WO2018113928A1

WO2018113928A1 - Wireless communication system with multiple radio bearers

Info

Publication number: WO2018113928A1
Application number: PCT/EP2016/081959
Authority: WO
Inventors: Jingyi Liao
Original assignee: Huawei Technologies Co Ltd
Current assignee: Huawei Technologies Co Ltd
Priority date: 2016-12-20
Filing date: 2016-12-20
Publication date: 2018-06-28
Anticipated expiration: 2019-06-20

Abstract

The invention relates to a scheduler adapted for a wireless communication system (100). The wireless communication system being configured to allow multiple bearers (140) and respective radio bearers (150) between the wireless communication system and a user equipment, UE (130). The scheduler being adapted to receive a radio bearer Transmission Time Interval, TTI reallocation configuration and a bearer information for the respective radio bearer, or receive a UE related TTI reallocation configuration and a UE reconfiguration information. The scheduler is further adapted to determine a reallocation of bearer data based on an available transport block resource for an at least one Transmission Time Interval, TTI and either the received radio bearer TTI reallocation configuration or the received UE related TTI reallocation configuration. The invention further extends to methods and devices for enabling the scheduler to operate efficiently.

Description

Wireless communication system with multiple radio bearers

TECHNICAL FIELD

The invention relates to devices for use in a wireless communication system. In particular, the invention relates to a scheduling node and a Mobility

Management Entity for use in a wireless communication system allowing multiple bearers to be set up between a network node and a user equipment.

BACKGROUND

In a radio telecommunication systems network, data can be transmitted over an air-interface between the network and a mobile user. In some digital radio telecommunications networks data is encapsulated in a so-called TTI, Transmission Time Interval, when data is transmitted in frames on the radio link layer. TTI refers to the duration of a transmission on the radio link. For example, UMTS (Universal Mobile Telecommunications System) uses the TTI as a parameter set in the telecommunication standard. The TTI is related to the size of the data blocks passed from higher network layers to the radio link layer. The time required to transmit one such block determines the length of the TTI.

In LTE (Long-Term Evolution), a TTI is defined as 1 ms (=14 OFDM,

Orthogonal frequency-division multiplexing, symbols, OS). For the evolution of LTE or next radio generation, the standard organization 3GPP envisages introduction of a short TTI (sTTI), the size of which can be from 1 up to 7 OFDM symbols. The packet latency can be reduced with a reduction of transport time of data and control by addressing the length of a TTI. It can be proved that the length of a TTI has an impact on both the time for

transmitting over the air and the processing time at the transmitter and the receiver. Further, reducing user plane latency for the scheduled UL (Up-Link) transmission with a resource efficient solution as a result of protocol and signalling enhancements are studied and compared to the pre-scheduling solutions allowed by the standard today, see 3GPP TR36.881 , "Technical specification group radio access network; Evolved universal terrestrial radio access (EUTRA); study on latency reduction techniques for LTE (release 13)", 201 6-02 and 3GPP RP-1 60667,"WI: L2 latency reduction techniques for LTE", Ericsson.

There are some agreements in the 3GPP meeting of RAN1 #84bis 3GPP R1 - 163961 ," Final report of 3GPP TSG RAN WG1 #84bis v1 .0.0", MCC support, 201 6-05 to the effect that:

A UE (User Equipment) can be dynamically (with a subframe to subframe granularity) scheduled with either PDSCH (Physical Downlink Shared Channel) or sPDSCH (shortened PDSCH) unicast, and either PUSCH (Physical Downlink Shared Channel) or sPUSCH (shortened

PUSCH).

If DL (Downlink) data transmission is scheduled in a short TTI (sTTI), the processing time for preparing the HARQ (Hybrid Automatic

Repeat Request) feedback by a UE and the processing time for preparing a potential retransmission by an eNodeB (evolved NodeB) are assumed to be reduced. A similar effect is assumed for UL (Uplink) data (re)transmission.

