Basics of GSM network

Figure: GSM Network Architecture.

The GSM network consists of the following components:

a. Mobile Station (MS)

b. Base Transceiver Station (BTS)

c. Base Station Controller (BSC)

d. Mobile Switching Center (MSC)

e. Home Location Register (HLR)

f. Visitor Location Register (VLR)

g. Authentication Center (AuC)

h. Equipment Identity Register (EIR)

Functions of Base Transceiver Station (BTS):

The BTS is a part of the Base Station Sub system (BSS) and it contacts Mobile Station (MS) through the radio interface. The BTS is in charge of management of simultaneous transmission and reception on the radio interface.

Functions of Base station Controller (BSC):

The BSC is connected on one side to one or several Base transceivers (BTS) and on the other side to the Mobile Switching Center (MSC). The main function of the Base Station Controller (BSC) is allocation and release of radio channels(or allocated ARFCH) and the handover (HO) management.

Functions of Mobile Switching Center (MSC)

The Mobile Switching Center (MSC) responsible for the basic function of switching. The main function of the Mobile Switching Center (MSC) is to co-ordinate the setting up of calls to and from GSM users and the external network The Mobile Switching Center (MSC) has interface with the Base Station Subsystem (BSS) on one side and the external network on the other side.

Functions of Home Location Register (HLR)

The Home Location Register (HLR) together with the Mobile Switching Center (MSC), provide the call ­routing and roaming capabilities of GSM. The Home Location Register (HLR) contains all the administrative information of each subscriber registered in the related to GSM network, along with the current location of the mobile.

Functions of Visitor Location Register (VLR):

The Visitor Location Register(VLR) contains roaming information. Once the visited system automatically detects the mobile, the Visitor Location Register (VLR) of that system enquires the Home location Register (HLR) to make sure you are a valid subscriber. It temporarily stores the last location area visited by the Mobile Station (MS), the power the mobile uses, the special services the Mobile Station (MS) is subscribed to and so on.

Functions of Equipment Identity Register (EIR):

The Equipment Identity Register (EIR) is a database that stores data related to the mobile equipment. It contains a list of all valid mobile equipment on the network, where each mobile station (MS) is identified by International Mobile Equipment Identity(IMEI). This is useful when searching for stolen mobile equipment or when monitoring misuse of Mobile Station (MS). If a Mobile operators want to prevent the misuse of Mobile phone; It's not too difficult for them.

Functions of Authentication Centers (AuC):

The Authentication Center is a database that stores a copy of the secret key stored in each subscriber's in Subscriber Identity Module (SIM) card, which is used for authentication and ciphering of the radio channel.

Find more Information:

• RF Planning and Optimization question (wimaxtec.blogspot.com)
• RF (Radio Frequency) Engineering (wimaxtec.blogspot.com)
• Implementation Of 4G network in Bangladesh (wimaxtec.blogspot.com)
• GSM Base Station KPI Analysis

RF Planning and Optimization question

Here is few question about RF planning and optimization, All the questions were collected from recruiter. these questions are frequently asked in viva board.

1। What is the basic procedure for RF planning using RF planning tool in GSM?

Answer:

• Analyze the system requirement and plan for data acquisition.

• Select proper Planning Tool

• Loading of digital map data of planning area on the planning tool

• Model tuning for prediction of network on the planning tool

• Nominal cell planning for the coverage area

• Frequency planning and interference calculation.

• Final system planning.
  

2। What are the different types of antennas used in a GSM network?

Answer:

Antennas may be categorize based on antenna beam width and gain, In GSM we have

• Space diversity antenna

• Cross polarized antenna

• Omni directional antennas.

3। How do the power, orientation, beam width, tilt and height of the antenna affect the coverage?

Answer:

Power

Antenna output power, always proportional to the coverage area. So power increases coverage increases.

Proper Orientation

Orientation of an antenna gives us coverage on specific direction of desired planning area, Antenna orientation tuning is a major treatment when we prescribe for a network optimization.

Beam width and tilt

Antenna beam width and tilt improves the coverage of the planned area. Proper tuning of beam width and tilt gives better coverage and performance.

Antenna height

Increase in antenna height improves the coverage.

4। What is EIRP? How is it calculated?

Answer:

Effective isotropic radiated power is the total output power of Base station

EIRP=BTS Output power + Antenna gain – {cable losses - other (combiner) losses}

5। What is frequency planning? Why is frequency reuse pattern used?

