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The authors investigate the performance of a decision-feedback equalizer in the presence of co-channel interference. Through ideal calculations and simulations under static channel conditions, they show that a DFE is capable of achieving significantly better performance in the presence of CCI than in an equal amount of noise. Furthermore, they observe that DFE performance in the presence of co-channel interference improves with the use of large pulse excess bandwidths. Under such conditions, the equalizer performance can be optimized with judicious choices of equalizer delay and size. >

The throughput of slotted ALOHA in a mobile radio channel is degraded due to signal fading and a packet may not be received successfully even when there is no collision. A retransmission combining technique is introduced in which a packet received with errors is not discarded; instead, it is stored and combined with the packet(s) received in the following retransmission(s). The throughput performance of slotted ALOHA with retransmission combining is studied, and an improvement in performance is observed. A comparison with space diversity is made. >

The performance of a fractionally spaced decision feedback equalizer (DFE) for spread-spectrum multiple access (SSMA) systems, which does not make explicit use of the interferers' spreading sequences, is evaluated. It is found that the system performance is acceptable even for small spreading gains in a slow-fading multipath environment. Good performance has been achieved without the knowledge of the desired user's spreading sequence. This could lead to less complex receivers and higher capacity of users for SSMA than that of other access techniques. >

Investigation of the mechanisms of radio propagation in the indoor environment can only be performed using a detailed simulation of the environment. To this end, a model of the environment has been developed using ray tracing techniques. The model inherently incorporates the near-field effects of multipath environments where the transmitter and receiver are in close proximity. Statistical analysis of the resulting model has shown that an adequate match between the real environment and the simulation can be achieved. A Nakagami model is found to describe the fast fading component of the channel well. >

An adaptive multiple-beam antenna array is proposed for use in an indoor wireless environment to direct 'narrowbeams' at the desired paths and create nulls towards the cochannel interference (CCI) paths to mitigate the multipath and the CCI impairments. The array performance is evaluated in terms of symbol error rate (SER) for a coherent QPSK signalling scheme. It was discovered that the SER improves with more array elements. The SER with large array is better when there is a dominant path among the multipath. The performance degradation due to CCI depends on the signal-to-interference ratio (SIR) and the CCI path DOA. >

The performance of pi /4-QDPSK system is presented in a fast Rayleigh fading/slow lognormal shadowing/delay spread/AWGN channel in the presence of cochannel interference. The performance of the system is measured in terms of symbol error rate (SER). The system was simulated using two-ray model for normalized value of Doppler shift (0.001), degree of shadowing ( sigma =6), and several values of time delays and carrier-to-interference ratios. It is seen that the system performance is limited by the presence of cochannel interference. When cochannel interference is negligible, the system performance is dominated by the ratio between the main path signal and the delayed path signal, and the differential time delay between them. It is observed that the shadowing degrades the system performance at low CNR but not at high CNR (i.e., CNR>50 dB). The irreducible symbol error rate (ISER) does not vary significantly as the differential time delay between the two path varies. >

A linear group-wise successive interference canceller in a synchronous CDMA system is considered in this work. The proposed hybrid detector that combines successive and parallel cancellation techniques makes use of advantages offered by the two techniques. The convergence of the hybrid interference cancellation (HIC) detector is guaranteed by an adjustable parameter that depends upon the largest eigenvalue of the system's transition matrix. Since this largest eigenvalue is difficult to estimate, an upper bound is necessary for successful convergence. For this reason, we propose a new ordering and grouping algorithm that yields a tight upper bound, which, in turn, results in a higher convergence speed. Simulation results show that a significant improvement in performance is obtained when this technique is used.

A fractionally spaced decision feedback equalizer (DFE) is proposed for code division multiple access (CDMA) in an interference-dominated environment. This system assumes no knowledge of the interferers' spreading codes. The calculation of optimum receiver taps shows good improvement in the capacity of the proposed system over others. The DFE receiver is simulated in a multiuser multipath environment. Performance results show the expected convergence of the DFE, with and without knowledge of the desired user's spreading code. Results also show the effect of sudden birth and death of interferers in the system. The bit error rate of the simulated DFE system is presented.

