GB2547671A

GB2547671A - Methods and devices for scheduling transmissions in a cellular communication system

Info

Publication number: GB2547671A
Application number: GB1603246.8A
Authority: GB
Inventors: Marco Olivier; Vivier Guilaume; Katranaras Efstathios; Winiecki Thomas
Original assignee: TCL Communication Ltd
Current assignee: TCL Communication Ltd
Priority date: 2016-02-25
Filing date: 2016-02-25
Publication date: 2017-08-30
Anticipated expiration: 2036-02-25
Also published as: GB201603246D0; CN109076519B; GB2547671B; CN109076519A; WO2017143893A1

Abstract

In an LTE cellular communications system (100) with Carrier Aggregation, a User Equipment, UE (106) is configured to ignore the Scheduling Request Prohibit Timer, sr-ProhibitTimer (107), which is set running 207 on transmission of a Scheduling Request, SR, on one Component Carrier and to identify further Scheduling Request opportunities on another Component Carrier 208 and send further Scheduling Requests on the other Component Carriers 209 prior to expiry of the Timer (107). This can result in a reduction in the average latency for an uplink packet sent from a UE (106) to an eNode B (101). The UE is configured with an index associated with each of a first and second Component Carriers whose state depends on whether a Component Carrier has been used to send a Scheduling Request. A UE informs the network element of its capability to transmit Scheduling Requests prior to expiry of the scheduling request prohibit timer.

Description

Methods and Devices for Scheduling Transmissions in a Cellular

Communication System

Technical Field

Embodiments of the present invention generally relate to cellular communication systems and in particular to devices and methods for scheduling transmissions from a User Equipment to network elements of the cellular communication system.

Background

Cellular communication systems, such as the third-generation (3G) of mobile telephone standards and technology are well known. Such 3G standards and technology have been developed by the Third Generation Partnership Project. The 3rd generation of wireless communications has generally been developed to support macro-cell mobile phone communications. Such macro cells utilise high power base stations (NodeBs) to communicate with wireless communication units within a relatively large geographical coverage area. Typically, wireless communication units, or User Equipment (UEs) as they are often referred to, communicate with a Core Network (CN) of the 3G wireless communication system via a Radio Network Subsystem (RNS). A wireless communication system typically comprises a plurality of radio network subsystems, each radio network subsystem comprising one or more cells to which UEs may attach, and thereby connect to the network. Each macro-cellular RNS further comprises a controller, in a form of a Radio Network Controller (RNC), operably coupled to the one or more NodeBs. Communication systems and networks have developed towards a broadband and mobile system. The 3rd Generation Partnership Project has developed a Long Term Evolution (LTE) solution, namely, an Evolved Universal Mobile Telecommunication System Territorial Radio Access Network, (E-UTRAN), for a mobile access network, and a System Architecture Evolution (SAE) solution, namely, an Evolved Packet Core (EPC), for a mobile core network. A macrocell in an LTE system is supported by a base station known as an eNodeB or eNB (evolved NodeB). A further development, LTE-Advanced, has introduced the concept of Carrier Aggregation (CA) in order to increase bandwidth. Each aggregated carrier is referred to as a Component Carrier (CC). There is a serving cell for each component carrier, which may all be supported by a single eNB. A concept of primary cell (PCell) and secondary cell (SCell) has been introduced to support CA. The PCell, which is akin to a serving cell in the non-CA case, is typically used (amongst other functions) for PUCCH (Physical Uplink Channel) transmissions and RRC (Radio Resource Control) connection and re-establishment. An SCell may be added to the PCell or a set of serving cells through an RRC connection reconfiguration procedure.

Before a UE can transmit data to an eNB it must receive an Uplink (UL) grant message from the eNB. In LTE systems, UL grants are sent to UEs using dynamic scheduling (i.e. using the so-called Scheduling Request (SR) procedure), random access procedure or Semi-Persistent Scheduling (SPS).

