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Military Communications Conference, 1995. MILCOM '95, Conference Record, IEEE

Date 5-8 Nov. 1995

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  • Conference Author Index

    Publication Year: 1995
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  • Application of trellis coded modulation to tactical troposcatter transmissions

    Publication Year: 1995 , Page(s): 1036 - 1040 vol.3
    Cited by:  Papers (1)
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    This paper presents an optimized solution applicable to the transmission of data and radiotelephony at low data rates for troposcatter tactical transmissions. In the proposed system, diversity is obtained thanks to the association of frequency hopping, interleaving and efficient coding scheme. The latter uses an outer Reed-Solomon code concatenated with a TCM (trellis coded modulation) inner code. The presented approach is applied to the coherent demodulation of an 8-PSK modulation transmitted on a frequency and time non-selective Rayleigh channel. As a first step the most promising codes are selected based on an extensive bibliographical research. As a second step, the overall performance is evaluated using computer simulations including the effects of imperfect channel estimation and non-ideal interleaving. It is shown that the proposed solution fulfils all the requirements (particularly those relative to the maximal transmission end to end delay) View full abstract»

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  • Adaptive interference suppression for joint acquisition and demodulation of direct-sequence CDMA signals

    Publication Year: 1995 , Page(s): 1200 - 1204 vol.3
    Cited by:  Papers (8)
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    It has shown that adaptive interference suppression methods for the demodulation of CDMA signals provide immunity to the near-far problem, and perform much better than the conventional matched filter receiver even with perfect power control. Demodulation must, however, be preceded by acquisition of the timing of the desired signal, and conventional methods for acquisition are interference-limited and vulnerable to the near-far problem to the same extent as conventional demodulation. We present two interference suppression schemes for the joint acquisition and demodulation of direct sequence CDMA signals. Roughly speaking, the idea is to run several adaptive demodulation algorithms serially or in parallel, each under a different hypothesis regarding the desired transmission's timing, and to choose the one that gives the best performance. Thus, our schemes have the unique feature that the output of the acquisition process is not merely the timing of the desired transmission, but a near-far resistant demodulator which implicitly takes into account the timing and amplitudes of all transmissions in order to achieve interference suppression. Our acquisition schemes are amenable to efficient decentralized or centralized implementations, and are near-far resistant by virtue of the near-far resistance of the demodulation schemes on which they are based View full abstract»

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  • An active squelch technique for HF communication systems

    Publication Year: 1995 , Page(s): 1071 - 1075 vol.3
    Cited by:  Papers (1)
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    A reliable squelch feature has long been a difficult goal in the low signal to noise ratio and high interference environments typical of HF links. Many passive techniques have been attempted and implemented. These passive techniques range from simple power measurement to elaborate neural network based speech detection systems. All of these approaches suffer from a decrease in reliability as channel conditions degrade due to the presence of noise and interference. However, it is under these degraded channel conditions where a reliable squelch function is most desirable to reduce operator fatigue. In addition, a reliable squelch function can be useful in the implementation of HF/HF or HF/VHF automated re-transmission systems, or as the basis for a robust field radio wakeup feature. This paper will discuss the design and implementation of an HF squelch system based on a burst serial tone waveform that operates in low signal to noise ratio and high narrowband and impulsive interference environments. The paper will present our initial design goals, an implementation overview, and final system performance. Performance data, including the rate of false unsquelch occurrences and the probability of missed unsquelch in various channel conditions will also be presented View full abstract»

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  • Parallel acquisition in mobile DS-CDMA systems

    Publication Year: 1995 , Page(s): 1165 - 1169 vol.3
    Cited by:  Papers (2)
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    This paper presents the performance of a direct sequence spread spectrum acquisition scheme in a mobile terrestrial communications system. The effects of fading, multipath, power control, shadowing, multiple access interference, adjacent cell interference, and vehicle speed are examined. The acquisition scheme uses non-coherent detection and a parallel search strategy. The analysis is done for the reverse link of a mobile CDMA system. The paper derives the acquisition performance of a mobile communications system under practical assumptions, and gives realistic capacity estimates based on acquisition performance criteria View full abstract»

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  • Enhancing the performance of C3 traffic in a real-time, distributed Ada application through the use of scheduling algorithms

