Studies on Trade-off Between Throughput and Reliability in Wireless Systems

Diversity-multiplexing;time-varying channel;Electrical and Computer Engineering

Ansari Sadrabadi, Mehdi

University of Waterloo

关键词: Diversity-multiplexing;    time-varying channel;    Electrical and Computer Engineering;   

Others  :  https://uwspace.uwaterloo.ca/bitstream/10012/3450/1/main.pdf

瑞士|英语

来源: UWSPACE Waterloo Institutional Repository

【 摘 要 】

In the first part of the thesis, we study the trade-off between the transmission reliability and datarate in high signal-to-noise ratio regime in ad-hoc wirelessnetworks. Bandwidth allocation plays a significant role in thistrade-off, since dividing bandwidth reduces the number of users oneach band and consequently decreases the interference level, howeverit also decreases the data rate. Noting that the interference poweris substantially influenced by the network density, this trade-offintroduces a measure for appropriate bandwidth allocation amongusers considering the network density. The diversity-multiplexing trade-offis derived for a one-dimensionalregular ad-hocnetwork.In the second part of the thesis, we study the performance of point-to-point and broadcast systems with partial channel state information at the transmitter in a time-varying environment. First, the capacity of time-varying channels withperiodic feedback at the transmitter is evaluated. It is assumed that thechannel state information is perfectly known at the receiverand is fed back to the transmitter at the regular time-intervals. The system capacity is investigated in two cases: i) finite state Markov channel, andii) additive white Gaussian noise channel with time-correlated fading. In amultiuser scenario, we consider a downlink system in which a single-antenna basestation communicates with single antenna users, over atime-correlated fading channel.It is assumed thatchannel state information is perfectly known at each receiver, whilethe rate of channel variations and the fadinggain at the beginning of each frame are known to the transmitter.The asymptotic throughput of thescheduling that transmits to the user with the maximum signal tonoise ratio is examined applying variable code rate and/or variablecodeword length signaling. It is shown that by selecting a fixed codeword length for all users, the order of the maximum possible throughput (corresponding to quasi-static fading) is achieved.