2. Fundamentals of EVDO Dr. Shahzada Alamgir Khan

3. Contents Introduction Basic Concepts Air Interface New technology

4. EVDO Rev A What is CDMA2000 1xEV_DO Rev. A? –3G evolved from IS-2000 and optimized for packet data/packet voice services –High data rates –Download:3.072 Mbps –Upload :1.8432 Mbps

5. Network Structure

6. Comparison 1x EV_DO Rev 01x EV_DO Rev A Multi-Address TypesF:TDMA+CDMA+H_AR Q R:CDMA F:TDMA+CDMA+H_AR Q R:CDMA+H_ARQ ServicesPacket Data Service only F/R Data Rate()2.4576Mbps/153.6Kbps3.072Mbps/1.8Mbps Chip Rate1.2288Mcps Channel CodingTurbo code Modulation TypeF:QPSK/8-PSK/16-QAM R:BPSK F:QPSK/8-PSK/16-QAM R:BPSK/QPSK/8-PSK Frame Length26.667ms Power ControlF: No power control R:Open & Closed loop F: No power control R:Open & Closed loop/T2P Soft HandoffF: Virtual Soft/Softer Handoff R:Soft/Softer Handoff F: Virtual Soft/Softer Handoff R:Soft/Softer Handoff

7. EVDO 0 key technology Forward link TDM P-fair scheduler Forward link virtual soft handoff Adaptive modulation and coding Hybrid-ARQ Reverse channel enhanced

8. Forward link TDM Forward channel is TDM shared by users. The smallest assignment unit for one user is slot, which can be assigned to a single user or to overhead message. If there is traffic or overhead in the slot called active slot, otherwise called idle slot.

9. Forward channel slot structure MAC 64 Chips Pilot 96 Chips Pilot 96 Chips MAC 64 Chips MAC 64 Chips MAC 64 Chips Data 400 Chips Data 400 Chips Data 400 Chips Data 400 Chips MAC 64 Chips Pilot 96 Chips MAC 64 Chips MAC 64 Chips Pilot 96 Chips MAC 64 Chips ½ Slot 1024 Chips ½ Slot 1024 Chips Active Slot Idle Slot 1 time slot = 1.666…msec = 2048 chips Full power transmit Data part in slot is shared by traffic channel and control channel

10. P-fair scheduler 1. Function ： Used to decide which user is to be served next slot. 2. Goals: –Do the best to be fair to all users in the same sector –Do the best to get the peak of sector throughput

11. Forward virtual soft handoff Reverse Link: Soft Handoff Forward link: Virtual soft handoff –There is only one leg which sends packet data to one single AT –It is decided to choose which sector is serving sector by AT according to quality of different sectors forward channel

12. Forward virtual handoff servering sector Pilot/MAC on FWD link Pilot/DRC/ACK/Traffic on REV Link (AP’s in AT’s active set) Forward data from AP2 after handoff AP 1 AP 4 AP 2 AP 3 Server before t 1 Server before t 1 Server after t 1 Server after t 1 AP 1 AP 2 Time Serving AP t1t1 t1t1 Serving AP change Serving AP change

13. Virtual handoff realization Mechanism ： –AT sends information to AN in DRC channel –DRC channel information ： DRC cover and DRC value –DRC Cover is for choosing serving sector, DRC Value is for choosing downlink data rate

14. Self-adaptation coding and modulation Decision of data rates: –Data rate from 38.4 kbps to 2.4576Mbps, （ QPSK 、 8-PSK 、 16QAM ）、 code rate （ 2/3 、 1/3 、 1/5 ） –Why to choose different rates?

15. Forward traffic channel rate level Data Rate (kbps) Slots per Packet Packet Size (bits) Code Rate Modulation Preamble (chips) 38.41610241/5QPSK1024 76.8810241/5QPSK512 153.6410241/5QPSK256 307.2210241/5QPSK128 307.2410241/3QPSK128 614.4110241/3QPSK64 614.4220481/3QPSK64 921.6230721/38QPSK64 1228.8120481/3QPSK64 1228.8240961/316QAM64 1843.2130721/38QPSK64 2457.6140961/316QAM64