In practice, the DS-CDMA system is equipped with a finite number of Channel Element (CE)s that performs the baseband spread signal processing for a given channel in the base station. In this situation, the call blocking can be caused not only by the insufficient number of channel elements but also by the limit of available traffic channels. In this paper, we focus on analyzing the effect of the limited number of CEs on the Erlang capacity of multimedia DS-CDMA systems in the reverse link when the CDMA cells are sectorized with 3 sectors. For the performance analysis, a multi-dimensional Markov chain model is developed. As a result, the more CE results in the larger Erlang capacity. However, the Erlang capacity is saturated after a certain value of CEs where the call blocking is mainly caused by the insufficient channels per sector.

In this paper, we present an approximate analysis method for computing the call blocking probability and Erlang capacity of CDMA systems. The approximated results provide only a few percent difference from the exact values, while reducing the calculation complexity. For CDMA systems with 3 sectors, we also show that the system performances such as call blocking probability and Erlang capacity can be characterized just with two traffic parameters (the traffic load of the most loaded sector and the sum of traffic loads of the other remaining sectors) instead of three sector traffic loads especially when the required call blocking probability is given less than 2e-2, which makes the traffic engineers manage the system more easily.

In this letter, we present a procedure to analyze the delay distribution of data traffic in CDMA systems supporting voice and delay-tolerant data services with a finite buffer. The queueing method using a buffer for a delay-tolerant traffic can be used to improve the system utilization or the availability of system resources. Under the first-come and first-serve (FCFS) service discipline, we present a numerical procedure for the formation of delay distribution that is defined as the probability that a new data call get a service within the maximum tolerable delay requirement, based on a two-dimensional Markov model.

In this paper, the capacity is analyzed for a CDMA system supporting heterogeneous traffic with on/off activity. The capacity is analyzed by modeling the on/off traffic activity as a binomial random variable and compared to the conventional analysis with the simplified traffic activity factor which is a constant. It has been shown that the capacity with the conventional analysis is more optimistic than the capacity analyzed with the binomial modeling of traffic activity. The effect of traffic activity on the capacity is further investigated for two different cases. One is the case under the same transmission rate where the average rate changes according to the traffic activity. The other is the case under the same average rate where the transmission rate changes according to the traffic activity. As the traffic activity factor becomes larger, the capacity increases for the case under the same average rate, whereas it decreases for the case under the same transmission rate.

In this paper, we propose an analytical procedure for the Erlang capacity in the reverse link of the DS-CDMA systems supporting voice and data services with the limited number of channel elements. Especially, we focus on IS-95B type systems with sectorized directional antenna that support the medium data rates for data traffic by aggregating multiple codes in both directions, to and from the mobile device. For the performance analysis, a 6-dimensional Markov chain model is developed, and the Erlang capacity is depicted as a function of the offered traffic loads of voice and data. The call blocking is caused not only by the scarcity of channel elements that perform the baseband spread spectrum signal processing for the given channel in the base station, but also by insufficient available channels per sector. The effect of the different Grade of Service (GoS) requirements on the Erlang capacity is observed, and the optimum values of the system parameters such as channel elements are selected with respect to the Erlang capacity. Furthermore, we expand our approach to the multi-FA systems that support multiple CDMA carriers more than one. It is observed that Erlang capacity for a high FA can be well estimated through the linear regression with the Erlang capacity results of low FAs.

In this letter, a resource allocation scheme is proposed to efficiently utilize the resource of CDMA systems with respect to the throughput. When we let the throughput be a function of various data rates for multimedia traffics, the scheme is to find the optimum set of data rates for concurrent user groups with which we can achieve the maximum throughput. It is also shown that the optimum data rate set always includes one non-trivial rate while all the others keep the minimum required data rate.