CDMA TRAINING MODULE CDMA TRAINING MODULE

FDMA(Frequency Division Multiple Access): Each user has a private frequency. e.g. AMPS

TDMA(Time Division Multiple Access): A user’s channel is a specific frequency, but it only belongs to the user during certain time slots in a repeating sequence. Each user has a private time on a private frequency. e.g. GSM

CDMA(Code Division Multiple Access): Each user has a private code. e.g. IS-95, CDMA-2000, 1xEV-DO etc. Each user’s signal is a continuous unique code pattern buried within a shared signal, mingled with other users’ code patterns. If a user’s code pattern is known, the presence or absence of their signal can be detected, thus conveying information.

Multiple Access Multiple Access TechniquesTechniques

CDMA One CDMA2000

Generation 1G 2G 2.5G 3G

Technology AMPS IS-95A IS-95B CDMA2000 1x

CDMA2000 3x

EVDO–REV A

CDMA2000 1x Ev-DV

Signalbandwidth 30kHz 1.25MHz 1.25MHz 1.25MHz 3.75MHz 1.25MHz 1.25MHz

# of Users 1 20-35 25-40 50-80 120-210 59 (Theoretical)

DataCapability n/a 14.4kbps 64kbps 153/230/307

kbps 2Mbps 3.1Mbps 5Mbps

FeaturesVoiceOnly

Analog

VoicePacket

Data

VoicePacket

Data

2 timesvoice

capacitypacket core net

2 times voice

capacity3 times

data rate

1xEv Data only overlay

Integrated voice and

data

Year 1995 1998-1999 2000-2001 n/a 2001-2002 2002-2004

CDMA2000 CDMA2000 EvolutionEvolution

Higher capacity interference limited => high efficiency uses voice activity detection to reduce transmission bandwidth

Improved quality Soft handoff CDMA has frequency, spatial, and time diversity to adapt to wireless errors EVRC coding at 8kbps of voice includes error correction etc.

Ease of deployment No frequency planning since frequency reuse=1

Greater coverage Cost effective in sub-urban and rural areas

Increased privacy Spreads small signal (9.6kbps) over large spectrum (1.25Mbps) so that signal

appears like noise

Increased talk time Power control (performed 800 times a second) ensures that the mobile

station transmits at optimum power resulting in longer battery life

The Four RF parameters in CDMA are Rx Level, Tx Level, EcIo & FFER.

• Rx Level The signal mobile is experiencing in a particular band.

• Tx Level The power mobile is transmitting in a particular band.

• EcIo Energy per chip over noise; Signal to noise ratio.

• FER Frame Error Rate.

Except that PN and Channel No.

=> Collection of Lat/Long of the problematic area

Azimuth Check of the nearby sites and re orientation of the antenna towards problematic area

Pilot Power Modification of the particular sector to improve coverage.

Sector Addition to cater low coverage zone

In case of data complaints reduction of Pilot Power to avoid the Overlapping and Frequent Hand Off

TROUBLESHOOTING

Evolution-Data Optimized or Evolution-Data only (EV-DO, EV, etc.) is a telecommunications standard for the wireless transmission of data through radio signals, typically for broadband Internet access. It uses multiplexing techniques including code division multiple access (CDMA) as well as time division multiplexing (TDM) to maximize both individual users' throughput and the overall system throughput. It is standardized by 3rd Generation Partnership Project 2 (3GPP2) as part of the CDMA2000 family of standards.

EVDO is a spectrally efficient solution optimized for high-speed wireless Internet access:

1X EvDO Rev A Principles: 1x = single 1.25 MHz spaced carrier EV = Evolution DO = Data Optimized (no voice traffic)1xEV-DO systems have their own dedicated RF channel (frequency assignment) Internet working with cdma2000-1x system is supported by means of hard handoff

HSIA Data Rates :- Forward Link : 38.4 kbps to 3.1 Mbps Reverse Link : 9.6 kbps to 1.8 Mbps

Actual Data rate varies depending on numerous factors :-

Number of users per sector (Maximum Sector Throughput 3.1 mbps) Application (Load of the server customer is accessing) Signal to Interference and Noise Ratio (SINR) Backhaul capacity

There have been several revisions of the standard as :-

Release 0 (Rel. 0) - Data rate up to 2 Mbit/s Revision A (Rev. A) - Data rate up to 3.1 Mbit/s Revision B (Rev. B) - Data rate up to 4.9 Mbit/s Revision MC (Rev. MC) - Data rate up to 5.5 Mbit/s

Digital Rate Control (DRC) it communicates the information to the serving sector in the form of an integer between 1 and 14 on the DRC channel. Alternatively, the mobile can select a "null" rate (DRC 0), indicating that the mobile either cannot decode data at any rate, or that it is attempting to hand off to another serving sector.

DRC Index Data Rate(kbit/s) Slots Scheduled Payload Size (bits) Code Rate Modulation1 38.4 16 1024 1/5 QPSK2 76.8 8 1024 1/5 QPSK3 153.6 4 1024 1/5 QPSK4 307.2 2 1024 1/5 QPSK5 307.2 4 2048 1/5 QPSK6 614.4 1 1024 1/3 QPSK7 614.4 2 2048 1/3 QPSK8 921.6 2 3072 1/3 8-PSK9 1228.8 1 2048 2/3 QPSK

10 1228.8 2 4096 1/3 16-QAM11 1843.2 1 3072 2/3 8-PSK12 2457.6 1 4096 2/3 16-QAM13 1536 2 5120 5/12 16-QAM14 3072 1 5120 5/16 16-QAM