WO2012022369A1

WO2012022369A1 - Empty buffer status reporting from an user equipment in uplink transmissions

Info

Publication number: WO2012022369A1
Application number: PCT/EP2010/061888
Authority: WO
Inventors: Claudio Rosa; Benoist Pierre Sebire; Wolfgang Payer
Original assignee: Nokia Siemens Networks Oy
Priority date: 2010-08-16
Filing date: 2010-08-16
Publication date: 2012-02-23

Abstract

When a user equipment has no data to transmit on uplink resources granted to said user equipment, determining whether said user equipment is required to transmit on said uplink resources an indication that said user equipment has no data to transmit.

Description

Description Title

EMPTY BUFFER STATUS REPORTING FROM AN USER EQUIPMENT IN UPLINK TRANSMISSIONS

This application relates to controlling the operation of a 5 communication device in a system where communication devices are granted respective resources for making uplink

transmissions .

A communication device can be understood as a device provided with appropriate communication and control capabilities for0 enabling use thereof for communication with others parties.

The communication may comprise, for example, communication of voice, electronic mail (email) , text messages, data,

multimedia and so on. A communication device typically

enables a user of the device to receive and transmit

5 communication via a communication system and can thus be used for accessing various service applications.

A communication system is a facility which facilitates the communication between two or more entities such as the

communication devices, network entities and other nodes. A0 communication system may be provided by one or more

interconnect networks. One or more gateway nodes may be

provided for interconnecting various networks of the system. For example, a gateway node is typically provided between an access network and other communication networks, for example5 a core network and/or a data network.

An appropriate access system allows the communication device to access to the wider communication system. An access to the wider communications system may be provided by means of a fixed line or wireless communication interface, or a

0 combination of these. Communication systems providing

wireless access typically enable at least some mobility for the users thereof. Examples of these include wireless

communications systems where the access is provided by means of an arrangement of cellular access networks. Other examples of wireless access technologies include different wireless local area networks (WLANs) and satellite based communication systems .

A wireless access system typically operates in accordance with a wireless standard and/or with a set of specifications which set out what the various elements of the system are permitted to do and how that should be achieved. For example, the standard or specification may define if the user, or more precisely user equipment, is provided with a circuit switched bearer or a packet switched bearer, or both. Communication protocols and/or parameters which should be used for the connection are also typically defined. For example, the manner in which communication should be

implemented between the user equipment and the elements of the networks and their functions and responsibilities are typically defined by a predefined communication protocol. Such protocols and or parameters further define the frequency spectrum to be used by which part of the communications system, the transmission power to be used etc.

In the cellular systems a network entity in the form of a base station provides a node for communication with mobile devices in one or more cells or sectors. It is noted that in certain systems a base station is called ^vNode B (NB) ' or "eNode B (eNB)". Typically the operation of a base station apparatus and other apparatus of an access system required for the communication is controlled by a centralised control entity (which centralised control entity is typically interconnected with other centralised control entities of the particular communication network) , or every base station (e.g. eNodeB) contains its own local control entity. Examples of cellular access systems include, in order of their evolution, GSM (Global System for Mobile) EDGE (Enhanced Data for GSM Evolution) Radio Access Networks (GERAN) , Universal Terrestrial Radio Access Networks (UTRAN) and evolved UTRAN (E-UTRAN) . With the aim of avoiding interference between uplink

transmissions at the receiver of an access node,

communication devices simultaneously served by an access node are granted respective resources for making uplink

transmissions to said access node. The resources may, for example, comprise a resource block defined as the aggregation of consecutive sub-carriers in the frequency domain during a time duration called a slot. The inventors have identified the challenge of providing an efficient mechanism by which a communication device can indicate to an access node that it has no data to send on uplink resources granted to it.

It is an aim to meet this challenge.

There is provided a method comprising: when a user equipment has no data to transmit on uplink resources granted to said user equipment, determining whether said user equipment is required to transmit on said uplink resources an indication that said user equipment has no data to transmit.

According to one embodiment, the method further comprises: determining that said user equipment has had no data to transmit for no more than a predetermined period of time since (a) a most recent transmission indicating that said user equipment has no data to transmit or (b) a most recent predetermined number of consecutive transmissions indicating that said user equipment has no data to transmit; and as a result of said determining, refraining from making any transmission on said uplink resources.

According to one embodiment, the method further comprises: determining that said user equipment has had no data to transmit for more than a predetermined period of time since (a) a most recent transmission indicating that said user equipment has no data to transmit or (b) a most recent predetermined number of consecutive transmissions indicating that said user equipment has no data to transmit; and as a result of said determining, transmitting on said uplink resources a new indication that said user equipment has no data to transmit. According to one embodiment, said predetermined period of time comprises a predetermined number of time transmission intervals .

