Amps

First Generation Systems,AMPS Architecture and Components

1. AMPS

2. HISTORY
•Advanced Mobile Phone System is the first generation wireless in US.
•Earlier systems used line of sight radio (e.g. AT&T’s Improved Mobile
Telephone Service in 1960s)
•AT&T developed cellular concept in 1940s
•1971 proposed High Capacity Mobile Phone Service to FCC
•1979 FCC standardized it as AMPS in 800-900 MHz

3. WHAT IS AMPS?
•AMPS is known as the first generation (1G) analog commercial cellular systems.
It introduced in early 1980s.
•Invented by Bells Labs and first installed in the U.S. in 1982
•It is based on Analog modulation (FM) and RF bandwidth 30 kHz.
•It is the earliest radio standard in North America.
•First generation systems targeted to few subscribers with car phones
•Capacity can be increased by smaller cells but: More difficult to place base
stations at locations for necessary radio coverage
•Frequency allocated by FCC on 824-849 MHz for downlink and 869-894 MHz
for uplink traffic.
•Increased signaling for handoffs, and more frequent handoffs

4. North american systems
Generation

2nd
1st
AMPS
NAMPS TDMA CDMA

5. Introduction
First Generation (1G) Systems developed late 70’s early 80’s, deployed in 80’s.
•Advanced Mobile Phone System (AMPS) – USA
•Total Access Communications Systems (TACS) - UK
•Nordic Mobile Telephone (NMT) System – Scandinavia
•C450 - W. Germany
•NTT System - Nippon Telephone & Telegraph (NTT) – Japan

6. Advanced Mobile Phone Service
•AMPS was the first cellular system. 1970s in the bell laboratories,
•This first-generation analog cellular system has been considered A
revolutionary accomplishment.
•The amps specification was generated from a laborious
•Process of research, system design, and switching design over A period of
10 years. From 1974 to 1978, A large-scale AMPS trial was conducted in
chicago.
•Commercial amps service has been available since 1983. Based on
frequency division multiple access (FDMA)
•Technology for radio communications,
•High-capacity system based on A frequency reuse scheme.

7. Advanced Mobile Phone Service
•Voice channels are assigned to radio frequencies using FDMA.
•A total of 50MHz in the 824-849 MHz and 869-894MHz bands
is allocated for AMPS.
•This spectrum is divided into 832 full-duplex channels using
1664 discrete frequencies,
•832 downlinks and
•832 uplinks.
•Downlinks are the transmission paths from base stations to
handsets,
•Uplinks are the transmission paths from handsets to the base
stations.

8. AMPS
•Cells are grouped into clusters.
•Cells of within a cluster may interfere with each other, and thus
must use different frequencies.
•Frequencies may be reused by cells in different clusters.
•In AMPS, the typical frequency reuse plan employs either a
•12-group frequency cluster using omni-directional antennas
or
•7-group cluster using three sectors per base station. Thus,
there are about 50 channels per cell.
•Motorola uses a 4-cell, 6-sector design in its AMPS system.
GS1
•AMPS follows the EIA/TIA IS-41 standard for roaming
management, as described later in Chapter 5.

9. AMPS
•Compared with the digital alternatives in the United States,
•AMPS service offers more complete geographical coverage at a
cheaper service charge (partly due to the low cost of mass
production of handsets).
•However, digital networks are replacing AMPS because the digital
technology can cope with higher user densities, and offer lower
costs.
•In 2000, Taiwan started replacing AMPS with the IS-95 CDMA
system.
•After the replacement, the new system will provide the same
service at less than half the bandwidth of the radio spectrum.

10. First Generation Systems

11. AMPS Architecture and Components
•Cell site with antenna
•Mobile Subscriber Unit (MSU)
•Public Switch Telephone Network (PSTN)
•Mobile Telephone Switching Office (MTSO)

12. AMPS/N-AMPS Characteristics and Bands
•Total number of
channels
832 MHz
AMPS N-AMPS
Channel spacing 30 kHz 10 kHz
Spectrum allocation 40 MHz 40 MHz
Additional spectrum 10 MHz 10 MHz
Total number of channels MHz 832 2496

13. FREQUENCY REUSE FACTOR 7
6
7
5
1
2
3
4
6
7
5
1
2
3
4
6
7
5
1
2
3
4
No of Channels
•832 channels: 25 MHz / 30 kHz, can be shared by two providers
•416 channels in each, 21 channels for control, 395 channels for voice (one way)
Frequency Reuse Factor 7
•Each cell uses some set of frequencies
not used by any of its neighbors

14. Channels used by the AMPS
Analog - FDMA (Frequency Division Multiple Access) ISM 800-MHz band
Control Channel
Forward
Control
Channel (FCC)
Primarily used by the BS to page and
locate the ms’s available within the
coverage area.
Control Channels - FSK
(Frequency Shift Keying) Reverse
Control
Channel (RCC)
Control for the reverse direction is little
involved as a number of mss
communicate with the BS
simultaneously.
Voice Channel (30kHz)

Forward Voice
Channel (FVC)
Communication from the BS to each
individual MS. (Tower to mobile)
Base Station → Mobile
Station: forward comm.
channels (824-849 MHz: 25
MHz band)
Reverse Voice
Channel (RVC)
Communication from MS to the BS
during calls in progress and is assigned
by the MS to BS for its exclusive use.
(Mobile to tower)
Base Station ← Mobile
Station: reverse comm.
Channel (869-894 MHz: 25
MHz band)