Answer:

Frequency planning is to be done for the GSM network for a given operator with A set of GSM frequency band .Frequency reuse pattern is used for capacity planning and for effective resource utilization.

6। What are all the patterns available? How is frequency planning done on planning tool ?

Answer:

7/21 pattern, 4/12 pattern, 3/9 pattern ।Automatic frequency planning can be done with planning tool।

7। What is co-channel interference and adjacent channel interference?

Answer:

The interference caused by using same channels in a network is called co - channel interference and interference caused by adjacent channels of is called adjacent channel interference. To distinguish actual signal from interface minimum power difference should be -9db.

8। How do you minimize co-channel interference?

Answer:

• Proper frequency planning

• Proper reuse pattern.

• Physical parameter tuning (Orientation, Height, Beam width, tilt etc)

• Finally resource addition ( Frequency and New BTS)

9. How do you minimize adjacent channel interference?
Answer:

• Proper frequency planning.

• Physical parameter tuning (Orientation, Height, Beam width, tilt etc)

10. What is model tuning? Why is it used? Okarama Hatta model?

Answer:

Model tuning is done for any network using planning tool to obtain proper prediction about network.

As there will be difference in actual and predicted data for planning tool. One of the Model is Okarama Hatta Model, generally known as Hatta model, is widely used which considers the signal propagation losses.

Implementation Of 4G network in Bangladesh

Implementation Of 4G network


4G network is global leading communication network across the globe. All most all leading giants in Telecom industry already launched their 4G service through (LTE, Wimax, HSPA etc). In Bangladesh there are more than 105 million active subscriber up to Feb,2012. Five global cellular mobile company establishes their network here including a local government owned company.

List of companies and market shares are given bellow:

• Grameen Phone Ltd (GP) - 41%
  
• Axiata (Bangladesh) Limited (Robi)-17%
  
• Orascom Telecom Bangladesh Limited (Banglalink)-25%
• PBTL (Citycell)-3%
• Teletalk Bangladesh Pvt Ltd.-2.8%
• Airtel Bangladesh Pvt Ltd. 11.2%

Also there's some wireless broadband service providers are playing here with Mobile and Fixed wimax (802.16e and 802.16d). All the cellular mobile subscribers are providing their voice service through GSM-2.5G and CDMA-2X. But subscribers are demanding more service from provider. Hence cellular operators are thinking about network up gradation. First their demand was 3G, but government delays to give them license and frequency allocation. Now it's too late, 4G network deploying across the globe. Subscribers demanding more, standard of living has been developed in recent few years, hence operators are in dilemma 3G or 4G ?


Now comes to the point, according to our feasibility study 4G network is not viable here from the bussiness aspect and although the demand of 4G is too high, Here Wimax operators are straggling, changes their strategy of business. Truly their customer and network growing very slow and selling their services in lower prices to survive. Hence 4G will be out of general customer's purchasing power. Because 4G needs at least two and a half times more access network equipment and huge bandwidth for each network. On the other hand government is planning a high licensing and bandwidth charge. They have already announced for 3G licensing fee, which is 15000 thousands crore in local currency. Operators are treating is too high. In December,2012 government of Bangladesh, ministry of Telecommunication is planning for bid of 4G licensing, BTRC is mapping their schedule according to plan.

So in this circumstances operators are planning to go slow, but in right way.
Thanks By
Hassan Imam
Manager, Network Service.
Huawei-TDC project in Malaysia.

Related articles

• Banglalion the leading Wimax provider in Bangladesh (wimaxtec.blogspot.com)
• Wimax and Bangladesh (wimaxtec.blogspot.com)
• WiMAX Opportunities in Africa (wimaxtec.blogspot.com)
• WiMax Definitions (wimaxtec.blogspot.com)

4G Network Dimensioning Procedure

Network Dimensioning procedure are just previous step of Network planning; it's a important part of network planning. The first step of network dimensioning procedure is collection of data. This data often collected from operators business plan. The data is analyzed very carefully and makes the requirement of network. Requirement consist of number of sites and amount of resources (like frequencies for access network and Microwave transmission network), types of network etc. Then plan for coverage and capacity of network. If you need any calibration in network try to simulate with software and tune in different planning parameter. Then recalculate the number of sites and resources. To meet the desired capacity and coverage, you need to plan a reliable transmission plan. Because if transmission have limitation, the total network will be disturb. So you should have to plan a balanced, dependable, flexible and functioning network.