The design and construction of an autonomous vehicle with fuzzy logic navigational control are described. The design incorporates a 16-bit, on board Motorola's MC68HC16Z1 microcontroller to coordinate the vehicle operations. Fuzzy logic is used in conjunction with the controlling software for steering and guidance. The optical guidance follows a UV sensitive track on which position information is encoded. Steering is performed through timing pulses from the microcontroller to a stepper motor connected to a home designed steering mechanism. The vehicle may be ordered to a chosen location by a remote handheld transmitter using frequency shift keyed data transmission on a radio link. The remote unit incorporates logic cell array (LCA) supporting circuitry. Track obstruction is detected by a front end infrared detection unit and a touch sensitive bumper.

Channel capacities of M-ary differential phase shift keying (DPSK) and M-ary adjacent D/sup 2/PSK on the time-selective Rician fading channels are analyzed, using the probability distribution factors (PDF's) of the first-order and second-order phase errors in the output of the detectors. The analyses are carried out for the systems with hard decision and soft decision. It is found that in terms of channel capacities for both DPSK and D/sup 2/PSK with soft decision and M/spl rArr//spl infin/, the penalty for the slow Rayleigh fading channel compared with the AWGN channel is about 4.8 dB for a high SNR.

In addition to the desired signal including direct and diffused components, the received signal is assumed to be contaminated by the Rician-faded interferences of other users within the same cell and the Rayleigh-faded interferences from adjacent cells, as well as the AWGN noise. The path loss is also taken into account. The analysis is based on the statistical distribution of the angle between two complex-valued vectors. An exact distribution of the co-cell interference is derived. Some numerical results of the binary case are presented. Results are compared with those obtained using the Gaussian assumption for the distribution of the interference based on the "law of large numbers".

The simulation of a microcellular mobile radio propagation environment is performed using a modified ray tracing technique. The modified ray tracing also accounts for building edge diffraction using Keller's geometrical theory of diffraction. Narrowband small area statistics are investigated by fitting Nakagami, Rice and Rayleigh distributions. The physical significance of Nakagami 'm' parameter is presented. It may be used for system design.

This paper describes the results of propagation measurements carried out in an office complex at 946 MHz with three objectives: to investigate the impact of desk population on the average propagation loss, to model average path loss, and to fit a statistical description to the measured results. The measurements were conducted on two identically structured floors: one fully occupied and the other completely empty. The loss in the fully occupied floor is found to be marginally higher, but the propagation loss factor is more uniform in different directions from the base. For the populated environment, diffraction calculations were found to show good correlation with the measurements. Fade margin obtained from site measurements was found to be significantly less severe than is predicted from the use of the Rayleigh fading model. The Nakagami fading model fits the results better than the generally accepted model in Rayleigh fading.

The performance of a hybrid direct sequence/frequency hopped (DS/FH) spread spectrum multiple access communication system is evaluated. The modulation considered is quadrature phase shift keying modulation. A mobile radio channel is investigated in the presence of interference and noise. Both deterministic and random signature sequences and memoryless random frequency-hopping patterns are considered. The maximum number of simultaneous users (capacity) at a desired level of bit error probability (10/sup -3/ - 10/sup -2/) and the spectrum efficiency are considered as performance measures. Simulation results for both synchronous and asynchronous hybrid systems are presented.

The results of propagation measurements carried out in an office complex at 946 MHz are described. The objectives are to investigate the impact of desk population on the average propagation loss, to model average path loss, and to fit a statistical description to the measured results. The measurements are conducted on two identically structured floors, i.e., one fully occupied and the other completely empty. The loss in the fully occupied floor is found to be consistently higher, but the propagation loss factor is more uniform in different directions from the base. Fade margin statistics are obtained for mean signal power levels which are between 50 dB and 60 dB less than the signal power at the base. It is found that the Nakagami fading model fits the results better than the generally accepted model in Rayleigh fading.

An architecture for a personal communication system (PCS) based on an intelligent network (IN) infrastructure is presented. Personal communication service is realized by identifying functions such as radio access, authentication, and location registration and incorporating them as service logics in the intelligent network. Call models based on the set of the trigger check points (TCPs) and functional entity actions (FEAs) are presented to show that IN capabilities can be used to support most PCS features.

A technique of modelling the indoor radio channel that provides an insight into the propagation mechanisms involved is presented. The model by its nature provides a detailed account of the channel, with access to system parameters that are otherwise inaccessible. To demonstrate the validity of this model, results are presented which show the close match between the real environment and the simulated environment. Although gross approximations are made about the environment, the model still gives good results, highlighting the important parameters that need to be considered in channel models.