According to one embodiment, said transmission indicating that said user equipment has no data to transmit comprises a transmission of a control element including one or more bits indicating a buffer size value of zero for said user

equipment .

According to one embodiment, said uplink resources comprise an aggregation of frequency sub-carriers during a time slot.

There is also provided a method comprising: receiving at a user equipment an indication as to how said user equipment should operate in the event of having no data to transmit on uplink resources granted to said user equipment. According to one embodiment, said indication specifies a period of time for which said user equipment is not required to make a transmission on uplink resources granted to said user equipment if said user equipment has no data to transmit on said uplink resources. According to one embodiment, the method further comprises: reading said indication at a layer at which said user equipment also reads an indication of uplink resources granted to said user equipment.

According to one embodiment, the method further comprises: reading said indication at a layer higher than a layer at which said user equipment reads an indication of uplink resources granted to said user equipment.

According to one embodiment, said uplink resources comprise an aggregation of frequency sub-carriers during a time slot. There is also provided a method comprising: when detecting no transmission from a user equipment on uplink resources granted to said user equipment, determining whether said uplink resources are resources for which said user equipment is required to transmit an indication that it does not have data to transmit.

According to one embodiment, the method further comprises: determining that no transmissions have been detected from said user equipment on uplink resources granted to said user equipment for no more than a predetermined period of time since receiving (a) a most recent transmission from said user equipment indicating that said user equipment has no data to transmit or (b) a most recent predetermined number of consecutive transmissions indicating that said user equipment has no data to transmit; and as a result of said determining, concluding that said user equipment continues to have no data to send on said uplink resources.

According to one embodiment, the method further comprises:: determining that no transmission from said user equipment on uplink resources granted to it has been detected for more than a predetermined period of time since receiving (a) a most recent transmission indicating that said user equipment has no data to transmit or (b) a most recent predetermined number of consecutive transmissions indicating that said user equipment has no data to transmit; and as a result of said determining, concluding that a failure has occurred.

According to one embodiment, said predetermined period of time comprises a predetermined number of time transmission intervals.

equipment.

There is also provided a method comprising: transmitting an indication as to how a user equipment should operate in the event of having no data to transmit on uplink resources granted to said user equipment.

According to one embodiment, said indication specifies a period of time for which said user equipment is not required to make a transmission on uplink resources granted to said user equipment if said user equipment has no data to transmit on said uplink resources.

According to one embodiment, the method further comprises: generating said indication at a layer at which is generated an indication of uplink resources granted to said user equipment .

According to one embodiment, the method further comprises: generating said indication at a layer higher than a layer at which is generated an indication of uplink resources granted to said user equipment.

There is also provided an apparatus comprising: a processor and memory including computer program code, wherein the memory and the computer program are configured to, with the processor, cause the apparatus to: when a user equipment has no data to transmit on uplink resources granted to said user equipment, determine whether said user equipment is required to transmit on said uplink resources an indication that said user equipment has no data to transmit.

According to one embodiment, the memory and the computer program are configured to, with the processor, cause the apparatus to make a determination as to whether said user equipment has had no data to transmit for no more than a predetermined period of time since (a) a most recent

transmission indicating that said user equipment has no data to transmit or (b) a most recent predetermined number of consecutive transmissions indicating that said user equipment has no data to transmit; and if a result of said determination is positive, to refrain from making any transmission on said uplink resources.

transmission indicating that said user equipment has no data to transmit or (b) a most recent predetermined number of consecutive transmissions indicating that said user equipment has no data to transmit; and if a result of said

determination is negative to, transmit on said uplink resources a new indication that said user equipment has no data to transmit.

According to one embodiment, said predetermined period of time comprises a predetermined number of time transmission intervals .

equipment .

According to one embodiment, said uplink resources comprise an aggregation of frequency sub-carriers during a time slot. There is also provided an apparatus comprising: a processor and memory including computer program code, wherein the memory and the computer program are configured to, with the processor, cause the apparatus to: receive at a user

equipment an indication as to how said user equipment should operate in the event of having no data to transmit on uplink resources granted to said user equipment.

According to one embodiment, the memory and the computer program are configured to, with the processor, cause the apparatus to read said indication at a layer at which said user equipment also reads an indication of uplink resources granted to said user equipment.

According to one embodiment, the memory and the computer program are configured to, with the processor, cause the apparatus to: read said indication at a layer higher than a layer at which said user equipment reads an indication of uplink resources granted to said user equipment.

