Patent Description:
In a typical cellular radio system, also referred to as a wireless communication system, User Equipments (UE)s, also known as mobile terminals and/or wireless terminals communicate via a Radio Access Network (RAN) to one or more core networks. The user equipments may be mobile stations or user equipment units such as mobile telephones also known as "cellular" telephones, and laptops with wireless capability, e.g., mobile termination, and thus may be, for example, portable, pocket, hand-held, computer-included, or car-mounted mobile devices which communicate voice and/or data with the radio access network.

The radio access network covers a geographical area which is divided into cell areas, with each cell area being served by a base station, e.g., a Radio Base Station (RBS), which in some networks is also called "eNB", "NodeB" or "B node" and which in this document is referred to as a base station. A cell is a geographical area where radio coverage is provided by the radio base station equipment at a base station site. The base stations communicate over the air interface operating on radio frequencies with the user equipment units within range of the base stations.

In the end of <NUM> the first release, Release <NUM>, of the 3GPP Long Term Evolution (LTE) standard was finalized and the release <NUM> is currently going on. Evolved Universal Terrestrial Radio Access (E-UTRA) is the air interface that is used in the LTE.

In wireless communication systems, the radio UpLink (UL) is the transmission path from the user equipment to a base station and the radio DownLink is the transmission path from a base station to the user equipment. In LTE Release <NUM>, the arrival of new UL data, of higher priority than the already existing data or new data of any priority when there is no previous data, to the UE buffer triggers a so-called Regular Buffer Status Report (BSR). There are side conditions to this, such as only data for a logical channel belonging to a Logical Channel Group (LCG) are considered, and "arrival of new UL data" is defined as when UL data becomes available for transmission in a Radio Link Controller (RLC) entity or in the Packet Data Convergence Protocol (PDCP) entity. The PDCP is an upper layer of the RLC entity.

However the basic idea is captured in the arrival of new UL data triggering a regular BSR. The regular BSR, in its turn, triggers a Scheduling Request (SR). The SR trigger triggers an SR to be conveyed to the base station which is then informed that the user equipment has new data that it would like to transmit. The SR is transmitted either on the user equipment's preallocated scheduling request resource on a Physical Uplink Control Channel (PUCCH) and is then known as dedicated SR (D-SR) since it is transmitted on a resource dedicated to the user equipment, or on the Physical Random Access Channel (PRACH) and is then known as a random access SR (RA-SR). In both cases, there is a fixed periodicity associated with the opportunities to transmit an SR. This means that the user equipment has to wait until such an opportunity is available.

When the base station receives a D-SR, the base station typically issues an UL grant. When the user equipment transmits on that grant, it will transmit a MAC Packet Data Unit (PDU) including a BSR in the shape of a so-called BSR Medium Access Control (MAC) control element, describing the size of its buffers. The BSR is mandated to reflect the buffer status after the MAC Packet Data Unit (PDU) including the BSR MAC control element is built. A BSR is always included if a BSR trigger is pending in the user equipment at the time of building the MAC PDU, unless all data can fit in the MAC PDU but there is not room enough for a buffer status report in addition to the data.

Once the size of the user equipment buffer has been reported to the base station, there is no need for the user equipment to send additional SRs as the base station now knows how much data the user equipment has to transmit. The SR trigger can hence be cancelled in the user equipment so that the user equipment will not send any D-SR on the next D-SR opportunity.

Please note that in the following, the following terminology will be used:
The term "arrival of new data" is used to indicate arrival of new UL data in the user equipment buffer, with all side conditions for triggering a Regular BSR satisfied.

The term "reception of grant" is used to indicate the reception of a Physical Downlink Control Channel (PDCCH) grant for Uplink Shared Channel (UL-SCH) resources for a new transmission.

The term "transmission of data" is used to indicate transmission of UL data on UL-SCH resources that have been made available for a new transmission.

The term "SR" and "scheduling request" is used to indicate signalling of D-SR on the PUCCH.

