Pricing and Power Control in a Multicell Wireless Data Network Po Yu Chen October, 2001 IEEE Journal on Select Areas in Communications

Prolog The data services in wireless networks necessitate efficient and efficiency radio resource management Power control is important in CDMA system

Outline Introduction Approach Simulation Result Conclusion and Discussion

Pricing and Power Control in a Multicell Wireless Data Network Introduction

Introduction (1/2) Why using power control ?  To provide each signal with adequate quality without causing unnecessary interference to other signals  To minimize the battery drain in portable terminals

Introduction (2/2) Paper Concept Extend reference [5] (single-cell environment) to multi-cell environment Power control for data network under a new light, powered by mathematics and concepts from microeconomics Pricing scheme to improve utility with respect to both the transmit power and BS assignment

Key word Utility function: measure performance in bits per joule (bits/joule) Nash equilibrium: no user has any incentive to change its power level since no individual improvement in utilities is possible Non-cooperative game: terminals operating independently to achieve best performance (a distributed power control algorithm ) Cooperative game: a centralized power control algorithm

Utility function & Nash equilibrium 將 Nash equilibrium 帶入所得之結果

Pricing and Power Control in a Multicell Wireless Data Network Approach

Functions SIR Utility function: 包含了 SIR 和 power control 的訊息 h ij : path gain p j : power of user j W: bandwidth R: data rate L/M: code rate, f(.): 能成功被接收的機率

BS Assignment Based on MRSS (1/2) MRSS (Max. Received Signal Strength) a j : 被 assigned 給 j 的 BS h ij :path gain d ij :distance between terminal and BS

BS Assignment Based on MRSS (2/2) 固定了 BS assignment 的方法，所以只剩 下 power control 的變數 Multi-cell power control game (MCPG) P -j : interference power vector, but not include p j

BS Assignment Based on MSIR (1/2) Generalize the MRSS ，將 BS assignment 也考慮進來。 方法：將有最大 SIR 值的 BS assign 給 terminal 所以在這裡 BS assignment 也變成了一個 變數

BS Assignment Based on MSIR (2/2) MCPG 的 utility function (two dimension) 簡化問題，分成兩項討論： 先解決 BS assignment 的問題（ MAX SIR ） 再處理 power control 的問題

Pricing (1/2) Define: every transmit power has pricing 加入 pricing 後的結果： new utility function c i :the pricing factor announced by BS Alpha is a scalar, N i is the number of the terminals assigned to BS

Pricing (2/2) Pricing 分為兩種： --Global Pricing --Local Pricing c i is based on the amount of traffic that is offered in its service area

Power control game with Pricing For MCPG-MRSS For MCPG-MSIR

Best equal-SIR Good for MCPG (no pricing, the same SIR) dependent on local information A centralized scheme, 由 BS 來計算 Terminal 的 SIR BS need to announce the best SIR The terminal needs to be applied an SIR balancing algorithm

Pricing and Power Control in a Multicell Wireless Data Network Simulation Result

System Model Multi-cell CDMA data system N=28 terminals K=4 base stations Frame size is fixed No forward error correction Simple path loss

Result (1/4)--utility Compare MCPG/MSIR and MCPGP/MSIR(LP)

Result (2/4)--power in cell Compare MCPG/MSIR and MCPGP/MSIR(LP)

Result (3/4)--utility Compare MCPG/MRSS and best equal-SIR

Result (4/4)--power in cell Compare MCPG/MRSS and best equal-SIR

Benefit of Local pricing (LP)1/2 congestion

Benefit of Local pricing (LP)2/2

Pricing and Power Control in a Multicell Wireless Data Network Conclusion and Discussion

Conclusion 此篇利用 microeconomics 的 concept 和 mathematics 來引導結果 — 證明加入 pricing scheme 有助於效能提升 傳 data 和傳 Voice 的方法不同，所以 MRSS 不能夠保證 data 的 QoS ，因為 power 最大 並不代表 SIR 就大。

Discussion 作者並沒有比較 MRSS 和 MSIR ，所以我們就不 知道 Best equal-SIR 有沒有比 MSIR 好，因為這 就是 Centralized 和 Distributed power control 的 比較 Utility 的可信度 缺乏其他參數的實驗數據，不知是否影響其的 參數的 performance 個人覺得此實驗的 model 不夠完整，實際狀況 應更為複雜