Kai-Erik Sunell

Coded Bi-directional Relaying

In this paper, bi-directional traffic between two nodes communicating via a relay node is considered. A novel relaying method based on joint data packet encoding in conjunction with exploitation of a priori known information is presented. Moreover, a specially crafted method for combining of the direct and relayed radio signal is suggested. The proposed scheme enables a reduced number of transmissions, whereby enhancing aggregate throughput. Evaluation, where optimal power and rate settings are derived, shows that the proposed method enhances the throughput up to 33% as compared to a (traditional) four-phase bi-directional protocol under a system energy constraint, both with and without the proposed combining method

Impact of power control on interference diversity in FH-CDMA systems

In cellular systems, the objective of transmitter power control is to minimize the average outage probability, which is the probability that the carrier-to-interference ratio for a randomly chosen user is below some threshold. In this paper, we study the impact of power control on the interference diversity properties of error control coding in a frequency hopping system. The results show that algorithms with favourable outage performance in static channel allocation (without interference randomization) does not necessarily improve the system performance in terms of average code-word error probability. It is also found that changing the code parameters does not affect the choice of power control policy.