In current LTE systems, the so-called Scheduling Request (SR) is used by a User Equipment for requesting uplink resources for sending a new transmission of data. Typically, an eNB configures a UE with an SR configuration index via Radio Resource Connection (RRC) signalling in order for the UE to transmit a Scheduling Request on the PUCCH (Physical Uplink Control Channel). A particular SR configuration index has an assigned periodicity and subframe offset value. The SR index is used by the UE to determine the subframe where the Scheduling Request should be transmitted and thereby determine the next available opportunity for sending an SR. The overall latency for uplink transmission delay of a first packet in a burst depends on how fast an uplink grant is received at the particular UE which has data ready to transmit. Scheduling Request periodicity is typically 10ms and studies have shown that the waiting time for an SR opportunity for a UE is around 30% of the overall Radio Access Network delay. Further studies have revealed that any improvement that can be made in latency reduction for transmitting the first uplink packet in a burst can have a significant effect on the overall TCP/IP (Transmission Control Protocol/lnternet Protocol) throughput.

In order to avoid unnecessary SR transmissions and reduce the load on the PUCCH, in Release-9 a Scheduling Request prohibit timer (sr-ProhibitTimer-r9) was introduced. The sr-ProhibitTimer-r9 Information Element is under mac-MainConfig and it can take values from 0 to 7. The sr-ProhibitTimer value is typically a number of SR period(s). Value 0 means that no timer for SR transmission on a PUCCH is configured. Value 1 corresponds to one SR period, value 2 corresponds to 2*SR periods and so on. A UE will start this timer after transmitting an SR. When the timer is running, the UE is effectively prohibited from transmitting an SR on the PUCCH.

In legacy (i.e. up to Release12) CA, only the PCell is configured with PUCCH; thus, UL grants via SR can be provided only through one carrier, that is, the PCell. It has been agreed that for Release 13 CA SR in the PUCCH on an Scell should be supported in order to relieve resource usage on the PCell. Further, up to two cells may be configured with PUCCH for a UE. Also, there should be only one SR procedure regardless of whether D-SR (dedicated Scheduling Request) is configured on multiple cells; that is, one SR_COUNTER which is increased when D-SR is sent on either PCell or SCell and one sr-Prohibit Timer. In cases where D-SR resources are configured on both the PCell and a PUCCH SCell, the sr-ProhibitTimer should be based on the shorter SR period.

It has also been agreed that where SRs are configured on both activated PUCCH SCell and PCell, when the first UL packet is ready for transmission, the UE’s MAC entity instructs the physical channels to send the SR when the first opportunity arises and the UE MAC (Median Access Control) entity chooses one SR when SRs on PUCCH SCell and PCell are in the same TTI (Transmission Time Interval). Which one to choose is left to the UE’s implementation. For example, if multiple PUCCH resources for SR are valid for a TTI, due to multiple CCs available for SR transmission at the same time, it is left to UE implementation to decide which PUCCH resource to be used.

It would be advantageous to provide a means for reducing the latency for a first uplink packet in a burst and which is compatible with the concept of a single sr-ProhibitTimer.

Summary

This Summary is provided to introduce a selection of concepts in a simplified form that are further described below in the Detailed Description. This Summary is not intended to identify key features or essential features of the claimed subject matter, nor is it intended to be used as an aid in determining the scope of the claimed subject matter.

According to a first aspect of the present invention there is provided a method for scheduling a transmission from a wireless communication device in a cellular communication system which supports Carrier Aggregation, the method including: configuring the wireless communication device with a scheduling request prohibit timer (sr-ProhibitTimer); configuring the wireless communication device with a first Component Carrier configuration; configuring the wireless communication device with a second Component Carrier configuration; configuring the wireless communication device with a first Scheduling Request configuration in respect of the first Component Carrier; configuring the wireless communication device with a second Scheduling Request configuration in respect of the second Component Carrier; identifying a Scheduling Request opportunity on one of the first and second Component Carriers, transmitting a Scheduling Request on the identified Component Carrier; starting the scheduling request prohibit timer, identifying a further Scheduling Request opportunity on the other Component Carrier and sending a Scheduling Request on the other Component Carrier prior to expiry of the scheduling request prohibit timer.

