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Published byMervin Townsend Modified over 9 years ago
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2 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 2. Common Control Channel in the Down Link 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
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4 What are the Information Transfer and Information Quality Attributes of These Services? Information Transfer Attribute Connection ModeConnectionless, Connection- oriented Traffic type attributeCBR, VBR, ABR, UBR Symmetry attributeBi, Uni Information transfer rate12 kbps, 2 Mbps Information Quality Attribute Maximum transfer delay80 ms, 1 s, 30 s Delay variation Bit Error Rate10 –6, 10 –9 Error CharacteristicsBursty, uniform
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5 How can the Common Air Interface be Optimized for Packet Data Services? The CAI should be able to support high bit rates (up to 2 Mbps), bursty, asymmetric, non-real time bearer capabilities The CAI should support the connectionless mode as well as the connection-oriented modes The CAI should be able to support packet switching as well as circuit switching transfer modes The QoS on demand and flexibility to provision various information quality attributes per connection (implications on physical layer, the MAC and DLC) Minimize interworking functionality Maintain the same QoS in the wireline and wireless systems Minimize interference at the air interface Minimize resource requirement at the base station Optimize the IP protocol suite for the air interface Implementation of optimum bandwidth allocation at the air interface
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6 WP-CDMA Distinguishing Features Common Packet Channel (All Rates) Common Packet Channel will transport all data rates up to and including 2.0489 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 Control Channel Structure
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7 F AB MOB ID F A B MOB ID F AB MOB ID B User i+1 Packet M User i Packet M M User i + 2 Packet 1 User i Packet E E User i+3 Packet 1 E User i+1 Packet M User i + 3 Packet 1 F = Free A = ACK B = Busy Mob ID = Temp ID for Collision Detection E = End M = More CPCH UL WP-CDMA Common Packet Channel Uplink
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8 Packet 1Packet 2Packet 3 t i User i T inactivity Packet 1Packet 2 t i+1 User i+1 T inactivity t i Packet 1 t i+2 User i+2 T inactivity Short Term Circuit Assignment Packet 2Packet 3Packet 4 t Packet 1Packet 2Packet 3 User n i+1 n t
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9 Closed Loop Power Control Courtesy of AT&T Labs
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10 Packet Length in Kbyte Capacity Ratio P-S/C-S Channel inactivity = 50 ms Channel inactivity = 500 ms Channel inactivity = 1 s Advantages of Statistical Multiplexing 144 kbps Capacity Ratio Versus Packet Length in Kbyte P B =2% 100% Duty Cycle
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11 384 Kbps Capacity Ratio Versus Packet Length in Kbyte P B =2% 100% Duty Cycle 8.176 2.85 R i19 R i10 R i1 272.5l i 8 051015202530 2 3 4 5 6 7 8 9 Packet Length in Kbyte Capacity Ratio P-S/C-S Channel inactivity time = 1 s Channel inactivity time = 500 ms Channel inactivity time = 50 ms Advantages of Statistical Multiplexing
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12 2048 Kbps Capacity Ratio Versus Packet Length in Kbyte P B =2% 100% Duty Cycle 42.84 7.427 R i19 R i10 R i1 425l i 8 51015202530354045 5 10 15 20 25 30 35 40 45 Channel inactivity time = 1 s Channel inactivity time = 500 ms Channel inactivity time = 50 ms Packet Length in Kbyte Capacity Ratio P-S/C-S Advantages of Statistical Multiplexing
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13 1 ms.25 ms I Q Data/Control Preamble ramp-up N x TBD ms UL-CPCH Burst Structure
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14.625 ms, 10 x 2 k bits (k=0,….6) N data bit 1 Data N data bit 1 Data Pilot N pilot bits Pilot N pilot bits TPC N TPC bits TPC N TPC bits RI N RI bits RI N RI bits CD bits N CD UL-CPCH I Q I Q Slots 0 Slots 1 UL-CPCH Slot Structure
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15.625 ms, 10 x 2 k bits (k=0,….6) N data bit 1 Data Pilot N pilot bits TPC N TPC bits RI N RI bits UL-CPCH I Q Slot #1Slot #2Slot #iSlot #16 T f = 10 ms UL-CPCH Frame Structure
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16 Data Power Control N x TBD ms 1 ms.25 ms DL-CCCH UL-CPCH CCCH: Common Control Channel CPCH: Common Packet Channel L1 ACK TBD Procedure Based Overall Protocol Operation
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17 DL-CCCH BS F 0 1 2 3 4 5 6 7 2.5 ms 8 mini-slots ACKCD TBD F 1.875 ms 1ms 250 s Slot 0 625 s BS MS UL-CPCH Collision Feedback Delay Cycle
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18 Overall Protocol Operation DL CCCH ACK/NAK 1.25 ms LI ACK UL CPCH CD PC ARQ
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21 Throughput Performance of DSMA Impact of Low Collision Feedback Delay
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22 Performance Advantages of Uplink Common Packet Channel (Summary-1) Proven improved throughput performance for short bursty traffic and high peak rate Sample pt: 384 kbps, L=4 Kbyte, Access overhead = 500 ms, P B = 2% Throughput improvement Ratio= 5 UDD Services Improved delay performance of M/M/1 (packet switched) over M/M/n (circuit switched) for longer packets Common Packet Channel approach requires an order of magnitude less BS resources (modems) as compared to Short Term Circuit Assignment. M/M/10 requires 10 times more modems in the BS as compared to M/M/1
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23 Statistical multiplexing advantages for bursty traffic Less delay M/M/1 versus M/M/n Resource minimization and less hardware complexity Facilitation of higher peak rates Performance Advantages of CPCH-UL Queuing time & transmission time Limitations of circuit switching trunking efficiency (Summary-2) Optimum prioritization scheme Optimum bandwidth allocation in a mixed circuit-switched/packet switched air interface operation in short time window (frame by frame basis)
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