There is also provided an apparatus comprising: a processor and memory including computer program code, wherein the memory and the computer program are configured to, with the processor, cause the apparatus to: when detecting no

transmission from a user equipment on uplink resources granted to said user equipment, make a determination as to whether said uplink resources are resources for which said user equipment is required to transmit an indication that it does not have data to transmit.

According to one embodiment, the memory and the computer program are configured to, with the processor, cause the apparatus to: conclude that said user equipment continues to have no data to send on said uplink resources, if a result of said determination is that no transmissions have been detected from said user equipment on uplink resources granted to said user equipment for no more than a predetermined period of time since receiving (a) a most recent transmission from said user equipment indicating that said user equipment has no data to transmit or (b) a most recent predetermined number of consecutive transmissions indicating that said user equipment has no data to transmit. According to one embodiment, the memory and the computer program are configured to, with the processor, cause the apparatus to: conclude that a failure has occurred, if the result of said determination is that no transmission from said user equipment on uplink resources granted to it has been detected for more than a predetermined period of time since receiving (a) a most recent transmission indicating that said user equipment has no data to transmit or (b) a most recent predetermined number of consecutive transmissions indicating that said user equipment has no data to transmit.

equipment .

There is also provided an apparatus comprising: a processor and memory including computer program code, wherein the memory and the computer program are configured to, with the processor, cause the apparatus to: transmit an indication as to how a user equipment should operate in the event of having no data to transmit on uplink resources granted to said user equipment .

According to one embodiment, the memory and the computer program are configured to, with the processor, cause the apparatus to: generate said indication at a layer at which is generated an indication of uplink resources granted to said user equipment.

According to one embodiment, the memory and the computer program are configured to, with the processor, cause the apparatus to: generate said indication at a layer higher than a layer at which is generated an indication of uplink resources granted to said user equipment.

There is also provided an apparatus configured to carry out any of the above methods.

There is also provided an apparatus comprising: a processor and memory including computer program code, wherein the memory and the computer program are configured to, with the processor, cause the apparatus at least to carry out any of the above methods.

There is also provided a computer program product comprising program code means which when loaded into a computer controls the computer to perform any of the above methods.

There is also provided a system comprising an access node and a user equipment, wherein the access node is configured to grant uplink resources to said user equipment and to also transmit to a user equipment an indication as to how said user equipment should operate in the event of having no data to transmit on uplink resources granted to said user

equipment; and when said user equipment has no data to transmit on uplink resources granted to said user equipment, said user equipment is configured to determine on the basis of said indication from said access node whether said user equipment is required to transmit on said uplink resources an indication that said user equipment has no data to transmit.

Hereunder, embodiments will be described, by way of example only, with reference to the following drawings, in which: Figure 1 illustrates a radio access network within which an embodiment may be implemented, which access network includes a number of cells each served by a respective base station (eNodeB) ;

Figure 2 illustrates a user equipment shown in figure 1 in further detail.

Figure 3 illustrates an apparatus suitable for implementing an embodiment at an access node or base station of the radio network shown in figure 1;

Figure 4 illustrates an example of the operation of a user equipment in accordance with a first embodiment;

Figure 5 illustrates an example of the operation of an access node in accordance with the first embodiment;

Figure 6 illustrates an example of the operation of an user equipment in accordance with another embodiment; and

Figure 7 illustrates the sub-division of a communication system into protocol layers.

Figures 1, 2 and 3 show respectively the communication system or network, an apparatus for communication within the network, and an access node of the communications network.

Figure 1 shows a communications system or network comprising a first access node 2 with a first coverage area 101, a second access node 4 with a second coverage area 103 and a third access node 6 with a third coverage area 105.

Furthermore Figure 1 shows a plurality of user equipments (UEs) 8 which are each configured to communicate with at least one of the access nodes 2, 4, 6. These coverage areas may also be known as cellular coverage areas or cells where the access network is a cellular communications network.

Figure 2 shows a schematic partially sectioned view of an example of user equipment 8 that may be used for accessing the access nodes and thus the communication system via a wireless interface. The user equipment (UE) 8 may be used for various tasks such as making and receiving phone calls, for receiving and sending data from and to a data network and for experiencing, for example, multimedia or other content.

The UE 8 may be any device capable of at least sending or receiving radio signals. Non-limiting examples include a mobile station (MS) , a portable computer provided with a wireless interface card or other wireless interface facility, personal data assistant (PDA) provided with wireless

communication capabilities, or any combinations of these or the like. The UE 8 may communicate via an appropriate radio interface arrangement of the UE 8. The interface arrangement may be provided for example by means of a radio part 7 and associated antenna arrangement. The antenna arrangement may be arranged internally or externally to the UE 8.