In some embodiments, there may be more than two Component Carriers configured for Scheduling Request. The cellular communication system may be an LTE Advanced system.

The invention is applicable to Component Carriers which are licensed or unlicensed.

Advantageously, in accordance with come embodiments, the method can enhance SR configuration procedure in cases where more than one UL SR-configured PUCCH CC is serving a UE.

By virtue of the invention, a wireless communication device MAC entity has the ability to ignore the sr-ProhibitTimer for Scheduling Request opportunities arising on CCs that have not yet been used to send a Scheduling Request. MAC protocol enhancements may be introduced to improve SR procedure when multiple PUCCH Component Carriers (CCs) are SR-configured to serve an LTE CA-enabled UE in connected mode.

The operation of the sr-ProhibitTimer is effectively decoupled from the per-CC: Scheduling Request opportunity realised at the UE MAC entity. Hence a UE is allowed to select an additional carrier for sending a scheduling request even though the sr-ProhibitTimer inhibiting such sending is still running. Advantageously, the Scheduling Request procedure becomes more robust and a UE can send its first packet to an eNB, with less delay than is currently the case.

In one embodiment, the method further includes sending a message from the wireless communication device to a network element of the cellular communication system whereby the wireless communication device informs the network element of its capability to transmit Scheduling Requests prior to expiry of the scheduling request prohibit timer. In such a case, a Scheduling Request configuration in respect of at least one Component Carrier may be modified by the network element in response to receipt of the message. The network element may be an eNB. If the eNB knows of this UE MAC entity behaviour then it can jointly configure the scheduling of SR opportunities from multiple Component Carriers in order to provide more frequent grant opportunities and therefore further reduce the average latency for a first uplink packet sent from a UE. Delay-sensitive applications in particular can benefit from this embodiment. Furthermore, the flexibility of a scheduler in an eNB is enhanced in cases where the sr-ProhibitTimer would present a bottleneck for a CC that could be used more often for SR opportunities by the UE or which experiences variable quality channel conditions over a short-time period.

According to a second aspect of the invention, there is provided a wireless communication device for use in a cellular communication system which supports Carrier Aggregation, wherein the wireless communication device is configured with a scheduling request prohibit timer (sr-ProhibitTimer) and arranged to: receive first and second Component Carrier configurations, receive first and second Scheduling Request configurations in respect of the first and second Component Carriers, identify a Scheduling Request opportunity on one of the first and second Component Carriers, transmit a Scheduling Request on the identified Component Carrier; start the scheduling request prohibit timer, identify a further Scheduling Request opportunity on the other Component Carrier and send a Scheduling Request on the other Component Carrier prior to expiry of the scheduling request prohibit timer.

In some embodiments, the wireless communication device may be configured with more than two Component Carrier configurations and Scheduling Request configurations.

In one embodiment, the wireless communication device is arranged to configure an index associated with each Component Carrier whose state depends on whether a Component Carrier has been used to send a Scheduling Request.

The wireless communication device may be a User Equipment or similar mobile communications device.

The invention may be used to introduce RRC protocol enhancements in order to improve Scheduling Request procedure when multiple PUCCH CCs are SR-configured to serve an LTE CA-enabled UE in connected mode.

According to a third aspect of the invention, there is provided a non-transitory computer readable medium having computer readable instructions stored thereon for execution by a processor to perform the method according to the first aspect.

The non-transitory computer readable medium may comprise at least one from a group consisting of: a hard disk, a CD-ROM, an optical storage device, a magnetic storage device, a Read Only Memory, a Programmable Read Only Memory, an Erasable Programmable Read Only Memory, EPROM, an Electrically Erasable Programmable Read Only Memory and a Flash memory.

