High Utilization Resource Allocation and Performance Evaluation for GPRS Networks 研 究 生：蔡鎮年 指導教授：柯開維 博士 無線分封數據服務網路之高使用率 資源分配策略與效能評估

2004/7/142 Outline Introduction Background Resource Allocation Strategy for GPRS Analytical Model Numerical Result Conclusion

2004/7/143 Introduction (1/2) Radio resource allocation for GPRS Single rate vs. multirate Time slots vs. radio blocks Different strategies to partition the available cell capacity Complete Sharing (CS) Complete Partitioning (CP) Partial Sharing (PS)

2004/7/144 Introduction (2/2) This thesis Focuses on CP and PS strategy. Allocates downlink radio resource by radio blocks. Two types (rates) of GPRS user. Analyzes and evaluates performance for different strategy.

2004/7/145 Background GPRS network architecture GPRS air interface TBF and TFI

2004/7/146 GPRS Network Architecture (1/2) It fits in with the existing GSM PLMN Two new network elements Serving GPRS Support Node (SGSN) Gateway GPRS Support Node (GGSN) Many new interfaces G b, G i, G n, etc.

2004/7/147 GPRS Network Architecture (2/2)

2004/7/148 GPRS Air Interface Frequency-Division Duplex, FDD Combination of Frequency and Time division multiple access, FDMA/TDMA 52-multiframe Physical channels and logical channels

2004/7/149 GPRS Air Interface 52-multiframe

2004/7/1410 GPRS Air Interface Physical Channels Eight physical channels (TS0 to TS7) per carrier. The physical channel that is used for packet logical channels is called a packet data channel (PDCH).

2004/7/1411 TBF and TFI (1/3) A temporary block flow (TBF) is a physical connection between the MS and the network side to support data transfer. Once the data transfer is finished, the TBF is released.

2004/7/1412 TBF and TFI (2/3) Each TBF is identified by a temporary flow identity (TFI) assigned by the network. PDCH multiplexing TBFs which belonging to different MS can share the same PDCH.

2004/7/1413 TBF and TFI (3/3)

2004/7/1414 Resource Allocation Strategy for GPRS Radio resource partition strategies Complete Partitioning (CP) Partial Sharing (PS)

2004/7/1415 Resource Allocation Strategy Complete Partitioning TS0 to TS4 are GSM user only, and TS5 to TS7 are GPRS user only This two partitions are independent

2004/7/1416 Resource Allocation Strategy Partial Sharing A shared time slot This two partitions are dependent

2004/7/1417 Analytical Model for CP In CP case, GSM and GPRS partitions are independent, so we can analyze this two partitions separately. System description State definition State transition diagrams Balance equations Performance metrics

2004/7/1418 Analytical Model for CP System Description Two types of user Class 1 (1+1) and class 2 (2+1) The request is Poisson. Arrival rate are λ 1 and λ 2, respective. The service time of each request is exponential distribution Mean service time are 1/μ 1 and 1/μ 2, respective.

2004/7/1419 Analytical Model for CP State Definition State x=(i, j, k) i = the number of PDCH is used j = the number of class 1 user k = the number of class 2 user An example

2004/7/1420 Analytical Model for CP State Transition Diagrams Define R = j + 2k, and MAX_PDCH is the maximum number of GPRS time slot that can be used. Four cases

2004/7/1421 Analytical Model for CP State Transition Diagrams The most straightforward No need to consider i An example MAX_PDCH = 3

2004/7/1422 Analytical Model for CP State Transition Diagrams Generalized state transition diagram for case 1

2004/7/1423 Analytical Model for CP Balance Equations

2004/7/1424 Analytical Model for CP Performance Metrics According steady-state probabilities, we can fine the class 1 and class 2 blocking probability (P b1 and P b2 ), and radio resource utilization U.

2004/7/1425 PS case is more complex than CP case. In addition to GPRS user, there is GSM user in the system as well. GSM user New call and handover call are Poisson Arrival rate Service time is exponential distribution Mean service time Analytical Model for PS (1/2)

2004/7/1426 Analytical Model for PS (2/2) State x=(i, j, k, l, m) i = the number of PDCH being used j = the number of GPRS class 1 user k = the number of GPRS class 2 user l = the number of GSM user m = indicate who is using shared TS 12 different cases, 12 different balance equations.

2004/7/1427 Analytical Model for PS Performance Metrics (1/2) According to these balance equations, we can calculate steady-state probabilities, and compute performance metrics as well. GPRS class 1 blocking probability GPRS class 2 blocking probability

2004/7/1428 Analytical Model for PS Performance Metrics (2/2) GSM new call blocking probability GSM handover call blocking probability Radio resource utilization

2004/7/1429 Numerical Result Comparison between analytic and simulated result. Comparison between CP and PS for GPRS traffic. Utilization vs. load Define GPRS load GSM load

2004/7/1430 Comparison between analytic and simulated result (1/2) CP case

2004/7/1431 Comparison between analytic and simulated result (2/2) PS case

2004/7/1432 Comparison between CP and PS for GPRS request

2004/7/1433 Utilization vs. offered load (1/2) CP case

2004/7/1434 Utilization vs. offered load (2/2) PS case

2004/7/1435 Conclusion Radio block based CP and PS strategies was proposed. Built analytic model for both strategies. Verified analytic model by simulation. Showed that PS case scheme performed better than CP one. GPRS radio resource can be fully utilized easily.

2004/7/1436 Future work Impact of cell-reselection. Priority for GSM handover call. Preemptive mechanism. Adaptive resource allocation.

2004/7/1437 The End