Study On Capacity And Transmission Strategy Of Interference Channels Based On Rate-Splitting

Two aspects are involved in increasing the capacity of network:one is to improvethe coverage of network as well as boost the data communication rate, and the other isto reduce the interference due to the high density of users. With the advent of MIMOtechnique, space-time code technique, opportunistic scheduling, modern channel coding(Turbo code, LDPC code and Rateless code) and relay cooperation technique, the frstproblem can be solved while aggravating the interference exiting in inter-cell, intra-cell andnetworks. Therefore, interference becomes the bottleneck of improving the property ofcommunication system. How to eliminate the impact of interference is the focus of wirelesscommunication research. This dissertation investigates the capacity and transmissionscheme of interference channel. The main results are summarized as follows:1) A novel algorithm for determination of decoding order for the Gaussian interferencechannel (GIC) is proposed based on max-min fairness. Based on the proposedalgorithm, an expression of the number of rate-splitting is derived for the sum-rate toapproach the maximum value. The proposed decoding order algorithm signifcantlyimproves the performance over the greedy algorithm on the two-user symmetricalGIC within a wide range of channel coefcients, and the sum-rate of the proposedscheme can approach the inner bound of Sason as increasing the interference factor.2) Based on the above decoding order algorithm, an optimal power allocation algo-rithm for two-user Gaussian symmetrical interference channel is proposed. In thissystem, each transmitter splits its information into multiple layers assigned withthe power which determined by optimal power allocation algorithm and transmitsthe superposition of those layers, and each receiver decodes the message from alllayers of the two users by the proposed decoding order algorithm. Combining thetwo algorithms can improve the sum-rate of the two-user interference channel with-out sacrifcing the rate of either user, and make a signifcant improvement of theperformance over that of equal power allocation. In the ideal case, the sum-rateeven approaches the inner bound of Sason.3) By analysing the performance of Han-Kobayashi (HK) strategy in multi-user sym-metric Gaussian cyclic interference channel, an adaptive odd-even symmetric rate-splitting scheme is proposed. With low complexity, the proposed scheme designsthe optimal split ratio and the rate-splitting’s scheme according to various channelconditions. In a large range of transmitted power and interference factor, the sum-rate achieved using the proposed scheme is higher than that using the symmetric scheme and the scheme proposed by Etkin et al. in high SNR and general SNRregimes. The sum-rate of the proposed scheme can also approach the inner boundof HK scheme in general SNR regimes.4) The HK strategy is further studied on cascade Gaussian Z interference channel byproposing a new inner bound and two new outer bounds of achievable rate. The newinner bound is proposed by adding some constraints on this channel. According tothe method proposed by Etkin et al, the new outer bounds are proposed by givingextra side information to the receivers. We show that a very simple and explicitHK type scheme can achieve to about a single bit per second per hertz (bit/s/Hz)of the capacity for all values of the channel parameters.