The above implies that a UE can simultaneously have several different TTI settings, for example, a UE can simultaneously have a legacy LTE TTI (14 OFDM symbol) for PDSCH, and at least one short TTI size (from 1 up to 7 OFDM symbol) for sPDSCH. If the UE have multiple bearers transmitting in the DL, these bearers can be carried on either PDSCH or sPDSCH. Each bearer provides a transport service for the traffic streams with specific QoS (Quality of Service) attributes. The QoS parameters associated to a bearer are typically: QoS Class Identifier(QCI), Allocation and Retention Priority(ARP), Guaranteed Bit Rate(GBR) and UE Aggregate Maximum Bitrate(AMBR). Different bearers can have different latency requirements, and a short TTI can reduce latency, on the other hand larger TTI can have less transmission overhead. A problem is then how to enable a good traffic bearer efficiency on the different TTIs, and at the same time meet the per bearer requirement(s). There is a constant desire to improve the performance of wireless

communication systems. Hence there is a need for an improved wireless communication system, in particular a wireless communication system making use of multiple bearers in the communication between the wireless communication system and a UE connected thereto.

SUMMARY

It is an object of the present invention to provide an improved wireless communication system. In particular, it is an object of the present invention to provide a scheduling node and a Mobility Management Entity to improve the efficiency of wireless communication system allowing multiple bearers to be set up between the network and a user equipment.

In accordance with a first aspect of the invention, a scheduler adapted for a wireless communication system is provided. The wireless communication system is configured to allow multiple bearers and respective radio bearers between the wireless communication system and a user equipment, UE. The scheduler is adapted to receive a radio bearer Transmission Time Interval, TTI reallocation configuration and a bearer information for the respective radio bearer, or to receive a UE related TTI reallocation configuration and a UE reconfiguration information; and to determine a reallocation of bearer data based on an available transport block resource for an at least one Transmission Time Interval, TTI and either the received radio bearer TTI reallocation configuration or the received UE related TTI reallocation configuration. Hereby a TTI setting for radio bearers can be achieved that matches current transmission requirements. In accordance with a first implementation of the first aspect, the scheduler is adapted to reallocate the bearer data to another radio bearer TTI when the available transport block resource for the another radio bearer TTI is configured to carry the bearer data. Hereby the TTI for a radio bearer can be dynamically changed.

In accordance with a second implementation of the first aspect, the scheduler is adapted to check if the reallocation to another radio bearer TTI is allowed based on an at least one received pre-determined condition and then adapted to make the reallocation to another radio bearer TTI for the respective radio bearer. Hereby it is achieved that reallocation to another radio bearer TTI only is performed when it is deemed appropriate based on some condition such as a Quality of Service, an average Packet Data Unit, PDU, size for the radio bearer, and a UE capability.

In accordance with a third implementation of the first aspect, the received radio bearer TTI reallocation configuration or the received UE related TTI reallocation configuration comprises an information about at least one TTI setting for an individual radio bearer. Hereby an individual setting of a radio bearer TTI can be made.

In accordance with a fourth implementation of the first aspect, the received bearer TTI reallocation configuration or the received UE related TTI reallocation configuration comprises an information about a different TTI setting for an uplink transmission and a downlink transmission, respectively. Hereby, the radio bearers are allowed to have different TTI settings in the Uplink and the Downlink, which can be advantageous since there can exist different transmission requirements in the different transmission directions.

In accordance with a second aspect of the invention, the scheduler as set out above can be located in an eNodeB comprising a transceiver for transmitting and receiving data to/from a UE. Hereby an eNodeB with an improved scheduler can be provided. In accordance with a first implementation of the second aspect, the eNodeB is adapted to send a radio bearer TTI reallocation configuration to a UE in a Radio Resource Control, RRC, message. Hereby it is achieved that the radio bearer TTI can be changed using RRC signaling.

In accordance with a first implementation of the second aspect, the eNodeB is adapted to send a radio bearer TTI reallocation configuration to a UE as a Downlink Control Information on a Physical Downlink Control Channel, PDCCH. Hereby it is achieved that the radio bearer TTI can be changed using Downlink control information signaling.

In accordance with a third aspect, the scheduler as set out above can be located in a UE comprising a transceiver for transmitting and receiving data to/from an eNodeB. Hereby a UE with an improved scheduler can be provided. In accordance with a first implementation of the third aspect, the UE is adapted to receive a TTI reallocation configuration in a non-Access Stratum, NAS, message. Hereby the UE can receive a TTI setting from a mobility management entity, MME.

