The DS-CDMA system with a bandwidth of approximately 1MHz, i.e. IS-95, is generally named as narrowband CDMA system. But WCDMA owns a chip rate of 3.84Mcps, bringing approximately 5MHz carrier bandwidth.This feature enables the system to support higher bit rate, and at the same time brings other benefits, for example, increasing of multi-path diversity.
Gold sequence is used as scrambling code in WCDMA
In IS-95, only coherence detection is used in the downlink, but in WCDMA, coherence detection based on pilot symbol or common pilot is adopted for both the uplink and the downlink, increasing the coverage scope and the capacity of the uplink. IS-95 only uses closed loop power control in the uplink, while WCDMA uses this in both of the uplink and the downlink.With the closed loop power control used in the downlink, link performance and downlink capacity is improved.
IS-95 system mainly aims at macro cell. Because BTS synchronization is necessary, BTS is generally placed on the roof, etc. for the sake of receiving GPS signal. In this case, a global time reference can be used. But this application is difficult to carry out in the places where it is hard to receive the GPS signals. WCDMA system supports asynchronous BTS operation, and it may not use the global reference, thus it is different with the IS-95 system requiring BTS synchronization operating mode. Thus, the application of indoor cell and microcell is much simpler. This makes that the handover of WCDMA is slightly different with that of IS-95.
IS-95 system mainly aims at macro cell. Because BTS synchronization is necessary, BTS is generally placed on the roof, etc. for the sake of receiving GPS signal. In this case, a global time reference can be used. But this application is difficult to carry out in the places where it is hard to receive the GPS signals. WCDMA system supports asynchronous BTS operation, and it may not use the global reference, thus it is different with the IS-95 system requiring BTS synchronization operating mode. Thus, the application of indoor cell and microcell is much simpler. This makes that the handover of WCDMA is slightly different with that of IS-95.
- Channel bandwidth: 5MHz
- Chip rate: 3.84Mcps
- Frame length: 10ms
- Voice coding: AMR (Adaptive Multi-Rate)
- Uplink and downlink modulation: QPSK/QPSK
- Coherence demodulation aided with pilot
- Fast closed loop power control: 1500Hz
- Handover: soft/hard handover
- Support synchronous and asynchronous NodeB operation
- Satisfy the minimum performance requirement of IMT2000
- Compatible with GSM-MAP core network
- Comparatively steady version R99 has been released
- Support open loop and closed loop transmit diversity mode
- Support Common Packet Channel(CPCH) and Downlink Share Channel, adapt to Internet data access mode
- Support macro diversity, selection diversity of NodeB location
- Support different fast power control algorithms and open loop, out loop power control
- Fully support UE locating services
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