Date of Award

8-2013

Document Type

Dissertation

Degree Name

Doctor of Philosophy (PhD)

Legacy Department

Computer Engineering

Advisor

Russell, Harlan B

Committee Member

Noneaker , Daniel L

Committee Member

Wang , Kuang-Ching

Committee Member

Martin , Jim

Abstract

In this work, we consider a heterogeneous multichannel ad hoc network consisting of frequency-agile radios with the ability to change their carrier frequency and chip rate over a wide range of possibilities. The radios in this type of network are permitted to utilize multiple non-overlapping channels, and each channel differs significantly in its characteristics such as achievable data rate and communication range. A channel-access protocol regulates access to the channels available, and a routing protocol determines how a packet should be forwarded from its source to its destination through the network. The initial focus of this research is on channel-access and routing protocols that are designed to take advantage of the heterogeneous channels available to a network of frequency-agile radios.
We develop a new approach to channel access that accounts for the heterogeneous nature of the channels available to the network. For this protocol, we designate one channel as the control channel, and terminals communicate on this channel to reserve access for one of the remaining traffic channels. The determination of the traffic channel selected for the data packet transmission is based on the characteristics of the traffic channels available to the network. We compare the performance of this protocol with previously-developed channel-access protocols and show that our new protocol is able to adapt to a wide variety of scenarios without requiring the parameters of the routing protocol to be carefully tuned.
For our routing protocol, a channel metric is used to characterize the traffic channels available for the link between a pair of terminals. We develop a new channel metric that characterizes a channel based on its characteristics and the characteristics of the particular network. This channel metric is used to assign a link resistance value for a link, and these link resistances are utilized by the routing protocol to determine routes. Our new channel-access protocol is modified to employ this channel metric such that the selection of a traffic channel for a data packet transmission considers the current network conditions in addition to the characteristics of the available channels. Results show that our new jointly-designed channel-access and routing protocol provides good network-layer performance for various network scenarios when compared to combinations of previously-developed channel-access and routing protocols.
Lastly, we investigate the selection of backbone terminals for a hierarchical and heterogeneous multichannel ad hoc network. In this network, a subset of the terminals form a backbone network and communicate with one another on a reserved traffic channel employing schedule-based access. The remaining terminals associate with a backbone terminal and communicate on the remaining traffic channels employing contention-based access. We present a centralized algorithm that selects the terminals forming the backbone network. This algorithm demonstrates that network-layer performance is highly dependent on how many terminals are included in the backbone and the selection of the channel utilized for the backbone network.

Share

COinS