Title of Invention

METHOD OF COUPON BASED UPLINK SCHEDULING OF SERVICES ASSOCIATED WITH RADIO BEARER

Abstract

The present invention relates to wireless communication systems. More specifically, the invention provides a method for radio resource management in wireless communication systems. The invention classifies the services in a wireless communication system into four different groups based on criterion like priority, bit rate, and periodicity of the services. First group of services has high priority and does not have a guaranteed bit rate. The first group is assigned coupons of infinite size and infinite validity. Second group of services has fixed size, fixed periodicity and guaranteed bit rate. The second group is assigned coupons having size and periodicity synchronised with their TTls. Third group of services has variable size, fixed periodicity and guaranteed bit rate. This group is assigned coupons with periodic validity and desired size. Fourth group of services does not have a guaranteed bit rate and includes services, which lack any fixed pattern of traffic. The fourth group is assigned coupons with size and periodicity matching their minimum bit rate. Depending upon this classification, the TFC selection algorithm is manipulated.

Full Text

FIELD OF INVENTION The present invention applies to the field of wireless telecommunication. It applies to the Data Link Layer (also known as Layer 2) in the Access Stratum of the Long Term Evolution (LTE) of the 3GPP Protocol Standards. The invention, using a newly introduced mechanism of Grant Coupons, specifies a method for the Uplink Scheduling and TFC Selection which will avoid a potential starvation of the lower priority Radio Bearers. More particularly, the present invention relates to a method of coupon based uplink scheduling and TFC selection. In addition, the present invention also specifies an alternative method of avoiding excessive segmentation at the layer 2. DESCRIPTION OF RELATED ART When an Uplink Channel is shared by many UEs, a scheduler entity is required at the eNB to allocate the resources to the competing UEs on this channel. The total data availability, called Buffer Status, for all the Radio Bearers of all the UEs are regularly reported to the eNB Scheduler. Based on the Buffer Status Report(s) received from the UE(s) and the priorities of the UE(s) and their corresponding Radio Bearer(s), the eNB Scheduler determines the allocation(s) for the UE(s) for the upcoming TTI. The determined allocation for a UE is indicated to it and the UE is then responsible for distributing the received allocation among its respective Radio Bearer(s). The UEs are required to maximize the transfer of the highest priority data and this condition has to be satisfied recursively for the other priority levels. Thus, the UEs act in strict priority order. LIMITATIONS It is possible that the allocation received by a UE is not able to meet the minimum QoS requirements for all of its active Radio Bearers. This could be due to: (a) The UE receiving less allocation than requested/required, or (b) A potential competition among the Radio Bearers with different traffic priorities. The scenario (a) is self-evident. If the UE does not receive the requested/required allocation it cannot meet the minimum QoS requirements for all its active Radio Bearers. The scenario (b) is possible in cases when the data availability is updated (increased) for a (high priority) Radio Bearer during the time interval since the reporting of the Buffer Status to the reception of the actual allocation. In this case, since the UE is required to satisfy the Radio Bearers in the priority order, the QoS of the lower priority Radio Bearer(s) may or may not be met every TTI. The same problem is encountered when the higher priority Radio Bearer has an adaptive application mapped onto it. in that case, the higher priority Radio Bearer increases its data rate to adapt with a higher allocation which was actually received for the lower priority Radio Bearer. There are mainly five possible approaches for avoiding low-priority Radio Bearer starvation: Q RB Prioritization (controlled from the ENB) □ Pre-defined Alternative Priority Schedule(s) □ Minimum bit-rate enforcement at the UE □ Maximum bit-rate enforcement at the UE □ Starvation avoidance by the UE The third approach of enforcing the minimum bit-rates at the UE is arguably the simplest. However, it is not clear how the minimum bit-rates could be enforced at the UE. The general methodology is to maintain the data transfer record for all the Radio Bearers (for which the MBR has to be met) for the last N TTIs (assuming that the averaging has to be done for N TTIs) and refer to it while taking TFC Selection decisions to ensure that the minimum data rate requirement is being met for every Radio Bearer. However, this methodology is very inefficient in terms of space and time complexity. Moreover, it is known that the segmentation overheads (header and padding space, Figure - 1) are dependent on the size of the segment. Therefore, the scheme, potentially, wastes a lot of space in the upper layer segmentation. SUMMARY OF THE INVENTION A new concept of 'Grant Coupon' is introduced in the invention. A 'Grant Coupon' is not a grant for a Radio Bearer for transmitting data. Instead, it is a certificate for the Radio Bearer to receive a preferential treatment during data transfer ahead of any other Radio Bearer. This invention, using a mechanism of Grant Coupons, specifies a method for the Uplink Scheduling and TFC Selection which will avoid a potential starvation of lower priority Radio Bearers. The following rules shall be applied to the working of Grant Coupons to enforce the minimum bit-rates at the UE and consequently avoid the starvation at the lower priority Radio Bearers: □ Grant Coupons shall be issued (periodically) to the RBs by the eNB. Q Grant Coupons shall be utilized in the First-In-First-Out (FIFO) order. Q Grant Coupons shall be based on the Minimum Bit-Rate (MBR) Requirements of a RB. □ Grant Coupons shall have a limited validity which shall be indicated while issuing them. □ Grant Coupons shall be considered by the UE before undertaking any other data transfer. Following is the list of possible service (Radio Bearer) types and the means to achieve their required QoS using the proposed approach: 1. High priority, non-adaptive, non-GBR services: These services are of the highest priority but they do not require any guaranteed bit-rates and are non-adaptive and bursty in nature e.g. signaling services. These RBs shall be provided coupons of INFINITE size with INFINITE validity so that they will get served ahead of any other Radio Bearer. 