Broadcast Systems: Alamouti Index Coding
Date
2017
Authors
Journal Title
Journal ISSN
Volume Title
Publisher
Tartu Ülikool
Abstract
Consider a wireless broadcast channel with a number of receivers, where each receiver possesses
some side information. In an index coding problem, the transmitter aims at delivering
different messages to different receivers. It is desirable to minimize the total number of message
transmissions in order to improve the bandwidth efficiency. It is known that the minimum
number of transmissions can be achieved by solving a minimum rank problem for a given side
information graph, which is a known NP-hard problem.
In this thesis, the index coding problem over additive white Gaussian noise and Rayleigh fading
channels is studied. Modulation techniques, such as phase shift keying and quadrature amplitude
modulation, are tested, and it is shown that a careful choice of modulation can improve the
performance.
It is also shown that a careful choice of a generator matrix can provide for further performance
gains, in particular for ”prioritized” receivers. A probabilistic soft information detection (PSID)
is compared to a simple hard decision scheme, and the PSID performance is shown superior in
achieving a lower error rate. Additional improvement in performance is achieved by using diversity,
when employing two transmit and two receive antenna system in conjunction with the
Alamouti code. All these techniques provide for the lower error rates and higher throughput
when compared to the traditional schemes.
Description
Keywords
Index coding, bit error rate, Alamouti STBC, soft information, modulation, indeks-kodeerimine, bitiveategur, Alamouti ruumilis-ajaline plokk-kood, pehme teave, modulatsioon