Method for transmitting scheduling requests from a mobile terminal to a base station and a mobile terminal and base station for use therewith

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Method for Transmitting Scheduling Requests from a Mobile Terminal to a Base Station, and a Mobile Terminal and Base Station for use therewith

DISCLAIMER

It is to be noted that only subject matter embraced in the scope of the claims appended hereto, whether in the manner defined in the claims or in a manner similar thereto and involving the main features as defined in the claims, is intended to be 5 included in the scope of the present invention, while subject matter described and exemplified to provide background and better understanding of the invention, is not intended for inclusion as part of the present invention.

FIELD OF THE INVENTION

The present invention relates generally to telecommunication systems. 10 Embodiments of the present invention relate to the scheduling of resources in a telecommunication system.

BACKGROUND OF THE INVENTION

Radio access technologies for cellular mobile networks are continuously being evolved to meet future demands for high data rates, improved coverage and improved 15 capacity. Examples of recent evolutions of the wideband code-division multiple access (WCDMA) technology are the High-Speed Packet Access (HSPA) protocols. Currently, further evolutions of the third generation (3G) systems, 3G Long Term Evolution (LTE), including new access technologies and new architectures, are being developed within the 3rd Generation Partnership Project (3GPP) standardisation body. - 2 - A main objective of LTE systems is to provide a flexible access technology that can be used in existing frequency allocations and in new frequency allocations. Also, LTE systems should enable the use of different duplex solutions. For example, both frequency division duplex (FDD) and time division duplex (TDD), where the uplink and 5 downlink are separated in frequency and in time, respectively, should be supported to provide usage in both paired and unpaired spectrum.

An access technology based on Orthogonal Frequency Division Multiplexing (OFDM) for the downlink and Single Carrier Frequency Division Multiple Access (SC-FDMA) for the uplink, for example, allows such flexible spectrum solutions. 10 Since the LTE concept is being designed to support fast scheduling in frequency and time both for the uplink and the downlink, the resource assignment in time and frequency should be preferably adjustable to the users' momentary traffic demand and channel variations. In the LTE uplink it is possible to schedule several users in one Time Transmission Interval (TTI) by assigning different frequency segments to 15 different users. To maintain the single carrier structure, each user should only receive contiguous assignments in frequency as illustrated in FIG. 1.

Referring now to FIG. 2, a scheduler 202 in an evolved Node B (base station) 204 may perform resource assignment. Scheduling resources among two or more users in the uplink is complicated by the fact that the scheduler 202 is not automatically aware 20 of each user's uplink data and resource demand. That is, for example, the scheduler 202 may not be aware of how much data there is in the transmit buffers of each user's mobile terminal 206 (e.g., mobile phone, portable digital assistant, or any other mobile terminal). Mobile terminal 206 may also be referred to as user equipment (UE). In order to support fast scheduling, the scheduler 202 would have to be made aware of the UE's 25 momentary traffic demands (e.g., the transmit buffer status).

The basic uplink scheduling concept is illustrated in FIG.2. Typically, to inform the uplink (UL) scheduler 202 of the UE's momentary traffic demands, the system 200 supports (i) a dedicated scheduling request (SR) channel and (ii) buffer status reports. Alternatively, a synchronized random access channel (RACH) can be used for the same 30 purpose.

The scheduler 202 monitors each UE's traffic demands and assigns resources accordingly. The scheduler 202 informs a UE (e.g., UE 206) of a scheduling decision by transmitting resource assignments 208 to the UE. In addition, there is a possibility to - 3 - configure a UE to transmit channel sounding reference signals to enable the evolved Node B (eNodeB) to do broad band channel estimation for fast link adaptation and channel dependent scheduling. A synchronized UE also has the opportunity to use, as a fallback solution, the 5 Random Access Channel (RACH) to request a UL resource. In general, however, the

RACH is intended mostly for non-synchronized UEs. In the dedicated SR channel approach, each active UE is assigned a dedicated channel for transmitting messages that indicate to the eNodeB that the UE requires a UL resource. Such a message is referred to as a scheduling request (SR) 210. The benefit with this method is that no UE 10 identifier (ID) has to be transmitted, since the UE is identified by virtue of the “channel” it uses. Furthermore, in contrast to the contention based approach, no intracell collisions will occur.

