In this paper, we have analyzed transmission time for WAP (Wireless Application Protocol) over Bluetooth using a multi-slot segmentation scheme. In order for SAR to improve the transfer capability, the transmission of messages have been simulated using a fragmentation scheme that begins with the total package and incremental fragmentation for each layer using the WTP (Wireless Transaction Protocol) to define the resultant packet size and the level of fragmentation for each proceeding layer. The data is divided into individual packets at the baseband level. This scheme decreases transmission time of L2CAP (Logical Link Control And Adaptation Protocol) baseband packets by sending packets that span multiple slots. From the results, we were able to obtain packet transmission time and optimal WTP packet size for WAP over Bluetooth in a Rician fading channel.

This paper investigates the asymptotic error rate behaviour for noncoherent OOK signalling scheme in the presence of Nakagami-m fading. A transcendental equation to compute the optimum threshold level is also derived. Comparison on trends in optimum threshold level and its corresponding ratio of the Mark and Space error probabilities between different channels are presented.

The transmission quality in mobile wireless communications is affected by not only the thermal noise but also the multipass fading which changes drastically an amplitude and a phase of received signal. The paper proposes the theoretical and approximate methods for deriving an average bit error rate in DS-CDMA systems under the Rician fading environment on the assumption of the frequency non-selective fading, as parameters of the number of simultaneous access stations, the maximum Doppler frequency and so on. It is confirmed from the coincidence of theoretical and approximate results with simulation ones that the proposed approach is applicable to a variety of system parameters.

This paper proposes a coherent detection scheme that can reduce the estimation errors of the carrier phase due to Gaussian noise in communication systems where pilot symbol assisted modulation is employed to compensate for Rician fading distortion. This paper introduces two functions in addition to conventional fading estimation methods using Wiener interpolation, etc. The first is the weighted average function for reducing the estimation errors of the fading distortion detected by pilot symbols. The second is the moving average function for estimating the phase errors that are residual after being compensated for by the estimated fading distortion. This paper evaluates the bit error rate (BER) performance for the proposed method in both Rician fading channel and additive white Gaussian noise (AWGN) channel by computer simulation. Simulation results verify that the BER performance of the proposed method is superior to that of a conventional method in both Rician fading channel and AWGN channel. Simulation results also confirm that the degradation of the BER performance of the proposed method is only 0.1 dB in AWGN channel and only 0.3 dB in Rician fading channel compared with the theoretical curves even if we reduce the number of computations by simplifying the calculation of interpolation coefficients optimized for Wiener interpolation.

Conventional approach for frequency estimation usually assume a single tone without data modulation. In many applications such an assumption, realized by using either a separate pilot beacon or synchronization preamble is not feasible. This paper deals with frequency estimation of phase-modulated carriers in the absence of timing information and known data pattern. We introduce new frequency estimators that are based on the generalized maximum likelihood principle. The communication channels under consideration include both additive white Gaussian noise (AWGN) channels and correlated Rician fading channels. For the latter class, we distinguish between the case when the fading (amplitude) process is tracked and that when it is not tracked.

The final closed-form expression of the bit error rate (BER) is presented for a DS-CDMA system using a maximal ratio combining (MRC) diversity in conjunction with simple channel coding over a Rician fading channel. The accuracy of the BER evaluated by this expression is verified through comparison with a semi-analytic simulation result. The effect of diversity order and channel coding on the bit error rate performance is also considered for typical multipath delay profiles with different Rician ratios.

The Rician factor is an important parameter in evaluating the outage probability and reuse distance of cellular systems. From the measurement of 1. 8 GHz radio propagation in outdoor urban microcells, it is found that the measured pdf of the Rician factor for low tier systems follows a lognormal distribution and the factor is independent on the propagation distance.

This paper presents a technique to transmit 16QAM signals in mobile radio environments by using extended symbol-aided estimation (ESAE) method for compensating the multipath fading effect. The main results of this paper are the symbol error rate (SER) performance analyses for BPSK and 16QAM systems using the proposed estimation method under Rician fading. The analytical results demonstrate better performance of the proposed systems compared with those of the conventional systems under fast and severe fading, especially in the region of high signal to noise ratio.

This paper proposes a novel FEC (forward error correction) scheme for high-speed wireless systems aiming at mobile computing applications. The proposed scheme combines inner nonredundant error correction with outer parallel encoding random FEC for differentially detected QPSK (quadrature phase shift keying) signals. This paper, first, examines error patterns after the differential detection with nonredundant error correction and reveals that particular double symbol errors occur with relatively high probability. To improve the outer FEC performance degradation due to the double symbol errors, the proposed scheme uses I and Q channel serial to parallel conversion in the transmission side and parallel to serial conversion in the receiving side. As a result, it enables to use simple FEC for the outer parallel encoding random FEC without interleaving. Computer simulation results show the proposed scheme employing one bit correction BCH coding obtains a required Eb/No improvement of 1.2 dB at a Pe of 10-5 compared to that with the same memory size interleaving in an AWGN environment. Moreover, in a Rician fading environment where directional beam antennas are assumed to be used to improve the degradation due to severe multipath signals, an overall Eb/No improvement at Pe of 10-5 of 3.0 dB is achieved compared to simple differential detection when the condition of delay spread of 5 nsec, carrier to multipath signal power ratio of 20 dB and Doppler frequency at 20 GHz band of 150 Hz.

An analysis of an imperfectly power controlled DS/CDMA slotted cellular system over the frequency selective Rician fading channel with an error correction coding is performed. The user capacity and packet throughput of reverse link are estimated to show the sensitivity to the power control error in a DS/CDMA system with Rician fading channel. The power control error are modeled with Gaussian random variables, which is a reasonable choice for its proved validity. The relative capacity decrease from the power control error in Rician channel are presented and compared with the results from flat fading channel. Performance results for the model considering multicell interference, pathloss exponent and power ratio of scattered component to direct component are presented.

The Shannon-Hartley theorem for channel capacity presupposes signal transmission over time-invariant Gaussian channels. In a mobile radio environment, communications channels have randomly time-variant characteristics. In this paper, an expression for the average capacity of Rician fading channels is derived. It is shown that the average capacity of Rician channels is always lower than that of the Gaussian channel, while the Rayleigh channel capacity values represent the worst situation. In addition, the Rician channel capacity is examined when reception by a maximal-ratio combining technique with M-branches is employed, indicating its positive effect on channel average capacity when weak signal power or severe fading conditions are present. Finally, the relation between Rician and Rayleigh fading environment with respect to channel average capacity is discussed.