TD-SCDMA Indoor Solution

TD-SCDMA standard is adopted by ITU in 2000 proposed by China as one of the 3rd generation mobile communication international standards. Proven by the experience of operating the 3rd mobile communication network in global, traffic generated in indoor is growing rapidly and accounts for major proportion in total traffic. A network with seamless coverage doesn't mean outdoor network construction only but also includes indoor network construction. Thus, a feasible TD-SCDMA indoor solution is quite vital to successful TD-SCDMA commercial deployment and business running.In 2007, TD-SCDMA trial network extended to 10 cities from 3 cities before, TD-SCDMA indoor network construction became focus consequently. Although operators accumulated a lot of experience in 2G indoor design and implementation as well as a little bit experience in WCDMA indoor, all of those experiences can not be copied completely to TD-SCDMA for technology differentiation between TD-SCDMA and the others. The principles of TD-SCDMA indoor design and implementation must be especially researched and defined based on TD-SCDMA technology characters. A joint team including operators, 3rd party and TD-TECH R&D center was set up to probe into TD-SCDMA indoor solution from three aspects: indoor design, implementation and acceptance via theoretical research and practical test.Based on the research and test results, the paper expatiates on the impact on TD-SCDMA solution from uplink capacity, downlink capacity, coverage balance, indoor link budget, minimum coupling loss, multi-system isolation, DAS loss estimation and so on. Since smart antenna can not be used in indoor environment, radio system performance and interference against ability is downgrade, capacity is interference limited but not codes limited. In order to improve capability of radio system, frequency in indoor should be different from that of outdoor. Certainly, in some special scenarios with very good isolation between indoor and outdoor, frequency can be reused by indoor or outdoor. Indoor link budget aims at maximum allowed transmission loss estimation used by DAS according to coverage balance between P-CCPCH and DPCH. As reference channel in indoor design, common control channel coverage must be balanced with dedicated physical channel coverage. Otherwise, call access failure rate and call drop rate will be growing up and can not be solved easily. Limited by link balance, power transmitting of signal source in indoor can not be increased arbitrarily, but practical loss requires much more power from signal source. In the case, repeater is necessary to compensate additional transmission loss if practical loss is much more than nominal maximum allowed loss. Therefore, in indoor solution, repeater can not be excluded entirely. Principally, noise floor increase must be controlled under 3dB in order to avoid capacity loss. The number of parallel connection repeaters should be less than 7.