In accordance with a second implementation of the third aspect, the UE is adapted to receive a TTI reallocation configuration in a Radio Resource Control, RRC, message. In accordance with a third implementation of the third aspect, the UE is adapted to receive a TTI reallocation configuration as a Downlink Control Information on a Physical Downlink Control Channel, PDCCH. Hereby the UE can receive a TTI setting from an eNodeB. In accordance with a fourth aspect of the invention, a Mobility Management Entity, MME for a wireless communication system is provided. The wireless communication system is configured to allow multiple bearers and respective radio bearers between the wireless communication system and a user equipment, UE. The Mobility Management Entity is adapted to receive bearer information of at least one bearer set up between a Serving Gateway of the wireless communication system and the UE and to determine a radio bearer Transmission Time Interval, TTI, reallocation configuration for at least one radio bearer. The TTI reallocation configuration can then be sent. Hereby a TTI setting can be changed by the MME.

In accordance with a first implementation of the fourth aspect, the Mobility Management Entity is adapted to send the TTI reallocation configuration to the UE via an eNodeB. Hereby, a changed TTI setting can be sent to the UE.

In accordance with a second implementation of the fourth aspect, the Mobility Management Entity is adapted to send the radio bearer TTI reallocation configuration in a non- Access Stratum, NAS, message. Hereby NAS signaling can be used to change a TTI setting.

In accordance with a second implementation of the fourth aspect, the TTI reallocation configuration comprises an information about TTI reallocation configurations that are allowed for said at least one radio bearer. Hereby it is achieved that reallocation to another radio bearer TTI only is performed when it is deemed appropriate based on some condition.

In accordance with a third implementation of the fourth aspect, the TTI reallocation configuration comprises an information about different TTI reallocation configurations for downlink and uplink transmission, respectively for said at least one radio bearer. Hereby, the radio bearers are allowed to have different TTI settings in the Uplink and the Downlink, which can be advantageous since there can exist different transmission requirements in the different transmission directions.

The invention also extends to methods for using the MME and scheduler in accordance with the above. In accordance with a fifth aspect of the invention a method performed in a Mobility Management Entity adapted to be used in a wireless communication system is provided. The wireless communication system is configured to allow multiple bearers and respective radio bearers between the wireless communication system and a user equipment UE. The method comprises receiving bearer information of at least one bearer set up between a serving Gateway of the wireless communication system and the UE and determining a radio bearer Transmission Time Interval, TTI, reallocation configuration for at least one radio bearer. The method further comprises sending the TTI reallocation configuration.

In accordance with a sixth aspect of the invention, a method performed in a Scheduler of a UE or an eNodeB of a wireless communication system is provided. The wireless communication system is configured to allow multiple bearers and respective radio bearers between the wireless communication system and a user equipment, UE. The method comprises receiving a radio bearer Transmission Time Interval, TTI reallocation configuration and a bearer information for each bearer, or receiving a UE related TTI reallocation configuration and a UE reconfiguration information. The method further comprises determining a reallocation of bearer data based on an available transport block resource for an at least one TTI and either the received radio bearer TTI reallocation configuration or the received UE related TTI reallocation configuration.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention will now be described in more detail, by way of example, and with reference to the accompanying drawings, in which:

Fig. 1 shows a wireless communication system, Fig. 2 shows a conventional multiplexing scheme,

Fig. 3 shows RRC signaling including TTI signaling,

Fig. 4 shows PDCCH signaling including TTI signaling,

Fig. 5 shows NAS signaling including TTI signaling, Fig. 6 illustrates multiplexing to different TTIs based on a multiplexing policy, Fig. 7 illustrates procedures performed by a scheduler during multiplexing Fig. 8 illustrates a UE, Fig. 9 illustrates an eNodeB, Fi. 10 illustrates an MME,

Fig. 1 1 illustrates some procedural steps performed in an MME, and Fig. 12 illustrates some procedural steps performed in a scheduler. DETAILED DESCRIPTION

The invention will now be described more fully hereinafter with reference to the accompanying drawings, in which certain embodiments of the invention are shown. The invention may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein; rather, these embodiments are provided by way of example so that this disclosure will be thorough and complete, and will fully convey the scope of the invention to those skilled in the art. Like numbers refer to like elements throughout the description.

