Friday, November 19, 2010

Network Jammers & Interceptors

What are Jammers?
So, what is the basic functionality of jammers? Jammers are high frequency transmitters deployed for blocking mobile signals from reaching BTS (for outgoing calls) or mobile phones (for incoming calls).

The jammers can act as a virtual transmitter and interfere with the normal working of cellphones, blocking both incoming and outgoing calls.

Jammers Vs Interceptors

Used mainly by military and law-enforcing agencies, deployment of jammers is considered illegal in most of the countries. The primary goal of jammers is to block cellphones in areas where they are forbidden by law, such as jails and in other places where it creates a nuisance, such as: churches, theatres, concerts halls, or conference halls.

For jails, service providers can opt for either of two solutions-detectors & jammers; and interceptors. In the first case, radio signals are detected by putting detectors in different cells, wherever required, and when the signals are detected it jams the signals.

This helps in jamming a particular area of the jail where prisoner movement takes place rather than jamming the entire jail and affecting the entire communications system. Its cost ranges between RS 200,000 and Rs 14,00,000.

Also, service providers can opt for interceptors that are currently in use by majority of the jails worldwide. Considered to be an intelligent device, the interceptors act as an all in one device and perform functionalities of a sensor, jammer, and recording system.

So, depending upon the conversation, one can either jam or record. The intelligent system costs are on a higher side and it is in the range of Rs 80,00,000.

But before deploying any of the two solutions, the service provider has to do a site survey to test the signal as is done in the case of installation of BTS. Since, jamming range is a function of signal strength received form a nearby base station and varies from one location to another. Even the jamming range varies with respect to different networks in a given location. Jamming also depends on topography of that area, thickness of the wall, reflection/absorption of signals in the given area, area to be covered, and frequencies to be jammed.

Once the survey is done, the service providers are in a better position to design an efficient system by knowing the number and positioning of the jammers. The service providers can either opt for a particular frequency band (GSM/CDMA) or can opt for a mix of VHF/UHF/CDMA/GSM/satellite phone/WI-Fi/Bluetooth/DECT. Care should also be taken to see that in case of power failure there are adequate backup facilities so that the jamming/interception systems can function even without assured power supply.

Once all these factors are taken into account, service providers can ensure that jamming/interception system is foolproof and will also help in preventing highly influential and powerful personalities from misusing mobile phones while being lodged in jail.

Thursday, October 21, 2010

The GSM Architecture- BSS

Base Station Subsystem

The Base Station Subsystem is mainly consists of two parts, the Base Transceiver Station (BTS) and the Base Station Controller (BSC). These communicate across the standardized Abis interface.

The Base Transceiver Station takes care of radio tranceivers that define a cell and handles the radio-link protocols with the Mobile phone. In a city like Mumbai there has to be a large number of BTSs deployed, thus the requirements for a BTS are ruggedness, reliability, portability, and minimum cost.

You may have also heard of an IBS( In-building solution). The next time you go out for dinner or to a hotel or even when you’re sitting in your office, look at the ceiling. You will find a conical shape. This is an IBS. It works as a BTS itself.

The BTS communicates with a BSC. A BSC will have multiple BTS. The Base Station Controller handles radio-channel setup, frequency hopping, and handovers.

So lets summarize:


1.Base Transceiver Station (BTS)
2.Base Station Controller (BSC)


  • Encodes,encrypts,multiplexes,modulates and feeds the RF signals to the antenna.
  • Frequency hopping
  • Communicates with Mobile station and BSC
  • Consists of Transceivers (TRX) units

  • Manages Radio resources for BTS
  • Assigns Frequency and time slots for all MS’s in its area
  • Handles call set up
  • Handover for each MS
  • Radio Power control
  • It communicates with MSC and BTS

The GSM Architecture- Mobile Station

Mobile Station/ Mobile Phone

The mobile station (MS) is not your mobile phone alone; it consists of a mobile phone and your SIM cards. ( SIM= Subscriber Identity Module) . Now in a GSM network, you can switch phones easily by simply inserting your SIM card into another phone. No hassles. That’s because, in a GSM network, your SIM card is attached to the network not your phone.

