2011年4月14日星期四

Greater system capacity

In the TD-SCDMA system, a single-frequency cell (1.6 MHz bandwidth) has a theoretical capacity of 23 AMR 12.2 kbps voice users, or 6 PS 64/64 kbps packet data service channels. A 3-carrier N-frequency cell (5 MHz bandwidth) has a theoretical capacity of 71 AMR 12.2 kbps voice channels, or 18 PS 64/64 kbps packet data service channels. Compared with other 3G systems with the same frequency resources, TD-SCDMA offers a larger system capacity:

  • For voice services, TD-SCDMA frequency utilization is 15 users/MHz/cell, while that of UMTS and of cdma2000 are 6 users/MHz/cell and 8 users/MHz/cell respectively. For data services, that of TD-SCDMA is 1.25 Mbps/MHz/cell, while that of UMTS and cdma2000 are 0.4 Mbps/MHz/cell and 1.0 Mbps/MHz/cell respectively. With the same spectrum width, the TD-SCDMA system can support more users and provide higher throughput.
  • The TD-SCDMA system adopts FDMA /TDMA/CDMA modes, which offer a high spectrum utilization and higher system capacity.
  • The TD-SCDMA system adopts smart antennas and joint detection technology to make full use of the space division feature, reducing intra-cell and inter-cell interference and improving system capacity.
  • The TD-SCDMA system is a synchronous system. Ideally, the signals from various terminals on the uplink are fully synchronized at the Node B demodulator to ensure that various code channels of the orthogonal spread code maintain orthogonality during the de-spread process, without Multiple Access Interference (MAI) for higher system capacity

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