Ray tracing and the geometrical theory of diffraction are applied to a simulation of the radio channel experienced by equipment communicating inside buildings. Comparisons are made between the simulated results and electromagnetic measurements through the use of probability distributions fitted to the data. The system parameters are determined from the simulation, and used to recreate the channel in a statistical manner, demonstrating that a limited set of information on the channel is sufficient to model the channel. >

The block error probabilities of noncoherent frequency-shift keying signals in a Nakagami fading channel are presented. The channel fading speed, slow or fast, is considered in evaluating block error probabilities. The effectiveness of diversity combining and error correction coding in improving block error performance is studied.

Frequency-shift decision feedback equalizer (FRESH-DFE) is a DFE in which the forward filter is replaced by a bank of frequency-shift (FRESH) adaptive filters. This would improve the DFE performance in a cyclostationary environment. FRESH-DFE can exploit the spectral redundancy of modulated signals. It also uses the feedback filter to remove the residual intersymbol interference (ISI) caused by earlier symbols. It is shown that the performance of the FRESH-DFE is superior to that of a DFE. This is particularly true in high adjacent channel interference.

This paper investigates the tracking of DS/SS signals based on an adaptive filtering technique. It is shown that a previously proposed system for code acquisition is also capable of code tracking and, by performing both acquisition and tracking with the same circuitry, significant simplification in the overall DS/SS receiver is gained. Analytical results show that the proposed scheme has a good tracking performance, as measured by the hold-in time and the false alarm penalty time, and less sensitivity to variations in the received SNR compared to conventional delay lock loops (DLLs).

Antenna diversity is an important technique to combat fading and reduce co-channel interference (CCI). When evaluating the system performance, such as the BER, Monte Carlo simulation is widely used due to the difficulty of analysis. This paper presents the analysis of BER for optimum combining (OC) with two cochannel interferers and maximal ratio combining (MRC) with arbitrary number of interferers. For a DPSK signal, an exact BER expression is derived. The paper also provides an upper bound for BPSK or QAM signals based on results of Foschini and Salz (1983).

Code acquisition in direct sequence spread-spectrum systems must occur before data demodulation can start. In this paper, a new hybrid approach to code acquisition is proposed by using an adaptive filter. The proposed system tests several phases concurrently and, hence, offers fast acquisition with small hardware requirements. Moreover, the same system could be employed in code tracking.

Recent advances in radio systems technology have led to the development of wireless systems which could provide universal access to the users. To support higher user density, high user mobility, and enhanced network capacity, extensive frequency reuse in microcellular systems becomes necessary. Small cell radii result in more frequent handovers which in general overload other vital functions of the network control. This paper presents a new fuzzy logic based handover algorithm which results in sharp reduction in the number of handovers from those when a conventional algorithm is used. Furthermore, the proposed handover decision may be extended to include multiple performance criteria in order to make the handover process more robust while minimizing the number of unnecessary handovers.

The focus in this paper is on physical interpretation of the Nakagami fading phenomenon in multipath mobile radio propagation through its parameters m and /spl Omega/. In the case of narrowband multipath propagation, it is shown that the m parameter is interpreted in a similar fashion as the K parameter of the Rice distribution. We also formulate a geometric theory of Nakagami multipath fading and relate the m parameter with the number of resolvable multipaths in a wideband multipath propagation scenario. We provide a physical interpretation of this geometric theory which can also be shown to be supported by channel measurements reported in literature. Finally the two interpretations are used together to quantify the multipath diversity of a given channel.

This paper presents analytical and simulation results on the output SINR of an antenna array for M elements and N interfering users in digital cellular system scenarios. The analytical expressions are given for the following three cases: (i) M=N; (ii) M

Investigates the performance of a hybrid DS/SFH spread spectrum multiple access communication system using BPSK modulation over a mobile radio channel in the presence of interference and noise. A decision feedback equalizer (DFE) which provides inherent diversity in a multipath environment is utilized at the receiver. The DFE is also known to significantly reduce cochannel interference and intersymbol interference. Simulation results are presented with minimum mean square error (MMSE) and bit error rate as performance measures. >

Investigates the average bit error rate (EER) and outage performance of a TDMA indoor wireless cellular system employing an adaptive fractionally spaced decision feedback equalizer (DFE) in the presence of adjacent and co-channel interference (ACI and CCI) and additive Gaussian noise. There exist performance gains in the presence of strong interference and negligible ambient noise relative to the equivalent stationary noise case. Moreover, a directly adapted RLS DFE performs better than a computed MMSE DFE which employs estimates of the channel impulse response (CIR) and interference plus noise autocorrelation. However, these comparative performance gains are compromised by the presence of appreciable noise power and/or more interferers than the receiver can process effectively, The use of a wide receiver bandwidth yields a performance improvement for channel spacings which allow for sufficient spectral overlap of the ACI with the desired signal bandwidth. Thus, a reduction in channel spacing increases the radio capacity while maintaining a desired average EER or outage performance. >

