GSM network is designed by using digital wireless technology. It offers compatible wireless services to all mobile users in all over the world. The basic requirements for GSM are following:

• Services

• Quality of services and security

• Radio frequency utilization

• Network

Services: The services, which are provided by the system, should be potable to all Mobile Stations or Mobile Phones so that it can b used in all over the world.

Quality of services and security: The quality of both voice and data services of GSM should be good. The voice data is encoded in digital form by using a modulation technique i.e.Gussian Minimum Shift Keying (GMSK).The security features should be provided by the system to protect the network against unauthorized users.

Radio frequency utilization: The system should use the available band of frequencies (For uplink: 890-915MHz & For downlink: 935-960MHz) efficiently.

Network: Network designers manage the identification and numbering plans while switching and mobility management based upon signaling system i.e. Signaling System Number 7(SS7).

GSM Architecture

The main component groups of GSM architecture are:

• Mobile Stations (MSs)

• Base Station System (BSS)

• Network and Switching Subsystem (NSS)

Mobile Stations (MSs):

The Mobile Station (MS) consist of two operational parts.

1. Mobile Equipment (ME)

2. Subscriber Identity Module (SIM)

Mobile Equipment (ME): This is the hard ware used by the subscriber to access the network and it has a unique identity number known as International Mobile Equipment Identity (IMEI).

Subscriber Identity Module (SIM): This is a type of electronic card that is plugs into ME and contains detailed information about the mobile subscriber.

Base Station System (BSS):

BSS is central equipment, which is located at the cell site. It provides the link between MS and NSS. The BSS consists of two operational parts.

Base Transceiver Station (BTS): BTS consists of transmitting and receiving antennas and signaling equipment that provide air interface for a cell to route the call. BTS communicates with the MS.A single BTS can support one or more cells.

Base Station Controller (BSC): All switching functions, which are performed in MSC, are controlled by BSC. It also supports handoff strategies and allocate or release temporary channels for those users whose needed handoff. Several BTSs can be controlled by a single BSC and one MSC can serve many BSCs

Network Switching Subsystem (NSS)

It is the main switching center of GSM network. NSS includes the following:

Mobile Switching Center (MSC): It is the basic unit of NSS, which supports call-switching or routing functions. Its purpose is the same as that of telephone exchange but due to advanced wireless technology, its working is much better than that of exchange. Each MSC provides coverage to a defined geographic area only.

Home Location Register (HLR): For subscriber its a reference data base. Current location of MS, identification numbers and various addresses are maintained in it.

Visitor Location Register (VLR): It’s also a type of database. When an MS moves from home location to a visited location then its location is registered as a visitor in the VLR of visited system and this information is also updated in HLR of MS, by the VLR.

Equipment Identity Register (EIR): Its again a type of database, which contains information about MS equipment and check and identify its international validity of hardware and software to work properly.

Authentication center (AUC): Its a processing center and is normally worked together with HLR.Like HLR its also require to continuously access or update subscribers data. Its main purpose is to provide data security features to authenticate the subscriber.

Code division multiple access (CDMA) is a form of multiplexing and a method of multiple access to a physical medium such as a radio channel, where different users use the medium at the same time thanks to using different code sequences.

A number of terms are used to refer to CDMA implementations. The original US standard defined by QUALCOMM was known as IS-95, where IS refers to an Interim Standard of the US Telecommunications Industry Association. IS-95 is often referred to as the second generation (2G) cellular, or as cdmaOne (the QUALCOMM brand name). CDMA has been submitted for approval as a mobile air interface standard to the International Telecommunication Union (ITU).

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Sony’s Walkman brand of cell phones often bring a little more to the table in terms of design, and the W380 is no exception. As mobiles go, the W380 is not designed for those of us who crave hi-tech features, but it should appeal to the funky, style-conscious youth of today. So, for all the cool dudes out there, here’s my take on the W380.

Form Factor
When I say ‘cutting-edge’ design, I mean something that looks really funky. By that yardstick, the W380 is definitely cutting-edge! It even looks as if its edge could cut you. I couldn’t resist that, sorry, but what I meant was the W380 seems a bit incomplete – when it’s open it has a very (how shall I put this?) cut-off-at-the-top look. But I loved the design ever since I first saw it last year.

The 1.9 inch TFT display (which I think could easily have been larger) has a resolution of 176 x 220 pixels and there's an external OLED mono display with a 128 x 36 pixel resolution. There are three audio player keys located under the external display that also provide haptic feedback when used.