The term "SR trigger" and "scheduling request trigger" is used to indicate a pending SR.

When expressions such as "buffer status report accounts for first data" are used, it means that the buffer status report reflects whatever is left of the first data after the transmission in which the buffer status report is included has been received.

Currently it is decided that an SR is considered pending until cancelled, i.e. an SR trigger that triggers the transmission of an SR, is considered pending until cancelled. This is confirmed by the 3GPP contribution document R2-<NUM>. It is cancelled in the first possible Transmission Time Interval (TTI) , also known as subframe, where UL-SCH resources for new transmission are granted.

Moreover, it has recently been decided that if UL-SCH resources are available for new transmission in this TTI, all pending SR(s) shall be canceled as it was considered unclear when UL-SCH resources were granted, at the reception of a PDCCH grant or in the TTI when the UL-SCH resources were available. The clarification says that the SR is cancelled in the TTI when UL-SCH resources are available.

It is an object of the invention to provide a mechanism in a user equipment that improves the performance in the wireless communications network.

In particular, the invention is defined by the appended set of claims.

The invention is described in more detail with reference to attached drawings illustrating exemplary embodiments of the invention and in which:.

As part of the present invention, a problem will firstly be identified and discussed. As mentioned above it was recently decided that all pending SR(s) shall be canceled if UL-SCH resources are available for new transmission in the TTI, as it was considered unclear when UL-SCH resources were granted at the reception of a PDCCH grant or in the TTI when the UL-SCH was available. Now, consider the case of cancelling the pending SR trigger in the TTI when UL-SCH resources are available, i.e. at transmission of new data, according to the recently decision.

<FIG> illustrates an analysis of the alternative to cancel a scheduling request at transmission of UL data when new second data arrives to the user equipment buffer before grant for the first data is received. Assume that the following has been performed: First data has arrived to the user equipment buffer. This first data has triggered a buffer status report. This first data has also directly or indirectly triggered a first scheduling request trigger for sending a scheduling request at the next scheduling request opportunity. The scheduling request opportunity has occurred and a first scheduling request has been transmitted to the base station. The first scheduling request trigger is still pending. It will be cancelled upon transmission of UL data. Looking at a time line, there are then two different cases that appear, case a) and b) illustrated in <FIG>. In case a), the user equipment has a scheduling request opportunity between receiving the UL grant and transmitting the data. In case b) the user equipment has no scheduling request opportunity between receiving the UL grant and transmitting the data; the next SR opportunity occurs after the transmission of the data.

For case b) there are less problems. Assume the following steps:.

In the case a), the scheduling request trigger has not yet been cancelled when the scheduling request opportunity occurs. Hence, a new scheduling request is sent, although the user equipment has already received a grant in response to its previous scheduling request. There is no need for the second scheduling request in the case shown, but the user equipment is mandated by the specification to send it. This is a waste of user equipment energy and of radio resources, since the scheduling request creates unnecessary interference on the Physical Uplink Control Channel (PUCCH). Hence, this extra scheduling request is unnecessary so this is a disadvantage. Additionally, it is not clear what the base station should do in response to the unnecessary scheduling request as described above. Note that the same procedure, with an extra unnecessary scheduling request and its unwanted consequences, would happen in case a) even if the user equipment received the first data but no second data so it is not an uncommon scenario.

However, there is an even more complicated case with worse problems in the following example related to <FIG> and <FIG>, where the user equipment gets new data to its buffer after a grant corresponding to the first scheduling request is received. This new data triggers a scheduling request trigger. Looking at a time line, there are then two different cases that appear, case a) illustrated in <FIG> and b) illustrated in <FIG>. In this example, as in the example in case a) relating to <FIG>, the user equipment has an scheduling request opportunity between receiving the UL grant and transmitting the data. In case b) the user equipment has no scheduling request opportunity between receiving the UL grant and transmitting the data; the next scheduling request opportunity occurs after the transmission of the data.

