Abstract
Semantic communication (SemCom) is an emerging technology that extracts
useful meaning from data and sends only relevant semantic information. Thus, it
has the great potential to improve the spectrum efficiency of conventional
wireless systems with bit transmissions, especially in low signal-to-noise
ratio (SNR) and small bandwidth regions. However, the existing works have
mostly overlooked the constraints of mobile devices, which may not have
sufficient capabilities to implement resource-demanding semantic
encoder/decoder based on deep learning. To address this issue, we propose in
this paper a new semantic relay (SemRelay), which is equipped with a semantic
receiver to assist multiuser text transmissions. Specifically, the SemRelay
decodes semantic information from a base station and forwards it to the users
using conventional bit transmission, hence effectively improving text
transmission efficiency. To study the multiuser resource allocation, we
formulate an optimization problem to maximize the multiuser weighted sum-rate
by jointly designing the SemRelay transmit power allocation and system
bandwidth allocation. Although this problem is non-convex and hence challenging
to solve, we propose an efficient algorithm to obtain its high-quality
suboptimal solution by using the block coordinate descent method. Last,
numerical results show the effectiveness of the proposed algorithm as well as
superior performance of the proposed SemRelay over the conventional
decode-and-forward (DF) relay, especially in small bandwidth region.