A cooperative TDMA MAC protocol using dynamic slot assignment scheme

In this paper, we propose and analyze a cooperative TDMA MAC protocol with dynamic slot assignment. Our protocol allows a source node to retransmit failed packet cooperatively during a neighbor node´s idle slot. The source node can select idle slots for a cooperative retransmission by a simple control packet exchange among neighbor nodes. The neighbor nodes that have the failed packet transmit during the selected slot at the same time. If there are no idle slots available, the cooperative retransmission is attempted during the source node´s time slot. The throughput of TDMA can be significantly improved by the proposed cooperative retransmission scheme at the expense of increased overhead. We formulate an analytic model for the proposed protocol for implementation over Rayleigh fading channels and validate it by simulation. The results show that the throughput of TDMA systems is improved significantly if there are a sufficient number of idle slots available for cooperative retransmission, even though overhead is introduced.