The UE 8 may be provided with at least one data processing entity 3 and at least one memory or data storage entity 7 for use in tasks it is designed to perform. The data processor 3 and memory 7 may be provided on an appropriate circuit board 9 and/or in chipsets.

The user may control the operation of the UE 8 by means of a suitable user interface such as key pad 1, voice commands, touch sensitive screen or pad, combinations thereof or the like. A display 5, a speaker and a microphone may also be provided. Furthermore, the UE 8 may comprise appropriate connectors (either wired or wireless) to other devices and/or for connecting external accessories, for example hands-free equipment, thereto.

As can be seen with respect to figure 1, the UE 8 may be configured to communicate with at least one of a number of access nodes 2, 4, 6. For example, a UE located in the coverage area 101 of a first access node 2 is configured to be able to communicate to the first access node 2; a UE in the coverage area 103 of a second node 4 may be able to communicate with the second access node 4, and a UE in the coverage area 105 of the third access node 6 may be able to communicate with the third access node 6. Figure 3 shows an example of equipment for access nodes, which in the embodiment described below are represented by evolved node Bs (eNBs) 2. The eNB 2 may comprise a radio frequency antenna 301 configured to receive and transmit radio frequency signals, radio frequency interface circuitry 303 configured to interface the radio frequency signals received and transmitted by the antenna 301. The radio frequency interface circuitry may also be known as a

transceiver. The access node (evolved node B) 2 may also comprise a data processor 306 configured to process signals from the radio frequency interface circuitry 303, control the radio frequency interface circuitry 303 to generate suitable RF signals to communicate information to the UE 8 via the wireless communications link. The access node may further comprise a memory 307 for storing data, parameters and instructions for use by the data processor 306.

It will be understood that both the UE 8 and access nodes shown in figures 2 and 3 respectively and described above may comprise further elements which are not directly involved with the embodiments described hereafter.

An embodiment is described below, by way of example only, in the context of a blind scheduling operation, in which one access node 2 allocates respective uplink resources on PUSCH (Physical Uplink Shared Channel) to a plurality of UEs regardless of whether or not they have data to transmit and without requiring any UE 8 to transmit to the access node 2 a specific request for uplink resources when it has data in its buffer to send to access node 2. One advantage of blind scheduling is that there can be less delay between new data arriving in the buffer and that data being transmitted to the access node 2, because the user equipment does not need to first transmit a scheduling request to the access node 2 and wait to receive a grant of uplink resources from the access node 2. Blind scheduling can be a particularly suitable scheduling technique in low load situations, in which allocating uplink resources to UEs that happen not to have any data to transmit to the access node 2 does not have a major impact on the level of service that can be provided to UEs that do have data to transmit to access node 2. For example, the blind scheduling operation might be implemented only where load traffic conditions are appropriate, and even then only to a limited extent depending on the traffic load conditions. Switching between blind scheduling and normal scheduling, or between different amounts of blind scheduling, can be seamless.

Figure 4 illustrates the operation of one UE 8 in accordance with a first embodiment. The UE 8 detects via a physical downlink control channel (PDCCH) a grant to the UE 8 of uplink physical resources (STEP 402), but determines that it has no data in its buffer to transmit via said physical resources (STEP 404) . The UE 8 first calculates the number of consecutive transmission time intervals (TTIs) for which

UE 8 has not made a transmission on resources allocated to it since most recently transmitting to access node 2 an

indication that the buffer of UE 8 is empty (i.e. that its buffer size is zero) (STEP 406) . The UE 8 compares the calculated number with a predetermined number X (STEP 408) . If the calculated number is no more than the predetermined number, X (e.g. 40 TTIs), the UE 8 refrains from making any transmission via the uplink resources allocated to it (STEP 410) . In particular, UE 8 does not send on those uplink resources any indication that its buffer size is zero.

On the other hand, if the calculated number is more than said predetermined number X, the UE transmits via the uplink resources allocated to UE 8 an indication that the buffer size of UE 8 is zero, i.e. that it has no data in its buffer to send (STEP 412). With reference to sections §5.4.5 and §6 of 3GPP TS 36.321 V9.3.0, this indication can take the form of a transport block (TB) with only a Padding Buffer Status Report (BSR) indicating that the buffer size is zero. For example, with reference to the protocol stacks for the user- plane and control-plane illustrated at Figure 7, the UE 8 may generate at the MAC (Medium Access Control) sub-layer (702) of Layer 2 a padding BSR; and transmit the Padding BSR as a transport block at the physical layer (Layer 1) (704) . The above-mentioned predetermined number X of TTIs can be a network configurable parameter, or a constant value to be specified in an industry standard. Where the predetermined number X of TTIs is a network configurable parameter, the access node 2 could, for example, inform the UE 8 of the size of the number X via higher layer signalling, such as RRC (Resource Radio Control) signalling, which involves

generating a message including an indication of the number X at the RRC layer ( Layer 3) (706), i.e. the layer directly above the layer at which (i) said Padding BSRs are generated at UE 8 and read by access node 2, and (ii) uplink resource grant indications are generated at access node 2 and read at UE 8.

