Data Traffic Control and Capacity Evaluations for Voice/Data Integrated Transmission in DS-CDMA


IEICE TRANSACTIONS on Communications   Vol.E81-B   No.7   pp.1355-1364
Publication Date: 1998/07/25
Online ISSN: 
Print ISSN: 0916-8516
Type of Manuscript: Special Section PAPER (Special Issue on Third Generation Land Mobile Communication Systems)
voice/data integrated transmission,  DS-CDMA,  traffic control,  circuit switching method,  contention-type packet switching method,  reservation-type packet switching method,  

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The next generation mobile communications systems must support multimedia communications services as well as conventional voice service. DS-CDMA is regarded as the most promising candidate, because it is indispensable to cope with multimedia. The system capacity of DS-CDMA system is limited by the total interference level. As a result, in DS-CDMA systems many users suffer very poor communication quality if the total interference level exceeds this limit. Therefore, this paper considers smoothing interference fluctuation using the difference between voice and data in a type of QoS (quality of service). In other words, voice communication is suitable for a loss system because the quality of voice communication is delay-sensitive. On the other hand, data communication is suitable for a waiting system because the quality of data communication is non-delay-sensitive. This paper focuses on a system that applies a circuit switching method for voice traffic and a reservation type packet switching method for data traffic and proposes a data traffic control method. In this proposed data traffic control method, a base station controls data transmission from a mobile station to utilize unused voice traffic resources. As a result, the proposed method achieves highly efficient use of the radio spectra by smoothing interference fluctuation in DS-CDMA systems. This paper evaluates the performance level of the proposed method from a system capacity standpoint. It is shown that the proposed method achieves higher system capacity in voice/data integrated transmission.