In response to receiving an SR 210, the scheduler 202 may issue to the UE a scheduling grant (SG) 208. That is, the scheduler may select the resource(s) (e.g., time 15 slot and/or frequency) the UE shall use and communicate this information to the UE. The scheduler 202 may also select, with support from the link adaptation function, a transport block size, a modulation scheme, coding scheme and an antenna scheme (i.e., the link adaptation is performed in the eNodeB and the selected transport format is signalled together with information on the user ID to the UE). The scheduling grant 20 addresses a UE and not a specific radio bearer. In its simplest form, the scheduling grant is valid only for the next UL TTI. However, to reduce the amount of control signalling required, several proposals with alternative durations are possible.

After transmitting an initial SR, the UE may transmit a more detailed buffer status report to the scheduler 202. The buffer status report may be transmitted in-band 25 (e.g., the buffer status report may be included as part of a medium access control (MAC) header). It is a common view in, for example, 3GPP that the buffer status report should contain more information than is contained in the initial SR.

The above described procedure is further illustrated in FIG. 3. As shown in FIG. 3, a UE 302 having data to transmit to an eNodeB 304 first transmits an SR 306 to the 30 eNodeB 304, which SR 306 is then processed by an uplink scheduler 308 of eNodeB 304. In response to SR 306, uplink scheduler 308 transmits an SG (e.g., resource assignments) 310 to UE 302. Thereafter, UE 302 transmits data 312 to eNodeB 304 together with a buffer status report 314, which report is processed by the uplink - 4 - scheduler 308. As discussed above, buffer status report 314 may be transmitted in-band with data 312. US 2005/0135416 discloses an MAC having a protocol stack comprising one or more of the following: an adaptation layer, a data link control layer, a physical layer, 5 and a layer manager. In another aspect, physical layer feedback is used for adaptation layer processing. In one embodiment, physical layer feedback is used for segmentation. In another embodiment, physical layer feedback is used for multicast mapping onto one or more unicast channels. In another aspect, a data unit for transmission from a first station to a second station comprises zero or more complete sub-data units, zero or one 10 partial sub-data units from a prior transmission, and zero or one partial sub-data units to fill the data unit. In one embodiment, a pointer may be used to indicate the location of any complete sub-data units. US 2007/0047451 discloses a method and mobile terminal for performing a data allocation process for scheduled data, non-scheduled user data and non-scheduled 15 control data obeying restrictions on the resource utilization defined by a scheduling grant and at least one non-scheduled grant. In order to reduce the delays to control signaling implied by a conventional HARQ process restriction mechanism the present invention suggests a new categorization of uplink data into scheduled data, non-scheduled user data and non-scheduled control data and a new HARQ process 20 restriction mechanism disabling certain HARQ processes for non-scheduled user data only. US 2007/0047452 discloses a method and apparatus for reconfiguring a MAC entity of a MAC layer of the apparatus receiving protocol data units from a mobile terminal via on uplink upon reconfiguration of the uplink channel. Methods and mobile 25 terminals are disclosed for triggering the transmission of a status report from an RLC entity configured for an uplink channel of a network element in a radio access network, as well as a method and terminal for configuring the MAC layer of the mobile terminal. In order to enable an efficient and fast generation of RLC status reports after an uplink channel reconfiguration mechanisms are provided to trigger the transmission of status 30 reports upon uplink reconfiguration. US 2007/0201397 discloses a wireless communication system including a wireless transmit/receive unit (WTRU) and a Node-B, wherein an uplink (UL) scheduling request is transmitted by the WTRU to the Node-B when the WTRU has - 5 - 235328/2 buffered (user) data to transmit to the Node-B, but needs to have a scheduling grant for UL data transmission. The WTRU determines whether to transmit to the Node-B a short-version UL scheduling request or a full-version UL scheduling request, whereby the short-version UL scheduling request uses less channel resources than the full- 5 version UL scheduling request by omitting information pertaining to WTRU status parameters. The short-version UL scheduling request is a one-bit indicator or a multi-bit indicator that indicates an amount of scheduling grants or resources requested. The full-version UL scheduling request includes at least one of a WTRU buffer status and a WTRU link budget. 10 US 2005/0047416 discloses a method and an apparatus for reporting a buffer status of a buffer storing packet data to be transmitted by a user equipment for a scheduling assignment of an uplink packet data service in a mobile communication system supporting the uplink packet data service. A user equipment stores packet data having a priority corresponding to a plurality of priority queues having inherent 15 priorities and relating to at least one service, and transmits buffer status information containing queue identifiers of the priority queues and buffer payload information representing an amount of the packet data stored in the priority queues. Herein, the user equipment inserts the buffer status information into a header part of a protocol data unit for the uplink packet data service, inserts the packet data into a payload part of the 20 protocol data unit, and then transmits the protocol data unit.