2. Fixed Size, Fixed Periodicity, GBR Services: These services generate PDUs of fixed size with a fixed periodicity e.g. VoIP without silence suppression. To guarantee this bit-rate these services shall be provided the coupons of a size and periodicity matching their traffic pattern. A coupon shall remain valid for a single TTI due to the fixed periodicity requirement of the traffic. 3. Variable Size, Fixed Periodicity, GBR Services: These services have no definite PDU size but their traffic is mostly periodic in nature e.g. VoIP with silence suppression. A part of the bandwidth requirements of such services is generally guaranteed. To guarantee this bit-rate these services shall be provided the grant coupons of the size and periodicity matching the guaranteed part of their bandwidth. The coupons can be valid for multiple TTIs. 4. Non-deterministic, non-GBR Services: These services do not have any fixed pattern of traffic nor have any guaranteed bandwidth e.g. TCP based applications like FTP. Such services shall be assigned a minimum bit-rate to keep them from starving. To guarantee this bit-rate these services shall be provided with grant coupons of the size and periodicity matching this MBR. The coupons can be valid for multiple TTIs. it should be noted that, for the service types (3) and (4), since the traffic is not periodic, an averaging of the grant coupons need to be done over a period of time. This parameter (let us call it T_AVG, the time period over which the averaging has to be performed) shall be equal to the validity period of the grant coupon. Thus we have three traffic parameters - Coupon Size, Coupon Periodicity and Coupon Validity - corresponding to every Radio Bearer. These three parameters together are determined by the nature of the Radio Bearer as captured in the table below: The minimum overhead is incurred with a best-fit type of segment size. Overheads due to the header and the padding increase for a smaller and a larger segment size respectively. Accordingly the invention explains a method of coupon based uplink scheduling and TFC selection wherein the said method classifies the services in a wireless communication system into four different groups based on criteria like priority, bit rate, and periodicity of the services. These and other objects, features and advantages of the present invention will become more apparent from the ensuing detailed description of the invention taken in conjunction with the accompanying drawings. BRIEF DESCRIPTION OF ACCOMPANYING DRAWINGS Figure 1 depicts Segmentation Overheads. Figure 2 depicts reduction in Segmentation Overheads with the proposed mechanism. Figure 3 depicts a case of better Traffic Regulation in case of bursty traffic behaviour. Figure 4 depicts the concept of active coupon level vis-a-vis current coupon level. Figure 5 depicts the algorithm used for TFC Selection. Figure 6 depicts the algorithm used for TFC Selection with the alternative solution for Segmentation Overhead Reduction. DETAILED DESCRIPTION OF INVENTION The preferred embodiments of the present invention will now be explained with reference to the accompanying drawings. It should be understood however that the disclosed embodiments are merely exemplary of the invention, which may be embodied in various forms. The following description and drawings are not to be construed as limiting the invention and numerous specific details are described to provide a thorough understanding of the present invention, as the basis for the claims and as a basis for teaching one skilled in the art how to make and/or use the invention. However in certain instances, well-known or conventional details are not described in order not to unnecessarily obscure the present invention in detail. 1. For the service type 1, the traffic parameters are pretty straightforward. A one-time allocation of a Grant Coupons of size INFINITY with the corresponding validity also being INFINITY is sufficient to take care of the traffic requirements of the service. Thus the periodicity of allocation does not come into picture here. The traffic parameters can then be summarized as follows: 2. For the service type 2, let us assume that a packet data unit (PDU) of size SPOU bits (including the protocol header, rf any) is generated at every TPDU seconds. Let us also assume that a TTI is Tm seconds long. Case 1: TPDU Total number of PDUs generated in a single TTI = Tm / TPDU Total size of data generated in a single TTI = Spou * Tm / TPDU bits Let us assume that a total of extra SHOR bits are required for the protocol header for concatenating the Tm / TPDU PDUS generated in single TTI. Let us take a variable Sm = SPDu • TTTI / TPOU + SHDR bits. The traffic parameters can then be summarized as follows: Case 2: TPDU > Tm: It is generally expected that the TPDU shall be an integral multiple of Tm in this case. In the cases where this assumption is not correct appropriate approximations shall be considered and all such approximations are implicitly covered in this I PR. Let us take the number of TTIs taken for generating a single PDU Nm = TPDU / Tm. The traffic parameters can then be summarized as follows: Alternatively, Grant Coupons of size Sm= Spou * Tm / TPDU bits can be allocated every TTI. The validity of the Grant Coupons shall remain same i.e. Nm TTIs. In fact, any Coupons Size S bits with Coupons Periodicity N per TTI such that their product, shall be able to meet the traffic requirements of the service. All such possible alternatives are implicitly covered in this IPR. Case 3: TPDU = Tin: For this case, since Trn / Tpou = 1, following the discussion for cases (1) and (2) above, the traffic parameters can be specified as follows: 3. For the service type 3 let us assume that a PDU is generated at every TPDU seconds. The size of the PDU is not definite and can change depending on the application behaviour. Let us also assume that a TTI is Trn seconds long. Let us assume that the Guaranteed Bit-Rate for this service is GBR bits per second. Let us assume that the intended Minimum Bit-Rate to be enforced at the UE is same as the Guaranteed Bit-Rate. Let us also assume that this Guaranteed Bit-Rate has to be averaged out over a period of TAVQ seconds. It can be argued that TAVG >= MAX (TPDU, Trn). * [TAVG >= Tm] is self-evident - averaging of data rate cannot be performed for a time period less that Trn since data can be transmitted only at every TTTI seconds. * (TAVG >= TPDU] is necessary to make the system work - if the averaging is done before a PDU gets generated (and transmitted) the outstanding Grant Coupons in the TTI of averaging cannot be utilized for data transfer. Thus we have, TAVO >= MAX (TPDU, Tm). Since TAVG is guaranteed to be at least equal to Tm, the validity of Grant Coupons shall be equal to the TAVG- It is generally expected that the TAVG shall be an integral multiple of Tm. In the cases where this assumption is not correct appropriate approximations shall be considered and all such approximations are implicitly covered in this IPR. Let us take SAVG = GBR * TAVG bits and Nm = TAVG / Tm. The traffic parameters can then be summarized as follows: Alternatively, Grant Coupons of size Srn= SAVG * Tm / TAVG bits can be allocated every TTI. The validity of the Grant Coupons shall remain same i.e. Nm TTIs. in fact, any Coupon of Size S bits with Coupon Periodicity N per TTI such that their product, shall be able to meet the traffic requirements of the service. All such possible alternatives are implicitly covered in this IPR. 4. For the service type 4, the traffic parameters are pretty random. Neither the size of a PDU nor the periodicity of PDU generation is fixed. However, it can be assumed that at least one PDU is generated every Tpou seconds. Let us also assume that a TTI is Tm seconds long. Let us assume that the Minimum Bit-Rate to be enforced at the UE for this service is MBR bits per second. Let us also assume that this Minimum Bit-Rate has to be averaged out over a period of TAVG seconds. Following the arguments as done in the case (3), it can be shown that TAVG >= MAX (TPDU, Tm). Since the TAVG is guaranteed to be at least equal to Tm> the validity of Grant Coupons shall be equal to the TAVG. It is generally expected that the TAVG shall be an integral multiple of TM. In the cases where this assumption is not correct appropriate approximations shall be considered and ail such approximations are implicitly covered in this IPR. Let us take SAVG = MBR * TAVG bits and Nm = TAVG / Tm. The traffic parameters can then be summarized as follows: Alternatively, Grant Coupons of size SM= SAVG * TM / TAVG bits can be allocated every TTI. The validity of the Grant Coupons shall remain same i.e. Nm TTIs. In fact, any Coupon of Size S bits with Coupons Periodicity N per TTI such that their product, shall be able to meet the traffic requirements of the service. All such possible alternatives are implicitly covered in this IPR. The TFC Selection Algorithm The following rules shall be applied to the working of Grant Coupons to enforce the minimum bit-rates at the UE and consequently avoid the starvation at the lower priority Radio Bearers: □ Grant Coupons shall be issued (periodically) to the RBs by the eNB. □ Grant Coupons shall be utilized in the First-In-First-Out (FIFO) order. □ Grant Coupons shall be based on the Minimum Bit-Rate (MBR) Requirements of a RB. □ Grant Coupons shall have a limited validity which shall be indicated while issuing them. □ Grant Coupons shall be considered by the UE before undertaking any other data transfer. The TFC Selection Algorithm (Figure - 5) for this scheme can be specified as follows: The working of this algorithm is explained for two consecutive TTIs with the help of an example consisting of four Radio Bearers and their corresponding traffic parameters as specified in the table below: 4 The Coupon Periodicity of 2 TTIs has been taken just for explanation. It is expected that the only real Coupon Periodicity that shall be used, shall be one coupon per TTI. Let us assume that the current TTI is an even-numbered one so that no Grant Coupon is received by the RB4 in the next TTI. The working of the algorithm shall be as shown below: 17 Let us assume that a total of 2, 4 and 8 units of data are generated at the RB1, RB2 and RB4 respectively. As assumed, a total of 4 and 6 units of Grant Coupons are received by the RB2 and RB3 respectively. The working of TFC Selection Algorithm shall be as shown below: It can be seen that RB4 is left with 2 grant coupons in the current TTI which are utilized in the next one. On the other hand, RB3 is left with 2 data units in the current TTI which are transmitted using fresh grant coupons in the next one. RB3 and RB4 (respectively in the two TTIs) get the grants left after serving all the grant coupons. 