# ABORt: Acknowledgement-Based Opportunistic Routing Protocol for High Data Rate Multichannel WSNs
## 2 Related Work  
In [11], the authors propose a Multi-Channel Real-Time (MCRT) joint MAC and routing protocol designed for real-time communications in multichannel WSNs. It organizes the network into different partitions based on data flows such that interference among different flows can be minimized. The routing approach is based on the packet delay between the node and its upstream neighbors combined with the node transmission power. Simulation results using the Network Simulator (NS-2) show that MCRT is able to achieve better end-to-end delays and energy consumption compared to three other protocols. However, MCRT is not tested in a congested network, in the evaluation, traffic is generated by only 10% of nodes in the network generating only one packet every 4 s.  
Authors of [12; 13] propose a Distributed Routing and Channel Selection scheme (DRCS) for multichannel WSNs. DRCS is a joint channel assignment and quality aware routing protocol for multichannel WSNs that aims at improving network lifetime. Channel assignment and next hop neighbor selection are based on the remaining battery level and the link quality of the next hop neighbors evaluated based on the expected transmission count (ETX). DRCS performance evaluation shows that the proposed approach reduces energy consumption by avoiding overhearing and thus improves the network lifetime. However, DRCS was evaluated under low traffic rate (0.4 packets per second) as well. In [14], a tree-based multichannel protocol (TMCP) is proposed. TMCP divides in a static manner the whole network in several sub-trees where a common communication channel is allocated to each sub-tree. The idea followed by sub-trees creation is to put the same number of nodes in different sub-trees. The routing approach is tree-based and nodes have to choose one parent that brings less interference among all its potential parents. The approach proposed by TMCP reduces inter-tree interference, but the intra-tree interference problem remains unsolved. In [15], the authors propose a Hybrid Multi-Channel MAC protocol (HMC-MAC) with a tree-based routing approach. The routing approach follows a tree where each node chooses a parent among its potential next hop neighbors. Simulation results using the NS-2 simulator show that, compared to the Carrier-Sense Multiple Access with Collision Avoidance (CSMA/CA) and 2-hop channel assignment, HMC-MAC improves the network throughput and reduces the number of dropped packets due to a medium access problem. HMC-MAC suffers from high end-to-end delay due to the synchronization phase and high number of packets lost due to queue overflow at nodes close to the sink. In [16], authors propose a Multi-Channel Collection (MCC) protocol that aims at optimizing data collection in multichannel WSNs. MCC is a time-scheduled protocol with globally synchronized Time-Division Multiple Access (TDMA) scheduling. Through experiments with Tmote Sky nodes, MCC shows that the network throughput can be improved by mixing channel allocation, routing approach and time scheduling. MCC increases the overall network throughput but requires a precise time synchronization, which is hard to obtain in large scale WSNs. The authors of [17] propose a Joint Routing and Channel Assignment (JRCA) scheme for wireless mesh networks. JRCA aims at improving the quality of the communication in multi-radio multi-gateway wireless mesh networks. The routing approach is based on the multi-hop route quality in terms of end-to-end probability of success and the delay experienced by packets. Performance evaluation using NS-2 simulator shows that JRCA improves network throughput, delivery ratio and end-to-end delay compared to a single channel protocol and some existing multichannel protocols. JRCA is proposed for wireless mesh networks, and applying it in WSNs needs adaptations and modifications due to the limited capacities of sensor nodes (such as queue length of 200 packets with a packet size of 1000 bytes, in addition to throughput and channel access differences).