A novel channel-adaptive uplink access control protocol for nomadic computing

We consider the uplink access control problem in a mobile nomadic computing system, which is based on a cellular phone network in that a user can use the mobile device to transmit voice or file data. This resource management problem is important because an efficient solution to uplink access control is critical for supporting a large user population with a reasonable level of quality of service (QoS). While there are a number of recently proposed protocols for uplink access control, these protocols possess a common drawback in that they do not adapt well to the burst error properties, which are inevitable in using wireless communication channels. In this paper, we propose a novel TDMA-based uplink access protocol, which employs a channel state dependent allocation strategy. Our protocol is motivated by two observations: 1) when channel state is bad, the throughput is low due to the large amount of FEC (forward error correction) or excessive ARQ (automatic repeated request) that is needed and 2) because of item 1, much of the mobile device's energy is wasted. The proposed protocol works closely with the underlying physical layer in that, through observing the channel state information (CSI) of each mobile device, the MAC protocol first segregates a set of users with good CSI from requests gathered in the request contention phase of an uplink frame. The protocol then judiciously allocates channel bandwidth to contending users based on their channel conditions. Simulation results indicate that the proposed protocol considerably outperforms five state-of-the-art protocols in terms of packet loss, delay, and throughput.published_or_final_versio

A quantitative comparison of multiple access control protocols for integrated voice and data services in a cellular wireless network

The multiple access control (MAC) problem in a tireless network has intrigued researchers for years. An effective MAC protocol is very much desired because efficient allocation of channel bandwidth is imperative in accommodating a large user population with satisfactory quality of service. MAC protocols for integrated data and voice services in a cellular wireless network are even more intricate to design due to the dynamic user population size and traffic demands. Considerable research efforts expended in tackling the problem have resulted in a myriad of MAC protocols. While each protocol is individually shown to be effective by the respective designers, it is unclear how these different protocols compare against each other on a unified basis. In this paper, we quantitatively compare six recently proposed TDMA-based MAC protocols for integrated wireless data and voice services. We first propose a taxonomy of TDMA-based protocols, from which we carefully select six protocols, namely CHARISMA, D-TDMA/VR, D-TDMA/FR, DRMA, RAMA, and RMAV, such that they are devised based on rather orthogonal design philosophies. The objective of our comparison is to highlight the merits and demerits of different protocol designs.published_or_final_versio

On the synergy between adaptive physical layer and multiple-access control for integrated voice and data services in a cellular wireless network

In this paper, we propose a novel design to exploit the synergy between the multiple-access control (MAC) layer and the physical layer of a cellular wireless system with integrated voice and data services. As in a traditional design, the physical layer (channel encoder and modulator) is responsible for providing error protection for transmitting the packets over the hostile radio channel, while the MAC layer is responsible for allocating the precious bandwidth to the contending users for voice or data connections. However, a distinctive feature of our proposed design is that in the physical layer, a variable-rate adaptive channel encoder is employed to dynamically adjust the amount of forward error correction according to the time-varying wireless channel state such that the MAC layer, which is a reservation-based time-division multiple-access protocol, is able to make informed decisions as to bandwidth allocation. Specifically, based on the channel state information provided by the physical layer, the MAC protocol gives higher priority to users with better channel states. This novel synergistic mechanism between the two protocol layers can utilize the system bandwidth more effectively. The multiple-access performance of the proposed scheme is compared with two baseline systems. The first baseline system consists of the same reservation-based MAC protocol but with a traditional fixed-rate physical layer. The second system consists of the same reservation-based MAC protocol and the same channel adaptive physical layer, but without interaction between the two layers. All three protocols have a request queue, which stores the previous requests that survive the contention but are not allocated information slots. Our extensive simulation results demonstrate that significant performance gains are achieved through the exploitation of the synergy between the two protocol layers.published_or_final_versio

Joint design of adaptive channel coding and multiple access control for integrated voice and data services in a cellular wireless network - with contention queue

A new MAC protocol employing a joint design of the multiple access control (MAC) layer and the physical layer is proposed for cellular wireless systems with integrated voice and data services. This is a novel concept and is shown to achieve very significant gains (in capacity, packet loss and delay) compared to existing protocols through the exploitation of the synergy between the two protocol layers.published_or_final_versio

Performance analysis of CAR: Centralized adaptive reservation

A centralized adaptive reservation (CAR) protocol has been proposed in [1] for supporting constant bit rate (CBR), variable bit rate (VBR) and unspecified bit rate (UBR) services in a starconfigured network. This protocol has two main features. First, both the access probability and the bandwidth for reservation requests are varied dynamically to enhance efficiency. Second, by using a request-mini-slot method, UBR traffic can only utilize the residual bandwidth of the other traffic. In this paper, we derive a Markov chain model for analyzing the performance of the CAR protocol by means of a bi-state traffic source. The focus is to analyze the performance of the VBR stations when both the access probability and the bandwidth for reservation requests are changed dynamically.published_or_final_versio

