Multihop Wireless Networks: Opportunistic Routing

11.2 Future Research Directions

The frameworks proposed in Chapters 4 and 5, which compute the throughput bound and capacity of OR need to find all the feasible concurrent transmitter sets, which is a NP-complete problem. How to find, efficiently, a good subset of all the CTSs to approach the optimal solution within a controllable gap could be an interesting topic. Some heuristic algorithms similar to that in Tang et al. (2007), or a column generation technique (Zhang et al. 2005) may be adopted to serve this purpose.

In multiradio multichannel networks, it is interesting to investigate distributed algorithms to solve the channel assignment and candidate selection issues. As we discussed in Chapter 5, there is a tradeoff between spatial diversity and multiplexing when applying OR in multiradio multichannel networks. Designing an efficient algorithm that leads to near-optimal channel assignment and candidate selection is desirable.

Routing metrics with various performance objectives, such as maximizing throughput, minimizing delay, and maximizing energy efficiency, can be studied and the tradeoff between conflicting goals can be analyzed and considered for OR.

Another potential direction for research is to investigate further the error of link quality (PRR) estimation and its impact on the OR performance in different types of networks, and design protocols accordingly that are robust to estimation error. We plan to break down this task into three subtasks.

First, geographical routing ...