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P-TDMA-SYS: A TDMA System over Commodity 802.11 Hardware for Mobile Ad-Hoc Networks

Zechen Lin, Zhizhong Ding, Qingxin Hu, and Shuai Tao
School of Computer and Information, Hefei University of Technology, Hefei, 230009, China

Abstract—In some scenarios such as catastrophes and military operations, there is a need for communication without an infrastructure. In urgent cases, in-time and reliable channel access must be ensured. However, the channel access delay in widely used CSMA/CA (Carrier Sense Multiple Access with Collision Avoidance) network increases unpredictably when the channel is sensed busy. Therefore, TDMA (Time Division Multiple Access) gets more and more attention in mobile ad-hoc network research. This paper presents a TDMA network system (named as P-TDMA-SYS) that is designed to support real-time applications in mobile ad-hoc networks (MANETs) and successfully works on commodity 802.11 hardware. The key feature of P-TDMA-SYS is its microsecond synchronization and adaptive medium access policy. P-TDMA-SYS’s implementation contains two major modules. One is the P-KER-MAC, a TDMA-based MAC protocol, running over commodity 802.11 hardware. The other is P-TCP, a cross-layer TCP congestion control algorithm specifically for P-KER-MAC. The presented TDMA-based MAC over commodity 802.11 hardware has been tested with a detailed accounting of the hardware and operation system overheads. Furthermore, P-TDMA-SYS has been compared with 802.11 CSMA/CA-based network in the single-hop/multi-hop scenarios. The test results show that our implementation achieves reliable throughput and low delay/jitter for supporting real-time applications.

Index Terms—TDMA MAC, ad-hoc networks, IEEE 802.11

Cite: Zechen Lin, Zhizhong Ding, Qingxin Hu, and Shuai Tao, “P-TDMA-SYS: A TDMA System over Commodity 802.11 Hardware for Mobile Ad-Hoc Networks," Journal of Communications, vol. 11, no. 8, pp. 710-725, 2016. Doi: 10.12720/jcm.11.8.710-725