Presentation on theme: "1. 2 WP-CDMA Distinguishing Features 1. Uplink Common Packet Channel (All Rates) Common Packet Channel will transport all data rates up to and including."— Presentation transcript:
2 WP-CDMA Distinguishing Features 1. Uplink Common Packet Channel (All Rates) Common Packet Channel will transport all data rates up to and including 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) 6. Multi-code Option for Higher Rates The relationship between the VSF and number of multi-codes is the subject of further study TM Common Pilot for coherent demodulation Adjustable Power SCH1 And SCH2 for faster initial Cell search 7. Higher APC Rates 8. Removal of Link Maintenance Channel
3 Hard Handover Hard Handover Physical Layer Procedure The gain of Soft Handover over Hard Handover diminishes as B.W. increases. Soft Handover is critical for N-CDMA, but not W-CDMA The order of diversity is much higher in W-CDMA as compared to N-CDMA, so the gain of Soft Handover over Hard Handover is much less. Hard handover is less complex as compared to soft handover
4 Hard Handover Proposal D PKT U1 D PKT U2 D PKT U3 PKT U4PKT U5 T offset PC t DDD PKT D1 PKT D2PKT D3 MS t t BS 1 Controlling Base BS 2 Target Base T offset PC PKT D4PKT D5 Common Pilot T offset = time offset between BS 1 and BS 2 UL and DL Frames are assumed to be time- aligned Common Pilot
5 Hard Handover Physical Layer Procedures: Mobile Station monitors all Base Stations in neighbor list Mobile Station sends RSSI measurements to it’s controlling Base Station Controlling Base Station decides to handover (procedure based) Controlling Base Station notifies Mobile Station and target Base Station The target Base Station notifies both the controlling Base Station and the MS of the scrambling code and channelization code for the Mobile Station. The controlling base station notifies both the MS, target BS and the switch of the time of handover. At a pre-determined time, the MS starts transmitting the frame which has PC bits at higher rate (TBD), as well as rate information indicating the rate of the next data frame. The MS ramps up the power from the beginning of the frame. At a pre-determined time, the target BS starts transmitting the PC frame to the MS at the initial open loop power level. The power will be ramped up in a stepwise fashion. The PC bits will be +1 while there is no response from the other side. The MS and the target BS send a single PC frame and compress the next data frame and begin transmitting the data frames subsequent to the PC frame.
6 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 1 = 250 km/h, t 1 =288 ms, v 2 =125 km/h, t 2 = 576 ms 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) BS1BS2BS3BS4BS5BS6BS7 t 625 sec. 1 slot MF t S SSSSSS