22-09-2012, 05:36 PM
PCS (personal communications services)
PCS.ppt (Size: 827.5 KB / Downloads: 37)
Personal communications services (PCS) refers to a wide variety of wireless access and personal mobility services provided through a small terminal, with the goal of enabling communications at any time, at any place, and in any form.
Business opportunities for such services are tremendous, since every person (not just every home) could be equipped, as long as the service is fairly inexpensive.
Several PCS systems have been developed to meet rapid growth prompted by heavy market demand.
Meet of them are connected to the public Switched telephone network (PSTN) to provide access to wire-line telephones.
The PCS umbrella also includes:
Special data systems such as Cellular Digital Packet Data, RAM Mobile Data, and Advanced Radio Data Information System (ARDIS)
Paging system
Specialized mobile radio (SMR) access technologies
Mobile-satellite systems such as the existing American Mobile . Satellite Company (AMSC), as well as numerous proposed mobile satellite systems, including S-band, L-band, low-earth orbit (LEO), mid-earth orbit (MEO), geosynchronous orbit, and geostationary earth orbit (GEO), for both data and voice applications
Unlicensed industrial, scientific, and medical (ISM) band technologies, as well as wireless local area networks (LANs) should also be thrown into the PCS mix
Goal
This book describes network management, protocols, and services for PCS systems.
Besides the mobile telecommunications issues, we also cover wireless Internet.
We attack this problem from the telecommunication aspect.
And because this book is designed for readers without a radio background, we try to avoid the details of the physical radio technologies.
PCS Architecture
Radio Network
PCS use mobile stations (MSs) to communicate with the base stations (BSs) in a PCS network.
MS is also referred to as handset, mobile phone, subscriber unit, or portable.
For example,
subscriber unit : wireless local loop;
portable: low-tier systems (PACS); and
mobile station: GSM system.
PCS Architecture
Modern MS technology allows the air interface to be updated (e.g., from DECT to GSM) over the air remotely
The MS can also be remotely monitored by the system maintenance and diagnostic capabilities.
Different types of MSs have various power ranges and radio coverage.
hand‑held MSs have a lower output power (where the maximum output power can be as low as 0.8 watts for GSM 900) and shorter range compared with vehicle‑installed MSs with roof‑mounted antennas (where the maximum output power can be as high as 8 watts in GSM900).