Reference is also made to the following publication:

“Buffer Reporting for E-UTRAN”, 3RD GENERATION PARTNERSHIP PROJECT (3GPP); TECHNICALSPECIFICATION GROUP (TSG) RADIO ACCESS NETWORK (RAN); WORKING GROUP 2 (WG2), XX, XX, vol. R2060829, 27 25 March 2006. This publication deals with buffer status reports in E-UTRAN uplink. Buffer status reporting is a critical feature both for the achievement of high trunk efficiency (and hence high cell throughput performance) and for QoS differentiation. On the other hand, buffer reports represent an overhead which has a direct impact on the uplink capacity. 30 To find an optimal trade-off between these two effects, it is proposed to introduce priority-based reports to limit the signalling overhead while conveying buffer status information on a traffic priority basis (thus allowing QoS-aware radio resource allocation). - 5a - 235328/1

SUMMARY OF THE INVENTION

It is an object to provide improved systems and methods for triggering uplink scheduling requests in a telecommunication system.

This object is realized by a method for transmitting scheduling requests from a 5 mobile terminal to a base station, and a mobile terminal and base station for use therewith having the features of the respective independent claims.

In one aspect, the invention provides a method for transmitting scheduling requests from a mobile terminal (or “UE”) to a base station. In some embodiments, the method starts with the UE transmitting a first scheduling request (SR) to the base station 10 in response to data becoming available for transmission to the base station. After transmitting the first SR, the UE receives a scheduling grant (SG) transmitted from the base station. In response to receiving the SG, the UE transmits to the base station transmit buffer status information. After transmitting the buffer status information to the base station, but prior to transmitting any subsequent SRs to the base station and while 15 at least some of the data is waiting to be transmitted to the base station, the UE: determines whether a scheduling request triggering event has occurred, and, if a triggering event has occurred, then the UE transmits a second SR to the base station at a next opportunity in response to determining that the triggering event has occurred.

In some embodiments, otherwise, if a triggering event has not occurred, then, 20 the UE transmits to the base station at the next opportunity a message indicating that a triggering event has not occurred in response to determining that the triggering event has not occurred. - 6 -

In some embodiments, the step of determining whether a scheduling request triggering event has occurred includes: (a) determining whether additional data that became available for transmission to the base station after the first SR was transmitted has a higher priority than the initial data; (b) determining whether the amount of time 5 that has elapsed since the first SR was transmitted exceeds a threshold; and/or (c) determining whether the difference between the current amount of data in the transmit buffer and a previous, non-zero amount of data that was in the transmit buffer exceeds a threshold. In this or other embodiments, the step of determining whether a scheduling request triggering event has occurred includes: comparing the transmit buffer status 10 information transmitted to the base station with new information concerning the status of the transmit buffer.

In some embodiments, the message indicating that a triggering event has not occurred is a one bit message and the SR is also a one bit message. Additionally, in some embodiments, the thresholds may be configured in the UE by the base station 15 through radio resource control (RRC) signaling. Further, in some embodiments the UE is configured so that it transmits an SR at the next available opportunity every time that data arrives to an empty transmit buffer in the UE.

