Characterizing interference in wireless mesh networks.

Hui, Ka Hung.Thesis (M.Phil.)--Chinese University of Hong Kong, 2007.Includes bibliographical references (leaves 123-126).Abstracts in English and Chinese.Abstract --- p.iAcknowledgement --- p.ivChapter 1 --- Introduction / Motivation --- p.1Chapter 2 --- Literature Review --- p.6Chapter 2.1 --- Introduction --- p.6Chapter 2.2 --- The Capacity-Finding Problem --- p.6Chapter 2.3 --- Interference Models --- p.8Chapter 2.4 --- Considering Interference in the Capacity-Finding Problem with Perfect Scheduling --- p.9Chapter 2.4.1 --- Conflict Graph --- p.10Chapter 2.4.2 --- Independent Set Constraints --- p.11Chapter 2.4.3 --- Row Constraints --- p.11Chapter 2.4.4 --- Clique Constraints --- p.12Chapter 2.4.5 --- Using the physical model --- p.13Chapter 2.5 --- Considering Interference in the Capacity-Finding Problem with Random Access --- p.15Chapter 2.6 --- Chapter Summary --- p.17Chapter 3 --- Partial Interference - Basic Idea --- p.18Chapter 3.1 --- Introduction --- p.18Chapter 3.2 --- Deficiencies in Previous Models --- p.18Chapter 3.2.1 --- Multiple Interferers --- p.19Chapter 3.2.2 --- Non-binary Behavior of Interference --- p.19Chapter 3.2.3 --- Impractical Perfect Scheduling --- p.21Chapter 3.3 --- Refining the Relationship between Interference and Throughput Degradation --- p.21Chapter 3.4 --- Capacity Gain by Exploiting Partial Interference . --- p.23Chapter 3.5 --- Chapter Summary --- p.28Chapter 4 --- Partial Interference in 802.11 --- p.29Chapter 4.1 --- Introduction --- p.29Chapter 4.2 --- The 802.11 Model --- p.29Chapter 4.2.1 --- Assumptions --- p.30Chapter 4.2.2 --- Transmission Probability Calculation --- p.31Chapter 4.2.3 --- Packet Corruption Probability Calculation --- p.34Chapter 4.2.4 --- Loading Calculation --- p.35Chapter 4.2.5 --- Summary --- p.36Chapter 4.3 --- Some Analytical Results --- p.37Chapter 4.4 --- A TDM A/CDMA Analogy --- p.40Chapter 4.5 --- Admissible (Stability) Region --- p.42Chapter 4.6 --- Chapter Summary --- p.44Chapter 5 --- Partial Interference in Slotted ALOHA --- p.45Chapter 5.1 --- Introduction --- p.45Chapter 5.2 --- The Finite-Link Slotted ALOHA Model --- p.46Chapter 5.2.1 --- Assumptions --- p.46Chapter 5.2.2 --- Stability of Slotted ALOHA --- p.46Chapter 5.3 --- Stability Region of 2-Link Slotted ALOHA under Partial Interference --- p.47Chapter 5.4 --- Some Illustrations --- p.50Chapter 5.5 --- Generalization to the M-Link Case --- p.53Chapter 5.6 --- Chapter Summary --- p.58Chapter 6 --- FRASA --- p.59Chapter 6.1 --- Introduction --- p.59Chapter 6.2 --- The FRASA Model --- p.60Chapter 6.3 --- Validation of the FRASA Model --- p.66Chapter 6.3.1 --- Simulation Results --- p.66Chapter 6.3.2 --- Comparison to Previous Bounds --- p.72Chapter 6.4 --- Convex Hull Bound --- p.75Chapter 6.5 --- p-Convexity --- p.80Chapter 6.6 --- Supporting Hyperplane Bound --- p.86Chapter 6.7 --- Extension to Partial Interference --- p.89Chapter 6.7.1 --- FRASA under Partial Interference --- p.90Chapter 6.7.2 --- Convex Hull Bound --- p.93Chapter 6.7.3 --- p-Convexity --- p.97Chapter 6.7.4 --- Supporting Hyperplane Bound --- p.101Chapter 6.8 --- Chapter Summary --- p.102Chapter 7 --- Conclusion and Future Works --- p.110Chapter 7.1 --- Conclusion --- p.110Chapter 7.2 --- Future Works --- p.111Chapter A --- Proof of (4.13) in Chapter 4 --- p.113Bibliography --- p.12

Network-Level Performance Evaluation of a Two-Relay Cooperative Random Access Wireless System

In wireless networks relay nodes can be used to assist the users' transmissions to reach their destination. Work on relay cooperation, from a physical layer perspective, has up to now yielded well-known results. This paper takes a different stance focusing on network-level cooperation. Extending previous results for a single relay, we investigate here the benefits from the deployment of a second one. We assume that the two relays do not generate packets of their own and the system employs random access to the medium; we further consider slotted time and that the users have saturated queues. We obtain analytical expressions for the arrival and service rates of the queues of the two relays and the stability conditions. We investigate a model of the system, in which the users are divided into clusters, each being served by one relay, and show its advantages in terms of aggregate and throughput per user. We quantify the above, analytically for the case of the collision channel and through simulations for the case of Multi-Packet Reception (MPR), and we provide insight on when the deployment of a second relay in the system can yield significant advantages.Comment: Submitted for journal publicatio

ACCESS AND STABILITY ISSUES IN SPECTRUM COMMONS

Ph.DDOCTOR OF PHILOSOPH

Decentralised Algorithms for Wireless Networks.

Designing and managing wireless networks is challenging for many reasons. Two of the most crucial in 802.11 wireless networks are: (a) variable per-user channel quality and (b) unplanned, ad-hoc deployment of the Access Points (APs). Regarding (a), a typical consequence is the selection, for each user, of a different bit-rate, based on the channel quality. This in turn causes the so-called performance “anomaly”, where the users with lower bit-rate transmit for most of the time, causing the higher bit-rate users to receive less time for transmission (air time). Regarding (b), an important issue is managing interference. This can be mitigated by selecting different channels for neighbouring APs, but needs to be carried out in a decentralised way because often APs belong to different administrative domains, or communication between APs is unfeasible. Tools for managing unplanned deployment are also becoming important for other small cell networks, such as femtocell networks, where decentralised allocation of scrambling codes is a key task

PERFORMANCE ANALYSIS OF NETWORK CODING WITH IEEE802.11 DCF USING MULTI PATH TRANSFR PROTOCOL IN WIRELESS NETWORK

In this paper investigated the throughput and end to end delay of network coding under IEEE802.11 Distributed coordination Function (DCF). In this paper proposed the random medium access of CSMA/CA   as in IEEE802.11 distributed coordination function with Multi Path Transfer Protocol (DCF-MPTP). In an CSMA/CA is based on the combination of physical carrier sensing and exponential back off algorithm and then formulate the probability of successful transmission, collision probability and the re-transmission mechanism. In our model multi hop network used the MPTP (protocol) it prevent the delay and packed loss of source to destination. Finally use computer simulation to verify an analytical  model