01-09-2012, 02:55 PM
MOBILE COMMUNICATION AND OVERVIEW OF GSM ARCHITECTURE
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Introduction
One of the finest things that happened in 20th century is the use of radio channels for personal mobile communication systems. Considered to be a revolution of sorts in telecommunications. Considered to be a revolution of sorts in telecommunications, mobile communication is the fastest growing market segment and the field of intense research. Mobile communication today is, perhaps, the most powerful catalyst for change in lifestyle of the people all over the world. Mobile communication slowly, but surely is evolving as the backbone for business transactions, efficiency and success silently taking over the role of the elder cousin PSTN.
The first mobile telephone service started in 1946 in St. Louis, Missouri, USA as a manually operated system. Between 1950 and 1960, it evolved as an automatic system with reduced cost and increased, but small subscriber base. Mobile telephony service in its useful form appeared in 1960s.
The first generation mobile communication systems appeared in 1970s and remained till 1980s. They used analog transmission techniques for the radio link and confined its users to their respective system areas for which the mobile phone was designed. Capacity of the system was very limited and roaming between the coverage areas of the different systems was impossible. Apart from being very expensive, these systems provided poor QoS and supported only voice communication.
MOBILE COMMUNICATION TERMINOLOGY:
Like any other technology, mobile communication too has a set of unique terminology. A few often sued ones are given below:
PLMN - Public Land Mobile Network. A PLMN is the network set up by a cellular licensee in his licensed area. Each network of each of the licensees in a lincensed area is considered to be a separate PLMN. Thus as per the new licensing policy of Government of India, there will a maximum of 4 PLMNs in each of the licensed area. A licensed area, typically, is coterminus with a telecom circle. In India there are 58 private PLMNs working and another 22 PLMNs are launched by BSNL and two by MTNL.
HOME PLMN - Every mobile customer has to register himself with a service provider in a licensed area. The PLMN with which he registers is known as his Home PLMN (HPLMN). All the administrative data of his subscription will be available in the Home PLMN.
VISITED PLMN - When a mobile subscriber enters a PLMN area other than his Home PLMN, then he is said to be in the area of a Visited PLMN (VPLMN).
ROAMING - Whenever a customer, with an intention of availing service, enters a Visited PLMN area then he is said to Roaming.
CELLULAR PRINCIPLE:
The central concept that made mobile communication as a usable commercial proposition is the cellular principle. BELL Laboratories, US in 1970 first introduced cellular principleUnder cellular concept, the service area is divided into a number of CLUSTERS, each cluster consisting of a number of CELLS and each cell is assigned as many CARRIERS as required by the traffic in that cell. There is a one-to-one correspondence between the cells in each of the clusters that these cells use the same carrier frequencies.
Since the frequency used being the same, the principle of frequency reuse demands that the interference between them when serving different cells and therefore different customers should be kept within permissible limits. Figure-2 below shows the cluster and frequency re-use.
Figure-2 shows a 7-CELL reuse pattern. The 7 cells, shown as seven different hexagons that are tagged in contiguity are called a cluster. The cluster can be repeated any number of times to provide coverage for the service area using the very same frequencies F1-F7. This is called a 7-CELL cluster. There are different types of reuse pattern each governed by interference and capacity requirements of individual systems.
BILLING AND CUSTOMER CARE SYSTEM (B&CCS):
Billing and Customer Care System is responsible for obtaining the call details of each of the customers from the HPLMN as well as from all the VPLMNs for raising the invoice. B&CCS incorporates a powerful and flexible rating engine that would enable the service provider to offer innovative and competitive tariff packages.
The Customer Care module includes an automatic Service Provisioning Module that will activate / deactivate a customer account from a Customer Care terminal without the need for any manual intervention. The CC module also would handle the Trouble Tickets generated on faults reported by the customer and routes such tickets automatically to appropriate terminal for action.
The B&CCS also incorporates a sophisticated Printing Subsystem for distributed printing of the customer invoices.
CONCLUSION:
GSM is a 2nd generation mobile communication systems. The data transmission speed of GSM was only 9.6 Kbps and this speed is considered to be too inadequate for many applications. The data speed of GSM can be increased to 171.2 Kbps using GPRS and to 384 Kbps using EDGE. 3G system, which is already operational in Japan, is capable of delivering bandwidth of up to 2 Mbps to mobile terminal.