Redefining mobility

Nokia N92

Nowadays cell phones have become an integral part of our daily life. Cell phone enables us to collect information instantly without wasting our valuable time. But facilities are limited to voice calls and some data services.

In the near future due to the fabulous development of cell phone technology people will be able to watch news casting, do video-conferences, identify their location and even make phone calls without cell phone operators.

In this article I chronologically describe the advanced features of next generation cell phones such as TV enabled phone, Wi-Fi phone, and GPS phone respectively.

TV enabled phone
In 2003, Samsung and Vodafone unveiled TV phones in Korea and Japan. These phones basically received local analog TV broadcasts for free. But these new technologies compromised with video quality and in the same time responsible for drained phone battery. The underlying concept of TV phone is very simple; it's a cell phone with a built-in TV receiver. Cell phones generally pick up radio signals all the time. In the case of TV phones, they have the ability to receive radio signals in the TV-allocated frequency bands in addition to the bands allocated for cell-phone voice data. For instance, a TV phone in the United States might tune in to the 2110-to-2170-MHz band for a conversation and the 54-to-60-MHz band to pick up TV channels.

Transmitting TV signals for cell phones are considered as a challenging mission. Because streaming video requires fast transmission speeds. Existing '2G' GSM networks provided data-delivery speeds of 10 to 14 Kbps, and '2.5G' networks offered 30 to 100 Kbps. At 10 Kbps, a TV show seems to be stagnant; and at 100 Kbps, it's pretty choppy.

There's also the bandwidth issue. Television data takes up a lot more space than voice data, and delivering live TV to thousands of cell phones simultaneously can degrade the network's performance. Aside from these, receiving, processing, and displaying video content requires huge battery power, which means short battery life.

But these problems are eliminated in '3G' networks. Fast 3G networks provide data transfer rates from 144 Kbps up to 2 Mbps. 3G multicasting technology saves bandwidth by allowing multiple subscribers to access a single broadcast stream. Manufacturers are implementing power-saving transmission techniques like time slicing, which transmits data in spaced intervals so the receiver can turn off in between transmissions. There are several broadcast and delivery methods currently utilised in TV enabled cell phones. TV programs are distributed to TV phones via WiFi / WiMAX networks, satellites, and terrestrial towers.

A web enabled smart-phone with data capabilities can pick up the video stream from any WiFi hotspot or WiMAX coverage area. Land-based broadcasting methods send out analog or digital TV signals over the air from terrestrial base stations. A phone with a TV antenna and an analog or digital TV tuner can pick up the signals. There are a bunch of mobile-TV versions that utilise land-based broadcast including analog broadcast TV, digital broadcast TV and 3G-network broadcasting. Standards like T-DMB (Terrestrial Digital Multimedia Broadcast), MBMS (Multimedia Broadcast and Multicast Services), MediaFLO (a proprietary Qualcomm technology), and DVB-H (Digital Video Broadcasting-Handheld) all utilise aspects of 3G technology. DVB-H uses Orthogonal Frequency Division Multiplexing (OFDM) to make efficient use of bandwidth. The typical maximum transfer rate for a DVB-H system is 15 Mbps.

Satellite broadcasting employs two approaches such as MBSAT and S-DMB. In the S-DMB system, a content server sends the live TV feed through an encoder and transmits the data to an S-DMB satellite in the frequency range of 13.824 to 13.883 GHz. The geo-stationary satellite rebroadcasts the signals directly to terrestrial repeaters at 12.214 to 12.239 GHz and directly to cell phones on the S-band, 2.630 to 2.655 GHz. An S-DMB system can reach data rates of 128 Kbps.

WiFi Phone
WiFi phones use data networks instead the traditional PSTN. As a result phone with WiFi capability bypass the operator's network and make phone calls by connecting itself to the nearest WiFi hot spot. With 802.11 networking, or WiFi, VoIP can go wireless. A WiFi phone has an antenna that transmits information to a computer, base station or wireless router using radio waves. An antenna at a base station or router picks up the signal and passes it on the internet. WiFi phones that use the 802.11b or 802.11g standards transmit at 2.4GHz. Phones that use the 802.11a standard transmit at 5 GHz. When you make a call on a WiFi phone, you dail the number of the person you want to call, just like you would with a conventional cell phone. If you're calling another VoIP user, you may enter a VoIP address instead of a phone number, depending on the service provider's requirements.

The phone translates the number you dial into packets of data. It uses radio waves to transmit the packets to a wireless receiver. The receiver passes the information over the Internet to the call processor like an ordinary VoIP call. When you begin your conversation, the phone transmits your voice in packets of data as well. Although VoIP doesn't use huge bandwidth but sharing bandwidth with a lot of other traffic can result in poor voice quality or lost signals. Fortunately, quality, quality-of-service requirements can be built-in to new WiFi networks. With the right hardware and software, a hotspot can separate and prioritise the voice traffic, treating it as a separate signal and providing better voice quality.

GPS Phone
GPS enabled phones depend on Global Positioning System (GPS) satellites in order to establish communication link. GPS phone is basically a GPS receiver and it establishes links with three satellites at a time to identify the location.

The receiver then uses trilateration to determine your exact location. Basically, it draws a sphere around each of three satellites it can locate. These three spheres intersect in two points -- one is in space, and one is on the ground. The point of the ground at which the three spheres intersect is your location.