Dissertation Proposal
By Chi-Tung Chen
Time: 2:00 PM, Friday, May 14, 2004
Place: 202 ECEC, New Jersey Institute of Technology (NJIT), Newark NJ. Directions

 Abstract

Mobile terminals (MTs) in wireless environments rely on their limited battery energy for proper operation. Power consumption is a critical design criterion in a wireless network model. In conventional cellular networks, MTs need to spend larger transmitted power to communicate with BSs when the positions of MTs are far from their own BSs. Moreover, provisioning of quality of service (QoS) for multimedia traffic in wireless networks is complicated due to user mobility and limited wireless resources. In the first part of the presentation, we propose QoS constrained minimum-power cellular ad hoc augmented network architecture (QCMP CAHAN) for next generation wireless networks. The QCMP CAHAN can find the optimal minimum-power routes under the QoS constraints. CAHAN has a hybrid architecture, in which each MT of CDMA cellular networks has CDMA ad hoc communication capability. We show that the total energy consumed by the MTs is lower in the case of CAHAN than in the case of pure cellular networks. As the ad hoc communication range of each MT increases, the total transmitted power in CAHAN decreases. However, the saving in the total transmitted power does not come free. Due to the increased number of hops involved in information delivery between the source and the destination, the end-to-end delay increases. The maximum end-to-end delay will be limited to a specified tolerable value, and CAHAN has ability to adapt to various delay constraints in different regions/intervals/services. An MT in CAHAN will not relay any messages when its ad hoc communication range is zero, and if this is the case for all MTs, then CAHAN reduces to the traditional cellular network, i.e. cellular networks are a special case of CAHAN.

In peer-to-peer communication, the messages need to be forwarded via relay MTs. Because of various transmission distances or unbalanced traffic load, some relay MTs may tend to drain their batteries faster than others. After a certain number of MTs deplete their battery energy, the network may become disconnected. Depletion of the battery energy of any relay MT will degrade the wireless network performance. The network lifetime is defined as the time at which an MT runs out of its battery energy for the first time within the entire network. Therefore, in the second part of the presentation, we will use the network lifetime as a performance criterion and propose QoS constraint network lifetime extension cellular ad hoc augmented network architecture (QCLE CAHAN) that is designed to achieve the maximum network lifetime under QoS constraints. We show that the network lifetime is higher in the case of QCLE CAHAN than in the case of pure cellular networks or QCMP CAHAN. In QCLE CAHAN, a novel QoS-constrained network lifetime extension routing algorithm will dynamically select suitable adhoc- switch-to-cellular points (ASCPs) according to the MT remaining battery energy such that the selection will balance all the MT battery energy and maximizes the network lifetime. As the number of ASCPs in an ad hoc subnet decreases, the network lifetime will be extended. Maximum network lifetime can be increased until the end-to-end QoS in QCLE CAHAN reaches its maximum tolerable value.

Committee Members:

Dr. Sirin Tekinay, Advisor, Associate Professor, NJIT

Dr. Cem Saraydar, Co-advisor, Adjunct Professor, NJIT

Dr. Nirwan Ansari, Professor, NJIT

Dr. Constantine N. Manikopoulos, Associate Professor, NJIT

Dr. Symeon Papavassiliou, Assistant Professor, NJIT

Dr. Andrej Stefanov, Assistant Professor, Polytechnic University.