non-transitory memory storage comprising instructions; and

communicate with at least one of a plurality of cells to send or receive each of a plurality of packet streams, the plurality of cells comprising at least one serving cell and a target cell, wherein the plurality of packet streams comprise either or both of uplink communications and downlink communications for at least one service;

transmit at least one measurement report or transmitting a reference signal;

receive instructions to complete a handover, in respect of a first packet stream of the plurality of packet streams, from one of the at least one serving cell to the target cell; and

after the handover, continue to communicate with one of the at least one serving cell and the target cell, in respect of a second packet stream of the plurality of packet streams.

20. The UE of claim 19 wherein:

the one or more processors executing the instructions to communicate with the at least one of the plurality of cells comprises the one or more processors executing the instructions to, in respect of a first service, communicate the first packet stream with a first serving cell of the at least one serving cell and, in respect of a second service, communicate the second packet stream with a second serving cell of the at least one serving cell;

the one or more processors executing the instructions to transmit at least one measurement report or transmit a reference signal comprises the one or more processors executing the instructions to transmit, to the first serving cell or the second serving cell, at least one measurement report in respect of at least one of the first serving cell or the target cell;

the one or more processors executing the instructions to receive instructions comprises the one or more processors executing the instructions to receive a control message from the first serving cell indicating that the UE should handover from the first serving cell to the target cell in respect of the first service; and

the one or more processors further execute the instructions to complete the handover from the first serving cell to the target cell in respect of the first service; and

the one or more processors executing the instructions to continue to communicate comprises the one or more processors executing the instructions to continue to communicate with the second serving cell in respect of the second service.

21. The UE of claim 19 wherein:

the one or more processors executing the instructions to communicate with the at least one of the plurality of cells comprises the one or more processors executing the instructions to, in respect of a first service, communicate the first packet stream with a first serving cell of the at least one serving cell and, in respect of a second service, communicate the second packet stream with the first serving cell of the at least one serving cell;

the one or more processors executing the instructions to transmit at least one measurement report or transmit a reference signal comprises the one or more processors executing the instructions to transmit, to the first serving cell, at least one measurement report in respect of at least one of the first serving cell or the target cell;

wherein the one or more processors executing the instructions to continue to communicate comprises the one or more processors executing the instructions to continue to communicate with the first serving cell in respect of the second service.

22. The UE of claim 19 wherein:

the one or more processors executing the instructions to communicate with the at least one of the plurality of cells comprises the one or more processors executing the instructions to, in respect a first service, communicate the first packet stream with a first serving cell of the at least one serving cell and, in respect of a second service, communicate the second packet stream with the target cell; and

the one or more processors executing the instructions to transmit at least one measurement report or transmit a reference signal comprises the one or more processors executing the instructions to transmit at least one measurement report in respect of at least one of the first serving cell or the target cell;

wherein the one or more processors executing the instructions to continue to communicate comprises the one or more processors executing the instructions to continue to communicate with the target cell in respect of the second service.

23. The UE of claim 19 wherein:

the one or more processors executing the instructions to communicate with at least one of the plurality of cells comprises the one or more processors executing the instructions to, in respect of a downlink communication, communicate the first packet stream with a first serving cell of the at least one serving cell and, in respect of an uplink communication, communicate the second packet stream with the first serving cell of the at least one serving cell; and

the one or more processors executing the instructions to receive instructions comprises the one or more processors executing the instructions to receive a control message from the first serving cell indicating that the UE should handover from the first serving cell to the target cell in respect of the downlink communication; and

the one or more processors further execute the instructions to complete the handover from the first serving cell to the target cell in respect of the downlink communication; and

wherein the one or more processors executing the instructions to continue to communicate comprises the one or more processors executing the instructions to continue to communicate with the first serving cell in respect of the uplink communication.

24. The UE of claim 19 wherein:

the one or more processors executing the instructions to communicate with the at least one of the plurality of cells comprises the one or more processors executing the instructions to, in respect of an uplink communication, communicate the first packet stream with a first serving cell of the at least one serving cell and, in respect of a downlink communication, communicate the second packet stream with the first serving cell of the at least one serving cell; and

the one or more processors executing the instructions to receive instructions comprises the one or more processors executing the instructions to receive a control message from the first serving cell indicating that the UE should handover from the first serving cell to the target cell in respect of the uplink communication; and

the one or more processors further execute the instructions to complete the handover from the first serving cell to the target cell in respect of the uplink communication; and

wherein the one or more processors executing the instructions to continue to communicate comprises the one or more processors executing the instructions to continue to communicate with the first serving cell in respect of the downlink communication.