    Publication Year: 1995 , Page(s): 901 - 905 vol.3
    Cited by:  Patents (1)
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    A realistic, real-world distributed Ada application-taken from a current US government project requiring real-time C3 traffic-is used as the model for multimedia traffic. The traffic modelled has three characteristics typical of the traffic requirements of many existing C3 systems: (1) real-time constraints, (2) continuous, as well as, bursty, traffic generation at different frequencies, and (3) varying semantic priority classes. We present a simulation study which explores the way real-time scheduling algorithms can be used to enhance the performance of real-time, distributed C3 traffic. Throughout the simulation, existing standards are utilized whenever possible. For example, the standard ATM network protocol is used, and the real-time scheduling algorithms used are selected from among those in current use View full abstract»

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  • Polynomial matrix whitening and application to the multichannel blind deconvolution problem

    Publication Year: 1995 , Page(s): 988 - 992 vol.3
    Cited by:  Papers (1)
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    A method for whitening a polynomial matrix is described, including the calculation of the eigenvalue polynomials and eigenvector polynomials of an FIR polynomial matrix. The multichannel blind deconvolution problem is briefly described and FIR polynomial matrix whitening is applied to the problem. Benefits of the whitening technique are demonstrated through simulation. Data prewhitening or the use of an exact least squares adaptation is necessary in any problem of moderate complexity. The group theoretic aspects of FIR polynomial matrix algebra are discussed View full abstract»

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  • Tactical PCS deployment

    Publication Year: 1995 , Page(s): 1248 - 1252 vol.3
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    Personal communication services (PCS) promise to be the telecommunications wave of the future. Ubiquity and mobility are key aspects of PCS which are particularly attractive to the military. Also, PCS systems using digital spread spectrum technology can provide the military with performance in the areas of security and low probability of intercept (LPI)/low probability of detection (LPD). Given that current policy is advocating the use of commercial equipment and systems wherever possible, it is appropriate that DOD contractors investigate the use of and incorporate commercial off-the-shelf (COTS) equipment as much as possible and where appropriate. The mobile subscriber equipment (MSE) provided by GTE represents the largest investment in tactical communication systems the Army has undertaken. Preservation of this investment through the use of judicious product improvement in times of stringent military budgets is of utmost importance. MSE consists of a number of node center switches, large and small extension nodes, line of sight equipment, and mobile subscriber terminals. Access to the small extension nodes (SENs) of the MSE switches is via field wire. Providing a “wireless” access to the SENs via commercial PCS equipment will greatly enhance the performance and warfighting capability of MSE. Thus, GTE has established a program whose objectives are the integration of commercial PCS with MSE View full abstract»

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  • Overview of open shortest path first, version 2 (OSPF V2) routing in the tactical environment

    Publication Year: 1995 , Page(s): 925 - 930 vol.3
    Cited by:  Papers (3)  |  Patents (5)
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    The United States Department of the Army is expected to mandate the use of the open shortest path first, version 2 (OSPF V2) as the interior gateway routing protocol for use across tactical communication systems that use the Internet Protocol (IP). This paper provides an overview of the OSPF V2 routing protocol and analysis of OSPF V2 routing overhead. The paper describes the minimum OSPF V2 routing overhead that can be expected when operating through the Single Channel Ground and Airborne Radio System (SINCGARS). The paper also suggests changes that will allow OSPF V2 to operate better in the tactical environment View full abstract»

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  • Analysis of a simple protocol for short message data service in an integrated voice/data CDMA system

    Publication Year: 1995 , Page(s): 1160 - 1164 vol.3
    Cited by:  Papers (13)
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    In a mobile cellular CDMA system, the transmissions of the users are power controlled such that their received energies at the base station are approximately equal. This is done with a desire to maximize the capacity of such systems, and further, stability is maintained by limiting the arrival rates of users into the system. This paper analyzes a simple protocol for transmission of short data messages in an integrated voice/data wireless DS-CDMA network. Voice calls are given preemptive priority over data calls and the protocol for data calls is controlled by the QoS (quality of service) requirement for the voice calls. Imperfections in power control for such CDMA systems are included while studying the effect of the protocol on average performance measures like throughput, blocking probability and delay for the short message data service View full abstract»

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  • Rapid fading effects on airborne satellite communication receivers employing Granlund pre-detection diversity combiners