Figure 5 illustrates the operation of the access node 2 in accordance with this same embodiment. If the access node 2 does not detect any transmission from UE 8 (including a Padding BSR) on uplink resources allocated to UE 8 (STEP 502), the access node 2 first calculates the number of consecutive TTIs for which access node 2 has not detected any transmission from UE on uplink resources allocated to UE 8 since access node most recently received an indication from the UE 8 that it has no data in its buffer to send (e.g. a Padding BSR from UE 8) (STEP 504) . The access node 2 compares the calculated number with a predetermined number X (STEP 506) . If the calculated number is no more than said predetermined number X, the access node 2 determines that the absence of any transmission from UE on the uplink resources allocated to UE 8 is an indication that UE continues not to have any data in its buffer to send (STEP 508) . On the other hand, if the calculated number is more than said

predetermined number X, access node 2 determines that the absence of any transmission from UE on said uplink resources allocated to UE 8 is the result of a failure, such as UE 8 missing the indication on PDCCH (Physical Downlink Control Channel) as to which uplink resources it has been allocated, or access node 2 (eNB) failing to decode transmission from UE 8 on uplink resources (STEP 510); and determines to take investigative and/or corrective action.

According to one variation of the above-described embodiment, the predetermined number X of TTIs is a number of consecutive TTIs for which UE 8 has not made a transmission on uplink resources granted to it since the most recent occurrence of the transmission of a predetermined number Y of consecutive Padding BSRs indicating a UE buffer size of zero (or from the point of view of access node 2, the number of consecutive TTIs for which access node 2 has not detected any

transmission on uplink resources granted to UE since the most recent occurrence of the reception at access node of a predetermined number Y of consecutive Padding BSRs indicating a UE buffer size of zero) .

For example, the predetermined number X might be 40 and the predetermined number Y might be 2. If, for example, the blind scheduling was such that UE 8 is granted uplink resources once every TTI, then for as long as the UE 8 has no data to send (buffer size = 0), the UE 8 would only send Padding BSRs in 2 of every 42 TTIs.

In this variation also, either or both of the above-mentioned pre-determined numbers X and Y can be a network configurable parameter, or have a constant value to be specified in an industry standard. Where X and/or Y are network configurable parameters, the access node 2 could, for example, inform the UE of the value of X and/or Y via the same kind of higher layer signalling mentioned above.

Figure 6 illustrates the operation of the UE 8 in accordance with another embodiment. When generating for transmission via the PDCCH an indication of which uplink resources are allocated to each UE, the access node 2 includes an

indication as to whether the respective UE 8 is required to send a Padding BSR (or other indication that it has no data in its buffer to send) in the event that it has no data in its buffer to send via said uplink resources. For example, the indication could take the form of a specific code point whose value can be one of two values to distinguish between (a) grants of uplink resources for which the respective UE can refrain from making any transmission via those uplink resources if it has no data in its buffer to send, and (b) grants of uplink resources for which the respective UE is required to at least transmit via those uplink resources a Padding BSR indicating that it has no data in its buffer to send. When the UE 8 detects via PDCCH that it has been allocated uplink physical resources (STEP 602), and

determines that it has no data in its buffer to send via the allocated uplink resources (STEP 604), the UE 8 determines whether the grant of uplink resources is accompanied by an indication of a requirement to send at least a Padding BSR indicating buffer size = 0 (STEP 606) . If the UE 8 does not find such an indication, the UE 8 refrains from making any transmission via said uplink resources (STEP 608) . On the other hand, if the UE 8 does find such an indication, the UE 8 transmits via said uplink resources a Padding BSR

indicating buffer size = 0.

According to one variation of the second embodiment, the access node 2 uses higher layer signalling (e.g. RRC

signalling at Layer 3 (706)) to indicate to the UEs 8 which grants of uplink resources come with a requirement for the respective UE 8 to at least send indication Padding BSR that there is no data in its buffer to send, and which grants of uplink resources can be ignored by the respective UE if it has no data in its buffer to send.

