在無線通道中訊號會因路徑介質本身的損耗(path loss)、屏蔽效應(shadowing, fading)等情形而造成能量衰減。動態資源分配(Dynamic resource allocation)為對抗此時變效應而採取的一種依據各通道的優劣情形來進行的資源分配方式。本篇論文探討一雙使用者系統在有或無透過使用者合作(User cooperation)的機制來傳遞訊號時，依循總速率最大化(Sum rate maximization)準則及長程功率總和限制(Long-term sum power constraint)下的最佳資源分配決策為何，以及此決策對系統效能如流量(Throughput)及佇列延遲(Queueing delay)的影響。
在未利用合作機制來傳輸的情形下，使用者僅直接將訊號傳送至基地台(Direct transmission)，此通道即為一多工擷取通道(Multiple-Access Channel)。而當使用者透過合作機制作傳輸時(Cooperative transmission)，我們假設其中一個使用者在任何時間皆可同時作為另一使用者之轉送點(Relay node)，即利用解碼並送出(Decode-and-forward)的方式來幫助另一位使用者傳送訊號。在使用者透過合作機制傳輸的模式下，每次傳輸分為兩個階段：第一階段由非轉送點的使用者廣播訊號至轉送點及基地台；第二階段則兩位使用者同時傳輸訊號至基地台，其中轉送點所傳輸之訊號除了自己本身欲傳者外，也包括在上一階段由非轉送點接收到的訊號。我們利用數值方法來解出上述問題的最佳解，並比較此兩者在系統效能上的表現。模擬過程中則亦將佇列長度(queue length)及資料到達速率(arrival rate)列入考量。其結果顯示，當作為轉送點的使用者之通道情形較佳時，透過合作機制可使得系統效能在某些通道情形下獲得提昇；反之，系統效能反而降低。

[1] A. Goldsmith, Wireless Communication. Cambridge University Press, 2005.
[2] A. J. Goldsmith and P. P. Varaiya, “Capacity of fading channel with channel side information,” IEEE Trans. Inform. Theory., vol. 43, pp. 1986–1992, 1997.
[3] X. Liu and A. J. Goldsmith, “Opitmal power allocation over fading channels with stringent delay constraints,” in Proc. IEEE Int. Conf. Commun., pp. 1413–1418, May-June 2002.
[4] G. Caire, G. Taricco, and E. Biglieri, “Optimum power control over fading channels,”IEEE Trans. Inform. Theory, vol. 45, pp. 1468–1489, 1999.
[5] D. N. C. Tse and S. Hanly, “Multiaccess fading channels-part I: Polymatroid structure, optimal resource allocation and throughput capacities,” IEEE Trans. Inform. Theory, vol. 44, pp. 2796–2815, 1998.
[6] S. Hanly and D. N. C. Tse, “Multiaccess fading channels-part II: Delay-limited capacities,”IEEE Trans. Inform. Theory, vol. 44, pp. 2816–2831, 1998.
[7] A. Sendonaris, E. Erkip, and B. Aazhang, “User cooperation diversity–part I: System description,” IEEE Trans. Commun., vol. 51, pp. 1927–1938, 2003.
[8] J. Laneman, D. Tse, and G. Wornell, “Cooperative diversity in wireless networks: Efficient protocols and outage behavior,” IEEE Trans. Inf. Theory, vol. 50, no. 12, pp. 3062–3080, Dec. 2004.
[9] Y.-W. Hong,W.-J. Huang, F.-H. Chiu, and C.-C. J. Kuo, “Cooperative communications in resource-constrained wireless networks,” IEEE Signal Process. Mag., vol. 24, no. 3, pp. 47–57, May 2007.
[10] D. G¨und¨uz and E. Erkip, “Opportunistic cooperation by dynamic resource allocation,”IEEE Trans. Wireless. Comm., pp. 1446–1454, 2007.
[11] R. A. Berry and E. M. Yeh, “Cross-layer wireless resource allocation,” IEEE Signal Processing Mag., vol. 21, pp. 59–68, 2004.
[12] M. Goyal, A. Kumar, and V. Sharma, “Power constrained and delay optimal policies for scheduling transmission over a fading channel,” INFOCOM, IEEE Computer and
Communications Societies, 2003.
[13] ——, “Optimal cross layer scheduling of ransmissions over a multiaccess channel,”IEEE Trans. Inform. Thoery., vol. 54, pp. 3518–3537, 2008.
[14] R. J. McEliece and W. E. Stark, “Channels with block interference,” IEEE Trans. Inform. Theory, vol. 30, pp. 44–53, 1984.
[15] L. Kleinrock, Queueing Systems - Volumn I: Theory. John Wiley & sons, 1975.
[16] D. P. Palomar and M. Chiang, “A tutorial on decomposition methods for network utility maximization,” IEEE Jour. on select. area in commun., vol. 24, pp. 1439–1451, 2006.
[17] D. Tse and P. Viswanath, Fundamentals of Wireless Communication. Cambridge, 2005.
[18] M. Goyal, A. Kumar, and V. Sharma, “Delay optimal control algorithm for a multiaccess fading channel with peak power constraint,” in Proceedings of the International
Symposium on Information Theory, (Adelaide, Australia), 2005.
[19] D. P. Bertsekas, Dynamic Programming and Optimal Control. Athena Scientific, 2006, vol. II.
[20] D.-J. Ma, A. Makowski, and A. Shwartz, “Estimation and optimal control for constrained markov chains,” IEEE Conference on Decision and Control, Athens, Greece, 1986.