The upcoming personal communication services (PCS) require the need for integration of wireless services to provide for transmission of voice and data. The proposed system is simulated, (by considering Rayleigh faded channels) for two different data rates using the same spectrum and under moderate to high interference conditions. The integration concept using a decision feedback equalizer with a relatively short forward filter gives good performance and its usefulness in service integration is established.

Narrowband indoor communication channels can be characterised by statistical distributions. The Rayleigh and Ricean distributions are commonly used to describe measured channels, but in some instances, other distributions may be found to be more appropriate for the task. Determining the reason for one particular distribution being more appropriate for one environment over another may be a non-trivial task, In order to assist in this process, a channel simulation based on the physical structure of the environment is presented, along with narrowband results, obtained both from measurement and simulation experiments. Using these results, the basis for a Nakagami distributed channel, observed in some indoor communication environments, is be shown.

Digital cellular radio (DCR) communications occur over a fading multipath channel. In the case of low bit-rate, narrowband communications, a fast adaptive algorithm is required to track the rapid time variations in the DCR channel. The authors demonstrate the feasibility of a novel block-adaptive strategy which computes the time-varying channel impulse response (CIR) by interpolating a set of CIR estimates obtained through periodic training. Furthermore, they have discovered that channel tracking is limited by the CIR estimation noise rather than by the CIR interpolation. >

The feasibility of a digital cellular radio (DCR) system which uses a jointly adaptive decision-feedback equalizer and diversity combiner is discussed. The current estimates of the channel impulse response (CIR) are utilized at each diversity branch to compute the receiver parameters periodically. A block-adaptive strategy that computes the time-varying CIR by interpolating a set of CIR estimates obtained through periodic training is proposed. Despite incurring some inherent processing delay and throughput reduction, this interpolation strategy is shown to have the advantage of immunity to decision errors which would quite likely occur during a deep fade. It is shown that the system performance is limited mainly by the CIR estimation caused by imperfect training which is manifest in the form of an irreducible bit error rate at high signal-to-noise ratios (SNRs). >

A new adaptive combined array and multiuser detector (spatial and temporal) structure for direct sequence code division multiple access (DS-CDMA) has been proposed by Legnain, Falconer and Sheikh (see CCECE'98) to combat cochannel interference and increase the capacity for cellular CDMA. The structure uses a L-sensor (element) linear array. Each element is followed by a chip matched filter (CMF) and a fractionally spaced adaptive equalizer. The proposed structures combine the multipath component as well as suppressing interference. It outperforms the conventional receiver and the structures proposed by Abdulrahman, Sheikh and Falconer (IEEE JSAC, vol.12, no.4, p.698-706, 1994) and by Miller (see IEEE Tran. Comm., vol.43, no.2/3/4, p.1746-55, 1995) in-terms of capacity, near far resistance, multipath combining. The proposed structure can also operate in heavy traffic channels with many users having the same angle of arrival (AOA) as the desired user when the conventional array can not. The focus in this paper is the cochannel interference rejection and multipath combined capabilities of this structure. Analysis of the optimum tap weights and the minimum mean square error in multipath fading channels are provided, and comparison between this structure and the structures propose by Abdulrahman et al. and by Miller is also provided.

The acquisition-based capacity of a DS/CDMA system is defined as the maximum number of simultaneous users that can achieve PN code acquisition with certain reliability. This paper introduces a novel PN code acquisition scheme utilizing an LMS adaptive filter structure to estimate the delay offset of the desired user in the presence of multiple access interference. It is shown that the adaptive filter significantly outperforms conventional matched filter acquisition schemes. It improves the acquisition-based capacity because it takes into consideration the presence of the multi-user interference while finding the optimum tap-weight setting as opposed to the matched filter which completely neglects the interference. For a PN code length of 127 chips, the matched filter can support only 6 users while the adaptive filter supports up to 40 users at a probability of acquisition failure of 1%. This is essentially the same as the capacity achieved at 10/sup -3/ bit-error-rate.