In another aspect, the invention relates to an improved mobile terminal. In some embodiments the improved mobile terminal includes a transmit buffer and a data 20 processor. The data processor may be configured to cause the mobile terminal to transmit a first scheduling request (SR) to a base station in response to data arriving at an empty transmit buffer in the mobile terminal and cause the mobile terminal to transmit to the base station status information concerning the transmit buffer in response to receiving a scheduling grant (SG) from the base station. In some embodiments, the 25 data processor may further be configured to determine whether a scheduling request triggering event has occurred; cause the mobile terminal transmit a second SR to the base station at a next opportunity in response to determining that a triggering event has occurred; and cause the mobile terminal to transmit to the base station, at a next opportunity, a message indicating that a triggering event has not occurred in response to 30 determining that no triggering event has occurred. Preferably, these three steps are performed while at least some of the first data is waiting to be transmitted to the base station and after the UE transmits the buffer status information, but prior to the UE transmitting any subsequent SRs to the base station. - 7 -

In some embodiments the improved mobile terminal includes: means for transmitting a first SR to a base station in response to an empty transmit buffer in the mobile terminal receiving data; means for receiving an SG transmitted from the base station; means for transmitting to the base station status information concerning the 5 transmit buffer status in response to receiving the SG; triggering event detections means for determining whether a scheduling request triggering event has occurred; and means for transmitting to the base station, at a next opportunity, a second SR in response to determining that a scheduling request triggering event has occurred. In some embodiments, the triggering event detection means is configured to perform the determination 10 while at least some of the data is waiting to be transmitted to the base station.

In another aspect, the invention relates to a method performed by a base station for granting uplink resources to mobile terminals. In some embodiments, the base station: allocates an uplink resource to a first mobile terminal, thereby enabling the first mobile terminal to transmit data to the base station; receives an SR from a second 15 mobile terminal while the first mobile terminal is utilizing the uplink resource; reallocates the uplink resource to the second mobile terminal in response to receiving the SR; receives from the second mobile terminal information related to the priority of the data in the second mobile station that is waiting to be transmitted to the base station; compares the priority of the first mobile terminal's data to the priority of the second 20 mobile terminal's data using respective priority information; reallocates the uplink resource to the first mobile terminal in response to determining that the first mobile terminal has higher priority data than the second mobile terminal; receives a subsequent SR from the second mobile terminal, where the subsequent SR is received after receiving the priority information from the second mobile terminal but before receiving 25 any other priority information from the second mobile terminal; and reallocates the uplink resource to the second mobile terminal in response to receiving the subsequent SR.

In another aspect, the invention relates to an improved base station. In some embodiments, the improved base station includes means for communicating with a 30 plurality of mobile terminals; means for allocating an uplink resource to one of the mobile terminals based on respective buffer status data transmissions from the terminals; means for reallocating the uplink resources to another one of the plurality of - 8 - terminals based on receipt of a single bit message indicating a change of buffer status data of the other terminal.

In yet another aspect, the invention relates to a telecommunication system comprising an improved mobile terminal and improved base station. 5 The above and other aspects and embodiments of the present invention are described below with reference to the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

In order to understand the invention and to see how it may be carried out in practice, embodiments will now be described, by way of non-limiting example only, 10 with reference to the accompanying drawings, in which: FIG. 1 schematically illustrates resource allocation to different users in an SC-FDMA system. FIG. 2 illustrates uplink scheduling in an LTE system. FIG. 3 illustrates a scheme for providing to a UE a resource for data transmis- 15 sion. FIG. 4 illustrates an improved scheduling message flow between an eNodeB and two UEs. FIG. 5 illustrates a further improved scheduling message flow between an eNodeB and two UEs. 20 FIGS. 6a and 6b illustrate a process according to an embodiment of the invention. FIG. 7 is a functional block diagram illustrating some of the components of a mobile terminal. FIG. 8 is a functional block diagram illustrating some of the components of an 25 uplink scheduler. FIG. 9 is a flow chart illustrating a process according to an embodiment of the invention.

DETAILED DESCRIPTION OF EMBODIMENTS

One possible scheduling request scheme is to define an SR as being a single bit 30 message where the single bit (i.e., the “signal request bit”) has been set to a particular predefined value (e.g., set to “1”) and to configure the UEs such that the UEs transmit - 9 - an SR to the scheduler whenever: (1) the UE has data to transmit (e.g., the UE has data in a transmit buffer) and (2) the UE does not have an uplink resource allocation for transmitting the data to the eNodeB. However, a potential drawback of this approach is illustrated by the example scheduling message flow shown in FIG. 4. 5 The example shown in FIG. 4 assumes there are two synchronized UEs (i.e., UE1 and UE2), neither of which initially has an uplink resource allocation for data transmission. It is further assumed that the UEs have a dedicated SR channel.

