Rana Diab

Overview on Multi-Channel Communications in Wireless Sensor Networks

In this paper, we focus on multi-channel MAC protocols specifically designed for Wireless Sensor Networks (WSNs). The use of multiple channels helps overcome interferences and thus enhance the overall network performance. In order to establish channel and slot allocation to enable simultaneous transmissions, many protocols have been proposed in the literature. Some of them are based on a TDMA approach which offers a more deterministic behavior but requires a strict synchronization, while others are based on CSMA/CA which is an asynchronous medium access algorithm that suffers from collisions due to its probabilistic behavior. Different classifications have been proposed in previous survey papers depending on the periodicity of channel switching, on whether they are centralized or distributed, synchronized or asynchronous, etc. In this paper, we present a survey of the different techniques used in WSNs and that are applicable on the IEEE 802.15.4 standard. We detail some of the most popular protocols and discuss their advantages and weaknesses. We conclude the paper with an open discussion concerning future research directions.

Hybrid Multi-Channel MAC Protocol for Wireless Sensor Networks: Interference Rate Evaluation

This paper evaluates a channel allocation algorithm of a Hybrid Multi-Channel MAC protocol, HMC-MAC, that tries to improve communication performance in Wireless Sensor Networks (WSNs). We also analyze different techniques that are used in multi-channel MAC protocols proposed for WSNs. These protocols often use either a schedule-based or a contention based MAC protocol to communicate with each others. HMC-MAC takes advantage of the synchronous activity of TDMA to achieve collision free communications, of the flexibility offered by CSMA/CA to offer a scalable network, and of the parallel transmissions over different channels provided by FDMA to enhance the overall throughput. HMC-MAC assumes that sensor nodes are equipped with one half-duplex radio interface. We define a new method for channel allocation that enables nodes to choose the most convenient channel in its three-hop neighborhood in order to minimize interference as much possible. Simulation results demonstrate that HMC-MAC provides smaller interference rate and outperforms other mechanisms.

Channel allocation evaluation for a multi-channel MAC protocol

In recent years, the use of multi-channel MAC protocols in the Wireless Sensor Networks has attracted the attention of many researchers. In this paper, we analyze the different techniques that are used in multi-channel MAC protocols proposed for WSNs. These protocols often use either a centralized or a distributed manner to select and allocate channels. We present HMC-MAC, a Hybrid Multi-Channel MAC protocol that takes advantage of the synchronous activity of TDMA to achieve collision free communications, of the flexibility offered by CSMA/CA to offer a scalable network, and of the parallel transmissions over different channels provided by FDMA to enhance the overall throughput. It is based on a decentralized method for channel allocation that enables nodes to choose the most convenient channel in its 3-hop neighborhood. The method used to evaluate this channel allocation scheme is based on the number of conflicts generated by the use of the same channel in a three-hop neighborhood. We present simulation results using NS-2 that show the efficiency of the proposed channel allocation method.

Enhanced multi-channel MAC protocol for multi-hop wireless sensor networks

In this paper, we address the challenge of achieving high throughput with limited number of channels in a wireless sensor network (WSN). The use of multiple channels helps overcome, on one hand, interference generated from inner network activity, and on the other hand, interference caused by neighboring systems operating in the same frequency band. We propose a multi-channel MAC protocol with multi-interface nodes for WSNs. In our proposition, we enhance the channel allocation method of HMC-MAC in order to take into account a multi-interface sink and network segmentation into two groups of nodes. We evaluate our protocol using NS2 simulator with different number of available channels in order to emulate a limited number of interference-free channels. Results show that our MAC protocol improves the overall network performance compared to other protocols with limited number of channels and high data rate traffic.

Evaluation of a hybrid multi-channel MAC protocol for periodic and burst traffic

The use of multiple channels in wireless sensor networks helps avoid interference and increases the overall network throughput. In addition, introducing multi-interface nodes further helps in increasing the packet delivery rate for those specific nodes. In this paper, we propose a channel allocation method that takes into consideration the existence of multi-interface nodes in a multi-hop wireless sensor network. It is based on HMC-MAC, a hybrid MAC protocol that uses CSMA/CA, for data exchange, TDMA sequencing nodes activity and FDMA for allowing simultaneous collision free exchange. We evaluated our method using NS2 simulator and results show that our MAC protocol improves the overall network performance compared to other protocols with periodic high data rate traffic and burst traffic.