Now, it isn’t necessary that a SIM card is used for a Mobile phone alone, it can be used for other mobile equipment. I will explain this in my next posts. For now, for the purpose of simplicity, let us consider the Mobile station as a mobile phone+ SIM card.

Every mobile Phone is identified by The IMEI. (International Mobile Equipment Identity). Its like the fingerprint of a phone. You wont find two phones with the same IMEI.

Useful Info: IMEI’s are tracked by the Mobile Operator. It is registered in EIR of your networks MSC.

(EIR= Equipment Identity register)

Just like the IMEI is the fingerprint of the Phone. The IMSI( International Mobile subscriber identity is the fingerprint of the SIM card. The IMSI is used to identify the subscriber to the system, a secret key for authentication, and other information. The IMEI and the IMSI are independent, thereby allowing phones to be interchanged. The SIM card may be protected against unauthorized use by a password or personal identity number( PIN code)

Wednesday, October 20, 2010

How does a call flow in a GSM network?

The first time I read this off Wikipedia, I was petrified, thinking my career in Telecom has ended before it began. Before 2007, all I knew was a call was passed on from one cellsite to another to reach my handset. Little did I know, there were multiple entities involved in the process.

Lets start by switching your phone on.

When a mobile phone or in telecom parlance mobile station is switched on, it is necessary to read its BCCH(broadcast Control Channel) to determine its orientation within the network.

The mobile has to synchronize in frequency and time with its network. The mobile station will scan around the available frequencies and picks the strongest.

So do you ever wonder how your telecom operator knows where your phone is at all times? Your phone performs a Location Update to search for the strongest frequency and keeps contacting your telecom operator.

Let me just take you through the flow very simply.

Your phone is registered with your HLR (Home location Register). Imagine this as a register that records all customer information. The customers services, plans, products, history . ie if the customer has activated Caller or dialer tunes, his HLR will have it recorded. Even if the customer is suspended/ terminated, it will show.

So when the phones turned on, it first contacts the HLR, the HLR allows the connection and depending on whether you are in the same circle or in a different one, it will transfer your details to the VLR (Visited location Register) you have latched on to.

How does the call flow?

The user will enter the phone number he wants to call and press send/ dial. The mobile phone send s a call setup request to the users mobile network via the nearest BTS(Base transmission station)

The BTS transfers the call to a BS C( base station controller). One BSC handles multiple BTS.

The call setup request message is handled next by the Mobile Switching Center, which checks the subscriber's record held in the Visitor/ Home Location Register to see if the outgoing call is allowed.

If so, the MSC checks the NDC (National destination code) Eg: 919820 for Vodafone Mumbai and sends this request to the B party operators MSC.

The B party MSC will check if incoming calls are allowed to the called number and transfer this request to the BSC this number is currently latched on to. The BSC then transfers the call to the nearest BTS of the called number. Thus completing the call flow.


We all have heard of GSM and CDMA networks. But do we know what they mean and stand for. What are the major differences between the two?

GSM: Global System for Mobile Communications: 80% of the telecom market across the globe use GSM network. In India, Vodafone, Airtel, Aircel, Idea, TATA docomo, Reliance GSM are the important GSM providers

CDMA: Code division multiple access: MTS, Reliance, TATA

The GSM Association is an international organization founded in 1987, dedicated to providing, developing, and overseeing the worldwide wireless standard of GSM.

CDMA standard designed by Qualcomm in the United States, has been the dominant network standard for North America and parts of Asia. However, GSM networks continue to make inroads in India as CDMA networks make progress in other parts of the world.

There are camps on both sides that firmly believe either GSM or CDMA architecture is superior to the other.

To an end user, the architecture doesn’t really matter. The end result does.

Subscriber Identity Module (SIM) cards:

GSM phones use SIM cards. The removable SIM card allows phones to be interchanged & upgraded without carrier intervention. The SIM itself is tied to the network, rather than the actual phone.

CDMA networks use a R-UIM card. CDMA operators sell handsets that are linked to one their network only and are not card-enabled. To upgrade a CDMA phone, the telecom operator must deactivate the old phone then activate the new one. The old phone becomes useless.

