Common packet channel (CPCH) access is an efficient approach to support packet data transmissions in a wideband code division multiple access (W-CDMA) system. This paper investigates a modified CPCH access method which provides prioritized services for various traffic classes. Each traffic type has a distinct transmit permission probability that is estimated at the new call initiation stage based on the status of CPCH channel occupancy. The differentiated service qualities are evaluated in terms of packet blocking rates. The overall system performance is also evaluated in terms of throughput.

Because of the continually increasing demand for mobile communications, it has been suggested that personal communication networks (PCNs) be established in the 1850-1990 MHz range. However, that band of frequencies is currently occupied by various microwave signals transmitted by users ranging from utility companies to state and local agencies. In order to allow both sets of users to occupy these frequencies as well as improve the spectral efficiency of this band, a spread-spectrum overlay is proposed, whereby a code-division multiple-access (CDMA) PCN would share the spectral band with the existing narrowband microwave traffic. The results of several field tests which have been designed to demonstrate the feasibility of an overlay of this type are discussed.>

Direct-sequence spread-spectrum (DS-SS) transmission are difficult to intercept. The theoretical analysis of intercept performance against such systems has always been a difficult task if the noise samples are correlated. Thus, many results are purely experimental and lack a generality which can only be achieved from theoretical considerations. The target system described is a DS-SS communications system operating environment which consists of additive white Gaussian noise and continuous wave interference. The interceptor uses a radiometer in conjunction with interference excision techniques to detect the presence of the target signal. It is shown that much of the interceptor's effectiveness is restored by the interference excision.>

The transmitted data rate is a function of the channel state and is varied in such a way as to keep the probability of bit error approximately constant. The performance measure of the system is the probability of successful message completion in a given time span T/sub D/. Optimum operational signal-to-noise ratios are found as well as practical limits on the maximum and minimum transmission data rates. It is shown that the adaptive data rate feature provides a significant improvement in system performance as compared to a system transmitting at a fixed data rate. The performance improvement which can be obtained by the use of forward error correction coding is also analyzed. The codes considered are Reed-Solomon codes with rates of 1/3, 1/2, and 2/3. A much simpler expression for the probability of successful completion of a message is derived and used in the optimization search.>

An analysis is presented of a BPSK-PN (binary phase shift-keyed with pseudonoise) demodulator when present narrowband interference is attenuated using transform domain filtering. The signal of interest is a wideband direct-sequence spread-spectrum signal (DS-SS). The interference is a narrowband signal which may be of high power and which is either intentionally or unintentionally collocated in frequency and interfering with the signal of interest. The effect of windowing the input signal by a rectangular or Hamming windows as well as the use of an overlap and save scheme is presented. It is shown that the Hamming window far outperforms the rectangular window, and that the interference is for all purposes completely eliminated when the Hamming window is used in conjunction with the overlap and save scheme. The criterion used to evaluate the effectiveness of the different interference rejection techniques is the bit error rate (BER) as measured at the output of the demodulator.>