In case a) and in case b) there are two respective alternatives, alternative I and alternative II. <FIG> depicts case a) alternative I and case a) alternative II, and <FIG> depicts case b) alternative I and case b) alternative II.

Hence <FIG> illustrates an analysis of the alternative to cancel SR at transmission of UL data, when new data arrives between reception of grant and transmission of data corresponding to the grant for case a) wherein the user equipment has an SR opportunity between receiving the UL grant and transmitting the data. Assume that the following has been performed: First data has arrived to the user equipment buffer. This first data has triggered a buffer status report trigger. This first data also directly or indirectly via the buffer status report trigger, has triggered a first scheduling request trigger for sending a scheduling request at the next scheduling request opportunity. The SR opportunity has occurred and a first scheduling request is transmitted to the base station. The first scheduling request trigger is still pending. It will be cancelled upon transmission of UL data.

For case a-I) assume the following steps:.

For case a-II) assume the following steps:.

In the case a), both case a-I and case a-II, an extra scheduling request is sent, but when receiving it, the base station only knows that it has received two scheduling request and cannot distinguish between case a-I and case a-II, i.e. whether the same data was behind both scheduling requests, or if additional data was received for the second scheduling request. Correspondingly, the base station does not know if the buffer status report it received actually reflects the user equipment buffer sizes, as new data could have arrived after the buffer status report was built. The base station hence has to guess, and depending on its guess it risks either wasting a grant or losing track of the new data, the base station having inaccurate buffer size estimation for the user equipment as new data has not been reported.

<FIG> illustrates an analysis of the alternative to cancel scheduling request at transmission of UL data, when new data arrives between reception of grant and transmission of data corresponding to the grant for case b) wherein the user equipment has no scheduling request opportunity between receiving the UL grant and transmitting the data; the next scheduling request opportunity occurs after the transmission of the data. Assume that the following has been performed: First data has arrived to the user equipment buffer. This first data has triggered buffer status report trigger. This first data also directly or indirectly via the buffer status report trigger, has triggered a first scheduling request trigger for sending a scheduling request at the next scheduling request opportunity. The scheduling request opportunity has occurred and a first scheduling request is transmitted to the base station. The first scheduling request trigger is still pending. It will be cancelled upon transmission of UL data.

For case b-I) assume the following steps:.

For case b-II) assume the following steps:.

As can be seen, case b-II) works well but case b-I) does not. In both cases, the triggered second scheduling request trigger is never sent as it is cancelled when the first data is transmitted. However, if the second data is not included in the buffer status report sent as in case b-I), the base station will not know about this data. Two things may save the situation: The user equipment receiving a grant for other data, not in response to the scheduling request never sent, since the transmission on that grant will include a buffer status report, or a new SR being triggered by the arrival of yet new data.

Unless one of these occurs, the user equipment has no means of sending a new scheduling request until the fallback mechanism known as "retransmit buffer status report timer" or "retx-BSR-Timer" expires, triggering a scheduling request. However, this timer has a minimum value of <NUM> which adds considerable delay.

Therefore it is an object of the invention to provide a mechanism in a user equipment that improves the performance in the wireless communications network.

Referring now to the present solution, <FIG> depicts a wireless communications system <NUM> in which the present solution is implemented. The wireless communications system <NUM> is a packet-based communications system which may be an LTE communications system, Worldwide Interoperability for Microwave Access (WiMax) or any other wireless communications system handling scheduling requests for uplink scheduling.

The wireless communications system <NUM> comprises a base station <NUM> serving a cell <NUM>. The base station <NUM> is a radio base station such as an eNB, a Radio Base Station (RBS) or any other network unit capable to communicate over a radio carrier with user equipments being present in the cell.