Data Transfer Speed: Now mobile phones are used for not only making calls but as streaming video devices & email devices. Speed is important to those who use the phone for more than making calls. CDMA has been traditionally faster than GSM, though both technologies continue to rapidly leapfrog along this path. Both boast "3G" standards.

EVDO(Evolution- Data Only), also known as CDMA2000, is CDMA's answer to the evergrowing need for speed with a downstream rate of about 2 megabits per second. However in reality the speed is somewhere between 300-700 kilobits per second (kbps). This is comparable to basic cable.

GSM's answer is EDGE (Enhanced Data Rates for GSM Evolution), which boasts data rates of up to 384 kbps. In reality the speed is between 70-140 kbps. With added technologies still in the works that include UMTS (Universal Mobile Telephone Standard) and HSDPA (High Speed Downlink Packet Access), speeds reportedly increase to about 275—380 kbps. This technology is also known as W-CDMA, but is incompatible with CDMA networks. An EDGE-ready phone is required. I will touch upon UMTS and HSDPA later.

Both require being within close range of a cell to get the best speeds, while performance decreases with distance.

National Roaming: Most of the telecom operators today such as Vodafone, Airtel, Idea, Aircel, TATA have coverage in all 23 circles. These operators tie-up within themselves (Aircel Mumbai with Vodafone Maharashtra & Goa) allowing coverage in areas where they themselves have weaker network coverage.

CDMA networks may not cover rural areas as well as GSM networks, and though they may contract with GSM cells for roaming in more rural areas, the charge to the customer will generally be significantly higher.

International Roaming: If you need to make calls to other countries, a GSM network can offer international roaming, as GSM networks dominate the world market. If you travel to other countries you can even use your GSM cell phone abroad, providing it is a quad-band phone (850/900/1800/1900 MHz).

By purchasing a SIM card with minutes and a local number in the country you are visiting, you can make calls from that local card to save yourself international roaming charges from your network back home. CDMA phones that are not card-enabled do not have this capability, however there are several countries that use CDMA networks.

According, CDMA networks support over 270 million subscribers worldwide, while tallies up their score at over 1 billion.

Please note now CDMA users can switch between CDMA operators and keep the same phone.

A total of 391.76 wireless subscribers were split between 12 wireless telecom operators. Bharti Airtel lead the way with 93.92 million followed by Reliance (GSM + CDMA). Sistema which launched its services few months back has 0.39 million subscribers (3.9 lakh).

Top 12 Wireless Operators in the country :


Wireless Group

Subscriber base in millions

Market share (%)

















































Market share of top 12 operators :

Of the 391.76 wireless subscribers GSM has a market share of 76% and here is how they are split :

Reliance has registered a 6.73 % market share which is quite impressive for service which was launched only 6 months ago.

CDMA subscribers are at 94.5 million and here is how they are split :

Tata Teleservices which launched its GSM operations under brand name Tata DoCoMo will be another player to look out for in this next few quarters. Swan Telecom and Unitech Wireless are 2 other operators which are gearing up for a launch.

Reliance rules CDMA followed by Tata Teleservices (Tata Indicom). Shyam telelink is now rebranding to MTS India. CDMA doesn’t look as much over-crowded as GSM but when put together the overall picture of Indian telecom looks crowded with 12 operators and 3 waiting in the wings. Reliance and Tata are the 2 companies to watch out for with the dual play of GSM and CDMA operations.

The average revenue per user of CDMA is 99 rupees and that of GSM is 205 rupees. With 3 new players coming in for GSM the ARPU’s will come down. CDMA which is supposed to be a better network for data access can use this opportunity to increase the ARPU’s and subscribers. They just have to sort out the handset availability issue.

Source : TRAI

So which network do you use? CDMA or GSM?

The first video call today!

Nokia Siemens Networks is the first company to successfully demonstrate the Time Division Duplex version of LTE (TD-LTE) using broadband wireless access (BWA) spectrum in India.

The first video call was made by Mr. Gurdeep Singh, Chief Operating Officer of Aircel. The call was conducted with the 4G mobile technology running on commercial hardware at the Nokia Siemens Networks’ Bengaluru R&D facility. It marks an important milestone moving 2.3 GHz TD-LTE closer to commercial availability.

