| Since it became commercial in September 1995, CDMA system developed rapidly as an important technology of providing wireless voice and data services. The data released by CDG(CDMA Development Group) show that more than 300 operators have deployed CDMA network, and CDMA2000 subscribers go up to 500 million, covering more than 100 countries or territories. As on November 2008 Qualcomm announced that they had gave up their 4G (the 4th Generation) network standard UMB (Ultra Mobile Broadband) and freezing its research and developing, CDMA operator around the world have chosen LTE as their evolutional technology via CDMA 1X EV-DO.At present, several cellular systems have deployed for seamless coverage, multi-system coexistence scenario is inevitable, coexistence interference could not be ignored. China Telecom, the CDMA operator in China owns two band on 800MHz and 2.1GHz. Due to the policy of co-construction and sharing, CDMA system deployed on 800MHz band has experienced a new coexistence scenario of the tower sharing and base station sharing, and system on the 2.1GHz band is also facing the coexistence of multi-system scenarios as deployed soon after.In this paper, coexistence scenarios through the evolution of CDMA system have been focused on, and coexistence interference has been studied.For the 800MHz band the field test has been studied, giving necessary isolation between systems of conexistence and construction advise on tower sharing and antenna sharing by interference test and drive test. And for the 2.1 GHz frequency band, specific analysis has been done on the two CDMA coexistence scenarios with TD-SCDMA and TDD LTE system, and gives recommendations to avoid interference. |
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