Joint routing and channel assignment in multi-channel wireless infrastructure networks

Abstract

Multi-channel wireless networks are increasingly being employed as infrastructure networks in metro areas. In addition, nodes in these networks employ directional antennas to improve spatial throughput. In such networks, given a source and destination, it is of interest to compute a path and channel assignment on every link in the path such that the path bandwidth is the same as that of the link bandwidth. Such a path must satisfy the constraint that no two consecutive links on the path are assigned the same channel, referred to as "channel discontinuity constraint."In this paper, we develop two graph expansion techniques to compute the minimum cost path between a given node pair that satisfy the channel discontinuity constraint. The first expansion provides the exact solution in polynomial time using minimum cost perfect matching algorithm. The second expansion results in a lesser complexity algorithm compared to the former and is amenable to distributed implementation, while it may result in infeasible paths at times. Through extensive simulations, we study the effectiveness of the routing algorithms developed based on the two expansion techniques and the benefits of employing the minimum cost perfect matching based solution. We show that the lesser complexity algorithm may not be able to compute a path for less than 2% of the calls in the networks considered.

Benefits of inter-flow bandwidth sharing in broadband wireless infrastructure networks

“…We refer to such a path as Channel Discontinuity Constrained (CDC) path. In our earlier work [3], we develop a polynomial time algorithm for computing the minimum-cost CDC-path between a given source-destination pair by transforming the given problem to the minimum-cost perfect matching problem.…”

“…Therefore, computing a path with bandwidth of B/2 is equivalent of computing a CDC-path in the graph G(N , L, 2C, B/2). We employ the approach developed in [3] to compute the CDCpath for a connection. Due to space constraints, we do not provide details of the graph expansion and refer the readers to [3].…”

“…The problem of computing an MCD-path is similar to computing path with minimum number of wavelength conversions in optical networks, hence graph expansion algorithms for computing such a path and wavelength assignment may be employed[4] 3. The value m is always assumed to include the source and destination, hence m ≥ 2.…”

On channel-discontinuity-constraint routing in wireless networks

“…At any given time, multiple flows may be present in the network. Based on this, the interference constraints in wireless networks may be divided into two categories [6]: inter-flow and intra-flow . The inter-flow interference refers to the scenario where two links belonging to two different flows cannot be active (on the same channel) at the same time as one receiver will experience interference due to the other transmission.…”

“…al. [6]. In such networks, the interference may be limited to primary interference between adjacent links (those that share an endpoint).…”