Ph.D Thesis

Ph.D StudentKatz Michael
SubjectCooperative Strategies in Wireless Networks
DepartmentDepartment of Electrical and Computer Engineering
Supervisors PROF. Shlomo Shamai )Shitz(
PROF. Yossef Steinberg


In this thesis, we propose and analyze several cooperative strategies suited for a class of wireless networks called colocated networks. These networks, which are
characterized by having some of their terminals located in close proximity to each other, exhibit some interesting features which impact the design and analysis of
cooperative communication protocols.

The first part of the thesis addresses a network where a remote source sends information to a user, embedded within a cluster of K colocated users. For this network, a distributive cooperative transmission scheme based on decode-and-forward is proposed and analyzed, giving rise to substantial throughput gains. An interesting feature of this scheme is that the source need not coordinate its transmission with the cooperating users in any way, and need not be aware of how

many cooperating terminals there are.

The second part of the thesis considers a specialization of the previous setting for K=2. Several cooperative strategies are considered. First, an amplify-and-forward
protocol is examined. Next, various combinations of amplify-and-forward and decode-and-forward are looked at and their performance is shown to be upper
bounded by the performance of the best user. Finally, a cooperative approach is considered in which the relay quantizes its observation, relying on the destination's
side information. Since channel state information is known only to the respective receivers, a certain modification of the scheme is introduced in order for it to be
implemented in the current setting, achieving a dramatic gain over the previous strategies.

The third part of the thesis addresses the case where a source sends information to a remote destination and where another relay terminal is occasionally present in close proximity to the source, but without the source's knowledge. The focus is on cooperative schemes which make efficient use of the relay when it is present, and
still maintain single user optimality when the relay is absent. One such scheme, called Block Markov decode-and-forward, involves correlated transmissions of the source and the relay. A characterization of the optimal correlation for this scheme is found by solving the optimal outage performance of a 2X1 multiple-input single-output (MISO) link under certain constraints. Finally, cooperative schemes based on compression with various degrees of side information are proposed and analyzed for the considered setting.