Power control in UMTS Release '99

The CDMA technology used in UMTS relies on accurate power control techniques, not only for maximising the battery life of mobile terminals and maintaining signal quality, but also as an important means of optimising system capacity by controlling interference. This paper provides a detailed review of the power control mechanisms specified for UMTS Release '99, with the primary emphasis being on the requirements placed on the mobile terminals (known as user equipment (UE)). The review covers ordinary outer-loop and inner-loop power control, as well as power control in soft handover and in the compressed mode.