1 research outputs found
Scheduling and Codeword Length Optimization in Time Varying Wireless Networks
In this paper, a downlink scenario in which a single-antenna base station
communicates with K single antenna users, over a time-correlated fading
channel, is considered. It is assumed that channel state information is
perfectly known at each receiver, while the statistical characteristics of the
fading process and the fading gain at the beginning of each frame are known to
the transmitter. By evaluating the random coding error exponent of the
time-correlated fading channel, it is shown that there is an optimal codeword
length which maximizes the throughput. The throughput of the conventional
scheduling that transmits to the user with the maximum signal to noise ratio is
examined using both fixed length codewords and variable length codewords.
Although optimizing the codeword length improves the performance, it is shown
that using the conventional scheduling, the gap between the achievable
throughput and the maximum possible throughput of the system tends to infinity
as K goes to infinity. A simple scheduling that considers both the signal to
noise ratio and the channel time variation is proposed. It is shown that by
using this scheduling, the gap between the achievable throughput and the
maximum throughput of the system approaches zero