Brief description of the drawings

Further details, aspects and embodiments of the invention will be described, by way of example only, with reference to the drawings. Elements in the figures are illustrated for simplicity and clarity and have not necessarily been drawn to scale. Like reference numerals have been included in the respective drawings to ease understanding.

Figure 1 is a simplified block diagram of a part of a cellular communication system and operating in accordance with an example embodiment.

Figure 2 is a simplified flowchart illustrating an example of a method for scheduling transmissions from a UE; and

Figure 3 is a simplified flowchart illustrating an example of operation of a User Equipment.

Detailed description of the preferred embodiments

Those skilled in the art will recognise and appreciate that the specifics of the examples described are merely illustrative of some embodiments and that the teachings set forth herein are applicable in a variety of alternative settings.

Referring now to FIG. 1, an example of part of an LTE cellular communication system operating in accordance with embodiments of the invention is illustrated and indicated generally at 100 and comprises an evolved Node B (eNB) 101. The eNB 101 includes a scheduler 102 and a transceiver 103. The eNB 101 utilises Carrier Aggregation and supports a first Component Carrier (CCx) and a second Component Carrier (CCy) which are represented respectively by cells 104 and 105. In other examples, more than two component carriers may be supported by the eNB 101. A User Equipment (UE) 106 which is CA-enabled is located within the coverage areas of both cells 104, 105. The transceiver 103 is arranged in a conventional manner to transmit and receive communication signals and data to and from the User Equipment 106. The User Equipment 106 is configured with a single scheduling request prohibit timer (sr-ProhibitTimer) 107 and a transmitter/receiver arrangement 108 for sending and receiving transmissions to and from the eNB 101.

The eNB 101 communicates with UEs (for example UE106) which are CA-enabled and in connected mode and that can be semi-statically configured with more than one UL CC. The UEs can also be configured with periodic SR opportunities both on the first Component Carrier and also on the second Component Carrier and have them activated to serve the UE at the same time. The scheduler 102 in the eNB may regularly monitor uplink scheduling load and UE activity and use this information for dynamically adapting SR scheduling parameters between the two Component Carriers CCx and CCy).

Applying a conventional approach to the situation where only one sr-Prohibit Timer is provided, the UE MAC entity instructs PHY to send a SR when the first opportunity arrives and any subsequent SR opportunities (including those related to another CC) will not be considered while the sr-ProhibitTimer is running. In contrast, in the embodiment of Figure 1, the UE MAC entity of UE 106 considers other SR opportunities arising on other component carriers even while the sr-ProhibitTimer is running. The sr-ProhibitTimer Information Element is configured in MAC-MainConfig for a cell group (i.e. for all CCs originating from a single eNB, CCx and CCy in the example of Figure 1).

The conventional approach mentioned above can result in some undesirable situations which the present invention can ameliorate. For example, say UE 106 had a requirement to send a Scheduling Request every 2 ms in order to satisfy data latency constraints. Moreover, say CCx can only (due to SR load constraints) offer opportunities every 4ms while CCy can offer opportunities every 2ms. If the sr-periodicity of both CCx and CCy were set at 2 ms and the sr-ProhibitTimer value was to be set at zero, the SR load on CCx would be unacceptable. On the other hand, if the sr-ProhibitTimer value were to be set at 1 it would not be possible to perfectly interleave the two component carriers CCx and CCy. By allowing the UE to ignore the sr-ProhibitTimer, the present invention sidesteps these problems.

The issue becomes more serious if the UE fails to receive a scheduling grant from the eNB in response to the first transmitted SR, e.g. on CCx. This could happen if CCx uplink coverage is very poor or due to an SR failure or even due to failure on reception of UL grant on the PDCCH (Physical Downlink Control Channel). In that event, the UE will try to send another SR at the first opportunity after the sr-ProhibitTimer has expired, thus wasting time. Again, this situation is ameliorated by the present invention.