During the test, Nokia Siemens Networks demonstrated high-definition video streaming and three-way video conferencing. Using interoperable TD-LTE dongles from Samsung, the demo showcased a peak throughput speed of 110 megabits per second (Mbps) and low latency in the range of 10-20 milliseconds.

The end-to-end demonstration was based on Nokia Siemens Networks’ LTE equipment and software. These include the company’s award-winning Flexi Multiradio Base Station and Evolved Packet Core – which comprises Flexi NS(Network Server) and Flexi NG (Network Gateway) – and standard-compliant software.

TD-LTE technology promises enhanced delivery of broadband to laptops on the move and smartphone services, thanks to increased data rates, reduced latency and its scalable all-IP flat network architecture. This technology ensures high-speed mobile broadband connectivity and a superior performance from mobile applications across a wide range of devices.

“Today’s demo reiterates our leadership and commitment to getting TD-LTE into new market. It also demonstrates our regional and global progress in this area,” said Juha Lappalainen, head of mobile broadband sales at Nokia Siemens Networks. “Our TD-LTE trials across the globe prove our capability in driving rapid commercial TD-LTE network deployments aimed at facilitating a new wave of advanced mobile broadband services.”

“This is an important milestone in building the TD-LTE ecosystem in India,” added Urs Pennanen, head of India region, Nokia Siemens Networks. “TD-LTE over the Broadband Wireless Access spectrum is important for the country, as it will allow operators to offer voice and data to the masses. We are ready to collaborate with partners to accelerate our progress toward a comprehensive deployment of TD-LTE in India.”

The Hunters & The Prey in the Indian telecom Jungle

Goldman Sacs made a presentation to Vodafone titled Hunt or be Hunted. Vodafone chose to Hunt and hunt they did. They grew their subscriber base from 5 Mn to 350 Mn around the globe. Just by inking partnerships. They grew into a GLOBAL GIANT.

Today, there are 14 telecom operators in India. Do you think the Indian market is big enough to accommodate all 14 players and help them grow profitably? Russia has about 20 operators and USA over 50.

Even though India has the second largest population, 14 operators is a bit too much according to industry veterans. While most of the industry seeks regulatory clarity on certain aspects of mergers or acquisitions in the sector -- for example, fee for excess spectrum, the 40% market-share cap on an operator in a circle.

The sure survivors in this telecom jungle include leaders Bharti Airtel, Vodafone and state-owned BSNL. Investment bankers are already lining up before the first two Indian giants to get a piece of the multi-billion dollar acquisitions that are expected in the future.

The Hunters

Vodafone Plc

Vodafone entered India in 2007 by acquiring 67% in Hutchison Essar — back then the second-largest Indian operator by subscribers. It has since slipped to number three –Airtel & Reliance being the first two.

Max Touch> Orange> Hutch> Vodafone> ( I wonder who’s next)

This company has a history of acquisitions and it might be open to acquiring some more. If the objective is synergies with its existing operations, Vodafone will look for assets that give it high-value, post-paid subscribers, additional 2G spectrum, and 3G spectrum that complements its own holding. However, some acquisitions may be difficult because of a government rule that disallows M&As in a circle if it leads to the market share of an operator exceeding 40%.

Vodafone may also choose to wait for the outcome of two big payouts. One, the Essar Group holds 33% in Vodafone India. It has an option to offer that stake, reportedly valued at $5 billion, to Vodafone by May 2011. Two, Vodafone’s $2 billion income-tax liability case related to its Indian acquisition is currently in the Supreme Court. Both these decisions could reduce its buying power significantly.


Japan’s leading telecom company entered India in November 2008, by acquiring 26% in Tata Teleservices. It has a representative driving the strategy of the Indian company and it is expected to increase its stake further.

NTT DoCoMo has nearly seven years of experience in 3G services in Japan, which it hopes to capitalise on in India. Customers in ‘A’-class circles, who are expected to show the highest growth in 3G services, will be key to that strategy, say bankers. The company, along with Reliance, is one of the two operators with both CDMA and GSM technologies. This gives it wider access and more capacity to offer data services, which are better supported on CDMA.

It may look at an acquisition of an equally-sized company. It might even complement that with a new telecom company that has 2G spectrum, but minimal operations like Videocon’s Datacom.