Fig. 1 schematically shows a wireless communication system 100. The system 100 in Fig. 1 is an LTE network, but the invention can also be implemented is similar types of wireless communication systems. Various network elements provide the functions and services for LTE radio bearers. This is shown in Fig.1 . The MME 1 10 hosts the function of bearer 140 management functions including dedicated bearer 140 establishment. The eNodeBs 120 are connected to the MME 1 10 by means of an S1 -MME interface. The eNodeB 120 typically hosts the following functions for Radio Resource Management, which provides the service for radio bearers 150: Radio Bearer Control, Radio Admission Control, Connection Mobility Control, Dynamic allocation of resources to UE 130. The UE 130 can, via the bearers 140 and the respective radio bearers 150 send and receive data from a Serving Gateway 105 of the system 100.

In existing wireless communication systems, there can exist multiple transmission time interval (TTI) settings. For example, the enhanced dedicated channel (E-DCH) was introduced into 3GPP release 8 HSPA specification, and it support for multiple TTI settings (e.g. 2ms and 10ms). A smaller TTI, such as 2ms, may be more advantageous from latency point of view, and a larger TTI, such as 10ms TTI may allow for a larger coverage area. To tradeoff between the benefits for a UE, a TTI switch mechanism, which is to dynamically select one TTI setting, is introduced for the E-DCH channel, see US2014001 6595, PCT/SE2014/050443, 3GPP TS25.212,

US7515579, and PCT/SE2014/050441 .

In LTE, the multiplexing function in MAC layer performs multiplexing of data from several logical channels into one transport channel. If a UE could have different TTI lengths, based on the current LTE RLC/MAC sublayers, as shown in Fig. 2, the multiplexing in the MAC layer could always be executed according to a pre-defined multiplexing rule, e.g. multiplex the logical channel for short latency bearers to sTTI transport block (TB), and multiplex normal latency bearers to large TTI transport block (TB). However, as has been realized, different bearers between the network and the UE have different latency requirements. Therefore, a UE might

simultaneously have different bearers running on different TTI time settings. An adaptation of TTI to the bearer rather than to the UE could not only adapt to the channel variation, but also fit for different bearers' different

requirements. However, the existing TTI switch solutions for E-DCH set out above do not satisfy the requirements to allow for a per bearer setting of the TTI. This is because in High Speed Packet Access (HSPA) networks, one E- DCH is assigned for one UE. The adaptation of the TTI for E-DCH is to decide one TTI setting during a period. In other words, for a fixed time period a UE can only have one TTI setting. On the other hand, in LTE, if the MAC layer would execute pre-defined multiplexing policies which always multiplex specific bearers to specific TTI lengths, e.g. always multiplex the logical channel for short latency radio bearers to sTTI transport block, it can lose the flexibility and the transmission will not be efficient.

For an efficient transmission, at least in some scenarios, the multiplexing should allow for a UE and its different radio bearers to reallocate to different TTI settings even if the radio bearers were granted with one single TTI setting. For example, if a normal latency radio bearer was granted with a 10ms TTI, and in a case where there is only a small packet, e.g. padding, or if there is only sPDSCH with short TTI available in the scheduling slot, the normal latency radio bearer's packet could be multiplexed with other short latency bearers' data packet, to be fitted into a sPDSCH short length TTI. The reallocation has the advantage that an efficient transmission is achieved. For example, the transmit block header and Cyclic Redundancy Check (CRC) overhead can be reduced. This will cost an extra process overhead, e.g. a bearer was allocated with 10ms TTI, when it was fit into a 2ms TTI. The UE then have to process the bearer from per 10ms to per 2ms.

