A Real-Time, Distributed, Directional TDMA MAC Protocol for QoS-Aware Communication in Multi-Hop Wireless Networks

Abstract

Time division multiple access (TDMA) based medium access control (MAC) schemes are widely used for communication among directional nodes since they can provide a conflict-free transmission schedule. However, the existing directional TDMA schemes introduce significant overhead and delay, and cannot adapt in real-time to topology changes in a directional multi-hop network. These schemes also incur considerable overhead and delay in order to support the QoS (quality of service) traffic. In this paper, a novel, real-time, distributed, directional TDMA scheme is presented for directional multi-hop wireless networks. This scheme adapts to the topology changes and/or flow requirements in real-time, and facilitates QoSaware communication with no notification overhead. In the proposed scheme, the 1-hop neighborhood of every node is divided into fully connected 1-hop neighborhoods, which allows the node to intelligently serve multiple routes without requiring a globally converged scheduling solution. This feature allows the use of a low-complexity rank-based mechanism to obtain a distributed, real-time transmission schedule for a directional multi-hop network. The following new features are also added in the proposed scheme: (i) REQ period which reduces slot wastage, (ii) throughput scaling which ensures fairness and helps in congestion management, and (iii) piggyback reservation period which increases the spatial reuse and adapts to the dynamic requirements of multiple flows in real-time. The control-period overhead in our scheme is low and linearly changes with the number of nodes in a fully connected 1-hop neighborhood, instead of the total number of nodes in the entire network. Simulation results and comparisons with other recent, distributed TDMA-based schemes show that our scheme provides a higher throughput with very low control overhead for both static and mobile network topologies. INDEX TERMS Directional communication, distributed medium access control (MAC), multi-hop network, mobile network, quality of service (QoS), time-division multiple access (TDMA).

An Asynchronous Multi-Beam MAC Protocol for Multi-Hop Wireless Networks

“…However, the TDMA based schemes introduce significant overhead and delay in computing a conflict-free transmission schedule in a multi-hop topology. Further, these schemes are not suitable for dynamic networks (such as an airborne network) because the current schedule would become outdated, and a new conflict-free schedule is required whenever the topology changes [18].…”

IRDB: Towards enjoying spatial, rate, and beam‐channel diversity in wireless networks for multimedia applications

“…4 Towards this goal, time division multiple access (TDMA) schedules interfering transmissions at different time slots, while non-interfering transmissions can be activated simultaneously. 5,6 Multi-radio technology and spatial diversity are other promising solutions to decrease the interference in wireless environments. [7][8][9] Transmissions on different non-overlapping channels do not interfere with each other.…”

“…The best direction of the available beam-channels for nodes 10, 18, and 20 at different data rates are shown in Figures 4 to 6, respectively. For example, in Figure 4A, DT (10,5,6) and DT (10,5,9) are configured in such a way that cover nodes 2, 8, 9, 14, and 15. However, they cover fewer nodes in other directions.…”

“…For more clarification, reconsider the directional transmissions shown in Figures 4 to 6. Let assume that transmissions DT (18,1,6), DT (18,1,9), DT (18,2,6), DT (18,2,9), DT (18,4,6), DT (20,1,6), DT (20,3,6), DT (20,3,9), and DT (20,4,6) are rejected in the call admission control mechanism. To select the best DT(x, k, 𝜌 i ), IRDB calculates the IRBS metric for all feasible directional transmissions according to Table 2.…”

“…Because it has no interference with DT(3, 5, 48) of tree T 1 . In the rest of process, IRDB adds DT (15,6,18) to tree T 2 and schedules it at time slots 25 to 48. This occurs because its transmitter, that is, node 15, is similar to the transmitter of DT (15,6,18).…”