Signal Space Cooperative Communication - Essay Example

This is possible with the help of expanded constellation; also it enables the destination to combine the received signals in the broadcast phase and the relay phase. Later the performance of the SSC scheme is analysed and numerical results are obtained, with the help of that result two design criteria are derived so that it can achieve the maximum performance from the system. Spatial diversity techniques are used in order to increase system reliability; also it won’t affect the bandwidth or performance.

We use cooperative diversity as alternative to achieve special diversity, where antenna diversity become impractical due to size and power limitation of mobile devices. The concept of cooperation among users to provide diversity was introduced by Sendonaris, and then Laneman (Motahari, Ahmadzadeh & Khandani) derived the formulation for cooperative diversity based on two cooperative schemes, namely Amplify and Forward (AF), and Decode and Forward (DF). Signal space diversity was introduced by Belfiore and Boulle (Motahari, Ahmadzadeh & Khandani), which is achieved with the modulation signal space.

Here we spread information carried by each signal point across all components of that particular signal point. And then send each component through an independent channel. The performance of the cooperative schemes, which uses the signal space diversity, is affected by the performance of the source-relay channel. Meanwhile, a method called Signal Space Cooperative (SSC) scheme has been proposed to overcome this problem however, which is not easy to scale larger constellations. And also here we take an assumption, that the destination is aware of whether the relay participates in the cooperative scheme or not.

Signal Space Cooperative Scheme SSC scheme is the major proposal by this paper. To demonstrate SSC scheme, first we have to see the Constellation Expansion Algorithm that enables the relay to effectively cooperate during the course of transmission. Then, the broadcast phase and the relay phase signals are described followed by a discussion on how the destination decodes received signals. Constellation Expansion In order to achieve maximum diversity gain, any two signal points in the system constellation must have the maximum number of distinct components.

Let us consider