Networking together hundreds or thousands of cheap microsensor nodes allows users to accurately monitor a remote environment by intelligently combining the data from the individual nodes. These networks require robust wireless communication protocols that are energy efficient and provide low latency. We develop and analyze low-energy adaptive clustering hierarchy (LEACH), a protocol architecture for microsensor networks that combines the ideas of energy-efficient cluster-based routing and media access together with application-specific data aggregation to achieve good performance in terms of system lifetime, latency, and application-perceived quality. LEACH includes a new, distributed cluster formation technique that enables self-organization of large numbers of nodes, algorithms for adapting clusters and rotating cluster head positions to evenly distribute the energy load among all the nodes, and techniques to enable distributed signal processing to save communication resources. Our results show that LEACH can improve system lifetime by an order of magnitude compared with general-purpose multihop approaches.

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An application-specific protocol architecture for wireless microsensor networks

The IEEE has standardized the 802.11 protocol for wireless local area networks. The primary medium access control (MAC) technique of 802.11 is called the distributed coordination function (DCF). The DCF is a carrier sense multiple access with collision avoidance (CSMA/CA) scheme with binary slotted exponential backoff. This paper provides a simple, but nevertheless extremely accurate, analytical model to compute the 802.11 DCF throughput, in the assumption of finite number of terminals and ideal channel conditions. The proposed analysis applies to both the packet transmission schemes employed by DCF, namely, the basic access and the RTS/CTS access mechanisms. In addition, it also applies to a combination of the two schemes, in which packets longer than a given threshold are transmitted according to the RTS/CTS mechanism. By means of the proposed model, we provide an extensive throughput performance evaluation of both access mechanisms of the 802.11 protocol.

https://www.cse.iitb.ac.in/~varsha/allpapers/wireless/802.11_DCF_analysis.pdf

Performance analysis of the IEEE 802.11 distributed coordination function

It is shown that, particularly for terrestrial cellular telephony, the interference-suppression feature of CDMA (code division multiple access) can result in a many-fold increase in capacity over analog and even over competing digital techniques. A single-cell system, such as a hubbed satellite network, is addressed, and the basic expression for capacity is developed. The corresponding expressions for a multiple-cell system are derived. and the distribution on the number of users supportable per cell is determined. It is concluded that properly augmented and power-controlled multiple-cell CDMA promises a quantum increase in current cellular capacity. >

On the capacity of a cellular CDMA system

In this paper, we present a family of adaptive protocols, called SPIN (Sensor Protocols for Information via Negotiation), that efficiently disseminates information among sensors in an energy-constrained wireless sensor network. Nodes running a SPIN communication protocol name their data using high-level data descriptors, called meta-data. They use meta-data negotiations to eliminate the transmission of redundant data throughout the network. In addition, SPIN nodes can base their communication decisions both upon application-specific knowledge of the data and upon knowledge of the resources that are available to them. This allows the sensors to efficiently distribute data given a limited energy supply. We simulate and analyze the performance of two specific SPIN protocols, comparing them to other possible approaches and a theoretically optimal protocol. We find that the SPIN protocols can deliver 60% more data for a given amount of energy than conventional approaches. We also find that, in terms of dissemination rate and energy usage, the SPlN protocols perform close to the theoretical optimum.

/pdf/adaptive-protocols-for-information-dissemination-in-wireless-2lo594hki6.pdf

Adaptive protocols for information dissemination in wireless sensor networks

The concept of punctured convolutional codes is extended by punctuating a low-rate 1/N code periodically with period P to obtain a family of codes with rate P/(P+l), where l can be varied between 1 and (N-1)P. A rate-compatibility restriction on the puncturing tables ensures that all code bits of high rate codes are used by the lower-rate codes. This allows transmission of incremental redundancy in ARQ/FEC (automatic repeat request/forward error correction) schemes and continuous rate variation to change from low to high error protection within a data frame. Families of RCPC codes with rates between 8/9 and 1/4 are given for memories M from 3 to 6 (8 to 64 trellis states) together with the relevant distance spectra. These codes are almost as good as the best known general convolutional codes of the respective rates. It is shown that the same Viterbi decoder can be used for all RCPC codes of the same M. the application of RCPC codes to hybrid ARQ/FEC schemes is discussed for Gaussian and Rayleigh fading channels using channel-state information to optimise throughput. >