Consider a further example where uplink coverage on CCx is very poor and CCx has an SR periodicity of 1 ms and CCy has a periodicity of 5 ms and the sr-ProhibitTimer value has to be set at 1 due to load constraints on PUCCH of CCx. In this example it is possible that any scheduling requests on CCy are totally disregarded because the UE keeps trying to make (failed) scheduling request on CCx. In addition, by the time a Scheduling Request opportunity becomes available on CCy, dsr-TransMax may have been reached, causing the SR procedure to be cancelled earlier rather than trying the alternative link. Once again, the invention can ameliorate these situations.

Reference will now be made to the flow chart of Figure 2 which illustrates an example of a method for scheduling transmissions from the UE 106 of Figure 1.

At 201, a single sr-ProhibitTimer is configured in the UE 106. At 202, a first Component Carrier CCx (represented by the cell 104 in Figure 1) is configured in the UE 106 by the eNB 101 transmitting the necessary configuration signalling. This configuration is carried out in accordance with known techniques (including, for example RRC connection procedures). At 203, in accordance with conventional techniques, a Scheduling Request Configuration for the Component Carrier CCx is configured in the UE 106 by the eNB 101 transmitting a Scheduling Request Configuration comprising a Scheduling Request Configuration Information Element. This Scheduling Request Configuration basically informs the UE of the PUCCH resources which will be available on the Component Carrier CCx for making a Scheduling Request. At 204, the second Component Carrier CCy (represented by the cell 105 in Figure 1) is configured in the UE 106 by the eNB 101 transmitting the necessary configuration signalling. This configuration is carried out in accordance with known Carrier Aggregation techniques. At 205, in accordance with conventional techniques, a Scheduling Request Configuration for CCy is configured in the UE 106 by the eNB 101 transmitting a Scheduling Request Configuration comprising a Scheduling Request Configuration Information Element. This Scheduling Request Configuration basically informs the UE of the PUCCH resources which will be available on the second Component Carrier CCy for making a Scheduling Request. At 206, the UE 106 identifies the first Scheduling Request opportunity that arises on either Component Carrier and sends a Scheduling Request in accordance with conventional techniques to the eNB 101. On sending this Scheduling Request the sr-ProhibitTimer starts running (at 207). Even before the sr-ProhibitTimer has expired, the UE 106 looks for further SR opportunities on another Component Carrier. When one such further SR opportunity is identified by the UE 106, at 208, the UE 106 can send, at 209, a further SR on the other Component Carrier. On receiving a Scheduling Grant from the eNB 101, the UE 106 can transmit a packet of data to the eNB, at 210 and then terminate the SR procedure. Just one SR procedure runs at UE MAC entity, therefore maintaining compatibility with currently defined procedures. Further, the embodiment of Figure 2 is also compatible with the agreement for having a single sr-ProhibitTimer for multiple Component Carriers in a group.

The behaviour of the UE of overriding the sr-ProhibitTimer can be a matter of choice. In a delay tolerant application for example, it may be considered to be more beneficial to put less strain on the UE and network (from having to deal with an increased number of SRs) rather than reduce the latency of UL data. If the scenario is considered fitting, the UE 106 could independently decide to apply such behaviour or alternatively, the eNB 101 could configure (by RRC signalling) such behaviour for the UE. Otherwise the SR operation can operate as conventional.

In one embodiment, the UE 106 is arranged to configure an index associated with each SR-configured serving Component Carrier whose state depends on whether a Component Carrier has been used to send a Scheduling Request. Such an embodiment will now be described with reference to Figure 3 and Figure 1.

