This document summarizes the IS-95 CDMA standard. It describes the key interfaces in IS-95 including A, Abis, B, C, D interfaces. It explains CDMA multiple access technique and how IS-95 uses unique codes to differentiate subscribers. It provides details on the forward and reverse CDMA channels, overhead channels, access channels, and framing in IS-95. It gives an overview of the key aspects of the IS-95 standard including the forward and reverse link architecture and channels.

1. GUIDED BY: PREPARED BY:
Prof. S.D.GANDHI Vijay Yadav (140403111014)
Ravi chaudhri(140403111016)
Sankalchand Patel collage of engineering
Subject: wireless communication
Is-95 Stander Cdma

2. Content
 Introduction
IS-95 Interfaces
Multiple Access
 CDMA
 Forward CDMA Channel of IS-95A
 Overhead Channels
Overhead Channels
Access Channel
 Framing and Signaling on the Traffic Channel
 IS-95 Standard
 Forward CDMA Channel
 Reverse CDMA Channel
 Reference.

3. CDMA Around the World

4. IS 95 interface
• A interface (BSC-MSC) .. this interface is between the BSC and the
MSC. It Supports both the control plane and user plane.
• Abis interface (bts-bsc)—this is the interface between the BSC and
BTS. This is internal interface and generally proprietary.
• B interface (MSC-VLR) this interface is defined by TIA IS-41.
• C interface (MSC-HLR) this interface uses IS-41 messaging as well.
• D interface (HLR-VLR) – HLR-VLR signaling is based on IS-41 as
well. It sits on top of SS7.

5. • CDMA
– unique digital codes are used to differentiate subscribers
– codes are shared by both MS and BS
– all users share the same range of radio spectrum
• Benefits of CDMA:
– Capacity increases: 4 to 5 times (GSM)
– Improved call quality
– Simplified system planning
– Enhanced privacy
– Improved coverage characteristics
– Increased talk time for portables
– Bandwidth on demand
Multiple Access

6. • There are two CDMA common air interface standards:
– Cellular (824-894 MHz) - TIA/EIA/IS-95A
– PCS (1850-1990 MHz) - ANSI J-STD-008
They are very similar in their features, with exceptions of the
frequency plan, mobile identities, and related message fields.
• IS-95A
– 45 MHz spacing for forward & reverse channel
– Permissible frequency assignments are on 30 kHz increments
CDMA

7. • From BSS to MS
• It carries traffic, a pilot signal, and overhead information.
• Pilot is a spread but unmodulated
• Pilot and overhead channels establish the system timing and station identity.
• Pilot channel is also used in the mobile-assisted handoff (MAHO) process
as a signal strength reference.
Forward CDMA Channel of IS-95A

8. • There are three types of overhead channel in the forward link:
– pilot, is required in every station
– sync
– Paging
• Pilot channel
– pure short code with no additional cover or information content
– always code channel zero
– a demodulation reference for the mobile receivers and for handoff level
measurements
– carries no information
– all stations use the same short code, distinguished by the phase
Overhead Channels

9. • Paging channel
– used to communicate with MSs when they are not assigned to a traffic
channel
– successful accesses are normally followed by an assignment to a
dedicated traffic channel
– paging channel may run at either 4800 or 9600 bps
– each BS must have at least one paging channel per sector, on at least
one of the frequencies in use
Overhead Channels

10. • Access Channel provides communications from MS to BS when MS is not
using a Traffic Channel.
• All Access Channel use 4800 bps mode
• Access Channel Message:
– call origination
– response to pages
– orders
– Registrations
• Control of Access Channel transmission is accomplished through the
Access Parameter Message sent on the Paging Channel
Access Channel

11. • Both forward & reverse Traffic Channels use 20 ms frames.
• Frames can be sent at 9600, 4800, 2400, or 1200 bps
• Signaling
– blank-and-burst signaling:
• sent at 9600 bps
• replace one or more frames of primary traffic data
– dim-and-burst signaling:
• sent at 9600 bps
• sends both signaling and primary traffic data in a frame
• degradation in voice quality is essentially undetectable
Framing and Signaling on the Traffic Channel

12. • Forward Link
– Pilot Channel
– Sync Channel
– Paging Channels (max. 7)
– Traffic Channels
• Power Control Sub-Channel
• Reverse Link
– Access Channels
– Traffic Channels
IS-95 Standard

13. IS-95
CDMA is an access method.
IS-95 was the first ‘operating system’ to use CDMA
•Invented by Qualcomm
•Began production in 1995.
•At this point, this is still called 2G wireless.
•Known as a narrowband system.
Being supplanted by CDMA2000 (WCDMA) and UMTS, fully 3G
systems.
•They both use CDMA.
• Known as wideband systems.

14. IS-95 Vocoders
 IS-95 uses extremely advanced vocoders that use variable encoding rates just
like GSM.
 They operate at variable rates, up to a maximum of 9600 bps.
 At a minimum, it encodes 1200 bps, so that the phone doesn’t seem dead.
 The quality, though less than AMPS, is much higher than GSM, on average.

15. Operates in the same bandwidth as GSM:
•1850 to 1910 mhz mobile to base
•1930 – 1990 mhz base to mobile
Channels are 1.25 mhz
•3.75 mhz in CDMA 2000, 5 MHZ in UMTS
•Results in approximately only 48 forward/reverse channel pairs in IS-
95.
 Adjacent cell phone towers use the exact same channels as all other
towers.
•This is a major difference.
•Allows for much better frequency reuse and makes setting up a
cellular network much easier.
How IS-95 Works

16. • E Interface (MSC-MSC)– Inter MSC signaling is defined in IS-41.
• L interface (MSC-IWF) This interface allows the ability for circuit
switched data in second generation network.
• Um Interface (BS-MS) – This is the air interface between the mobile and
the network.

17. Reference
www.google.com
www.wikipedia.com
www.is95cmda.com

18. THANK YOU