However, if the UE also can get the reallocation information, this could reduce UE processing. For example, in a system applying an enhanced PDCCH (ePDCCH), if a UE knows that reallocation is forbidden for a radio bearer, when the bearer is on larger TTI (1 ms), in the 1 ms, the UE would only need to blind detect the PDCCH. In other words, the UE can then be configured to not check the ePDCCH for each sTTI. This will save processing resources in the UE.

To allow for the efficient transmission the wireless communication system can be configured to during a bearer setup, or a RRC connection, RRC reconfiguration or RRC reestablishment, to have a signal indicating whether it allows a radio bearer to reallocate to other TTIs or not. This can be performed in different ways. Either an MME or an eNodeB can provide the radio bearer reallocation signal to a UE. The signal indicates whether the radio bearer(s) are allowed to reallocate to different TTIs. In both solutions, the MAC (Medium Access Control) layer in the eNodeB is provided with this information to be able to determine how the multiplexing policy work for the different radio bearers.

Thus, a signal containing the TTI configuration for a bearer or group of bearers is provided. The signal comprises data indicating whether a radio bearer is allowed to reallocate to a different TTI setting or not.

If the signal is transmitted from the eNodeB. The signal can be carried in RRC (Radio Resource Control) connection signals, e.g. RRC reconfiguration or RRC reestablishment and etc. This is shown is Fig 3. In Fig. 3, in step 1 1 , an event triggering a new TTI setting is received in the eNodeB. For example, events can be coming for RRC connection or RRC reestablishment for a UE, or RRC reconfiguration for new bearer(s) setup in step 1 1 . The multiplexing policy in a step 12 determines whether the radio bearers could be reallocated to different TTIs or not. Then multiplexing is performed. The new reallocation signal is added to RRC connection signal and sent to the UE in a step 13. This added signal does not have any impact on the

RRC_connection complete message sent in a step 14. The following factors can for example be used in the multiplexing policy in step 12 to determine whether it allows bearer(s) reallocation to different TTIs. The radio bearer's QoS (Quality of Service) e.g. latency requirement, average PDU (Packet Data Unit) size for the radio bearer(s), UE capabilities of (s)PDSCH and (s)PUSCH. Alternatively, the signal can be sent from the eNodeB as a DCI (Downlink Control Information) on a PDCCH (Physical Downlink Control Channel). This is illustrated in Fig. 4. In Fig. 4, in step 1 6, an event triggering a new TTI setting is received in the eNodeB. For example, events can be coming for RRC connection or RRC reestablishment for a UE, or RRC reconfiguration for new bearer(s) setup in step 16. The multiplexing policy in a step 17 determines whether the radio bearers are to be reallocated to different TTIs or not. Then multiplexing is performed. The new reallocation signal is added to a DCI signal on a PDCCH and sent to the UE in a step 18.

If the signal is transmitted by an MME, the signal can be contained in NAS (non- Access Stratum) signals, e.g. bearer setup and similar signaling. A new bearer setup will result in that the eNodeB sends a RRC connection reconfiguration for this radio bearer. The MAC layer in the eNodeB therefore gets the information in the signal for the specific radio bearer(s). Therefore, the multiplexing policy can determine whether the specific radio bearers could be reallocated to different TTIs or not. This is shown in Fig. 5. First, in a step 21 , an event such as a new bearer set up is received in the MME. Then, in a step 22, NAS signaling comprising the new bearer set up and a TTI configuration is sent from the MME to the eNodeB in a step 22. The multiplexing policy in the eNodeB then in a step 23 determines whether the radio bearers are to be reallocated to different TTIs or not. Then multiplexing is performed. A signal indicating the TTI configuration is added to RRC connection signal and sent to the UE in a step 24. Thus, the signal indicating the TTI configuration is added to step 22 and step 24, but it does not have any impact on the subsequent steps RRC_connection complete in a step 25 and bearer setup response in a step 26.

The signal carried in the RRC connection signals or NAS signals can comprise the following information: new TTI configuration for a radio bearer(s) or for a UE.

- If radio bearer(s) reallocation to different TTIs is allowed, or if all the bearers of a UE to be reallocated is allowed

- setting details for TTI settings allowing the reallocation of the radio bearers or the UE's data.