6. Alternative solution for excessive fragmentation at Layer 2 As described in the section titled "Limitations,* the segmentation overheads (header and padding space, Figure - 1) are dependent on the size of the segment. Therefore, if the coupons are of smaller sizes, most of the bandwidth shall be consumed by the layer 2 overheads. The solution described above, addresses this problem by reducing the frequency of coupon generation thereby increasing the size of the same. An alternative solution, based on the newly introduced concept of 'active (coupon) level' is specified below: • 'Current Coupon Level' indicates the number of bytes allowed to be transmitted. • 'Active Level' indicates the minimum value of 'Current Coupon Level' at which any coupons can be utilized for data transfer (Figure - 4). It can be seen that when the 'Current Coupon Level' is below the 'Active Level', coupons cannot be taken out for data transfer. In other words, the Radio Bearers for which the 'Current Coupon Level' is below the 'Active Level* will not be considered in the TFC selection procedure (Figure - 6). Therefore, if there is sufficient data to transmit, 'Active Level' also indicates the minimum size of a PDU that shall be transmitted on the concerned Radio Bearer. Thus, too small RLC PDU is avoided even for quite low bit rate services. ADVANTAGES This innovation is able to provide a specified data rate to a given Radio Bearer while doing the TFC Selection. The main advantage gained from this innovation, therefore, is the ability to avoid the starvation of a lower priority Radio Bearer. This innovation also achieves better resource utilization by avoiding the segmentation overheads since the size of segments can be controlled by determining the Size, Periodicity and Validity parameters for the Grant Coupons. In addition, this innovation also achieves better resource utilization by an alternative mechanism of 'Active (Coupon) Level' whereby the minimum RLC PDU size is kept above a certain threshold thereby reducing the overheads. It will also be obvious to those skilled in the art that other control methods and apparatuses can be derived from the combinations of the various methods and apparatuses of the present invention as taught by the description and the accompanying drawings and these shall also be considered within the scope of the present invention. Further, description of such combinations and variations are therefore omitted above. It should also be noted that the host for storing the applications include but not limited to a microchip, microprocessor, handheld communication device, computer, rendering device or a mutti function device. Although the present invention has been fully described in connection with the preferred embodiments thereof with reference to the accompanying drawings, it is to be noted that various changes and modifications are possible and are apparent to those skilled in the art. Such changes and modifications are to be understood as included within the scope of the present invention as defined by the appended claims unless they depart there from. GLOSSARY OF TERMS AND DEFINITIONS THEREOF eNB - Evolved Node-B GBR - Guaranteed Bit Rate HSDPA - High Speed Downlink Packet Access HSUPA - High Speed Uplink Packet Access LTE - Long Term Evolution MAC - Medium Access Control (Protocol) MBR - Minimum Bit Rate PDU - Packet Data Unit RLC - Radio Link Control (Protocol) SAE - System Architecture Evolution TFC - Transport Format Combination TTI - Transmission Time Interval WCDMA - Wideband Code Division Multiple Access We Claim: 1. A method of coupon based uplink scheduling and TFC selection wherein the said method classifies the services in a wireless communication system into four different groups based on criterion like priority, bit rate, and periodicity of the services. 2. A method as claimed in claim 1 wherein first group of services has high priority and does not have a guaranteed bit rate. 3. A method as claimed in claim 2 wherein the first group is assigned coupons of infinite size and infinite validity. 4. A method as claimed in claim 1 wherein the second group of services has fixed size, fixed periodicity and guaranteed bit rate. 5. A method as claimed in claim 4 wherein the second group is assigned coupons having size and periodicity synchronised with their TTIs. 6. A method as claimed in claim 1 wherein the third group of services has variable size, fixed periodicity and guaranteed bit rate. 7. A method as claimed in claim 6 wherein the group is assigned coupons with periodic validity and desired size. 8. A method as claimed in claim 1 wherein fourth group of services does not have a guaranteed bit rate and includes services which lack any fixed pattern of traffic. 9. A method as claimed in claim 8 wherein the fourth group is assigned coupons with size and periodicity matching their minimum bit rate. 10. A method as claimed in claim 1 wherein to enforce the minimum bit-rates at the UE, grant Coupons are issued (periodically) to the RBs by the eNB. 11. A method as claimed in claim 1 wherein to enforce the minimum bit-rates at the UE, Grant Coupons are utilized in the First-In-First-Out (FIFO) order. 12. A method as claimed in claim 1 wherein grant coupons are not utilized if the total number of available coupons is less than active coupon level. 13. A method as claimed in claim 1 wherein data from an RB is not considered for TFC selection if the said data has fewer coupons than active coupon level. 14. A method as claimed in claim 12 or 13 wherein the value of active coupon level is determined by the desired minimum RLC PDU size. 15. A method as claimed in claim 1 wherein to enforce the minimum bit-rates at the UE, the size of Grant Coupons shall be based on the Minimum Bit-Rate (MBR) Requirements of a RB. 16. A method as claimed in claim 1 wherein to enforce the minimum bit-rates at the UE, Grant Coupons shall have a limited validity which shall be indicated while issuing them. 17. A method as claimed in claim 1 wherein to enforce the minimum bit-rates at the UE, grant Coupons is considered by the UE before undertaking any other data transfer. 18. A method of coupon based uplink scheduling and TFC selection substantially described particularly with reference to the accompanying drawings.

