| Summary: | Cooperative communication techniques have been proposed in order to improve the quality of the received signals at the receivers by using the diversity added by duplication of signals sent by relay terminals situated between each transmission pair. Researches related to cooperative communication can be categorized into two fields; Cooperative transmissions and Cooperative setup. The first research field concerns with cooperative transmission techniques in the physical layer while the second research field concerns with issues on inter-layer interaction between cooperative transmissions in the physical layer to protocols in the upper layers (especially the MAC layer and the network layer). These research topics have been separately concerned but, for implementations, they have to work together. Since there is not any existing common frame work to describe entire functions in cooperative communication, we proposed an original framework of cooperative network at the system level called “Cooperative Network Model”. The model does not reflect the protocol layering; thus, we can generalize the cooperation process and obtain an analysis that is available for many solutions. For validity, the proposed model can clearly illustrate and systematically describe existing cooperative setup protocols. In addition, the proposed cooperative network model facilitates us to find and to solve problems in cooperative designs; especially in cooperative setup, which is in charge on the initiation of the terminal’s role (i.e., a source, a relay, and a destination terminal). Thus, we believe that this model can facilitate the design and updating of existing and future propositions in this domain. The cooperative network protocol is used to design an adaptive cooperative transmission called Proxy Cooperative Transmission. In contrast to other adaptive cooperative transmission techniques, our proposition is compatible to both of the basic access mode and the optional access mode of IEEE 802.11 Medium Access Control (MAC) protocol. The transmission mode for each data frame is adaptively switched between a proxy cooperative mode and a non-cooperative mode based on the absence of acknowledge (ACK) frame. Simulation results show that transmission performance is improved by decreasing the number of re-transmissions due to frame errors; thus, chances of multi-hop mode transitions that are costly in time and bandwidth are alleviated. Then, in order to fulfill ProxyCoop communications in part of cooperative setup, we propose a cooperative setup method called “Proxy Cooperative Setup”. The proposition is based on a routing standard protocol for ad hoc networks, AODV, so that it could be easily deployed. The impacts of ProxyCoopSetup when it works with ProxyCoop transmissions have been studied. From simulation results, it shows that ProxyCoop transmissions with ProxyCoopSetup has similar performance to the ProxyCoop transmissions without ProxyCoopSetup. Finally, when the implementation of the proxy cooperative communication and how it can be integrated on existing networks have been considered, it is shown that the design of proxy cooperative communication is also valuable for the 802.11s WLAN Mesh Network environments.
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