In the UE 106 an index is defined for each SR-configured serving CC (CCx and CCy of Figure 1 for example). There are three possible states for the index: ‘initial’, ‘override’ and ‘used’. In the ‘initial’ state, the sr-ProhibitTimer applies to the CC as in the conventional case. In the ‘override’ state, the sr-ProhibitTimer is ignored in respect of that CC thereby allowing selection of that CC (as an additional carrier) for sending the SR even though the sr-ProhibitTimer is running. In the ‘used’ state, the Component Carrier has been used to send a SR and once the SR has been sent and the sr-ProhibitTimer has started running, the index state cannot be changed until the specific SR procedure ends.

So if the sr-ProhibitTimer was last (re-)started on transmission of an SR on CCx, the next SR opportunity, arising at UE MAC on any other CC (CCy in the example of Figure 1) can be taken as long as this CC has not been used to transmit since the SR procedure started.

At 301, once Scheduling Request configurations for all serving CCs have been configured in the UE 106 and an SR procedure starts at UE MAC entity, each index for each CC is set to “initial”.

At 302 and on each TTI, the UE checks to determine whether the sr-ProhibitTimer is running and also checks the index of each CC with an SR opportunity to identify those CCs whose index is currently set at “initial”, “override” and “used” states.

At 303, in the UE, a set of “valid” CCs is created. A CC is included in this set only if it offers an SR opportunity at a particular TTI of interest and (i) the sr-ProhibitTmer is not running/has expired; or (ii) the sr-ProhibitTimer is running but the CC’s index is in the “override” state (and thus the sr-ProhibitTimer is ignored).

At 304, a CC is chosen from the set of valid CCs and as long as the sr-TransMax has not been reached, an SR is sent on this chosen CC.

Whenever an SR is transmitted on a CC, the sr-ProhibitTimer (re)starts, at 305, and in addition, at 306, the index of that CC is changed to “used” if not already in that state, and the indices of all other CCs in “initial” state, if any, are changed to “override.”

In an alternative embodiment, the eNB 101 of Figure 1 is modified such that it is made aware of the capability of the UE 106 to ignore the sr-ProhibitTimer; as described above with reference to Figures 2 and 3. The scheduler 102 of the eNB 101 uses this information in order to optimise the joint configurations of SR-related parameters on different Component Carriers resulting in further reductions of latency of a first packet in a burst sent by the UE 106.

For example, consider the scenario of three SR-configured carriers, CCx, CCy and CCz, where the SR periodicity for CCx= 1ms and the SR periodicity for CCy and CCz = 2ms and the sr-ProhibitTimer = 1 (i.e. 1ms). There are two possible configurations; a first where opportunities on CCy alternate with opportunities on CCz and a second where opportunities on CCy and CCz are aligned with each other. If the scheduler 102 knows that the UE can ignore the sr-ProhibitTimer, it will determine that the better configuration to use is the first configuration because even if a failure on first (or even second) SR transmission should occur, the next opportunity will arise at the immediately following TTI.

Notification of such UE capability to an eNB could be done in various ways (e.g. signalling such capability at UE initiation, or during operation when this can change dynamically, by RRC or L1 signalling, etc.).

In a further embodiment, UE MAC entity has the ability to treat the sr-ProhibitTimer differently for SR opportunities arising from different CCs. To give the above ability to a UE, additional signalling from the eNB to the UE would be needed in order to notify the UE of the appropriate interpretation for each CC.

The signal processing functionality of the embodiments of the invention, particularly the scheduler 102 and UE 106, may be achieved using computing systems or architectures known to those who are skilled in the relevant art. Computing systems such as, a desktop, laptop or notebook computer, hand-held computing device (PDA, cell phone, palmtop, etc.), mainframe, server, client, or any other type of special or general purpose computing device as may be desirable or appropriate for a given application or environment can be used. The computing system can include one or more processors which can be implemented using a general or special-purpose processing engine such as, for example, a microprocessor, microcontroller or other control module.

The computing system can also include a main memory, such as random access memory (RAM) or other dynamic memory, for storing information and instructions to be executed by a processor. Such a main memory also may be used for storing temporary variables or other intermediate information during execution of instructions to be executed by the processor. The computing system may likewise include a read only memory (ROM) or other static storage device for storing static information and instructions for a processor.