As shown in FIG. 4, when data arrives in the transmit buffer of UE1, UE1 provides to the scheduler notification of this event by transmitting an SR (e.g., a “1”) to 10 the scheduler using its next SR opportunity. In response, the scheduler grants UE1 some resources for data transmission and transmits an SG to the UE1. In response, the UE1 transmits a buffer status report to the eNodeB. The UE1 may also transmit data to the eNodeB, depending on the UL resources allocated to it.

As further shown in FIG. 4, when UE2 has data for transmission, UE2 transmits

15 an SR (e.g., a “1”) at its next SR opportunity. For the sake of this example, we shall assume that UE2's data has a lower priority than UE1's data. In response to receiving the SR transmitted by UE2, the scheduler, which at this point in time does not know that UE2's data has a lower priority than UE1's data, grants UE2 some resources blindly. UE2 uses the allocated resource to transmit a buffer status report containing QoS 20 information and some data depending on the size of the allocation. Using the buffer status reports transmitted by UE1 and UE2, respectively, the scheduler compares UE1's buffer status to UE2's buffer status and, based on the comparison, prioritizes the data from UE1 because the comparison indicates the low priority nature of UE2's data. Because the data from UE1 is prioritized, the scheduler does not schedule the UE2 25 further, thus preventing UE2 from transmitting its data. Consequently, because UE2 has data to send, UE2 will continue to transmit an SR in each of the TTI's in which it has an SR opportunity.

Relying on the data buffer report last transmitted from UE2, which reports indicated that the UE2 had only low priority data waiting for transmission, the scheduler 30 ignores the SRs transmitted from UE2. The scheduler ignores these SRs even after the UE2 subsequently has high priority data to send because, other than through transmitting a buffer status report, there is no way for UE2 to notify the scheduler that it - 10 - has higher priority data. Accordingly, in some cases, the scheduler may not be immediately aware of new high priority data arriving at UE2's transmit buffer.

This problem could be avoided if the scheduler were configured to grant some uplink resources to UE2 every once in a while, thereby providing the UE2 with 5 opportunities to transmit to the scheduler a buffer status report indicating the new high priority data. However, if there are many users, this solution is quite costly in terms of resources. Another solution is to extend the SR from one bit to more than one bit so that the SR can contain information regarding data priority. However, this solution creates significant overhead for the SR channel, particularly if there are many priority levels. 10 Embodiments of the present invention overcome the above described problem without the disadvantages suffered by these two solutions.

Embodiments of the present invention define an alternative SR triggering mechanism that is based on changes in transmit buffer status. With such an alternative triggering mechanism, the problems described above can be solved without increasing 15 the SR from one bit to several bits and without periodically scheduling UEs to transmit buffer status reports.

According to embodiments of the present invention, the UEs are configured to transmit an SR only when certain predefined conditions are met, such as, for example, changes in the UE's transmit buffer content compared to what has been reported 20 previously or what has been transmitted previously. For example, a predefined condition may be met whenever data arrives in the UE's transmit buffer and the data has a higher priority than the priority of the previously reported data (or transmitted data). The changes in buffer status that trigger an SR are typically configured through radio resource control (RRC) signaling. 25 In some embodiments, the UEs are configured to transmit an SR only when all of the following are true: (1) the UE has no uplink grant; (2) the UE has data to transmit to the eNodeB; and (3) the buffer status has “changed” since the last acknowledged buffer report was transmitted by the UE or the last acknowledged transmission was transmitted by the UE. In these embodiments, the scheduler is configured so that it will 30 not ignore an SR from a UE configured as described above.

