# Design and Performance Analysis of an In-Band Full-Duplex MAC Protocol for Ad Hoc Networks
## 1 Introduction  
In this epoch of modern technology, people are connected to each other by means of wireless communications. It incorporates billions of nodes without any physical medium. Nowadays, a lot of research works have been conducted in this area of wireless communication. Based on the architecture, wireless network is categorized into two types, infrastructure-based network and infrastructure less network. This infrastructure less network is named as ad hoc networks. The wireless ad hoc network is an assembly of wireless nodes where all the nodes are connected with each other without a fixed infrastructure, such as the Access Point (AP) or Base Station (BS). All nodes in an ad hoc network consist of transceivers and they also all act as routers; thus, every node in the network spontaneously forms their own network without the help of a fixed infrastructure. The ad hoc network is more economical, simple to establish and terminates in contrast to other networks; however, it is power consuming [1]. Moreover, ad hoc networks have a non-hierarchical distributed control, for which these nodes can be connected easily and can communicate quickly. In conventional Full Duplex (FD) communications, the transmitter and receiver can transmit and receive simultaneously by using either time splitting or frequency splitting, but without time and frequency splitting, the transceiver cannot transmit and receive simultaneously due to the self-interference in the receiver end [2]. In recent years, a substantial number of studies have been conducted to mitigate self-interference. A study is performed on self-interference suppression by using an adaptive filter called Analog LeastMean Square (ALMS) loop [3]. A noise cancellation chip is used to cancel noise as the echo signal suppression in the telecommunication system. However, this chip cannot suppress the self-interference completely. In [4], the digital self-interference cancellation technique is used to reduce the residue self-interference. Another research diminishes the self-interference by almost 120 dB [5]. These self-interference cancellation mechanisms enable a node to transmit and receive simultaneously using the same frequency. This communication technique is named as the In-band Full-duplex (IBFD) wireless communications. With the self-interference cancellation in the physical layer, an efficient Medium Access Control (MAC) protocol is mandatory in the datalink layer in IBFD communications. As the existing IEEE standard cannot support IBFD communications, an efficient MAC protocol is necessary to utilize the FD benefit efficiently. As the data traffic will be huge in the near future, it is crucial to develop a technique that will provide high throughput. The IBFD communications has the capability to increase the throughput up to twice theoretically compared with conventional FD [6]. Therefore, this IBFD communication technique has the capability to alleviate the huge data traffic problem in the near future. Moreover, it increases the spectral efficiency and ergodic capacity as well as reduces feedback delay and end to end delay [6]. The IBFD communication is classified as Bidirectional Full Duplex (BFD) and Three Node Full Duplex (TNFD) [7]. In this case, a FD capable node transmits data to one node while receiving data from another node. In the BFD transmission, two Full Duplex Nodes (FDNs) transmit and receive data simultaneously, as shown in Figure 1a. Here, node 1 and node 2 transmit and receive data simultaneously to/from each other. In Figure 1a, node 1 acts as a Primary Transmitter (PT), since it initiates the transmission and node 2 is the Primary Receiver (PR), since it is the receiver of the primary transmission. On the other hand, node 2 acts as the Secondary Transmitter (ST) and node 1 acts as the Secondary Receiver (SR). The TNFD transmission can be categorized as the Destination-Based TNFD (DTNFD) and Source-Based TNFD (STNFD). In DTNFD, node 4 (PT) transmits data to node 3 (PR) and node 3 transmits data to node 5 (SR) (Figure 1b).