Antenna diversity is an important technique to combat fading and reduce co-channel interferer (CCI). We present an analytical approach to derive the outage probability (OTP) for maximal ratio combining (MRC) in the presence of multiple CCIs. Based on the work presented by Cui, Falconer and Sheikh (see Proceedings of PIMRC'96, Taipei, Taiwan, p.53-7, 1996), the probability density function (PDF) of the signal to interference plus noise ratio (SINR) is derived with antenna diversity. A selection of numerical results highlights the impact of the number of antenna elements, the number of CCIs and SNR on the OTP. Since the PDF of the SINR is independent of any specific modulation signal, the results can be easily extended to any type of modulation format.

The performance of an ideal RAKE receiver, which exploits time/frequency diversity, is no different than the performance of an L branch space diversity receiver as shown by Proakis (see Digital Communications, McGraw Hill Book Co., 3rd edition, p.772-806, 1995). Therefore, the expressions for average probability of error for space diversity systems can be used as a starting point for RAKE performance. This paper extends this analysis to incorporate the effects of random path arrival on RAKE BER performance assuming the path arrival may be modeled as a modified (doubly stochastic) Poisson process as was suggested by Turin et. al. (1972) and by Suzuki (1977). The analysis results in a new measure for diversity which is the average number of paths for a given length of the power delay profile. As average number of paths (the Poisson parameter) is not necessarily an integer number, the notion of order of diversity, which is generally described in integer numbers, can be extended to fractional diversity for realistic channels.

A computer simulation study is made on the performance of slotted non-persistent digital sense multiple access with collision detection (DSMA/CD), the medium access control (MAC) protocol used in CDPD. A purpose built hierarchical simulation model based on the CDPD System Specification 1.1 is used. The performance of DSMA/CD in a noiseless, non-fading channel is evaluated when collisions are the only cause of transmission failure. The investigation mainly falls on the performance indices such as the channel throughput, the data delivery time, and the service grade. The influence of user queue size on the performance of DSMA/CD is also studied.

New adaptive combined array and multiuser detector (spatial and temporal) structure for direct sequence code division multiple access (DS-CDMA) is proposed to combat co-channel interference and increase the capacity for cellular CDMA. The structure uses an L-sensor (element) linear array. Each element is followed by a chip matched filter (CMF) and a fractionally-spaced adaptive equalizer. The proposed structure outperforms the conventional receiver and the structures proposed by Abdulrahman, Sheikh and Falconer (see IEEE JSAC, vol.12, no.4, p.698-706, 1994) and by Miller (see IEEE Tran. Comm., vol.43, no.2/3/4, p.1746-55, 1995) in terms of the capacity and near far resistance. The proposed structure can also operate in heavy traffic channels with many users having the same angle of arrival (AOA) as the desired user, while the conventional array can not. Analysis of the optimum weights and the minimum mean square error in the synchronous DS-CDMA channel is provided, and comparison between this structure and the structures proposed by Abdulrahman et al. and by Miller are also provided.

A code-aided adaptive equalization structure is presented for use in cellular mobile radio systems. The new structure combines adaptive equalization, decoding and interleaving. The performance of a TDMA system using the proposed equalizer is evaluated by means of computer simulation. Compared to the conventional equalizer, the proposed equalizer performs particularly well in a channel with moderate fade rate. In fast fading environments, e.g. at a maximum Doppler frequency f/sub D/=100 Hz, the proposed equalizer results in an order of magnitude reduction on the irreducible BER delivered by a conventional equalizer.

The capacity of a DS/CDMA system is essentially limited by the performance of the acquisition sub-system; i.e. the maximum number of users that can achieve signal acquisition with a certain degree of reliability. This paper presents a new code acquisition scheme utilizing an FIR adaptive filter that significantly outperforms matched filter based schemes. It is shown that the proposed scheme can achieve the same capacity obtained from the BER criterion.

In this paper, a new approach is proposed to analyze packet reservation multiple access (PRMA) protocols that integrate voice and buffered data users. Unlike the available analysis methods, the system state information is carried by the state equilibrium probabilities. As a result, the classical queueing theory results are used to analyze the behaviour of both voice users and data users which have a finite buffer capacity. Compared to equilibrium point analysis (EPA) or Markov analysis, the proposed method is much simpler and therefore can be applied to systems with greater complexity.