- setting details for DL and UL direction to enable DL and UL to have different TTI settings. During bearer setup, RRC connection setup or RRC reconfiguration, the scheduler determines which multiplexing policy is to be used, i.e. whether the bearers could be reallocated to different TTIs or not. In Fig. 6 the

corresponding RLC/MAC (Radio Link Control/Medium Access Control) sublayers are shown. The scheduler uses the multiplexing policy to

determine whether reallocation is allowed or not. This is shown in more detail in Fig. 7.

Fig. 7 illustrates the procedures performed by a scheduler for multiplexing the different bearers' PDU (Packet Data Unit) to TBs (transport blocks) when a PDU arrives. Thus, when a PDU arrives for a radio bearer, the multiplexing policy 701 is used in a step 703 to determine is a TB is allowed for the radio bearer. If yes, the procedure proceeds to a step 705. If the outcome is no in step 703, a pre-defined rule is used applied in a step 707 and the predefined TTI is used in a step 709.

In step 705 it is checked if the received PDU fits in the TB. If the PDU fits in the TB, a reallocation to the TB is performed in a step 71 1 , else a new attempt is performed in a step 713.

Thus, if reallocation is allowed for a radio bearer, when the MAC-scheduler is multiplexing the radio bearer, it reallocates the radio bearer to a different TTI setting. If it is DL transmission, this reallocation is done by the eNodeB's scheduler, and if it is UL transmission, the reallocation is executed by the scheduler of the UE. The scheduler checks whether the transport block can carry the PDU or not, if the check result is YES, the PDU could be reallocate to the available transport block regardless whether its TTI length is large or short. If the policy determines the reallocation is not allowed for the radio bearer, the radio bearer's PDU could only be multiplexing with its pre-defined TTI length.

The scheduler can be implemented in the eNodeB or the UE. In Fig. 8 a UE 130 is depicted. The UE 130 comprises transceiver circuitry formed by a receiver 810 and a transmitter 830 for wireless communication with a wireless network. The UE 130 further comprises a processor 840 that can use a memory 820. The processor 840 can perform all the scheduling activities of the UE and is operatively connected to the receiver 810 and transmitter 830.

In Fig. 9, an eNodeB 120 is depicted. The eNodeB 120 comprises

transceiver circuitry formed by a receiver 910 and a transmitter 930 for wireless communication with a UE 130. The eNodeB 120 further comprises a processor 940 that can use a memory 920. The processor 940 can perform all the scheduling activities of the eNodeB and is operatively connected to the receiver 910 and transmitter 930. The eNodeB 120 can further comprise an input/output unit 950 for communication with other entities in a wireless communication network such as an MME 1 10.

In Fig. 10, an MME 1 10 is depicted. The MME 1 10 comprises an input/output unit 1010 for communication with other entities of a network 100 such as an eNodeB. To perform different tasks the MME can comprise a processor 1040 connected to a memory 1020.

In Fig. 1 1 some steps that can be performed in a Mobility Management Entity, MME adapted to be used in a wireless communication system are illustrated. The wireless communication system is configured to allow multiple bearers and respective radio bearers between the wireless communication system and a user equipment UE. The method comprises to receive in a step 41 bearer information of at least one bearer set up between a serving Gateway of the wireless communication system and the UE. Next, in a step 42 a radio bearer Transmission Time Interval, TTI, reallocation configuration is determined for at least one radio bearer. Then, in a step 43 the TTI reallocation configuration is sent. In particular, the TTI reallocation configuration can be sent towards a UE.

In Fig. 12, some procedural steps of a method performed in a Scheduler 840, 940 of a UE 130 or an eNodeB 120 of a wireless communication system 100 is shown. The wireless communication system is configured to allow multiple bearers 140 and respective radio bearers 150 between the wireless communication system and a user equipment, UE, 130. The method comprises to receive in a step 51 a radio bearer Transmission Time Interval, TTI reallocation configuration and a bearer information for each bearer, or to receive in a step 52 a UE related TTI reallocation configuration and a UE reconfiguration information. Then, in a step 53, a reallocation of bearer data based on an available transport block resource for an at least one TTI and either the received radio bearer TTI reallocation configuration or the received UE related TTI reallocation configuration is determined.