    Publication Year: 1995 , Page(s): 1013 - 1020 vol.3
    Cited by:  Papers (1)  |  Patents (4)
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    A two ray fading model is used to illustrate the effects of over water flight on satellite communications when a Granlund (1956) pre-detection diversity combiner is used to extend the receive antenna coverage. An airplane with multiple antennas covering non-overlapping arrival angles is investigated. A linearized model developed for the combiner is applied to the task of estimating phase tracking error, regeneration frequency, and signal to noise ratio degradation. The cases of the direct and reflected (specular) component arriving in the same or different antennas is investigated. It is shown that when the direct and reflected waves arrive in the same antenna the combiner is nothing more than a gain controlled amplifier with a control transfer function determined by the chosen filter functions. It is shown that when the direct and reflected wave arrive in different antennas, the regeneration frequency becomes a weighted average related to the arrival frequencies of the direct and reflected waves (where the frequency difference is a function of aircraft velocity). An expression for the phase tracking error in the case of the signals arriving in the different antennas is derived. The effects of phase tracking error on the received signal to noise ratio are analyzed. The channel distortion effects are analyzed for a typical application of the airplane communicating with a geostationary satellite View full abstract»

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  • A three ray propagation model for PCS and micro-cellular services

    Publication Year: 1995 , Page(s): 1239 - 1243 vol.3
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    This paper presents a three ray propagation model for PCS and μ-cellular services. The salient concept of the proposed model is to maintain cell radii within the Fresnel zone break point. In this region, the path loss slope is similar to free space loss, irrespective of the propagation medium. This analogy is then used to predict cell radii for indoor and outdoor deployment of PCS; requiring virtually no computer aided prediction tools. It is further shown that the ceiling height plays an important role in antenna placement. The proposed method is appropriate for low power PCS and micro-cellular services, offering a greatly simplified and cost-effective deployment process View full abstract»

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  • Source-dependent channel coding of CELP speech over land mobile radio channels

    Publication Year: 1995 , Page(s): 1041 - 1045 vol.3
    Cited by:  Papers (2)  |  Patents (2)
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    We consider the problem of reliably transmitting CELP-encoded speech over a land mobile radio channel. We first quantify the “residual redundancy” inherent in the line spectral parameters (LSPs) of Federal Standard 1016 CELP. This is done by modeling the quantized LSPs as first- and second-order Markov chains; these models indicate that as many as one-third of the LSP bits are redundant. We then consider methods by which that residual redundancy can be exploited by an appropriately designed channel decoder. Before transmission, the LSPs are encoded with a forward error control (FEC) code; we consider both Reed-Solomon codes and convolutional codes. Soft-decision decoders that exploit the residual correlation in the LSPs are implemented assuming a Rayleigh fading environment. Simulation results using BPSK and DQPSK modulation indicate coding gains of 2 to 5 dB over soft-decision decoders that do not exploit the residual correlation View full abstract»

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  • HNMP: remote control and management protocol for HF radio networks

    Publication Year: 1995 , Page(s): 1083 - 1087 vol.3
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    Steady increases in the sophistication of automated high-frequency radio (HF) equipment have led to a resurgence in the popularity of the HF medium for challenging communication applications. This is resulting in complex HF networks, with equipment often placed at remote sites. This, along with programs to consolidate high-power HF assets among the military services, indicates the need for a standardized protocol for remotely controlling HF stations and for remotely diagnosing problems in HF networks. Unlike the higher-speed LAN and WAN technologies most commonly associated with the idea of a global information infrastructure, HF radio suffers from low bandwidth and rapidly fluctuating connectivity. The hostility of the medium presents clear challenges to the development of a mechanism for reliably monitoring and controlling distant stations. A protocol is described that addresses these challenges, while maintaining compatibility with the standard Internet network management protocol SNMP. This HF network management protocol (HNMP) was standardized in MIL-STD-187-721C. Following a description of the needs, the HF medium, and the protocol, an analysis is presented of the efficiency and performance of the protocol View full abstract»

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  • Department of Defense e-mail policy and government-wide e-mail initiatives

    Publication Year: 1995 , Page(s): 972 - 976 vol.3
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    In support of the goals of the National Performance Review (NPR), the Assistant Secretary of Defense (ASD) for Command, Control, Communications and Intelligence (C3I) is proactively advancing the administration's initiatives to streamline government operations through the use of information technologies. Since 1988, the ASD(C3I) has championed the Defense Message System (DMS) as the single electronic messaging capability for the Department of Defense (DoD). The DMS improves communications through secure, business-grade messaging for the DoD. The DoD also fosters and participates in several federal committees and their initiatives for implementing business-grade electronic mail (e-mail) services for federal, state, local, and tribal agencies. This paper describes the actions that ASD(C3I) is taking to advance the NPR's initiative to improve government operations. Defense level policy on DMS is well defined. Actions by government-wide messaging working groups and the role of the DMS Program are intertwined from two perspectives. First, the DMS has a basic requirement to interoperate with partners in other government agencies and industry, and second, these partners also need business-quality messaging. Many of the DMS initiatives are serving as examples for large-scale interoperable electronic mail initiatives that can be used for business-quality, secure messaging in the government (federal, state, local, and tribal), commercial, and private sectors View full abstract»