Rate-compatible punctured convolutional codes (RCPC codes) and their applications

Preface. PART I INTRODUCTION TO WIRELESS NETWORKS. 1 Overview of Wireless Networks. 1.1 Introduction. 1.2 Network Architecture and Design Issues. 1.3 Key Trends in Wireless Networking. 1.4 Outline of the Book. Questions. 2 Evolution of the Wireless Industry. 2.1 Introduction. 2.2 Three Views of the Wireless Industry. 2.3 Three Generations of Cellular Networks. 2.4 Trends in Wireless Technologies. Questions. PART II CHARACTERISTICS OF RADIO PROPAGATION. 3 Characterization of Radio Propagation. 3.1 Introduction. 3.2 Multipath Fading and the Distance-Power Relationship. 3.3 Local Movements and Doppler Shift. 3.4 Multipath for Wideband Signals. 3.5 Classical Uncorrelated Scattering Model. 3.6 Indoor and Urban Radio Propagation Modeling. Questions. Problems. Projects. 4 Modeling and Simulation of Narrowband Signal Characteristics. 4.1 Introduction. 4.2 Modeling Path Loss and Slow Shadow Fading. 4.3 Doppler Spectrum of Fast Envelope Fading. 4.4 Statistical Behavior of Fast Envelope Fading. 4.5 Simulation of Fast Envelope Fading. Questions. Problems. Projects. 5 Measurement of Wideband and UWB Channel Characteristics. 5.1 Introduction. 5.2 Time-Domain Measurement Techniques. 5.3 Frequency-Domain Measurement Techniques. 5.4 Advances in Frequency-Domain Channel Measurement. Questions. Problems. Project. 6 Modeling of Wideband Radio Channel Characteristics. 6.1 Introduction. 6.2 Wideband Time-Domain Statistical Modeling. 6.3 Wideband Frequency-Domain Channel Modeling. 6.4 Comparison Between Statistical Models. 6.5 Ray-Tracing Algorithms. 6.6 Direct Solution of Radio Propagation Equations. 6.7 Comparison of Deterministic and Statistical Modeling. 6.8 Site-Specific Statistical Model. Appendix 6A: GSM-Recommended Multipath Propagation Models. Appendix 6B: Wideband Multipath Propagation Models. Questions. Problems. Projects. PART III MODEM DESIGN. 7 Narrowband Modem Technology. 7.1 Introduction. 7.2 Basic Modulation Techniques. 7.3 Theoretical Limits and Practical Impairments. 7.4 Traditional Modems for Wide-Area Wireless Networks. 7.5 Other Aspects of Modem Implementation. Questions. Problems. Projects. 8 Fading, Diversity, and Coding. 8.1 Introduction. 8.2 Radio Communication on Flat Rayleigh Fading Channels. 8.3 Diversity Combining. 8.4 Error-Control Coding for Wireless Channels. 8.5 Space-Time Coding. 8.6 MIMO and STC. Questions. Problems. Projects. 9 Broadband Modem Technologies. 9.1 Introduction. 9.2 Effects of Frequency-Selective Multipath Fading. 9.3 Discrete Multipath Fading Channel Model. 9.4 Adaptive Discrete Matched Filter. 9.5 Adaptive Equalization. 9.6 Sectored Antennas. 9.7 Multicarrier, OFDM, and Frequency Diversity. 9.8 Comparison of Traditional Broadband Modems. 9.9 MIMO in Frequency-Selective Fading. Appendix 9A: Analysis of the Equalizers. Questions. Problems. Projects. 10 Spread-Spectrum and CDMA Technology. 10.1 Introduction. 10.2 Principles of Frequency-Hopping Spread Spectrum. 10.3 Principles of Direct-Sequence Spread Spectrum. 10.4 Interference in Spread-Spectrum Systems. 10.5 Performance of CDMA Systems. Questions. Problems. PART IV SYSTEMS ASPECTS. 11 Topology, Medium Access, and Performance. 11.1 Introduction. 11.2 Topologies for Local Networks. 11.3 Cellular Topology for Wide-Area Networks. 11.4 Centrally Controlled Assigned Access Methods. 11.5 Distributed Contention-Based Access Control. Questions. Problems. Project. 12 Ultrawideband Communications. 12.1 Introduction. 12.2 UWB Channel Characteristics. 12.3 Impulse Radio and Time-Hopping Access. 12.4 Direct-Sequence UWB. 12.5 Multiband OFDM. Questions. Problems. 13 RF Location Sensing. 13.1 Introduction. 13.2 RF Location-Sensing Techniques. 13.3 Modeling The Behavior of RF Sensors. 13.4 Wireless Positioning Algorithms. Questions. Problems. 14 Wireless Optical Networks. 14.1 Introduction. 14.2 Implementation. 14.3 Eye Safety. 14.4 IR Channel Characterization and Data-Rate Limitations. 14.5 Modulation Techniques for Optical Communications. 14.6 Multiple Access and Data Rate. Questions. 15 Systems and Standards. 15.1 Introduction. 15.2 GSM, GPRS, and EDGE. 15.3 CDMA and HDR. 15.4 Other Historical Systems. 15.5 Wireless LANs. 15.6 Speech Coding in Wireless Systems. Questions. References. Index. About the Authors.