Documents:

2413-CHE-2006 AMENDED PAGES OF SPECIFICATION 23-07-2013.pdf

2413-CHE-2006 AMENDED CLAIMS 23-07-2013.pdf

2413-CHE-2006 EXAMINATION REPORT REPLY RECEIVED 23-07-2013.pdf

2413-CHE-2006 FORM-1 23-07-2013.pdf

2413-CHE-2006 FORM-13 23-07-2013.pdf

2413-CHE-2006 FORM-3 23-07-2013.pdf

2413-CHE-2006 OTHER PATENT DOCUMENT 23-07-2013.pdf

2413-CHE-2006 POWER OF ATTORNEY 23-07-2013.pdf

2413-CHE-2006 AMENDED CLAIMS 03-09-2013.pdf

2413-CHE-2006 EXAMINATION REPORT REPLY RECEIVED 03-09-2013.pdf

2413-CHE-2006 POWER OF ATTORNEY 03-09-2013.pdf

2413-CHE-2006 ABSTRACT.pdf

2413-CHE-2006 CLAIMS.pdf

2413-CHE-2006 CORRESPONDENCE OTHERS.pdf

2413-CHE-2006 DESCRIPTION (COMPLETE).pdf

2413-CHE-2006 DRAWINGS.pdf

2413-CHE-2006 FORM 1.pdf

2413-CHE-2006 FORM 18.pdf

2413-CHE-2006 FORM 5.pdf

2413-che-2006-correspondnece-others.pdf

2413-che-2006-description(provisional).pdf

2413-che-2006-drawings.pdf

2413-che-2006-form 1.pdf

2413-che-2006-form 26.pdf