Mobility management in wireless cellular systems.

by Wing Ho Andy Yuen.Thesis (M.Phil.)--Chinese University of Hong Kong, 1997.Includes bibliographical references (leaves 85-[90]).Chapter 1 --- Introduction --- p.1Chapter 1.1 --- Design Issues in Wireless Cellular Systems --- p.1Chapter 1.1.1 --- Channel Assignment --- p.2Chapter 1.1.2 --- Handoff --- p.3Chapter 1.1.3 --- Multiple Accesses --- p.3Chapter 1.1.4 --- Mobility Management --- p.4Chapter 1.2 --- Motivation of the thesis --- p.5Chapter 1.3 --- Outline of the thesis --- p.6Chapter 2 --- Background Studies --- p.9Chapter 2.1 --- Current Standards --- p.9Chapter 2.2 --- Mobility Models --- p.11Chapter 2.2.1 --- Fluid Flow Model --- p.12Chapter 2.2.2 --- Markovian model --- p.13Chapter 2.3 --- Dynamic versus Static Location Strategy --- p.14Chapter 2.4 --- Location Registration Strategies --- p.14Chapter 2.4.1 --- Time Based Strategy --- p.15Chapter 2.4.2 --- Geographic Based Strategy --- p.17Chapter 2.4.3 --- Distance Based Strategy --- p.18Chapter 2.4.4 --- Miscellaneous Strategies --- p.19Chapter 2.5 --- Summary --- p.20Chapter 3 --- Hybrid Bloom Filter Location Update Algorithm --- p.21Chapter 3.1 --- Introduction --- p.21Chapter 3.2 --- System Model --- p.22Chapter 3.3 --- Hybrid Bloom Filter Algorithm --- p.23Chapter 3.3.1 --- Location Update Protocol --- p.23Chapter 3.3.2 --- Paging Protocol --- p.25Chapter 3.4 --- Performance Evaluation --- p.27Chapter 3.4.1 --- Comparison of the hybrid and time based Bloom filter algorithms --- p.32Chapter 3.5 --- Numerical Studies --- p.33Chapter 3.5.1 --- Cost versus mobility --- p.34Chapter 3.5.2 --- Cost versus call arrival rate --- p.37Chapter 3.6 --- Summary --- p.39Chapter 4 --- A Dynamic Location Area Assignment Algorithm --- p.40Chapter 4.1 --- Geographic versus Distance Based Strategies --- p.41Chapter 4.2 --- System Model --- p.42Chapter 4.2.1 --- cell layout --- p.42Chapter 4.2.2 --- mobility model --- p.43Chapter 4.2.3 --- cost function --- p.44Chapter 4.3 --- Dynamic Location Area Assignment Algorithm --- p.45Chapter 4.3.1 --- Measurement --- p.46Chapter 4.3.2 --- "Computation of (iopt, jopt)" --- p.46Chapter 4.3.3 --- Computation of location area size k --- p.51Chapter 4.4 --- Numerical Studies --- p.52Chapter 4.5 --- Summary --- p.57Chapter 5 --- Paging Cost Reduction Using Bloom Filtering As Auxilliary Strategy --- p.64Chapter 5.1 --- Introduction --- p.64Chapter 5.2 --- A Case Study - Joint DLA-HBF Algorithm --- p.65Chapter 5.2.1 --- The Algorithm --- p.65Chapter 5.2.2 --- Performance Evaluation --- p.67Chapter 5.3 --- Summary --- p.68Chapter 6 --- Conclusion --- p.70Chapter 6.1 --- Summary of Results --- p.70Chapter 6.2 --- Future Research Directions --- p.71Appendix --- p.73Chapter A --- Optimality of the Hybrid Bloom Filter Algorithm --- p.73Chapter B --- Derivation of the Expected First Passage Time ExTi and EyTj --- p.77Chapter C --- Optimality of the Dynamic Location Area Algorithm --- p.81Bibliography --- p.8

Managing terminals mobility for personal communication systems.