In some embodiments, the buffer status is considered to have “changed” only if one or more of the following conditions are met: (1) higher prioritized data has arrived in buffer; (2) the buffer size increase exceeds a predetermined threshold (Threshold A); - 11 - or (3) the elapsed time since the transmission of the last SR exceeds a predetermined threshold (Threshold B). The thresholds A and B can typically be configured through RRC signaling. One exception to the above rule is that when data arrives to an empty buffer in the UE, the UE should always transmit an SR at the next SR opportunity. 5 In the above examples, when a UE receives a UL scheduling grant from the scheduler, the scheduler is subsequently made aware of the UE’s buffer content through regular buffer status reports transmitted by the UE. This could be a continuous buffer report for each scheduled transmission. However, in some embodiments criterions are used for causing the UE to transmit buffer status reports. This means that if a UE is not 10 granted further UL resources the latest acknowledged buffer report will be up-to date. It is also possible to use a variation of the above described SR triggering rules in case the UE does not send regular buffer reports.

For example, assuming the UE employs strict priority between radio bearers (i.e., data from higher prioritised radio bearers is always transmitted before data from 15 lower prioritised radio bearers), then the scheduler will know that there is no higher priority data in the transmit buffer than what is being transmitted. In such a situation, the buffer status is considered to have “changed” only if one or more of the following conditions are met: (1) higher prioritized data has arrived in the buffer; or (2) the elapsed time since the last SR was transmitted exceeds a threshold (Threshold B). As 20 before, one exception to the rule is that when data arrives to an empty buffer in the UE, the UE should always transmit an SR at its next SR opportunity. The threshold B is typically configured through RRC signaling.

Several alternatives and combinations of the examples above can be constructed. The present invention provides an improvement in that, instead of configuring the UE to 25 transmit an SR whenever the UE has data to transmit, the UE is configured to transmit an SR only when it has data to transmit AND some other event has occurred (e.g., a certain amount of time has elapsed since the last SR was transmitted, the amount of data in the buffer grew by at least a certain amount since the most recent transmission of data or a status report, or the transmit buffer was empty just prior to it receiving the data). 30 In some embodiments, a triggered but not yet transmitted SR should be cancelled whenever the UE obtains a scheduling grant from the eNodeB before the SR transmission opportunity. In these cases, the UE will send high priority data first and - 12- optionally include a detailed buffer status report. In any case, the eNodeB is aware of the change even without obtaining a scheduling request.

FIG. 5 illustrates a message flow in a system according to an embodiment of the invention, which system includes two UEs (UE1 and UE2). The illustrated message 5 flow begins when UE1 receives high priority data in its transmit buffer. As shown in FIG. 5, in response to this event, UE1 transmits an SR to the eNodeB at its next SR opportunity.

In response, the eNodeB transmits an SG to UE1. In response to the SG, UE1 may transmit a buffer report that indicates the high priority of the data in UEl’s transmit 10 buffer. Some time after UE1 transmits the buffer report, UE2 may receive data in its transmit buffer, which event causes UE2 to transmit an SR at its next SR opportunity.

For the sake of this example, we shall assume that UE2’s data has a lower priority than UEl’s data. In response to receiving the SR transmitted by UE2, the eNodeB, which at this point in time does not know that UE2’s data has a lower priority 15 than UEl’s data, grants UE2 some resources blindly. UE2 uses the allocated resource to transmit a buffer status report containing QoS information and some data depending on the size of the allocation. Based on the buffer status report, which indicates the low priority nature of UE2’s data, the eNodeB prioritizes the data from UE1 and, thus, does not schedule the UE2 further, thereby preventing UE2 from transmitting its data (e.g., 20 the eNodeB transmits to UE2 a Hybrid Automatic Repeat Request (HARQ) ACK for the transmission containing the buffer report and the UE2 stores the latest ACK’ed report).

However, rather than continue to transmit an SR at each subsequent SR opportunity, as is shown in FIG. 4, UE2 is configured so as to not transmit an SR until 25 after one or more certain predefined events occur (e.g., the UE2 may transmit to the eNodeB the signal request bit with the bit set to the value of “0” instead of “1” until one of the events happen, as is shown in FIG. 5). Accordingly, UE2 is configured to check whether one or more certain events have occurred (such as the receipt of high priority data) prior to each subsequent SR opportunity so that, if one such event has occurred, 30 the UE2 can transmit an SR at that next SR opportunity.

