The three-dimensional (3-D) Fourier transform of the nonaccelerating object in an image sequence lies on a plane passing through the origin of the 3-D frequency domain. Instead of using a 3-D frequency planar filter, we propose a new filter design technique for object tracking using a one-dimensional trajectory filter-in the spatiotemporal domain. This filter can track a moving object with linear or nonlinear trajectory without prior knowledge of the target trajectory. Also, it is easy to design and has a very low computational complexity. More importantly, it can be implemented in real time.

The RAKE receiver is one of the most critical subsystems for CDMA communication systems. The RAKE receiver is used to combat multipath channel fading by using multiple fingers each targeted at a path of different delay and then soft-combine the signals from different fingers together. The "soft" combination at the RAKE receiver presents the intrinsic diversity gain spread over different paths. Usually, a traditional RAKE receiver combines the signals from different fingers based on the weights that are proportional to the measured pilot strengths at different fingers. This paper proposes using weights that are the ratios of the measured pilot strength to the measured variance at different fingers. By using the proposed weights, the performance of RAKE receiver can be improved up to 0.9 dB. An analytical methodology is derived to assess the performance. The performance improvement is reflected directly to the system capacity and system throughput.

This paper extends the traditional Clarke/Jakes (1968, 1974) model for a frequency flat fading process in a land mobile radio system to facilitate the examination of coherent space-time demodulation systems. The work develops a space-time correlation function using a ring of scatterers model around the mobile unit. The resulting correlation function permits the investigation of a variety of issues concerning base station configurations in space-time systems. The interrelationship of the fading process between the space and the time domain is explored. A detailed example regarding the effects of antenna separation in a receiver diversity system is considered. A set of design rules for interleaving depth and antenna separation in a space-time modem is presented and quantified.

This paper presents a methodology for analyzing the forward link performance of a pilot-aided coherent DS-CDMA system under correlated Rician fading. In the forward link of a CDMA system, orthogonal modulation is usually used to minimize the self-interference. To maintain the orthogonality and reduce the receiver complexity, a common pilot channel (shared by all users) is employed to provide the reference for coherent demodulation. A tradeoff shows that a higher pilot ratio yields good channel estimates but takes away some capacity from traffic users, while a lower pilot ratio results in poorer channel estimates and leads to higher traffic power per user. This paper derives the analytical error performance, which includes (1) imperfect channel estimation by the pilot channel, (2) a very general channel model where correlations between paths as well as Rician fading are considered, and (3) interference patterns due to multiple paths and the surrounding base stations' transmissions. This paper also considers self-interference due to the loss of orthogonality caused by pulse shaping.

Evaluation of forward link Erlang capacity for CDMA systems has been a troublesome issue. (1) CDMA systems do not have hard limitation in traffic channels due to resource partitioning such as frequency reuse, time slot multiplexing etc. (2) CDMA systems allow soft handoff which makes the computation on per cell or per sector basis difficult. Traditional ways to obtain the forward Erlang capacity can be too time-consuming by large scale simulations or not sufficiently accurate by table-lookup with weighted averaged number of users per cell. This paper presents a semi-analytical methodology to evaluate the Erlang capacity by iterative assessment of conditional probability distribution of traffic loading through all possible scenarios. Necessary statistics such as soft handoff and power consumption based on geometry are obtained via deployment-based simulation. A numerical evaluation is performed on the newly proposed cdma2000 system to demonstrate the methodology.

Pilot symbol assisted modulation (PSAM) is known to provide good performance in estimating the multiplicative distortion of fading channels. The 2-D space-time PSAM is derived and analyzed in this paper by applying the multiple-antenna reception at the base station. The interrelationship between temporal and spatial correlations is shown to provide better channel information than using the temporal correlation solely. The average mean square error (MSE) per antenna and the binary phase shift keying (BPSK) bit error probability (BEP) are used to characterize the performance analytically and draw comparisons with the traditional 1-D PSAM. When 5 antennas are used, the 2-D space-time PSAM has better average performance over the l-D PSAM for about 4 dB of MSE or 1 dB of BPSK BEP.

Transmitter diversity wireless communication systems over Rayleigh fading channels using pilot symbol assisted modulation (PSAM) are studied. Unlike conventional transmitter diversity systems with PSAM that estimate the superimposed fading process, we are able to estimate each individual fading process corresponding to the multiple transmitters by using appropriately designed pilot symbol sequences. With such sequences, special coded modulation schemes can then be designed to access the diversity provided by the multiple transmitters without having to use an interleaver or expand the signal bandwidth. The code matrix notion is introduced for the coded modulation scheme, and its design criteria are also established. In addition to the reduction in receiver complexity, simulation results are compared to, and shown to be superior to, that of an intentional frequency offset system over a wide range of system parameters.

Pilot symbol assisted modulation (PSAM) is a practical technique in mobile digital communications since it can provide high performance in fading with large constellations and it has a simple implementation. Maintaining high performance with PSAM requires an accurate estimate of the transmitted carrier frequency. This paper examines model-based frequency estimation for mobile digital communications with PSAM. Maximum-likelihood estimators (MLE), which include the model for the fading, are derived and compared with those in an additive white Gaussian noise (AWGN) channel, and performance hounds are computed. Reduced complexity frequency estimators based on the MLE are derived and the performance is quantified by Monte-Carlo simulation.