Abstract
Infrastructure-less (sometimes known as ad-hoc) networking paradigm is very appealing and potentially shaping its future into almost all emerging networks (i.e., IoT, wireless sensor networks, vehicular ad-hoc networks, emergency, and tactical radio networks, etc.). However, when conventional networking protocols are used, such networks often perform poorly, mainly because of interference within the network and limited network throughput. Recent advancements in wireless communications have enabled full-duplex (FD) operation by suppressing self-interference, which can theoretically double the network throughput. However, conventional medium access control (MAC) protocols like carrier-sense multiple access with collision avoidance (CSMA/CA) favor half-duplex (HD) operation and fail to benefit from FD transmission opportunities. This article proposes a novel hybrid MAC protocol for full-duplex ad-hoc networks. The proposed MAC combines time division multiple access (TDMA) and IEEE 802.11 distributed coordination function (DCF) strengths in chains of time-slotted contention-based control frames and collision-free data frames. The aim is to fully utilize FD transmission opportunities to increase network throughput. The proposed protocol modifies request-to-send (RTS) and clear-to-send (CTS) frames in IEEE 802.11 DCF MAC to form FD-RTS/CTS frames. These frames are used to enable collision-free FD communications among neighbors. The proposed scheme mitigates conventional MAC issues like hidden-node problem (HNP) and exposed-node problem (ENP). It also allows concurrent FD data transmissions in a collision-free manner. The model is generic and can be applied to any ad-hoc wireless network. In this article, the design is applied to a single channel ad-hoc network with FD transceivers. We compared the proposed design with IEEE 802.11 CSMA/CA protocol with both HD and FD transceivers. The simulation results show a 30% gain in throughput, reduced latency, and fairness among participating wireless nodes.
Highlights
The emerging requirement of pervasive wireless communications is resulting in the fast evolution of ad-hoc networks
This paper presents a novel collision-free full-duplex (CFFD) medium access control (MAC) protocol based on distributed coordination function (DCF)
We considered the same packet size in CFFD-MAC and carrier-sense multiple access with collision avoidance (CSMA/CA) (HD and FD transceivers); the change in packet size will have the same impact on throughput for all protocols
Summary
The emerging requirement of pervasive wireless communications is resulting in the fast evolution of ad-hoc networks. Most of the nodes use conventional half-duplex (HD) transceivers to either transmit or receive data These transceivers have fundamental design constraints and reduce potential network throughput. The physical carrier sensing based designs such as CSMA make the channel access dynamic and provide immediate data transmission but decrease the system throughput due to collisions and longer backoff periods [22]–[24]. The design distinctively blends TDMA with the IEEE 802.11 channel access mechanism with modest changes to incorporate full-duplex operation These changes include the segregation of contention-based control and reservation-based data slots. The proposed work is first to consider initial channel access collisions and enable opportunistic FD transmissions in non-contention based data slots in ad-hoc wireless networks. 4) Minimum number of collisions and helps to restrict the contention window to smaller values
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