New Entrants: France Telecom, Telefonica, Telstra, Vivendi & STC

These five foreign players have shown an interest in the Indian telecom market. If they do chose to enter, it will have to be through a massive acquisition of an existing operator/ operators. as the Uninor and Sistema experiences have shown that starting operations in the market can be extremely difficult.

France Telecom has a past relationship with Loop Mobile, which could help in a potential transaction. Uninor’s Norwegian parent Telenor has cash on its books. Now that it’s invested in the India, it could look at buyouts to capture a larger customer base.

The Prey

Idea Cellular

Market cap $5.5 bn
Fair enterprise value* $7.5-8 bn
Deal enterprise value** $10 bn

Kumar Mangalam Birla has said that Idea is not up for sale, but some of the investment bankers say Birla and its foreign investor Axiata might reconsider if the price was attractive. The Idea stock already trades at a premium to its larger peers on that expectation.

Idea has a loyal customer base, particularly in its eight original service-areas. Since August 2008, when it got additional spectrum, Idea has gone into expansion mode, and now has an all-India presence. Its average revenue per subscriber (ARPU) is among the highest in the industry, which is today viewed as a measure of subscriber stickiness.

This May, Idea bagged 3G bandwidth in 11 circles, mostly in premium locations, though it did not get Mumbai and Delhi. Given scarcity of this spectrum, and the value associated with it as data consumption is expected to explode, this can prove to be a substantial asset for an acquirer.


3 million subscribers
Fair enterprise value* $550-600 m
Deal enterprise value** $1-1.5 b

The company has two arms. Loop Mobile, formerly
BPL Mobile, operates solely in Mumbai. Loop Telecom has an all-India licence, but it is yet to report significant subscriber numbers. Its attractiveness lies in its Mumbai operations, where Loop Mobile has a first-mover advantage. BPL Mobile was one of the original licencees in the nineties, and thus has high-spending, loyal customers; they, typically, also use premium data services.

Of late, Loop has succeeded in capturing younger customers as it offers plans that cater to specific needs of customers in Mumbai rather than having to launch plans for all of India.

However, Loop Mobile is caught in an arbitration case with Vodafone Essar. Before Vodafone bought a majority stake in Hutchison Essar, the latter entered into a buyout pact for BPL’s operations. Hutchison (now Vodafone) says the agreement also included BPL’s Mumbai operations. BPL says it excluded Mumbai. The largest shareholder in Loop Mobile is the Essar group, which has just less than 10%.


110 million subscribers
Market cap $8.4 bn
Fair enterprise value* $14.5 bn
Deal enterprise value** Up to $15 bn

Reliance is the second-largest operator in the country by subscribers. Besides Tata Teleservices, it is the other operator with both CDMA and GSM technologies. On the flip side, it is burdened with a debt of Rs 30,000 crore. Hence, promoter Anil Ambani is looking to raise money by selling equity through a private placement.

The company may also look for a new deal to sell its telecom towers — its last deal with
GTL Infrastructure fell through due to differences in valuations — to raise these funds. Investment bankers say there aren't many suitors for Reliance because of its stiff asking price. The most likely transaction, they add, is a minority stake sale in the near term, possibly to a financial investor.


43 million subscribers

Market cap NA (unlisted)
Fair enterprise value* $4 bn
Deal enterprise value** $6 bn

It has a strong footprint in South India, where data consumption in states like Kerala and Andhra Pradesh is expected to take off first. The company has 3G spectrum in circles where it is the strongest. Having recently sold its towers, Aircel's debt is among the lowest in the sector. So, the liability of an acquirer will be lower.

Aircel's main promoter, Malaysia's Maxis, has historically exited investments in a finite timeframe with good returns. Both international and local buyers are interested in Aircel. Many bankers say Aircel might be merged with a mid-sized operator like Idea or Tata Teleservices, in a cash-and-stock deal.

*Estimated by analysts ** Estimated by investment bankers

Market cap as on October 15. Since bankers quoted enterprise-value estimates in dollars, we have converted the rupee value of market cap into dollars at the Friday exchange rate (Rs 44.09) to enable comparison