One advantage of the above-described techniques is that it is possible to reduce UE power consumption whilst at the same time providing an access node with a reasonable level of uncertainty that no failure has occurred. Another advantage is that skipping UE transmissions in accordance with the above-described technique can help to reduce interference towards transmissions in neighbouring cells.

The above-described operations may require data processing in the various entities. The data processing may be provided by means of one or more data processors. Similarly various entities described in the above embodiments may be

implemented within a single or a plurality of data processing entities and/or data processors. Appropriately adapted computer program code product may be used for implementing the embodiments, when loaded to a computer. The program code product for providing the operation may be stored on and provided by means of a carrier medium such as a carrier disc, card or tape. A possibility is to download the program code product via a data network. Implementation may be provided with appropriate software in a server.

For example the embodiments may be implemented as a chipset, in other words a series of integrated circuits communicating among each other. The chipset may comprise microprocessors arranged to run code, application specific integrated circuits (ASICs) , or programmable digital signal processors for performing the operations described above.

Embodiments may be practiced in various components such as integrated circuit modules. The design of integrated circuits is by and large a highly automated process. Complex and powerful software tools are available for converting a logic level design into a semiconductor circuit design ready to be etched and formed on a semiconductor substrate.

Programs, such as those provided by Synopsys, Inc. of

Mountain View, California and Cadence Design, of San Jose, California automatically route conductors and locate

components on a semiconductor chip using well established rules of design as well as libraries of pre-stored design modules. Once the design for a semiconductor circuit has been completed, the resultant design, in a standardized electronic format (e.g., Opus, GDSII, or the like) may be transmitted to a semiconductor fabrication facility or "fab" for

fabrication .

In addition to the modifications explicitly mentioned above, it will be evident to a person skilled in the art that various other modifications of the described embodiment may be made .

Claims

1. A method comprising: when a user equipment has no data to transmit on uplink resources granted to said user

equipment, determining whether said user equipment is required to transmit on said uplink resources an indication that said user equipment has no data to transmit.

2. A method according to claim 1, comprising: determining that said user equipment has had no data to transmit for no more than a predetermined period of time since (a) a most recent transmission indicating that said user equipment has no data to transmit or (b) a most recent predetermined number of consecutive transmissions indicating that said user equipment has no data to transmit; and as a result of said determining, refraining from making any transmission on said uplink resources.

3. A method according to claim 1, comprising: determining that said user equipment has had no data to transmit for more than a predetermined period of time since (a) a most recent transmission indicating that said user equipment has no data to transmit or (b) a most recent predetermined number of consecutive transmissions indicating that said user equipment has no data to transmit; and as a result of said determining, transmitting on said uplink resources a new indication that said user equipment has no data to transmit.

4. A method according to claim 2 or claim 3, wherein said predetermined period of time comprises a predetermined number of time transmission intervals.

5. A method according to any of claims 1 to 4, wherein said transmission indicating that said user equipment has no data to transmit comprises a transmission of a control element including one or more bits indicating a buffer size value of zero for said user equipment.

6. A method according to any of claims 1 to 5, wherein said uplink resources comprise an aggregation of frequency sub- carriers during a time slot.

7. A method comprising: receiving at a user equipment an indication as to how said user equipment should operate in the event of having no data to transmit on uplink resources granted to said user equipment.

8. A method according to claim 7, wherein said indication specifies a period of time for which said user equipment is not required to make a transmission on uplink resources granted to said user equipment if said user equipment has no data to transmit on said uplink resources.

9. A method according to claim 7, comprising: reading said indication at a layer at which said user equipment also reads an indication of uplink resources granted to said user equipment .

10. A method according to claim 7, comprising: reading said indication at a layer higher than a layer at which said user equipment reads an indication of uplink resources granted to said user equipment.

11. A method according to any of claims 7 to 10, wherein said uplink resources comprise an aggregation of frequency sub-carriers during a time slot.

12. A method comprising: when detecting no transmission from a user equipment on uplink resources granted to said user equipment, determining whether said uplink resources are resources for which said user equipment is required to transmit an indication that it does not have data to

transmit .

13. A method according to claim 12, comprising: determining that no transmissions have been detected from said user equipment on uplink resources granted to said user equipment for no more than a predetermined period of time since receiving (a) a most recent transmission from said user equipment indicating that said user equipment has no data to transmit or (b) a most recent predetermined number of consecutive transmissions indicating that said user equipment has no data to transmit; and as a result of said determining, concluding that said user equipment continues to have no data to send on said uplink resources.

