The main thrust of this project is to develop directional routing in protocols with the objective of assessing their effects on suppressing interference from other nodes in MANET. These protocols were primarily developed using Dynamic Source Routing (DSR). Our solution is based on selecting a route that can reduce the co-channel interference amongst the neighboring relay nodes in a multihop link, hence mitigating interference from other transmitting nodes.
Directional Single-Path RoutingThe major obstacle in supporting real-time traffic for MANET is the long delay associated with frequent route changes due to the dynamically changing network topology. This includes latency in detecting a link loss, as well as the time needed to discover a new route. Multipath routing has been shown to be an effective approach in reducing the blocking capabilities for multimedia traffic.
In wireless ad-hoc networks, smart antenna techniques capable of providing spatial reuse, longer ranges, interference suppression and other beneficial features, have been investigated to improve achievable performance and system capacity. Most existing works focus on the design and development of MAC protocols and ignore the effect of co-channel interference along an active path from source to destination.
Based on the original DSR and AODV routing protocols, we consider a new metric, which is based on the number of overlaps between beams in the route discovery process in order to select the best route. As shown in Figure. 1, when directional antennas are employed, the transmit beam of A-to- E does not overlap the receive beam of D-to-F, which means that the transmission from node A to node E does not impact interference on node D. Obviously, the transmit beam of A-to- B overlaps the receive beam of C-to-D, meaning that the transmission from node A to node B interferes with node D. Hence, in this case, the route of A-to-E-to-F–to-D is better than that of A-to-B-to-C-to-D.
Figure 1. Comparison of Directional Antenna Routing with/without reducing interference.
In the route discovery process, overlap-count has been considered as an important metric in selecting the best route from source to the destination. The routing protocol is capable of reducing interference from neighboring nodes by selecting a route with minimal overlaps, as illustrated in Figure 2.
Figure 2. New route selection considering reducing interference using Directional Antenna, compared with conventional DSR routing protocol.
Directional Multi-Path Routing
The directionality of directional antennas has also been exploited for multipath routing, and is aimed at suppressing both inter-path and intra path interference.
Figure 3. In the case of multipath schemes, routes A→G→H→D and A→I→J→D cannot be simultaneously selected for transmitting packets because of the inter-path interference between them. Instead, routes A→E→F→D and A→G→H→D, or routes A→E→F→D and A→I→J→D can be used for simultaneous packet transmission.