| CDMA is one of the promising technologies for future mobile communicationsystem. Its several features can not be compared with other multiple accesstechnologies. At the same time, CDMA communication system is aninterference-limited system, that is to say, various types of interference can influencethe capability of the system and the QoS of users in the system. So directly how toovercome interferences has become an urgent problem in the CDMA system. PowerControl technology is proposed as a new method to deal with the problem, which canconquer Edge Effects and Near-Far Effects to enlarge the capacity of system and theQoS.First, in this paper, powercontrol technology is discussed, including its principle,methods of realization and status of research. Then reverse outer-loop power controlarithmetic based on FER (Frame Error Rate) measurement and adaptive variablestep-size inner-loop power control arithmetic are proposed. The simulation is doneand the result shows the deviation is smaller using the arithmetic fortracking the idealFER. As the application of RAKE receivers with multitaps is widely used in cellularCDMA systems for exploiting path diversity, the closed-loop power control schemesshould make use of the multitap RAKE receivers for tracking the power variation dueto path loss, slow fading, and fast fading. Comparing with traditional fixed-steppower control, it gets smaller deviation. Last, the author introduces simply theconcept and content of network optimization and gives the material step.The outer-loop power control arithmetic in this paper deals with and balances thetransmit power and FER. The outer-loop power control arithmetic can satisfy with thedemand of different operation. Adaptive variable step-size inner-loop power controlarithmetic can rather track channel change. So transmit power can compensatechannel fading fast and compensate. The simulation is done and the result shows thecapacity of CDMA system will be improved. |
PDF Full Text Request