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WP-CDMA: High Data Rates, Fast Handover, and Improved Performance

WP-CDMA is a wireless technology with uplink and downlink channels that support data rates up to 2.048 Mbps. It features fast handover, collision detection, adjustable power, and improved performance in rapidly changing environments.

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WP-CDMA: High Data Rates, Fast Handover, and Improved Performance

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  1. WP-CDMA Distinguishing Features 1. Uplink Common Packet Channel (All Rates) Common Packet Channel will transport all data rates up to · and including 2.048 Mbps. · Constant Power Level Preamble with 16 possible sequences Closed Loop Power Control, Preamble Ramp-up mechanism · Fast L1 ACK mechanism (within 250 micro-seconds) · • Collision Detection with Low Feedback Delay (2 ms) • Downlink Common Power Control Structure is under 2. Common Control Channel in the Downlink 3. Intra-frequency Hard Handover 4. Quick Handover 5. Structure of the WP-CDMA CCPCH (Common Control Physical Channel) • TM Common Pilot for coherent demodulation • Adjustable Power SCH1 And SCH2 for faster initial Cell search 6. Multi-code Option for Higher Rates • The relationship between the VSF and number of multi-codes is the subject of • further study 7. Higher APC Rates 8. Removal of Link Maintenance Channel

  2. 0 1 2 64 0 1 2 64 0 1 2 64 0 1 2 64 Frame 1 Frame 2 Frame 3 Frame 4 Lowest call dropping • Fast link re-acquisition (call dropping) • Fast adaptation to rapidly changing multipath profile • (call dropping) Link Re-acquisition BS1 BS1 BSn Corner Effect … … … 0 1 2 64 0 1 2 64 … 0 1 2 64 … t. t1 t1

  3. Quick Handover Procedure 1. Each Mobile is maintaining a list of channelization codes of a list of scrambling codes corresponding to target Quick HO Base Stations. 2. In case of complete loss of signal, the Mobile invokes the quick HO procedure and starts the quick cell search algorithm. Once it determines the best BS, it switches over to that channel immediately. It waits for TBD ms and then it transmits its frames. 3. The Base will notify the neighbor base stations immediately in case the mobile signal is completely lost. 4. At a predetermined frame, Mobile Station transmits to target BS at the known common channelization code at the predetermined power level and ramps up. 5. During the same frame the target Base Station compresses the first frame (if needed) and perform switching. Subsequent frames are not compressed.

  4. WP-CMDA Performance Advantages • Significantly lowers the call drop rate • Combats corner effect • Adapts to rapidly changing multipath profile • Improves order of diversity

  5. WP-CDMA Performance Advantages Due to Adjustable Higher Power Synch Channel Handover Performance Fast searcher, fast neighbor detection for idle and active soft or hard handover De-correlation length for Vehicular = 20 m, v = 250 km/h, t1=288 ms, v2=125 km/h, t2= 576 ms 1 10 cells x 500 ms = 5 s (Without TM Common Pilot) 10 cells x 100 ms = 1000 ms (With TM Common Pilot WP-CDMA) Relevant to quick HO, idle and active HO (cold start cases) S S S S S S S BS1 BS2 BS3 BS4 BS5 BS6 BS7 t m 625 sec. 1 slot MF t

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