The computing system may also include an information storage system which may include, for example, a media drive and a removable storage interface. The media drive may include a drive or other mechanism to support fixed or removable storage media, such as a hard disk drive, a floppy disk drive, a magnetic tape drive, an optical disk drive, a compact disc (CD) or digital video drive (DVD) read or write drive (R or RW), or other removable or fixed media drive. Storage media may include, for example, a hard disk, floppy disk, magnetic tape, optical disk, CD or DVD, or other fixed or removable medium that is read by and written to by media drive. The storage media may include a computer-readable storage medium having particular computer software or data stored therein.

In alternative embodiments, an information storage system may include other similar components for allowing computer programs or other instructions or data to be loaded into the computing system. Such components may include, for example, a removable storage unit and an interface , such as a program cartridge and cartridge interface, a removable memory (for example, a flash memory or other removable memory module) and memory slot, and other removable storage units and interfaces that allow software and data to be transferred from the removable storage unit to computing system.

The computing system can also include a communications interface. Such a communications interface can be used to allow software and data to be transferred between a computing system and external devices. Examples of communications interfaces can include a modem, a network interface (such as an Ethernet or other NIC card), a communications port (such as for example, a universal serial bus (USB) port), a PCMCIA slot and card, etc. Software and data transferred via a communications interface are in the form of signals which can be electronic, electromagnetic, and optical or other signals capable of being received by a communications interface medium.

In this document, the terms ‘computer program product’, ‘computer-readable medium’ and the like may be used generally to refer to tangible media such as, for example, a memory, storage device, or storage unit. These and other forms of computer-readable media may store one or more instructions for use by the processor comprising the computer system to cause the processor to perform specified operations. Such instructions, generally referred to as ‘computer program code’ (which may be grouped in the form of computer programs or other groupings), when executed, enable the computing system to perform functions of embodiments of the present invention. Note that the code may directly cause a processor to perform specified operations, be compiled to do so, and/or be combined with other software, hardware, and/or firmware elements (e.g., libraries for performing standard functions) to do so.

In an embodiment where the elements are implemented using software, the software may be stored in a computer-readable medium and loaded into computing system using, for example, removable storage drive. A control module (in this example, software instructions or executable computer program code), when executed by the processor in the computer system, causes a processor to perform the functions of the invention as described herein.

Furthermore, the inventive concept can be applied to any circuit for performing signal processing functionality within a network element. It is further envisaged that, for example, a semiconductor manufacturer may employ the inventive concept in a design of a stand-alone device, such as a microcontroller of a digital signal processor (DSP), or application-specific integrated circuit (ASIC) and/or any other sub-system element.

It will be appreciated that, for clarity purposes, the above description has described embodiments of the invention with reference to a single processing logic. However, the inventive concept may equally be implemented by way of a plurality of different functional units and processors to provide the signal processing functionality. Thus, references to specific functional units are only to be seen as references to suitable means for providing the described functionality, rather than indicative of a strict logical or physical structure or organisation.

Aspects of the invention may be implemented in any suitable form including hardware, software, firmware or any combination of these. The invention may optionally be implemented, at least partly, as computer software running on one or more data processors and/or digital signal processors or configurable module components such as FPGA devices. Thus, the elements and components of an embodiment of the invention may be physically, functionally and logically implemented in any suitable way. Indeed, the functionality may be implemented in a single unit, in a plurality of units or as part of other functional units.

Although the present invention has been described in connection with some embodiments, it is not intended to be limited to the specific form set forth herein. Rather, the scope of the present invention is limited only by the accompanying claims. Additionally, although a feature may appear to be described in connection with particular embodiments, one skilled in the art would recognize that various features of the described embodiments may be combined in accordance with the invention. In the claims, the term ‘comprising’ does not exclude the presence of other elements or steps.