14. A method according to claim 12, comprising: determining that no transmission from said user equipment on uplink resources granted to it has been detected for more than a predetermined period of time since receiving (a) a most recent transmission indicating that said user equipment has no data to transmit or (b) a most recent predetermined number of consecutive transmissions indicating that said user equipment has no data to transmit; and as a result of said determining, concluding that a failure has occurred.

15. A method according to claim 13 or claim 14, wherein said predetermined period of time comprises a predetermined number of time transmission intervals.

16. A method according to any of claims 12 to 15, wherein said transmission indicating that said user equipment has no data to transmit comprises a transmission of a control element including one or more bits indicating a buffer size value of zero for said user equipment.

17. A method according to any of claims 12 to 16, wherein said uplink resources comprise an aggregation of frequency sub-carriers during a time slot.

18. A method comprising: transmitting an indication as to how a user equipment should operate in the event of having no data to transmit on uplink resources granted to said user equipment.

19. A method according to claim 18, wherein said indication specifies a period of time for which said user equipment is not required to make a transmission on uplink resources granted to said user equipment if said user equipment has no data to transmit on said uplink resources.

20. A method according to claim 18, comprising: generating said indication at a layer at which is generated an

indication of uplink resources granted to said user

equipment .

21. A method according to claim 18, comprising: generating said indication at a layer higher than a layer at which is generated an indication of uplink resources granted to said user equipment.

22. A method according to any of claims 18 to 20, wherein said uplink resources comprise an aggregation of frequency sub-carriers during a time slot.

23. An apparatus comprising: a processor and memory

including computer program code, wherein the memory and the computer program are configured to, with the processor, cause the apparatus to: when a user equipment has no data to transmit on uplink resources granted to said user equipment, make a determination as to whether said user equipment is required to transmit on said uplink resources an indication that said user equipment has no data to transmit.

24. An apparatus according to claim 23, wherein the memory and the computer program are configured to, with the

processor, cause the apparatus to: make a determination as to whether said user equipment has had no data to transmit for no more than a predetermined period of time since (a) a most recent transmission indicating that said user equipment has no data to transmit or (b) a most recent predetermined number of consecutive transmissions indicating that said user equipment has no data to transmit; and if a result of said determination is positive, to refrain from making any transmission on said uplink resources.

25. An apparatus according to claim 23, wherein the memory and the computer program are configured to, with the

processor, cause the apparatus to make a determination as to whether said user equipment has had no data to transmit for no more than a predetermined period of time since (a) a most recent transmission indicating that said user equipment has no data to transmit or (b) a most recent predetermined number of consecutive transmissions indicating that said user equipment has no data to transmit; and if a result of said determination is negative, to transmit on said uplink resources a new indication that said user equipment has no data to transmit.

26. An apparatus according to claim 24 or claim 25, wherein said predetermined period of time comprises a predetermined number of time transmission intervals.

27. An apparatus according to any of claims 23 to 26, wherein said transmission indicating that said user equipment has no data to transmit comprises a transmission of a control element including one or more bits indicating a buffer size value of zero for said user equipment.

28. An apparatus according to any of claims 23 to 27, wherein said uplink resources comprise an aggregation of frequency sub-carriers during a time slot.

29. An apparatus comprising: a processor and memory

including computer program code, wherein the memory and the computer program are configured to, with the processor, cause the apparatus to: receive at a user equipment an indication as to how said user equipment should operate in the event of having no data to transmit on uplink resources granted to said user equipment.

30. An apparatus according to claim 29, wherein said indication specifies a period of time for which said user equipment is not required to make a transmission on uplink resources granted to said user equipment if said user equipment has no data to transmit on said uplink resources.

31. An apparatus according to claim 29, comprising: wherein the memory and the computer program are configured to, with the processor, cause the apparatus to read said indication at a layer at which said user equipment also reads an indication of uplink resources granted to said user equipment.

32. An apparatus according to claim 29, wherein the memory and the computer program are configured to, with the

processor, cause the apparatus to: read said indication at a layer higher than a layer at which said user equipment reads an indication of uplink resources granted to said user equipment .

33. An apparatus according to any of claims 29 to 32, wherein said uplink resources comprise an aggregation of frequency sub-carriers during a time slot.

34. An apparatus comprising: a processor and memory

comprising computer program code, wherein the memory and the computer program are configured to, with the processor, cause the apparatus to: when detecting no transmission from a user equipment on uplink resources granted to said user equipment, make a determination as to whether said uplink resources are resources for which said user equipment is required to transmit an indication that it does not have data to

transmit .