Wireless Information Networks

Wireless data services and systems represent a rapidly growing and increasingly important segment of the communications industry. In the paper the authors present an overview of this field, emphasizing three major elements: (1) technologies utilized in existing and currently planned wireless data services, (2) issues related to the performance of these systems, and (3) discernible trends in the continuing development of wireless data systems. While the wireless data industry is becoming increasingly diverse and fragmented, one can identify a few mainstreams which relate directly to users requirement for data services. On one hand, there are requirements for relatively low-speed data services supporting mobile users over wide geographical areas, as provided by mobile data networks. On the other hand, there are requirements for high-speed data services in local areas, as provided by wireless LANs. The system-level issues are somewhat different for these two categories of services, and this has led to different technology choices in the two domains, which the authors discuss in the paper. >

Wireless data communications

This practical handbook provides communication systems engineers with guidance in the application of error-control coding It emphasizes the fundamental concepts of coding theory while minimizing the use of mathematical toolsdemonstrates the role of coding in communication system designshows the performance gains achievable with codingillustrates how codes should be used and how to select the right code parametersdiscusses the decoding techniques that should be considered and how they are implementedand examines how detailed performance results are obtained

Error-control techniques for digital communication

The problem of computing the probability of undetected error is considered for linear block codes used for error detection. The recent literature is first reviewed and several results are extended. It is pointed out that an exact calculation can be based on either the weight distribution of a code or its dual. Using the dual code formulation, the probability of undetected error for the ensemble of all nonbinary linear block codes is derived as well as a theorem that shows why the probability of undetected error may not be a monotonic function of channel error rate for some poor codes. Several bounds on the undetected error probability are then presented. We conclude with detailed examples of binary and nonbinary codes for which exact results can be obtained. An efficient technique for measuring an unknown weight distribution is suggested and exact results are compared with experimental results.

On the Probability of Undetected Error for Linear Block Codes

Real-time IP applications such as IP telephony, IP video streaming, and transport of time-sensitive information need predictable network resources. Examples of network resources include minimum guaranteed bandwidth, and special processing of certain types of packets at points of congestion, regardless of traffic fluctuations in the network. Support for such applications in mobile ad-hoc networks requires acceptable channel conditions, QoS aware mechanisms for channel access, identification of transit nodes that can sustain the resulting traffic, as well as measures for congestion prevention and management at the nodes. This paper provides a framework for QoS support in mobile ad-hoc IP networks, and discusses methods to enable QoS aware media access control, and routing IP packets with QoS constraints.

Allen H. Levesque

Papers

Wireless Information Networks

Wireless data communications

Error-control techniques for digital communication

On the Probability of Undetected Error for Linear Block Codes

Quality of service support in mobile ad-hoc IP networks