Comments: This is my Ph.D. dissertation. The file is on hadar.
ContactPerson: hongyiwu@cse.buffalo.edu
Remote host: icar.cse.buffalo.edu
### Begin Citation ### Do not delete this line ###
%R 2002-08
%U PhDDissertation.pdf
%A Wu, Hongyi
%T iCAR : an Integrated Cellular and Ad hoc Relaying System
%D May 16, 2002
%I Department of Computer Science and Engineering, SUNY Buffalo
%K iCAR, cellular, ad hoc, wireless, mobile, network, integrated
%X The cellular concept was introduced for wireless communication to 
address the problem of having scarce frequency resource. It is 
based on the sub-division of geographical area to be covered by 
the network into a number of smaller areas called cells. Frequency 
reuse in the cells far away from each other increases system's 
capacity. But at the same time, the cell boundaries prevent the 
channel resource of a system to be fully available for users. No 
access to Data Channels (or DCHs) in other cell by the  
mobile host (or MH) limits the channel efficiency and 
consequently the system capacity.   
In this dissertation, we propose a new wireless system 
architecture based on the integration of cellular and modern ad 
hoc relaying technologies, called iCAR. It can efficiently balance 
traffic loads and share channel resource between cells by using 
Ad hoc relaying stations (ARSs) to relay traffic from one 
cell to another dynamically. This not only increases the system's 
capacity cost-effectively, but also reduces transmission power for 
mobile hosts and extends system coverage. We analyze the system 
performance in terms of the call blocking probability and queuing 
delay using multi-dimensional Markov chains for the new call 
requests and the call dropping probability for handoff requests, 
and verify the analytical results via simulations. Our results 
show that with a limited number of ARSs and some increase in the 
signaling overhead (as well as hardware complexity), the call 
blocking/dropping probability in a congested cell as well as the 
overall system can be reduced. We also propose a seed-growing 
approach for ARS placement, and discuss the upper bound on the 
number of seed ARSs needed in the system. In order to 
quantitatively evaluate ARS placement strategies, we introduce the 
concept of a new performance metric called quality of (ARS) 
coverage (QoC) for the comparison of various ARS placement 
strategies, and propose three rules of thumb as guidelines for 
cost-effective ARS placement in iCAR. Furthermore, we propose the 
signaling and routing protocols for establishing QoS guaranteed 
connections for IP traffic in iCAR. In particular, we discuss how 
a relaying route between a MH and a BTS in a nearby cell can be 
established via ARSs, and evaluate the performance of the 
protocols in terms of request rejection rate and signaling 
overhead through simulations. In addition, we propose a novel 
concept called ``managed mobility" and address the ARS mobility 
management in iCAR.