1 research outputs found
Resource Allocation for Downlink Channel Transmission Based on Superposition Coding
We analyze the problem of transmitting information to multiple users over a
shared wireless channel. The problem of resource allocation (RA) for the users
with the knowledge of their channel state information has been treated
extensively in the literature where various approaches trading off the users'
throughput and fairness were proposed. The emphasis was mostly on the
time-sharing (TS) approach, where the resource allocated to the user is
equivalent to its time share of the channel access. In this work, we propose to
take advantage of the broadcast nature of the channel and we adopt
superposition coding (SC)-known to outperform TS in multiple users broadcasting
scenarios. In SC, users' messages are simultaneously transmitted by superposing
their codewords with different power fractions under a total power constraint.
The main challenge is to find a simple way to allocate these power fractions to
all users taking into account the fairness/throughput tradeoff. We present an
algorithm with this purpose and we apply it in the case of popular proportional
fairness (PF). The obtained results using SC are illustrated with various
numerical examples where, comparing to TS, a rate increase between 20% and 300%
is observed