In this example, some time after UE2 transmitted the buffer status report, high priority data arrives in UE2’s transmit buffer. The UE2 detects this event and, in response, transmits an SR (e.g., a “1”) to the eNodeB. The UE2 may be configured to - 13 - detect this event by comparing the last acknowledged buffer status report, which indicates the status of the transmit buffer at some previous point in time, to a newly generated buffer status information that indicates the current status of the transmit buffer. The eNodeB is configured to respond to the SR by granting an uplink resource 5 to UE2, as opposed to ignoring the SR, even though the eNodeB has not received from UE2 a new buffer status report indicating that UE2 now has higher priority data. Accordingly, in this manner, embodiments of the present invention solve the problem discussed in connection with FIG. 4. FIG. 6a is a flow chart illustrating a process 600, according to some 10 embodiments of the invention, performed by a UE. Process 600 may begin in step 602. Process 600 assumes that the UE initially has no data to transmit to the eNodeB (e.g., the UE's transmit buffer is initially empty), accordingly, in step 602 the UE waits until data is placed in the transmit buffer. In response to the UE having data to send to the eNodeB, the UE transmits an SR to the eNodeB (step 604). In step 606, the UE receives 15 an SG from the eNodeB. In step 608, the UE uses the resource allocated by the eNodeB to transmit to the eNodeB a buffer status report and/or some data depending on the allocated resource. In step 609, the UE may record a value representing the amount of data currently in its transmit buffer.

In step 610, the UE receives from the eNodeB a HARQ ACK for the transmis- 20 sion containing the buffer status report. In step 612, the UE stores the latest ACK'ed buffer status report (i.e., the report transmitted in step 608). In step 614, the UE determines whether it has data to send to the eNodeB (e.g., the UE determines whether its transmit buffer is empty). If it does not have data to send (e.g., the buffer is empty), process 600 may proceed back to step 602, otherwise it may proceed to step 616. 25 In step 616, the UE determines whether an SR triggering event has occurred. If so, process 600 proceeds back to step 604, otherwise process 600 may proceed to step 618. In step 618, at the very next SR transmission opportunity, the UE transmits to the eNodeB a message indicating that a triggering event has not occurred (e.g., the UE transmits a one bit message to the eNodeB where the value of the bit is set to “0”). After 30 step 618, process 600 may proceed back to step 616. FIG. 6b illustrates a process, according to some embodiments of the invention, for determining whether a triggering event has occurred. That is, FIG. 6b illustrates steps that may be performed in performing step 616 of process 600. - 14 -

As shown in FIG. 6b, the process may begin in step 656, where the UE determines whether new data has arrived in the transmit buffer since a particular point in time. For example, the UE may determine whether new data has arrived in the transmit buffer since the last buffer status report was generated or since the last time the 5 UE performed step 616. If the UE determines that new data has arrived, then the process may proceed to step 658, otherwise it may proceed to step 662.

In step 658, the UE determines whether the new data has a higher priority than the data that was in the transmit buffer when the new data arrived. The UE may determine this by comparing information in the buffer status report stored in step 612 to 10 newly generated information reflecting the status of the current state of the transmit buffer. If the new data has a higher priority, then process may proceed to step 604 (i.e., the UE transmits an SR to the eNodeB), otherwise the process may proceed to step 660.

In step 660, the UE determines whether the difference between the amount of data currently in the transmit buffer and the amount of data that was in the transmit 15 buffer at a previous point in time exceeds a threshold. For example, in step 660, the UE may find the difference between a value representing the amount of data currently in the transmit buffer and the value that was recorded in step 609 and compare the difference to the threshold value. If the difference equals or exceeds the threshold, then the process may proceed to step 604, otherwise the process may proceed to step 662. 20 In step 662, the UE determines whether the amount of time that has elapsed since the last SR was transmitted exceeds a threshold. If so, the process may proceed to step 604, otherwise the process may proceed to step 618.

We will now discuss error cases that may occur.

Error Case 1: In this first error case, either (a) the eNodeB misinterprets an SR 25 (e.g., the eNodeB detects that the signal request bit is set to a “0” instead of a “1”) and will not grant a resource or (b) the resource assignment message cannot be decoded by the UE. To handle this situation, the UE is configured to transmit an SR in all SR occasions until a UL grant is obtained (i.e., until the UE is given the opportunity to transmit data and/or a buffer status report).