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  • Proposed rating factor for operational C4I assessment

    Publication Year: 1995 , Page(s): 1115 - 1119 vol.3
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    The critical importance of command, control, communications, computer and intelligence (C4I) dominance of the battle space and possible effects of command and control warfare, and information based warfare (IW) creates the need for a concept that aides senior decision makers, battle staff and planners in quickly assessing the C4I sufficiency of force deployment options. Such a rating system must permit quick, meaningful assessments of C4I capabilities in terms of mission and type of unit. This paper presents a prototype “C4I” rating concept that meets this need View full abstract»

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  • Time delay spread measurements at two frequencies in a small city

    Publication Year: 1995 , Page(s): 942 - 946 vol.3
    Cited by:  Papers (2)
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    Time delay spread and signal level measurements were made in the streets of a small city at 850 MHz and 1.9 GHz. The results are compared to earlier measurements made in the same city at 850 MHz. The root mean square (rms) time delay spread was statistically the same at the two frequencies. The maximum rms time delay spread observed was 920 nanoseconds (ns). However, this dropped to under 476 ns for coverage radii under 300 meters. When the transmitter and receiver were on the same street, received power levels could be modelled by an averaged two-ray model with linear attenuation. The non-same-street distance exponent of path loss was 5.0 at 1.9 GHz. The rms time delay spread doubled, statistically, for every 18 dB increase in path loss at 1.9 GHz View full abstract»

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  • Secure communication between tactical and strategic networks

    Publication Year: 1995 , Page(s): 931 - 935 vol.3
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    The STU-III program has been very successful in providing secure, high quality communications. The STU-III program, however, has so far been restricted to strategic networks. Tactical networks use devices such as SINCGARS, VINSON, and MINTERM (tactical terminal) which can not interoperate with the STU-III network. The paper discusses the modifications to MINTERM that provide it with a STU-III-compatible mode. It is shown that most of the changes can be made in software and that the modified MINTERM can interoperate with the STU-III network over a large variety of media View full abstract»

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  • Superresolution in the presence of nonuniform noise power

    Publication Year: 1995 , Page(s): 1209 - 1213 vol.3
    Cited by:  Papers (1)
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    The effects of nonuniform noise power in the antenna elements on the performance of the standard MUSIC, reduced MUSIC, and the recursive suppression algorithms are examined. It is shown that the speeds of resolution of all the algorithms are slowed, but their steady-state errors do not exhibit much sensitivity to the noise-power variations. The reduced MUSIC algorithm is shown to provide nearly the same performance as the standard MUSIC algorithm while eliminating the need to estimate the number of signal sources. A simple adaptive superresolution system using the recursive algorithm can be decomposed into two parts, as illustrated View full abstract»

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  • Experimental implementations of multiwavelength photonic packet switches

    Publication Year: 1995 , Page(s): 1279 - 1283 vol.3
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    Photonic packet switches offer the high speed, data rate and format transparency, and flexibility required by future computer communications and cell-based telecommunications networks. We review the experimental progress in multiwavelength photonic packet switches with an emphasis on all-optical guided wave systems. The term all-optical implies that the data portion of a packet remains in an optical format from the source to the destination. While the data remains all-optical, both optical and optoelectronic techniques have been used to process packet routing functions based on extremely simple routing protocols. An overview of the design issues for all-optical photonic packet switching is given and contrasted to electronic packet switch implementations. Low level functions that have been experimentally implemented include routing, contention resolution, synchronization, and header regeneration. System level demonstrations, including centralized photonic switching and distributed all-optical multihop networks, are reviewed View full abstract»

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  • Haiti: projecting tactical network and systems management

