Throughput–delay performance of interference level-adaptive transmission in voice∕data integrated CDMA network with variable spreading gain

Abstract

The throughput and delay performance of adaptive spreading gain uplink packet transmission in real-time and non-real-time data integrated CDMA networks are analysed under AWGN and Rayleigh fading channels. The processing gain for the non-real-time data is adaptively changed according to the total uplink interference level so that a required signal-to-interference ratio (SIR) can be achieved. The optimum values for the required SIR with regard to maximising the throughput are derived as a function of packet length. The optimised adaptive rate system achieves significantly improved throughput compared to the non-adaptive rate system. In addition, the adaptive rate system achieves almost linear increase in packet delay with traffic density, while the packet delay of the non-adaptive rate system shows an abrupt increase as traffic density increases.

Performance of packet data in adaptive processing gain CDMA with correlated interferers and truncated ARQ

“…As compared to a fixed rate system, adaptive rate transmission is efficient in increasing the capacity of time varying wireless channel in which the transmission rate can be adaptively adjusted according instantaneous channel conditions or traffic intensity [1,3,4]. Adaptive rate transmission is achieved through adaptive variation of symbol rate, constellation size, spreading factor, coding rate/scheme or any combination of these parameters.…”

Transmissão Adaptativa em Redes Ad Hoc CDMA

“…Em sistemas com controle de potência e taxa de dados fixa, existe uma limitac ¸ão prática com relac ¸ão ao número de usuários de modo a garantir comunicac ¸ão segura. Outro problema relacionado a sistemas que utilizam taxa de dados fixa ocorre quando o nível de tráfego é muito menor que o número prático de usuários na rede, assim existe uma margem redundante na capacidade do sistema [10].…”

“…Estudos em transmissão adaptativa para minimizar os problemas citados acima e utilizar os recursos do sistema mais eficientemente são encontrados em [10]- [14]. Em [15] investigou-se os efeitos da modulac ¸ão adaptativa no contexto de redes ad hoc CDMA.…”

Adaptive Processing Gain Data Services in Cellular CDMA in Presence of Soft Handoff with Truncated ARQ

“…Several research papers have analyzed adaptive transmissions based on VSG [1][2][3][4] without considering the effects of soft HO. Since soft HO affects the generated interference, it is expected to have significant impact on spreading gain selection and successful transmission of packet data, which is considered in the present paper.…”

“…However for a fixed data rate system, there will be redundant margin on system capacity when traffic level is much lower than the maximum allowed number. Adaptive transmission schemes utilize the system resource more efficiently over a fixed rate scheme where the data transmission rate is controlled depending on generated interference or channel traffic intensity [1][2][3]. Packet data transmission is gaining importance in CDMA networks.…”