Abstract

Adaptive modulation has been widely adopted in broadband wireless communication systems to improve spectrum efficiency. On the other hand, user cooperative diversity has been investigated to improve system coverage and efficiency. How to take the advantage of adaptive modulation for user cooperative transmissions to maximize network throughput under the constraint of the bit error rate (BER) requirement is an open issue. In this paper, a simple user-cooperation strategy with adaptive M-ary Quadrature Amplitude Modulation (M-QAM) is proposed to fill the gap. We use an approximate BER expression of M-QAM modulation to formulate an easy-to-solve optimization problem, so the modulation types for the source node and the relay node can be optimized in real time to maximize the throughput under the BER constraint. To maximize the throughput for the whole network, we further use a worst-link-first (WLF) matching algorithm for selecting appropriate cooperators. Numerical results show that the proposed adaptive cooperative protocol can effectively improve system spectral efficiency.

Talk to us

Join us for a 30 min session where you can share your feedback and ask us any queries you have

Schedule a call

Disclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.