    Publication Year: 1995 , Page(s): 906 - 910 vol.3
    Cited by:  Patents (20)
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    The nature of recent military operations has been one of maximizing readiness (e.g., quick deployments) while minimizing in-theater personnel and equipment. Projecting technical expertise from the Continental United States (CONUS) to the deployed area of operations is critical to ensuring the success of the warfighter. Operation UPHOLD DEMOCRACY is the first of many opportunities to project tactical network and systems management (NSM) expertise from CONUS to tactical network managers and their respective tactical networks. NSM solutions were demonstrated and employed to provide remote monitoring and control capabilities from CONUS of the tactical packet network (TPN) and the mobile gateway van (MGV), both in Haiti. The TPN is the army tactical packet switched data network. The MGV provides users in the deployed tactical environment access to the non-classified Internet protocol router network (NIPRNET) for transmission of unclassified traffic. This paper will discuss the ways in which commercial off-the-shelf (COTS) NSM tools were used to manage the TPN and the MGV in support of operation UPHOLD DEMOCRACY. TPN management was accomplished using the integrated management system (IMS) application. An integrated set of COTS tools (Hewlett Packard Network Node Manager, Remedy Action Request System, and Cisco Systems CiscoWorks) have been configured to remotely manage the MGV in Haiti. Managing the TPN and MGV successfully demonstrate the technical feasibility of projecting NSM capabilities from CONUS to deployed tactical networks View full abstract»

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  • An application of random software testing

    Publication Year: 1995 , Page(s): 1098 - 1102 vol.3
    Cited by:  Papers (6)
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    Program testing remains the most commonly used method for verifying the reliability of software products. A popular method for integration testing is to develop a test plan based on the system requirements. We discuss some of the shortcomings of this approach and present our experiences with a random testing approach of a telecommunications project (a secure telephone conferencer). Among the benefits of this approach are improved requirements definition, improved fault detection, a simpler approach to system reliability estimation and reduced life-cycle costs View full abstract»

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  • A 300 to 3600 bps multi-rate HF parallel tone modem

    Publication Year: 1995 , Page(s): 1066 - 1070 vol.3
    Cited by:  Papers (1)
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    There have been many HF modems developed for voice frequency (3 kHz) operation. To achieve a certain bit rate it has been customary to select a particular waveform, error-control code and signalling protocol specifically for that rate. This methodology is unsuitable in adaptive systems, that regularly reconfigure the modem bit rate, because of the time needed to re-establish useful information flow after every configuration change. In this paper we describe a 16-tone parallel-tone modem that avoids this problem by making the information rate determined solely by the coded modulation selected. Results are given for rates of 300, 600, 1200, 2400 and 3600 bits per second (bps) on CCIR multipath fading channels. The results show that this multi-rate modem offers superior performance to contemporary modems while also supporting rate adaptation View full abstract»

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  • The calculation of the phase center for spacecraft phased array antennas

    Publication Year: 1995 , Page(s): 1046 - 1050 vol.3
    Cited by:  Patents (1)
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    Many distance measurement systems such as GPS require an accurate knowledge of the phase center of the system antenna. The phase center is normally thought of as the point where the phase terms of the field have minimum deviation from a spherical wavefront. In general, the phase center of an array is a rather complicated function involving array elements, array geometry, and reflection and diffraction from structures. Because of the complexity of the problem, this paper concentrates on the determination of the phase center of arrays assuming omni-directional elements View full abstract»

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  • Differentially amplitude and phase encoded QAM on Rayleigh fading channels

    Publication Year: 1995 , Page(s): 1026 - 1030 vol.3
    Cited by:  Papers (1)  |  Patents (2)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (484 KB)  

    Quadrature amplitude modulation (QAM) is an effective technique to achieve a high bit-rate transmission without increasing the transmission bandwidth. Due to the limitation on available spectrum, research in digital mobile data communications have considered employing QAM as the fundamental modulation format. This paper evaluates the bit error probability (BEP) of differentially amplitude encoded (DAPE) QAM over nonselective Rayleigh fading channels with switched diversity reception. The QAM transmitter employs a multiamplitude star constellation and modulates the information onto the amplitude ratio and phase difference between the transmitted signals in two consecutive signalling intervals. At the receiver, the amplitude ratio and phase difference between the received signals in two successive signalling intervals, corresponding to the diversity channel with the largest amplitude in the previous interval, are compared with preset thresholds for data demodulation. An exact closed form expression of BEP is given for a general system format and for channels with fading fluctuations. The results show how the DAPE QAM can be optimized and how fading fluctuations and the order of the switched diversity affect its performance View full abstract»

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