TAILIEUCHUNG - Wideband tdd wcdma for the unpaired spectrum phần 10

Hình 8,15 cho thấy rằng khi kiểm soát quyền lực không được sử dụng trong hệ thống TDD, xác suất bị cúp điện thoại di động TDD trở nên lớn hơn đáng kể khoảng cách 2 mét hoặc ít hơn (mặc dù khả năng thất bại vẫn còn dưới 20%). Khi kiểm soát quyền lực được kích hoạt, hiện tượng này gần như biến mất. | Coexistence 227 Figure TDD Outage Probability as a Function of Distance Figure shows that when power control is not used in the TDD system the outage probability of TDD mobiles becomes significantly larger for distances of 2 meters or less although the likelihood of failure is still below 20 . When power control is activated the phenomenon almost disappears. The outage probability becomes practically independent of the distance from an active FDD mobile. Conclusion The robustness of the TDD system to MS-MS interference is not surprising and stems from the unique features of TDD. CDMA systems are generally interference-limited. As new users are added while at the same time pathloss changes the power control functions guarantee that as long as BS power suffices each user is allocated just enough power to fulfill their C I requirements. Where traffic is too heavy BS power does not suffice at which point interference degrades the C I ratio beyond the threshold of the receiver detection capability. While both FDD and TDD share this general principle TDD differs from FDD in two important areas that have an impact on how radio resource management RRM in the network best handles each radio access mode to maximize capacity and coverage these are Multi-User Detection MUD and Dynamic Channel Allocation DCA . As explained in Section MUD provides significant C I performance improvements through cancellation of interference from other UEs within a given cell. The result of the MUD is that in those cases where FDD MS interferes with a TDD MS thus causing an increase in the required DL power for that user that increase will have no effect on other users in the cell as long as BS power suffices . This is markedly different from a system without intra-cell interference cancellation such as a standard 228 Deployment Scenarios FDD system where an increase in the power required by one of the users will create an increase in the power required for all causing a .

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