by Lee Ying Kit.Thesis (M.Phil.)--Chinese University of Hong Kong, 1996.Includes bibliographical references (leaves 79-[83]).Chapter 1 --- Introduction --- p.1Chapter 1.1 --- Overview of Personal Communication Systems --- p.1Chapter 1.2 --- Design issues on PCS --- p.2Chapter 1.2.1 --- Channel allocation --- p.2Chapter 1.2.2 --- Multiple Access --- p.3Chapter 1.2.3 --- Handoffs --- p.4Chapter 1.2.4 --- Location management --- p.6Chapter 1.3 --- Motivation of this thesis --- p.9Chapter 1.4 --- The theme of this thesis --- p.10Chapter 1.4.1 --- Methodology --- p.10Chapter 1.4.2 --- The system model and assumptions --- p.12Chapter 1.4.3 --- Outline of the thesis --- p.13Chapter 2 --- Overview of the traditional location update schemes --- p.15Chapter 2.1 --- Why do we need location registration? --- p.15Chapter 2.2 --- Location registration by Geographic and Time based methods --- p.16Chapter 2.2.1 --- Geographic Based Registration Schemes --- p.16Chapter 2.2.2 --- Time Based Registration Scheme --- p.20Chapter 2.3 --- Peformance Analysis of protocols --- p.20Chapter 2.3.1 --- Analytical Results --- p.22Chapter 2.3.2 --- A Numerical Study --- p.23Chapter 2.4 --- Summary of the results for time and geographic based location update protocol --- p.24Chapter 3 --- The Implementation of Bloom filter on location registration --- p.27Chapter 3.1 --- Introduction --- p.27Chapter 3.2 --- The Implementation of Bloom filter on location registration --- p.29Chapter 3.2.1 --- Location Update by Bloom filter --- p.29Chapter 3.2.2 --- Paging algorithm --- p.29Chapter 3.2.3 --- An example --- p.30Chapter 3.3 --- Performance evaluation of the Bloom filter based location update scheme --- p.32Chapter 3.4 --- Summary of the results for Bloom filter based scheme --- p.35Chapter 4 --- One-Bit-Reply protocol --- p.36Chapter 4.1 --- Introduction --- p.36Chapter 4.2 --- One-Bit-Reply protocol --- p.37Chapter 4.2.1 --- Grouping of MU's --- p.38Chapter 4.2.2 --- The Update Procedure --- p.39Chapter 4.2.3 --- Paging algorithm --- p.40Chapter 4.3 --- Performance evaluation of the OBR protocol --- p.42Chapter 4.3.1 --- Analytical Results --- p.42Chapter 4.3.2 --- A Simulation Study --- p.43Chapter 4.4 --- Comparison of the location registration schemes - A numerical study --- p.45Chapter 4.5 --- Summary --- p.46Chapter 5 --- A case study - Implementing the OBR protocol on GSM sytems --- p.49Chapter 5.1 --- Introduction --- p.49Chapter 5.2 --- The Architecture of Global System for Mobile Communicaitons (GSM) --- p.50Chapter 5.3 --- Location Update Procedure of GSM --- p.51Chapter 5.4 --- Implementing OBR protocol on GSM --- p.52Chapter 5.5 --- Influence of the OBR on the VLR's and HLR --- p.55Chapter 5.5.1 --- Analysis of traditional method --- p.57Chapter 5.5.2 --- Analysis of OBR --- p.58Chapter 5.6 --- Summary --- p.59Chapter 6 --- Conclusion --- p.61Chapter 6.1 --- Summaries of Results --- p.61Chapter 6.1.1 --- Cost functions --- p.61Chapter 6.1.2 --- Optimization of the cost functions --- p.62Chapter 6.1.3 --- Implementation of OBR into GSM --- p.64Chapter 6.2 --- Suggestions for further researches --- p.64Appendix --- p.65Chapter A --- Derivation of cost functions --- p.66Chapter A.1 --- Geographic based scheme --- p.66Chapter A.2 --- Time based scheme --- p.67Chapter A.3 --- Bloom filter based scheme --- p.68Chapter B --- On the optimality of the cost functions --- p.71Chapter B.1 --- Steepest Descent Algorithm for various protocols --- p.71Chapter B.2 --- Bloom filter based scheme --- p.72Chapter B.3 --- Time Based Scheme --- p.74Chapter B.4 --- One-Bit-Reply scheme --- p.75Chapter B.5 --- Geographic Based Scheme --- p.75Chapter C --- Simulation of OBR --- p.77Bibliography --- p.7

Persistent Protection in Multicast Content Delivery

Computer networks make it easy to distribute digital media at low cost. Digital rights management (DRM) systems are designed to limit the access that paying subscribers (and non-paying intruders) have to these digital media. However, current DRM systems are tied to unicast delivery mechanisms, which do not scale well to very large groups. In addition, the protection provided by DRM systems is in most cases not persistent, i.e., it does not prevent the legitimate subscriber from re-distributing the digital media after reception. We have collected the requirements for digital rights management from various sources, and presented them as a set of eleven requirements, associated with five categories. Several examples of commercial DRM systems are briefly explained and the requirements that they meet are presented in tabular format. None of the example systems meet all the requirements that we have listed. The security threats that are faced by DRM systems are briefly discussed. We have discussed approaches for adapting DRM systems to multicast data transmission. We have explored and evaluated the security protocols of a unicast distribution model, published by Grimen, et al.\, that provides ``persistent protection''. We have found two security attacks and have provided the solution to overcome the discovered attacks. Then we have proposed a more scalable architecture based on the modified model. We call the resulting architecture persistent protection in multicast content delivery. We present and formally validate the protocol for control and data exchange among the interacting parties of our proposal