A user equipment <NUM> being present within the cell <NUM>, is served by the base station <NUM>, and is therefore capable of transmitting data packet units such as MAC PDUs to the base station <NUM> over a radio channel <NUM>. The user equipment <NUM> may be a terminal, e.g. a mobile terminal or a wireless terminal, a mobile phone, a computer such as e.g. a laptop, Personal Digital Assistants (PDA), or any other radio network units capable to communicate with a base station over an air interface. The air interface may e.g. be an E-UTRA air interface used in LTE.

The user equipment <NUM> comprises a buffer, to which buffer new uplink data arrives that is to be transmitted to the base station <NUM>. The data may be voice data, video data, photo data, text data or any other kind of data that a user may want to transmit. The arrival of new UL data, of higher priority than the already existing data or new data of any priority when there is no previous data, to the user equipment buffer triggers a buffer status report. The arrived new data further directly or indirectly triggers a scheduling request trigger to be pending. The indirectly triggering may be performed such that the arrived data triggers a buffer status report which in turn triggers the scheduling request trigger. The scheduling request trigger will trigger a scheduling request to be sent to the base station <NUM> at a next scheduling request opportunity. The "scheduling request trigger" may also be referred to as "a pending scheduling request". As mentioned above there is a fixed periodicity associated with the opportunities to transmit scheduling requests to the base station <NUM>, so the user equipment <NUM> has to wait until such an opportunity is available. The base station <NUM> receiving the scheduling request is in that way informed that the user equipment <NUM> has new data that it would like to transmit. A scheduling request trigger is pending or not pending. A scheduling request is typically not associated with any specific arrived data and a scheduling request trigger does not need to be associated with any data although it is implicitly associated with the data that triggered it. But if further data, here called second data, arrives to the user equipment buffer, triggering a scheduling request trigger, a further scheduling request is triggered, even if a scheduling request trigger is already triggered.

As a response to a scheduling request the base station <NUM> typically sends an uplink grant to the user equipment <NUM>. The grant is specific to a user equipment but not associated with any specific arrived data in that user equipment. Priorities set by the eNB and signalled to the user equipment <NUM> decides which particular data that shall be transmitted on the resources that the user equipment <NUM> has been allocated.

To make the handling of the scheduling procedure more reliable which will improve the performance in the wireless communications network, a pending scheduling request trigger according to the present solution is cancelled as follows:
In a first embodiment, the pending scheduling request is cancelled when the data that triggered the scheduling request is accounted for in a buffer status report to be included in a scheduled data transmission to be transmitted to the base station <NUM>, or when the data that triggered the scheduling request is included in a scheduled data transmission to be transmitted to the base station, whichever occurs first. In this latter case the scheduled data need not be transmitted, just included in the patent data unit that a bit later will be transmitted.

Alternatively, in a second embodiment, the pending scheduling request is cancelled at any time by the user equipment, but the user equipment <NUM> keeps track of what data that has been accounted for in the buffer status report to be included in a scheduled data transmission and what data that has not been accounted for, and when a next scheduling request opportunity appears, the user equipment <NUM> sends a scheduling request if and only if the buffer comprises data that has not yet been accounted for in a buffer status report. This is equivalent to having a pending scheduling request in the first embodiment, but does not necessarily have to be called "having a pending scheduling request". The consequence will however be the same, at the next scheduling request opportunity, the user equipment <NUM> will send a scheduling request if there is data not yet included in a buffer status report, and that data has not yet been sent.

The present solution relating to a method in the base station <NUM> for handling a scheduling request trigger, according to some embodiments will now be described with reference to the flowchart depicted in <FIG>. As mentioned above, the user equipment <NUM> comprising a buffer.

The method comprises the following steps, which steps may as well be carried out in another suitable order than described below:.

The buffer in the user equipment <NUM> receives data to be transmitted to a base station <NUM>.

According to a first embodiment, the user equipment <NUM> generates a buffer status report trigger. The buffer status report trigger is triggered by the arrived data.