The 1.3 megapixel camera is in the front. There's a cool sensor under the camera that lights up when a call comes in. What’s interesting about this is, if you wish to silence the handset, a gesture control feature lets you simply slide your hand up and down over the sensor to switch it to silent.

There's a proprietary slot on one side for USB, charging, and handsfree connectivity. On the other side is the volume control that could also be used to silence incoming calls without cutting the call. A small key-lock slider is located on the rear just above the battery panel.

Though Sony Ericsson provides hot-swap slots for its handsets you still need to remove the back panel to access it. So should we consider this hot-swap or lukewarm-swap? Nevertheless, the W380 supports M2 cards though the slot is unfortunately under the rear panel.

The W380 has a nice large keypad with a 5 way nav-pad and shortcut keys for the internet and other functions. The problem is that for some reason the keys are a bit hard to depress. Not that it’s in any way much of a hindrance; it just slows down message typing a wee bit.

The W380 is not a handset that’s designed for the guy on the go; like I said earlier, it appears to cater to the fashion conscious or just plain funky generation. Feature-wise, the W380 is equipped with everything such folk would expect from a cool gadget.

Media
Since it’s a Walkman Series handset, the player has no issues except that it doesn’t have a manually adjustable EQ. Not that it matters; the MEGABass and other presets make up quite well. What I really liked was the FM radio pickup. I had no problem with signals during my lengthy daily commute. What I was a bit disappointed with was video player. Even though it has an option for full screen viewing, it refused to work. So I had to watch videos in a tiny window. Bummer. SE's Walkman handsets come with a 3.5mm handsfree converter, so you can opt to use your own earphones if you wish. The speakerphone is not too loud.

Connectivity
The W380 comes with the PlayNow application and Sony Ericsson’s Plus application for downloading content. The W380 supports HSCSD, GPRS and EDGE, which is great. You can set up your email and check it quite easily through the messaging menu. The proprietary USB connector supports 2.0 speeds. The inclusion of Bluetooth with A2DP profile means you can get yourself a good stereo Bluetooth headset and enjoy wire-free music. Sony’s TrackID feature is also supported.

Other Features
This handset is well-equipped with plenty of regular features that you’d use regularly. Some of these include Music Mate 2, and games like Extreme Snowboarding, QudraPop and Sims2. The W380 also has Sony Ericsson’s MusicDJ application for making music on the phone. Other usual features include a Calendar for reminders, a Notes feature, Tasks, Timer, Stopwatch and Code Memo for secure information.

The W380 has a separate voice recorder. The gesture control will take some getting used to, but it means you don't need to use the volume keys to silence a call. You have to slide your finger or hand back and forth over the camera lens area at least twice to silence the handset. Your hand can be at a maximum distance of about 2cm above the sensor, but I’d recommend you keep it closer.

Camera

The W380’s integrated 1.3 megapixel camera may not be able to record video, but it has plenty of useful features: white balance, a few effects, burst mode, a 12-second self timer, and also a night mode. The quality is not too bad; it's okay for camera of this sort.

Battery
The battery life is quite average. You’ll able to squeeze out about 3.5 hours of nonstop talking, provided you turn off all the animated screensavers and icons that Sony Ericsson is famous for. Thankfully the light sensor helps to certain extent by dimming the display a bit and shutting of the keypad backlight when not needed. This way you’ll be able to get about a day and half of usage, which is quite good.

The Bottomline
With a price tag of just about Rs 7990 (and that includes a 512MB card), this great-looking phone doesn’t function like a dream, but has plenty of relevant features that work just fine. It has a certain feel-good factor and you CAN get used to the keypad and gesture control. I’d say this phone is going to be quite popular – it even comes in some truly funky colors.

Specs

Sony Ericsson W380
Network	GSM 900/1800/1900, EDGE
Physical	92 x 49 x 16 mm, 100g
Display	176 x 220, 256k colors, TFT, 1.9 inch, External OLED , single color display
Memory	14MB internal, M2 for external (512MB provided)
Media	MP4, AAC+, MP3, and WAV, 3GP, Voice Recorder
Camera	1.3 megapixels
Connectivity	USB, Bluetooth with A2DP
Battery	300 hrs standby, 3.5 hrs talktime
Street Price	Rs 7990

Original Article : http://www.tech2.com/india/reviews/multimedia-mobile/sony-ericsson-w380/36071/0