Cooperative techniques in wireless communications: a game- and information- theoretic analysis

This dissertation consists in two parts. In the first part (Chapter 1-3) we study the notion of cooperative game theory and its applications to network engineering problems. The tools of cooperative game theory are shown to be advantageous for obtaining high-performance and good results in terms of fairness, and stability. In particular, the first part describes a theoretical framework for the design and analysis of resource allocation algorithms for wireless networks using OFDMA technology in uplink transmission. The resource allocation issue is modeled as a cooperative game in which every user terminal is assigned to a set of subcarriers, and them chooses its transmit power so as to achieve its demanded data rate exactly. The power distribution is obtained by a dynamic learning algorithm based upon Markov modeling. Simulation results show that the average number of operations of the proposed iterative algorithm are much lower than K . N, where N and K are the number of allocated subcarriers and of mobile terminals. The second part (Chapter 4-6) deals with the information theoretic issues around multi hop communication where some nodes act as intermediate relays. We present the advantages and limitations of different relaying strategies. We first review point-to-point communication assisted by one relay, and derive the upper bounds on the capacity of memoryless AWGN relay channel. We bound the capacity region of the channel using, the max-flow min-cut (cutset) theorem and find achievable rate regions for the amplify and forward, decode and forward, and compress and forward protocols. Then, we aim at studying the capacity of AWGN channels assisted by multiple parallel relay channels. We are interested in two cooperation models involving point-to-point and multiple access (multiple transmitters and single receiver). We derive the capacities of AWGN channels for different relaying techniques. In addition, we study a reliable network wherein some relays perform decode and forward strategy and others relays as compress and forward. We show that the improvement of the overall data rate strongly depends on the combination of relay’ positions and relaying strategy. Also, we will show that a multiple parallel relayed communication achieves its maximum capacity by either only one relay or all relays together. Adding a new relay/transmitter does not necessarily expand outer capacity region, and can even degrade the capacity of the network