The user equipment <NUM> generates a scheduling request trigger, which scheduling request trigger is pending until it is cancelled, and which generation is triggered directly or indirectly by the arrived data. In some embodiments, wherein this step of generating a scheduling request trigger is performed indirectly, the generation is triggered by the generation of the buffer status report trigger which in turn was triggered by the arrived data.

According to a first embodiment, the user equipment <NUM> cancels the pending scheduling request when the data that triggered the scheduling request is accounted for in a buffer status report to be included in a scheduled data transmission to be transmitted to the base station <NUM>, or the user equipment <NUM> cancels the pending scheduling request when the data that triggered the scheduling request is included in a scheduled data transmission to be transmitted to the base station, whichever occurs first. The pending scheduling request trigger may hence be cancelled at the same time instance as the MAC PDU including a buffer status report MAC control element is built.

When a packet data unit such as a MAC PDU is built, it includes a buffer status report such as a BSR MAC control element that accounts for data remaining in the user equipment buffer after the of building the packet data unit. Such a buffer status report is included if a buffer status report trigger is pending at the time that the MAC PDU is built, and all data cannot fit in the MAC PDU.

The user equipment <NUM> may cancel the pending scheduling request when the data that triggered the scheduling request is included in the a buffer status report represented by a BSR MAC control element or when all data that triggered the scheduling request has been included in a MAC PDU for transmission. In the context of the LTE standards, such a method of operation can be understood as the user equipment <NUM> canceling a pending scheduling request when the buffer status report that triggered the scheduling request is canceled. Here, "when" does not necessarily connote a coincidence in time, and can be understood as the pending scheduling request being canceled upon cancellation of the pending buffer status report that triggered that pending scheduling request. In other words, in at least one embodiment, a pending scheduling request trigger is canceled, e.g. along with canceling the corresponding buffer status report trigger, if a currently scheduled data transmission will include all of the new data that caused the corresponding buffer status report trigger to be generated, or if a buffer status report to be included in the next currently scheduled data transmission-which may have been generated because of one or more other pending buffer status report triggers-will account for the new data.

According to a second embodiment, as an alternative to step <NUM>, the user equipment <NUM> cancels the pending scheduling request at any time, but the user equipment <NUM> keeps track of what data that has been accounted for in the buffer status report to be included in a scheduled data transmission and what data that has not been accounted for, and according to some embodiments, nor been included in a scheduled data transmission.

According to the second embodiment, when a next scheduling request opportunity appears, the user equipment <NUM> sends a scheduling request if and only if the buffer comprises data that has not yet been accounted for in the buffer status report.

In this alternative embodiment, the user equipment <NUM> may internally cancel its pending scheduling request trigger whenever it wants, before or after the time the point of time that it is cancelled according to the first embodiment in step <NUM>, while still fulfilling the behaviour that can be tested by the 3GPP. This is as mentioned above performed by the user equipment <NUM> keeping track of data that has not yet been included in a buffer status report, and according to some embodiments, nor been included in a scheduled UL data transmission. This is equivalent to having a pending scheduling request in the first embodiment, but does not necessarily have to be called "having a pending scheduling request". The consequence will however be the same, at the next scheduling request opportunity, the user equipment <NUM> will send a scheduling request if there is data not yet included in a buffer status report, and that data has not yet been sent.

Further, in some embodiments as mentioned above, the buffer status report trigger may be generated in response to new data incoming to an uplink transmit buffer, and a scheduling request trigger may be generated corresponding to the buffer status report trigger. Thus, receiving new data into the uplink transmit buffer causes a new buffer status report trigger to be generated, which causes a new scheduling request trigger.

In one or more embodiments taught herein, advantageous handling and cancelling of pending buffer status report triggers and corresponding pending scheduling request triggers prevents uplink data from becoming stuck in the user equipment <NUM>, and/or prevents or at least reduces unnecessary scheduling request transmissions and resultant unnecessary uplink resource grants.