Our investigations in understanding the physical mechanism of the LOS microcellular channel reveal that the principle source of slow fading is the random interference pattern of a few strong contributing paths which causes what we term as deceptive shadowing. It is shown that in a comparative curve fitting of slow fading, Nakagami distribution also fits the fading data. Also in non-zero mean complex Gaussian channels, the segregation of slow and fast fading using moving mean normalization is illusionary as the fading parameters in both cases remain the same. We argue that radio link performance calculation based on the segregation of slow and fast fading are therefore unnecessary for Rice/lognormal or Nakagami/lognormal fading models and may be avoided in order to simplify complex analyses.

The mean acquisition time performance for a code acquisition scheme utilizing an FIR adaptive filter is investigated. Both frequency selective and frequency nonselective Rayleigh fading channels are considered. It is shown that fading causes a performance degradation of less than 3 dB for both the coherent and noncoherent cases when the carrier phase is varying slowly, and less than 5 dB for the noncoherent case with fast phase variations. This degradation is significantly smaller than that suffered by other systems based on using matched filters (about 10-15 dB degradation).

This paper proposes a new cellular system which combines code division multiple access (CDMA) and time division multiple access (TDMA) to improve the performance of the cellular system. A synchronized TDMA-FDMA system is used within cells and an asynchronous CDMA system is used across the cells. The cell signals are spread by unique spreading codes to reduce inter-cell interference. Simulations show that the bit error rate (BER) delivered by the proposed system for a E/sub b//N/sub 0/ greater than a certain value is better than that for conventional cellular TDMA system. This improvement is the direct result of spreading signals used to decrease the inter-cell co-channel interference (CCI). The improvement thus realized can be translated into reduction of cluster size and thus towards capacity improvement.

IA new technique is presented for the construction of substitution boxes (s-boxes). This has been developed in response to the need for a fast algorithm for obtaining large s-boxes with good properties. Because of the speed of the algorithm, many good s-boxes can be constructed quickly, with the best of these chosen for use based on a test of their cryptographic properties.

In emerging integrated wireless personal communications systems, the users are given freedom to choose a service out of many available. The integration of voice, data and video services to meet the user needs on to a common mode of transmission is a difficult task. An overlaid cellular CDMA system is proposed to carry different rate traffic on the same carrier frequency. It is shown that different rate services can coexists in a DS-CDMA-DFE system without any noticeable impact on the system capacity.

A new PHASE algorithm is proposed for blind adaptive extraction of signal in the presence of interference by cyclostationary signal processing using an antenna array. The algorithm operates in an interference-limited system in which the desired and interfering signals have equal symbol rates, but slightly different carrier frequencies. Compared to the SCORE algorithm and a modified version of SCORE, the new algorithm provides a simpler and faster converging means to estimate the channel phase for diversity combining. There is no need to solve eigenequations or to calculate the stochastic gradient. Analytical and simulation results are presented and performances are compared with DMI (direct matrix inversion), and SCORE algorithms in terms of their convergence rate, steady state SINR, and the computation complexity. This method is relatively simple and very promising in application to indoor wireless communication for its ability to reject heavy interference and increase the spectrum efficiency. Analysis and simulation results are presented to confirm this ability.

The performance of a direct sequence spread spectrum (DS-SS) code division multiple access (CDMA) communications systems is highly dependent upon the set of spreading sequences used in these systems. The multiple access interference could become very large if the spreading sequences are not carefully selected. A new numerical optimization procedure is proposed for the selection of spreading sequences based on minimizing the interference parameter among the sequences. The improvement in the average output signal-to-noise ratio or CDMA capacity improvement is used to compare the performance of the optimized code set with that of the set of Gold codes of the same length. An improvement of about 26% in the system capacity is obtained. Also, construction of different optimized code sets suitable for use in cellular systems applications is considered.

Analyzes the MSE performance of three fractionally spaced adaptive equalization schemes, viz., (1) an MMSE DFE computed with estimated channel parameters, and directly adapted; (2) RLS and (3) LMS DFEs, which all require training at the beginning of a TDMA burst to minimize intersymbol and interuser interference and noise. The authors derive for the computed MMSE DFE an upper bound expression for its excess MSE which can indicate that this scheme performs worse than the directly adapted RLS DFE. They also employ an MSE convergence analysis to show that the directly adapted LMS DFE exhibits prohibitively slow MSE convergence in the presence of interference due to its sensitivity to the eigenvalue spread of the equalizer input signal autocorrelation matrix and the existence of a significantly lower MMSE in interference than in an equivalent amount of stationary noise. Thus, of the three equalization approaches considered, the directly adapted RLS DFE yields superior performance in interference.