The invention has been described above with reference to a few

embodiments. However, as is readily appreciated by a person skilled in the art, other embodiments than the ones disclosed above are equally possible within the scope of the invention, as defined by the appended claims. Using the invention can result in different advantages. For example, it can allow the adaptation of TTI size to the radio bearer level, which can not only adapt to the channel variation, but also fit for different radio bearers' requirement. Also, it can allow the bearer's data reallocating to different TTI settings. With the TTI configuration signal the MAC multiplexing and scheduling can adapt to a per bearer's requirement in different scenarios. The solution can be used in other systems other than LTE if multiple TTI settings for a UE are allowed.

Claims

1 . A Scheduler (840, 940) adapted for a wireless communication system (100), the wireless communication system being configured to allow multiple bearers (140) and respective radio bearers (150) between the wireless communication system and a user equipment, UE (130), the scheduler being adapted to:

- receive a radio bearer Transmission Time Interval, TTI

reallocation configuration and a bearer information for the respective radio bearer, or

- receive a UE related TTI reallocation configuration and a UE reconfiguration information; and

- determine a reallocation of bearer data based on an available transport block resource for an at least one Transmission Time Interval, TTI and either the received radio bearer TTI reallocation configuration or the received UE related TTI reallocation configuration.

2. The scheduler according to claim 1 , wherein the scheduler is adapted to reallocate the bearer data to another radio bearer TTI when the available transport block resource for the another radio bearer TTI is configured to carry the bearer data.

3. The scheduler according to any of claims 1 or 2, wherein the scheduler is adapted to check if the reallocation to another radio bearer TTI is allowed based on an at least one received pre-determined condition and then adapted to make the reallocation to another radio bearer TTI for the respective radio bearer.

4. The scheduler according to claim 3, wherein said at least one predetermined condition comprises at least one of a Quality of Service, an average Packet Data Unit, PDU, size for the radio bearer, and an UE capability.

5. The scheduler according to any of claims 1 - 4, wherein the received radio bearer TTI reallocation configuration or the received UE related TTI reallocation configuration comprises an information about at least one TTI setting for an individual radio bearer.

6. The scheduler according to any of claims 1 - 5 wherein the received bearer TTI reallocation configuration or the received UE related TTI reallocation configuration comprises an information about a different TTI setting for an uplink transmission and a downlink transmission, respectively.

7. An eNodeB (120) comprising a transceiver (910, 930) and scheduler (940) according to any of claims 1 - 6.

8. The eNodeB according to claim 7, wherein the eNodeB is adapted to send a radio bearer TTI reallocation configuration to a UE in a Radio Resource

Control, RRC, message (13).

9. The eNodeB according to claim 7, wherein the eNodeB is adapted to send a radio bearer TTI reallocation configuration to a UE as a Downlink Control Information on a Physical Downlink Control Channel, PDCCH (18).

10. A User equipment, UE (130) comprising a transceiver (810, 830) and a scheduler according to any of claims 1 - 6.

1 1 . The UE according to claim 10, wherein the UE is adapted to receive a TTI reallocation configuration in a non-Access Stratum, NAS, message (24).

12. The UE according to claim 10 or 1 1 , wherein the UE is adapted to receive a TTI reallocation configuration in a Radio Resource Control, RRC, message (13).

13. The UE according to any of claims 10 - 12, wherein the UE is adapted to receive a TTI reallocation configuration as a Downlink Control Information on a Physical Downlink Control Channel, PDCCH (18).

14. A Mobility Management Entity (1 10) for a wireless communication system (100), the wireless communication system being configured to allow multiple bearers (140) and respective radio bearers (150) between the wireless communication system and a user equipment, UE (130), the Mobility

Management Entity being adapted to: - receive bearer information of at least one bearer set up

between a Serving Gateway (105) of the wireless

communication system and the UE (130),

- determine a radio bearer Transmission Time Interval, TTI, reallocation configuration for at least one radio bearer; and - send the TTI reallocation configuration.

15. The Mobility Management Entity according to claim 14, wherein the Mobility Management Entity is adapted to send the TTI reallocation configuration (22, 24) to the UE via an eNodeB (120).