Those skilled in the art will also appreciate that buffer status report triggers and corresponding scheduling request triggers may be implemented as flags or other logical indicators, which may be set or otherwise created to indicate the pending status, and cleared or otherwise deleted for cancellation.

<FIG> illustrates an analysis of the present solution according to the first embodiment when new second data arrives to the user equipment buffer before grant for the first data is received. the first embodiment comprising cancelling the scheduling request trigger when the data that triggered the scheduling request is accounted for in a buffer status report to be included in a scheduled data transmission to be transmitted to the base station <NUM>, or the user equipment <NUM> cancels the pending scheduling request when the data that triggered the scheduling request is included in a scheduled data transmission to be transmitted to the base station, whichever occurs first. Assume again that the following has been performed: First data has arrived to the user equipment buffer, which corresponds to step <NUM> in <FIG>. This first data has triggered a buffer status report, which corresponds to step <NUM> in <FIG>. This first data has also directly or indirectly triggered a first scheduling request trigger for sending a scheduling request at the next scheduling request opportunity, which corresponds to step <NUM> in <FIG>. The scheduling request opportunity has occurred and a first scheduling request has been transmitted to the base station <NUM>. The first scheduling request trigger is still pending. Looking at a time line, there are then two different cases that appears, case a) and b) illustrated in <FIG>. In case a), the user equipment <NUM> has a scheduling request opportunity between receiving the UL grant and transmitting the data. In case b) the user equipment <NUM> has no scheduling request opportunity between receiving the UL grant and transmitting the data; the next scheduling request opportunity occurs after the transmission of the data.

Hence, neither case a) nor case b) is any unnecessary scheduling request sent and there is no ambiguity in the user equipment <NUM> as to what a scheduling request means. In both cases a) and b), a scheduling request means that there is new data in the user equipment <NUM> that the user equipment <NUM> was not previously aware of. There is still an error case where the scheduling request opportunity <NUM> is before the packet unit build <NUM>, in which case there will be an extra scheduling request sent and an ambiguity in the user equipment <NUM> as to what the SR means similar to the analysis of case a) in <FIG>, but there is a much smaller probability of having an SR opportunity between arrival of second data and build of packet unit as in the possible error case in <FIG>, than there is of having an SR opportunity between arrival of second data and transmission of data as in <FIG>.

<FIG> and <FIG> illustrates an analysis of the present solution according to the first embodiment where the user equipment <NUM> gets new data to its buffer after a grant corresponding to the first scheduling request is received. This new data triggers a scheduling request trigger. Looking at a time line, there are then two different cases that appears, case a) illustrated in <FIG> and b) illustrated in <FIG>. In case a), the user equipment <NUM> has a scheduling request opportunity between receiving the UL grant and transmitting the data. In case b) the user equipment <NUM> has no scheduling request opportunity between receiving the UL grant and transmitting the data, the next scheduling request opportunity comes after the transmission of the data.

Hence <FIG> illustrates an analysis according to the present solution in the scenario when new data arrives between reception of grant and transmission of data corresponding to the grant for case a) wherein the user equipment <NUM> has a scheduling request opportunity between receiving the UL grant and transmitting the data. Assume that the following has been performed: First data has arrived to the user equipment buffer, which corresponds to step <NUM> in <FIG>. This first data has triggered a buffer status report, which corresponds to step <NUM> in <FIG>. This first data also directly or indirectly via the buffer status report trigger, has triggered a first scheduling request trigger for sending a scheduling request at the next scheduling request opportunity, which corresponds to step <NUM> in <FIG>. The scheduling request opportunity has occurred and a first scheduling request is transmitted to the base station. The first scheduling request trigger is still pending. According to the present solution the scheduling request trigger will be cancelled when the data that triggered the scheduling request is accounted for in a buffer status report to be included in a scheduled data transmission to be transmitted to the base station <NUM>, or the user equipment <NUM> cancels the pending scheduling request when the data that triggered the scheduling request is included in a scheduled data transmission to be transmitted to the base station, whichever occurs first.