35. An apparatus according to claim 34, wherein the memory and the computer program are configured to, with the

processor, cause the apparatus to: conclude that said user equipment continues to have no data to send on said uplink resources, if a result of said determination is that no transmissions have been detected from said user equipment on uplink resources granted to said user equipment for no more than a predetermined period of time since receiving (a) a most recent transmission from said user equipment indicating that said user equipment has no data to transmit or (b) a most recent predetermined number of consecutive transmissions indicating that said user equipment has no data to transmit.

36. An apparatus according to claim 34, wherein the memory and the computer program are configured to, with the

processor, cause the apparatus to: conclude that a failure has occurred, if the result of said determination is that no transmission from said user equipment on uplink resources granted to it has been detected for more than a predetermined period of time since receiving (a) a most recent transmission indicating that said user equipment has no data to transmit or (b) a most recent predetermined number of consecutive transmissions indicating that said user equipment has no data to transmit.

37. An apparatus according to claim 35 or claim 36, wherein said predetermined period of time comprises a predetermined number of time transmission intervals.

38. An apparatus according to any of claims 34 to 37, wherein said transmission indicating that said user equipment has no data to transmit comprises a transmission of a control element including one or more bits indicating a buffer size value of zero for said user equipment.

39. An apparatus according to any of claims 34 to 38, wherein said uplink resources comprise an aggregation of frequency sub-carriers during a time slot.

40. An apparatus comprising: a processor and memory

comprising computer program code, wherein the memory and the computer program are configured to, with the processor, cause the apparatus to: transmit an indication as to how a user equipment should operate in the event of having no data to transmit on uplink resources granted to said user equipment.

41. An apparatus according to claim 40, wherein said indication specifies a period of time for which said user equipment is not required to make a transmission on uplink resources granted to said user equipment if said user equipment has no data to transmit on said uplink resources.

42. An apparatus according to claim 40, wherein the memory and the computer program are configured to, with the

processor, cause the apparatus to: generate said indication at a layer at which is generated an indication of uplink resources granted to said user equipment.

43. An apparatus according to claim 40, wherein the memory and the computer program are configured to, with the

processor, cause the apparatus to: generate said indication at a layer higher than a layer at which is generated an indication of uplink resources granted to said user

equipment .

44. An apparatus according to any of claims 40 to 42, wherein said uplink resources comprise an aggregation of frequency sub-carriers during a time slot.

45. An apparatus, configured to: when a user equipment has no data to transmit on uplink resources granted to said user equipment, determine whether said user equipment is required to transmit on said uplink resources an indication that said user equipment has no data to transmit.

46. An apparatus configured to: receive at a user equipment an indication as to how said user equipment should operate in the event of having no data to transmit on uplink resources granted to said user equipment.

47. An apparatus configured to: when detecting no

transmission from a user equipment on uplink resources granted to said user equipment, determine whether said uplink resources are resources for which said user equipment is required to transmit an indication that it does not have data to transmit.

48. An apparatus configured to: transmit an indication as to how a user equipment should operate in the event of having no data to transmit on uplink resources granted to said user equipment .

49. A computer program product comprising program code means which when loaded into a computer controls the computer to: when a user equipment has no data to transmit on uplink resources granted to said user equipment, determine whether said user equipment is required to transmit on said uplink resources an indication that said user equipment has no data to transmit.

50. A computer program product comprising program code means which when loaded into a computer controls the computer to: receive at a user equipment an indication as to how said user equipment should operate in the event of having no data to transmit on uplink resources granted to said user equipment.

51. A computer program product comprising program code means which when loaded into a computer controls the computer to: when detecting no transmission from a user equipment on uplink resources granted to said user equipment, determine whether said uplink resources are resources for which said user equipment is required to transmit an indication that it does not have data to transmit.

52. A computer program product comprising program code means which when loaded into a computer controls the computer to: transmit an indication as to how a user equipment should operate in the event of having no data to transmit on uplink resources granted to said user equipment.

53. An apparatus configured to carry out the method of any of claims 1 to 22.

54. An apparatus comprising: a processor and memory

including computer program code, wherein the memory and the computer program are configured to, with the processor, cause the apparatus at least to carry out the method of any of claims 1 to 22.

55. A computer program product comprising program code means which when loaded into a computer controls the computer to perform a method according to any of claims 1 to 22.

56. A system comprising an access node and a user equipment, wherein the access node is configured to grant uplink resources to said user equipment and to also transmit to a user equipment an indication as to how said user equipment should operate in the event of having no data to transmit on uplink resources granted to said user equipment; and when said user equipment has no data to transmit on uplink resources granted to said user equipment, said user equipment is configured to determine on the basis of said indication from said access node whether said user equipment is required to transmit on said uplink resources an indication that said user equipment has no data to transmit.