Wireless Collaboration

To achieve performance gains in the wireless channel, spatial diversity is employed. These higher order transmit diversity gains generally require multiple transmit antennas at the source. This requirement is not always possible in real world applications, where practical concerns limit the number of antennas a wireless device can have. Recently, a new method to achieve transmit diversity has been proposed: collaborative communications. In this framework, a node in a wireless network can use the resources of other idle nodes and form what can be viewed as a virtual transmitting antenna array. This chapter presents an overview of the development of collaborative communications. Two-phase protocols that can achieve collaboration are presented. A discussion on the improvement of collaborative communications protocols is given. A broader perspective of collaborative communications is given by discussing ideas such as power allocation and multiple relays.