Hence, neither case a-I) nor case a-II) is any unnecessary scheduling request sent and there is no ambiguity in the base station <NUM> as to what a scheduling request means. In both cases a-I) and a-II), a scheduling request means that there is new data in the user equipment <NUM> that the base station <NUM> was not previously aware of. The same error case as described for <FIG> is still present, but with a much smaller probability of happening with the invention.

Hence <FIG> illustrates an analysis according to the present solution in the scenario when new data arrives between reception of grant and transmission of data corresponding to the grant for case b) wherein the user equipment <NUM> has no scheduling request opportunity between receiving the UL grant and transmitting the data, the next scheduling request opportunity occurring after the transmission of the data. Assume that the following has been performed: First data has arrived to the user equipment buffer, which corresponds to step <NUM> in <FIG>. This first data has triggered a buffer status report, which corresponds to step <NUM> in <FIG>. This first data also directly or indirectly via the buffer status report trigger, has triggered a first scheduling request trigger for sending a scheduling request at the next scheduling request opportunity, which corresponds to step <NUM> in <FIG>. The scheduling request opportunity has occurred and a first scheduling request is transmitted to the base station. The first scheduling request trigger is still pending. According to the present solution the scheduling request trigger will be cancelled when the data that triggered the scheduling request is accounted for in a buffer status report to be included in a scheduled data transmission to be transmitted to the base station <NUM>, or the user equipment <NUM> cancels the pending scheduling request when the data that triggered the scheduling request is included in a scheduled data transmission to be transmitted to the base station, whichever occurs first.

To perform the method steps referred to in <FIG> above for handling a scheduling request trigger, the user equipment <NUM> comprises an arrangement depicted in <FIG>.

As mentioned above, the user equipment <NUM> comprises a buffer <NUM> configured to receive data to be transmitted to the base station <NUM>.

The user equipment <NUM> further comprises a generating unit <NUM> configured to generate a scheduling request trigger, which scheduling request trigger is pending until it is cancelled, and which generation is triggered directly or indirectly by the arrived data.

The user equipment <NUM> further comprises a cancelling unit <NUM>.

According to a first embodiment, the cancelling unit <NUM> is configured to cancel the pending scheduling request trigger when the data that triggered the generation of the scheduling request trigger is accounted for in a buffer status report to be included in a scheduled data transmission to be transmitted to the base station <NUM>, or when the data that triggered the generation of the scheduling request is included in a scheduled data transmission to be transmitted to the base station <NUM>, whichever occurs first.

According to a second embodiment, the cancelling unit <NUM> is configured to cancel the pending scheduling request trigger at any time, but keeping track of what data that has either been accounted for in the buffer status report to be included in a scheduled data transmission or included directly in the scheduled data transmission and what data that has not been accounted for in any of these two ways.

According to a combined first and second embodiment the cancelling unit <NUM> is configured to cancel the pending scheduling request trigger when the data that triggered the generation of the scheduling request trigger is accounted for in a buffer status report to be included in a scheduled data transmission to be transmitted to the base station <NUM>, or when the data that triggered the generation of the scheduling request is included in a scheduled data transmission to be transmitted to the base station <NUM>, whichever occurs first, or alternatively to cancel the pending scheduling request trigger at any time, but keeping track of what data that has been accounted for in the buffer status report to be included in a scheduled data transmission and what data that has not been accounted for.

According the a second embodiment and the combined first and second embodiment the user equipment <NUM> comprises a sending unit <NUM> configured to, when a next scheduling request opportunity appears, send a scheduling request if and only if the buffer comprises data that has not yet been accounted for in any of the two ways mentioned.

According the combined first and second embodiment the sending unit <NUM> is configured to, when a next scheduling request opportunity appears, send a scheduling request if and only if the buffer comprises data that has not yet been accounted for in the buffer status report.