Furthermore, although individually listed, a plurality of means, elements or method steps may be implemented by, for example, a single unit or processor. Additionally, although individual features may be included in different claims, these may possibly be advantageously combined, and the inclusion in different claims does not imply that a combination of features is not feasible and/or advantageous. Also, the inclusion of a feature in one category of claims does not imply a limitation to this category, but rather indicates that the feature is equally applicable to other claim categories, as appropriate.

Furthermore, the order of features in the claims does not imply any specific order in which the features must be performed and in particular the order of individual steps in a method claim does not imply that the steps must be performed in this order. Rather, the steps may be performed in any suitable order. In addition, singular references do not exclude a plurality. Thus, references to ‘a’, ‘an’, ‘first’, ‘second’, etc. do not preclude a plurality.

Although the present invention has been described in connection with some embodiments, it is not intended to be limited to the specific form set forth herein. Rather, the scope of the present invention is limited only by the accompanying claims. Additionally, although a feature may appear to be described in connection with particular embodiments, one skilled in the art would recognise that various features of the described embodiments may be combined in accordance with the invention. In the claims, the term ‘comprising’ or “including” does not exclude the presence of other elements.

Claims

1. A method for scheduling a transmission from a wireless communication device in a cellular communication system which supports Carrier Aggregation, the method including: configuring the wireless communication device with a scheduling request prohibit timer (sr-ProhibitTimer); configuring the wireless communication device with a first Component Carrier configuration; configuring the wireless communication device with a second Component Carrier configuration; configuring the wireless communication device with a first Scheduling Request configuration in respect of the first Component Carrier; configuring the wireless communication device with a second Scheduling Request configuration in respect of the second Component Carrier; identifying a Scheduling Request opportunity on one of the first and second Component Carriers, transmitting a Scheduling Request on the identified Component Carrier; starting the scheduling request prohibit timer, identifying a further Scheduling Request opportunity on the other Component Carrier and sending a Scheduling Request on the other Component Carrier prior to expiry of the scheduling request prohibit timer.

2. The method of claim 1 including configuring the wireless communication device with an index associated with each of the first and second Component Carriers whose state depends on whether a Component Carrier has been used to send a Scheduling Request.

3. The method of claim 1 or claim 2 including sending a message from the wireless communication device to a network element of the cellular communication system whereby the wireless communication device informs the network element of its capability to transmit Scheduling Requests prior to expiry of the scheduling request prohibit timer.

4. The method of claim 3 including, at the network element, modifying a Scheduling Request configuration in respect of at least one Component Carrier in response to receipt of said message from the wireless communication device.

5. A wireless communication device for use in a cellular communication system which supports Carrier Aggregation, wherein the wireless communication device is configured with a scheduling request prohibit timer (sr-ProhibitTimer) and arranged to: receive first and second Component Carrier configurations; receive first and second Scheduling Request configurations in respect of the first and second Component Carriers; identify a Scheduling Request opportunity on one of the first and second Component Carriers; transmit a Scheduling Request on the identified Component Carrier; start the prohibit timer; identify a further Scheduling Request opportunity on the other Component Carrier; and send a Scheduling Request on the other Component Carrier prior to expiry of the scheduling request prohibit timer.

6. The wireless communication device of claim 5 wherein the wireless communication device is arranged to configure an index associated with each of the first and second Component Carriers whose state depends on whether a Component Carrier has been used to send a Scheduling Request.

7. A non-transitory computer readable medium having computer readable instructions stored thereon for execution by a processor to perform the method according to claim 1.

8. The non-transitory computer readable medium of claim 7 comprising at least one from a group consisting of: a hard disk, a CD-ROM, an optical storage device, a magnetic storage device, a Read Only Memory, a Programmable Read Only Memory, an Erasable Programmable Read Only Memory, EPROM, an Electrically Erasable Programmable Read Only Memory and a Flash memory.