In this paper, we consider an integrated voice and data system over CDMA Slotted-ALOHA (CDMA S-ALOHA). We investigate its performance when multi-code CDMA (MC-CDMA) is applied as a multi-rate scheme to support users which require transmission with different bit rates. Two different classes of data users are transmitted together with voice. Performance measurement is obtained in respect of throughput for data and outage probability for voice. Moreover, we consider the Modified Channel Load Sensing Protocol (MCLSP) as a traffic control to improve the throughput of data. As a result, we show that the MC-CDMA technique is an effective one to obtain good throughput for data users at an acceptable voice outage probability. Furthermore, we show that with MCLSP, the throughput of data can be improved to reach a constant value even at a high offered load of data users.

In this paper, we discuss the access control in multimedia CDMA ALOHA protocol. We introduce a new algorithm for the access control based on Modified Channel Load Sensing Protocol (MCLSP) in an integrated voice and two different classes of data users, high bit rate and low bit rate, exist in a multi-code CDMA Slotted ALOHA system. With our new algorithm, we show that the throughput of high bit rate data users, as well as, the total throughput of the data medium can be optimized and take a maximum value even at high values of offered loads. We also investigate the performance when voice activity detection (VAD) is considered in voice transmission.

In this letter, performance evaluation of a system that combines between Code-Division Multiple Access (CDMA) and ALOHA protocol in multimedia networks is presented. In our analysis, we compare the performance between the two basic techniques of ALOHA protocol, i.e., Slotted-ALOHA (S-ALOHA) and Unslotted-ALOHA (U-ALOHA), when combined with CDMA scheme to support voice and data users operating in same CDMA channel. The quality of service (QoS) required for voice and data media is completely taken care of. We obtain the throughput of data media, and the outage probability for voice considering both voice and data offered loads. Throughput performance of S-ALOHA technique is almost twice of that of U-ALOHA. However, we show in this letter that when we combine CDMA with the two basic techniques of ALOHA to accomplish multimedia transmission, both techniques have almost same performance. And, thus, CDMA U-ALOHA can be a good candidate for multimedia networks.

In this letter, we present bit error analysis (BER) of orthogonal multi-carrier direct sequence code division multiple access (DS-CDMA) system with multi-rate (multimedia) traffic. Analysis is carried out with random signature codes for an AWGN channel. Interference in such a system is severe because all users of all media transmit over the same assigned sub-carriers. This makes the analysis difficult. In our analysis, we divide this interference into different types and carry out our analysis to obtain the BER taking into account all these types. We show that the performance of the system is improved as the number of assigned sub-carriers M increases until a limit where the improvement does not continue even when M increases more. This is because of, as we show, the interference due to other sub-carriers becomes constant even in the case of M , and the interference in a multi-rate multi-carrier system is bigger than that in a single-carrier (M=1) by a factor of π2/3.

In this paper, we focus on an integrated voice and data system over a CDMA Unslotted ALOHA and investigate the effect of transmission control for data traffic. We consider Channel Load Sensing Protcol (CLSP) as a transmission control protocol and investigate the effect of the thresholds, which may differ due to the requirement of each medium. As a result, we find that the threshold assigned for data is very effective to improve both performances of the throughput for data and the Erlang capacity for voice users, and also, to correspond to the priority for both media. Consequently, we obtain an optimum threshold for data to make the best use of the total channel capacity.