The present mechanism for handling a scheduling request trigger may be implemented through one or more processors, such as a processor <NUM> in the user equipment <NUM> depicted in <FIG>, together with computer program code for performing the functions of the present solution. The program code mentioned above may also be provided as a computer program product, for instance in the form of a data carrier carrying computer program code for performing the present solution when being loaded into the user equipment <NUM>. One such carrier may be in the form of a CD ROM disc. It is however feasible with other data carriers such as a memory stick. The computer program code may furthermore be provided as pure program code on a server and downloaded to the user equipment <NUM>.

<FIG> depicts one embodiment of the user equipment <NUM>, including processing circuits operatively associated with transceiver circuits (radiofrequency receiver front-end, transmit modulator/amplifier, etc.), and one or more transmit/receive antennas.

The user equipment <NUM> is, for example, a mobile terminal or other type of user equipment configured for operation in a wireless communication system based on the LTE standards.

In any case, the user equipment <NUM> is configured to implement any of the embodiments described herein. For example, the processing circuits may comprise one or more baseband processors. In at least one embodiment, the processing circuits comprise one or more microprocessor-based circuits, such as a Digital Signal Processor (DSP) or other digital processor. Further, those skilled in the art will appreciate that the user equipment <NUM> includes one or more memory circuits-e.g., non-volatile and volatile-for storing program instructions, configuration and provisioning data, working data, etc..

In particular, the processing circuits within the user equipment <NUM> include an uplink transmit buffer such as the buffer <NUM>-which may be a reserved portion of working memory-for buffering data for uplink transmission, and an associated controller for implementing all or part of the control and processing described herein and as referred to in the text above related to <FIG>. That is, one or more embodiments of the controller such as the cancelling unit <NUM>, are configured to cancel a pending scheduling request when the data that triggered the scheduling request is included in a buffer status report MAC control element or the data that triggered the scheduling request is transmitted, whichever occurs first as described above. In an LTE context, the user equipment <NUM> can be understood as being configured to cancel a pending scheduling request when the buffer status report that triggered the scheduling request is canceled.

Alternatively, the user equipment's controller can be configured via hardware, software, or some combination thereof, to track what data has been included or otherwise accounted for in a buffer status report and what data has not. Accordingly, when a scheduling request opportunity comes, the user equipment <NUM> sends a scheduling request if it has data that has not yet been accounted for in a buffer status report (the buffer status report does not have to have been sent; for example, it is sufficient if the buffer status report is included in a MAC PDU that has been assembled for transmission.

Both embodiments <NUM> and <NUM> lead to the same behavior, the advantage of which is that it is natural to cancel a pending SR when it has served its purpose. This is only guaranteed if cancelled when the data that triggered it is accounted for in a buffer status report, or the data that triggered it is transmitted. Any other solution will lead to ambiguities or unnecessary SRs sent and/or unnecessary grants.

According to some embodiments, the present solution may be referred to as follows. When a scheduling request is triggered, it shall be considered as pending until it is cancelled. All pending scheduling requests shall be cancelled when a MAC PDU is assembled and this PDU includes a buffer status report which contains buffer status up to (and including) the last event that triggered a buffer status report, or when the uplink grant can accommodate all pending data available for transmission.

When using the word "comprise" or "comprising" it shall be interpreted as nonlimiting, i.e. meaning "consist at least of". The word "built" is equal to the word "assembled" in this text.

Claim 1:
A method performed by a user equipment (<NUM>) for handling a scheduling request, the method comprising:
triggering (<NUM>) a scheduling request in response to the generation of a buffer status report which was triggered in response to receiving (<NUM>) data into a buffer of the user equipment (<NUM>) to be transmitted to a base station (<NUM>), said scheduling request being pending until it is cancelled;
characterized in that the method further comprises:
cancelling (<NUM>) the pending scheduling request if a Medium Access Control Packet Data Unit, MAC PDU, is assembled for transmission and including the buffer status report, the buffer status report accounting for the data that triggered the scheduling request.