30 Error Case 2: In the second error case, the eNodeB fails to decode the message containing the buffer status report or the initial data transmission. Waiting for the HARQ retransmission could cause excessive delay. The scheduler repeats the UL grant: (1) until a reliable report is obtained if buffer reports are transmitted with each UL - 15 - transmission; (2) if buffer reports are triggering with similar criterions as for the SR (the UE will have a buffer change compared with the latest acknowledged report and continue to transmit reports until a reliable report is obtained); or (3) if no buffer reports are triggered new data is transmitted until the eNodeB is able to decode. 5 Error Case 3: In the third error case, the eNodeB detects the message containing the buffer report or the initial data transmission but the HARQ ACK is misinterpreted as a NACK by the UE. In this situation, the UE performs a regular HARQ retransmission, which fails as the eNodeB does not expect any further transmission attempts. The UE stops after the maximum number of transmission 10 attempts. The UE does not need to perform another scheduling request if some subsequent transmission has succeeded. With the error handling in case 2, the eNodeB would have issued another grant if the transmission had failed. FIG. 7 is functional block diagram of some components of a UE 700 according to an embodiment of the invention. As shown in FIG. 7, the UE may include: a transmit 15 buffer 702 for buffering data to be transmitted to an eNodeB; a storage unit 704 for storing the last transmitted buffer status report; a data processor 706 for executing software 708 for determining whether an SR should or should not be transmitted (i.e., software 708 may be configured to perform, among other steps, steps 616-622 of process 600) and for causing an SR to be transmitted if it determines that an SR should 20 be transmitted; a transmitter for wirelessly transmitting data to an eNodeB; and other elements. FIG. 8 is functional block diagram of uplink resource scheduler 202 according to an embodiment of the invention. As shown in FIG. 8, scheduler 202 includes: a storage unit 804 for storing buffer status reports 810; a data processor 806 for executing 25 software 808. Software 808 is configured such that, when executed by data processor 806, software 808 causes the scheduler 202 to function as described above. That is, for example, software 808 may cause the scheduler 202 to schedule uplink resources based on a comparison of the buffer status of the UE's attempting to communicate with the eNodeB 240 and to respond to each SR. Although not shown, data processor 806 is 30 coupled to a transmission means (e.g., transmit buffers and/or transmitters or the like) that enables the scheduler to communicate with UEs. FIG. 9 is a flow chart illustrating a process 900 performed by a base station configured according to an embodiment of the invention. As illustrated in FIG. 9, in - 16 - step 902 the base station allocates an uplink resource to a first UE (UE1), thereby enabling UE1 to transmit data to the base station. In step 904, the base station receives an SR from a second UE (UE2) while UE1 is utilizing the uplink resource. In step 906, the base station reallocates the uplink resource to UE2 in response to receiving the SR. 5 In step 908, the base station receives from UE2 information related to the priority of the data in UE2 that is waiting to be transmitted to the base station. In step 910, the base station compares the priority of UE1's data to the priority of UE2's data using the respective priority information. In step 912, the base station reallocates the uplink resource to UE1 in response to determining that UE1 has higher priority data than UE1. 10 In step 914, the base station receives a subsequent SR from UE2, wherein the subsequent SR is received after receiving the priority information from UE2 and before receiving any other data priority information from UE2. In step 916, the base station reallocates the uplink resource to UE2 in response to receiving the subsequent SR.

One advantage of embodiments of the invention is that the scheduler in the base 15 station (eNodeB) is provided with selected updates of the terminal's buffer status and appropriate quality of service (QoS) knowledge even with a single bit SR, while decreasing the UE power consumption for the scheduling request channel (in case ON/OFF keying is used).

While various embodiments/variations of the present invention have been 20 described above, it should be understood that they have been presented by way of example only, and not limitation. Thus, the breadth and scope of the present invention should not be limited by any of the above-described exemplary embodiments. Further, unless stated, none of the above embodiments are mutually exclusive. Thus, the present invention may include any combinations and/or integrations of the features of the 25 various embodiments.

Additionally, while the processes described above and illustrated in the drawings are shown as a sequence of steps, this was done solely for the sake of illustration and does not imply a required order of performing the method steps.