RF (Radio Frequency) Engineering

RADIO FREQUENCY ENVIRONMENT AREA (Photo credit: elycefeliz)

RF (Radio Frequency) Engineering


RF engineering deals with the wireless system or device which frequency ranges from 3khz to 300Ghz. To be a RF engineer you need a clear concept on Mathematics,Physics,General Electrical and electronics theory. Besides you need specialized taring and education on propagation rule and behavior,microstrip design etc. RF engineering may categories into four parts. These are:

• Network Planning and Design or NPD.
  
• Network Implementation and Optimization or NIO.
• Network Operation and Maintenance (Net O&M).
  
• Network Quality and Performance (Net Q&P).

To be a good RF engineer we need several years of professional knowledge from field, as well as from planning and design section. RF engineer has good knowledge on transmission system,device and antenna system. Antenna is such a device which is a key concern of a RF engineer. Actually quality of a wireless network largely depends on the antenna. Every RF engineer should capable of design a antenna required for his system. Actually shape and size of a network largely depends on RF engineer. The device of Transmitting and Receive end be selected by the RF engineer. Hence the supporting device should be by the choice of RF engineer.

WiFi Wireless Fidelity_Part-2

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History

In the early 1992 Australia's Commonwealth Scientific and Industrial Research Organization (CSIRO) obtained a model/patent in Australia for wireless data transfer technology. In late 1996, Australia obtained another patent for the same technology in the USA. IEEE 802.11 uses the mathematical formula in the model. In the mid 2000 Australia's Commonwealth Scientific and Industrial Research Organization (CSIRO) established the world's first wireless local area network (WLAN) internet connection.

In April 17th-20th, 2009, fourteen tech companies including major market share holder like Intel, Microsoft, HP, Dell, decided to issue CSIRO two hundred and fifty million dollar for their Wi-Fi model/patent development.

EU influences overall in deploying of wireless phone system, but the USA leads in Wi-Fi technology moderately because it leads in notebook pc usage. In mid July 2005, there were nearly seventy thousands Wi-Fi networks worldwide, most of in the USA, followed by the UK and Germany. The USA and EU have about eighty percent of the worldwide Wi-Fi service holder. Tactics are in progress in urban areas of the USA to afford cost free public Wi-Fi network. Even with these numerous numbers and more expansion, the extent of actual Wi-Fi usage is much less than expected. A research company Jupiter Research found that only fifty percent of people have used Wi-Fi and only six percent in an open place.

WiFi Wireless Fidelity_Part-1

Image via Wikipedia

History


Wi-Fi supports both single-carrier direct-sequence spread spectrum radio technology (a portion of the larger family spread spectrum systems) and multi-carrier orthogonal frequency-division multiplexing radio technology. The deregulation of convinced radio-frequencies for unlicensed spread spectrum employment enabled the expansion of Wi-Fi products, IEEE 802.11 just the once contestant HRF (Home Radio Frequency), Bluetooth, and lots of other products like a few types of cordless telephones.
In the USA, the Federal Communication Commission (FCC) pioneer of unlicensed spread spectrum presented in rules implemented on 9th, May, 1985.
Many countries just after implemented these FCC standards, enabling apply of this technology almost all key countries. The FCC plan was offered by Michael Marcus of the FCC personnel in 1980 and the consequent authoritarian action took half a decade. It was portion of a broader suggestion to permit civil use of spread spectrum technology and was denied at the time by majority equipment manufacturers and most of the radio system operators.
IEEE 802.11 (Wi-Fi) technology started in a 1985 under the U.S. Federal Communications Commission that released numerous bands of the radio spectrum for unlicensed utilization.

Mobile VPN

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Concept of Virtual Private Networks

Concept of Virtual Private Networks predates data networking. The term is used by the traditional phone companies to refer to services offered to various entities. In some cases it is as simple as a leased line facility. In others it is a complete outsourced network that is carved out of the “public network” for an entity’s exclusive use.

A virtual network essentially a connection that appears to the users as a dedicated end to end connection. It is not important for the user to know actual route by the data. In fact the route will often change during the course of session. In order to make the network private (in an IP environment) other services must be implemented.

To ensure privacy several things must happen. The user must be verified to be eligible to use the VPN. This is accomplished through the use of RADIUS servers and share certificate methods. The data must be protected or made private. This is accomplished through various tunneling techniques.

With a private network, user expects a certain level of service. This requires the ability to implement Quality of Service schemes. While this can be accomplished, it becomes more complex in an IP environment with varied paths and providers. In a Mobile IP environment it is further complicated by mobility and roaming issues.

Banglalion the leading Wimax provider in Bangladesh

Banglalion is the pioneer of Wimax (World wide interoperability of microwave access ) in Bangladesh,it is a sister company of "Sunman Group of Companies". Banglalion acquired first BWA license on November 18, 2008 in Bangladesh, whoich is provided by the Bangladesh telecommunication regulatory commission (BTRC). BTRC is the only regulatory body of Bangladesh which regulates the countries telecommunication and networking companies. Banglalion is committed to provide country wide Broadband Internet services and other associated service via Wimax.Banglalion plans to bring the whole country under WiMAX coverage and make WiMAX technology an essential part of everyday life. Within the 2nd quarter of 2010, Banglalion plans to bring the whole mega city Dhaka and it's surroundings under WiMAX coverage. Within the 2nd quarter of 2011, Banglalion's vision to bring most areas of the country under its seamless coverage and thus Banglalion will provide its valuable customers with innovative, affordable and useful product line of Banglalion.

Wireless LAN Standard

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IEEE WLAN Standard

The International Electronics, Electrical Engineers (IEEE ) a governing and regulating body of today's electrical, electronics and communication technology. IEEE standards are developed by groups of people that come from many different organizations, like academics, corporate business, government and the defense service. Because standard developed by the IEEE can have such a blow on the innovation and expansion of technology, the student can take many years to be formed and determined upon, although approval of 802.11 standards seems to have accelerated sincerely in the last few years, may be due to the excessive demand for 802.11 products and service.

But the critic views are that IEEE is not enough to meet today’s wireless demand. Their recommendation is to strengthen World Telecommunication Union (ITU) by balancing to keep adequate representative of Africa and South East Asia.

RF Properties.

Radio Frequency Properties

• Amplitude
• Frequency
• Wavelength
• Phase
  
• Polarity
  

Wimax and Bangladesh

Now a days there is a hard talked between wireless professionals in Bangladesh is WiMAX. Everyone in the industry is sincere of the technology and its value to the future of the Bangladesh. But there is a com vital difference about WiMAX license. In a recent workshop ‘WiMAX in Bangladesh: now and future’ held in Dhaka, Bangladesh, BTRC chairman Mr. Manzurul Alam expressed that BTRC is likely to invite application for WiMAX license in half of the July. The chairman said they have yet to take decision on the frequency rate for WiMAX and possible target group for the license. Now the question is who these target groups are and who will be the one get priority over others and why?

But the Bangladeshi technical persons point of view, " it should be give to the native entrepreneur".
They have also said about ninety percent of the countries wireless communication market is already captured by the foreign companies, as a result a huge amount of foreign currencies are going out annually.

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Low Power WiMAX Chipsets Accelerate the Broad Adoption of WiMAX in Mobile Devices

Broad adoption of WiMAX networks and the fulfillment of the WiMAX "vision" greatly depend on the proliferation of WiMAX chipsets into battery operated mobile devices, including handsets, ultra mobile PCs and a variety of consumer electronic devices. One gating factor had been the power consumption of the WiMAX subsystem which puts a drain on batteries. The WiMAX chipset ecosystem has made great strides in this area. But have they met the "low power bar" necessary for wide adoption of WiMAX into mobile devices?

Trendsmedia, the organizers of the WiMAX World 2008 show, which took place in Chicago, USA on September 30 through October 2nd 2008 wanted to find out. WiMAX20/20, a leading WiMAX consultancy was recruited to organize the WiMAX Live - Low Power CPE Chipset Shootout. A first in the WiMAX industry, this session gave an opportunity to WiMAX chipset vendors to show live measurements of their low power solutions and explain how they are meeting the low power challenge. Among the merchant chipset vendors that were invited to the shootout were Altair, Beceem, Comsys, GCT, Intel, NextWave, Runcom, Sequans, and WaveSAT.

In order to establish a low power performance bar, the latest and most popular 3G handheld devices were surveyed to determine the battery life performance of these devices. Both EVDO and HSDPA based products were reviewed including the Palm Treo, Apple 3G iPhone, and the RIM Blackberry. A review of specifications concluded that "Talk Time" for these devices ranged between 4 hours and 6 hours. Similarly, Internet usage time averaged between 5 hours and 6 hours. WiMAX20/20 established two performance bars as follows:

More......