Wireless Communication Systems

Introduction
Wireless communication is part of today’s world and is greatly in demand as such resources are preferred in today’s world and so the sales are increasing day by day with equipment which involves wireless communication. The G which means generation, in the technology today amongst phones covers the technology improvement in the last few decades. The first mobile phone technology started with 1G which involved analogue technology. In the early 1990s the next generation of communication developed named 2G which was in a digital technology which also had text messaging with the idea of SIM cards coming into practice. SIM is short for (Subscriber Identity Module). Other technologies that evolved were CDMA(Code Division Multiple Access) and GSM (Global System for Mobile Communication). The next generation which followed made the data carrying better, making it potential to carry information such as websites as how they were originally. In 3G technology the iPhone has become the latest.

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As of today the agreement of 4G technology has not yet been established. It has been planned to have fast transfer speeds and should have good security. Something else that the 4G technology should meet is that it should reduce blips in transfer of the device when moving between different networks. The 4G mobile network should also be able to use the networks like the ones on the internet with IP addresses.
4G mobile is not yet implemented as an approved set of standards, so its characteristics are at present simply goals rather than requirements. As well as considerably desired increasing data transfer speeds, 4G mobile as well as should use improved security measures, When a device moves one place to another place between this area covered by different network reduce the blips in transmission is the another goal .4G mobile networks should also use a network based on the IP address system used for the internet.
Two major systems using 4G technologies are WiMax and Long Term Evolution. WiMax began testing its 4G technology in Baltimore in 2008. The opposite system LTE was expected to be ready to be tested in 2010 and is expected to be ready for use in 2013.
All this information above is described in detail in this research. All the topics covered above are broadened below.
3G
3G technology comes with better features than previous mobile network technologies. It has transmission which is at high speed, better multimedia access as well as connection globally.3G used with mobile phones a connects the phone with the internet and other IP connections which allow voice as well as video calls to be accessed. Not only this but also helps to download and surf the internet.
From lower mobile technologies, 3G technology has higher data speed, better audio and video access, video calling support, Web use at quicker speeds and TV through the Internet.
In 3G networks the transfer speed is between 128 and 144 kbps for devices that are fast and 384 kbps for slower ones. Wireless fixed LAN’s have a sped beyond 2Mbps. W-CDMA,TD-SCDMA, WLAN and cellular radio, among others are some of the technologies that 3G includes.[1]
WCDMA
The third-generation Universal Mobile Telecommunications System (UMTS) will be able to deliver high data rates of up to 384 kb/s at widearea applications or even 2 Mb/s indoors . This is achieved by using wide-bandwidth signals with Code-Division for Multiple Access (W-CDMA). The user data are multiplied by a fast pseudorandom spreading sequence before phase modulating the radio-frequency (RF) carrier. The resulting signals which are then broadcast have a bandwidth of approximately 4.5 MHz.

Parameter

W-CDMA

Uplink

1920-1980 MHz

Downlink

2110-2170 MHz

Access

DS-CDMA

Duplex procedure

FDD

Modulation

QPSK

Pulse shaping

Root-raised cos,

Chip rate

α = 0:22

User data rate

384 kb/s; 2 Mb/s

Bandwidth/channel

5MHz

Max. output power

21 dBm (Class IV)

TD-SCDMA
It was proposed by the China Wireless Telecommunication Standards group to the ITU in 1999.60MHz has been reserved for CDMA2000 and UMTS, but TD-SCDMA has reserved 155MHz.In common with UMTS-TDD,TD-SCDMA does not require separate uplink and downlink and offer speeds from as low as 1.2kbps up to 2 Mbps. Uplink and downlink traffic can be transferred in the same frame but in different time slots, and there can be up to 16 codes allocated per slot, more time slot can be devoted to downlink transfer than in the uplink. This allocation of time slots is dynamic and if a symmetric allocation is required, which is usually the case for a telephone call, then this will also be allocated the required resources. The minimum frequency band required for this system is 1.6 MHz and the chip rate is 1.28Mcps.it does not have soft handover mechanism but has a system similar to GSM where the mobile device are tightly synchronized to the network, and it is from here that the term ‘syschronous’ is derived. it is designed to work with a GSM core network is similar way to WCDMA and can also use the UTRAN signalling stack when it is deployed as a complementary technology. The frame is 5 ms rather than 10ms in WCDMA and split into seven slot.[2].
4G
The future system technology of 4G should bring something that is very enchancing when compared to the previous technologies. 4G yet does not have a meaning as it has not yet been established. However the current targets for it are as follows:
system interoperability:-flexible interoperability of the various kind of existing wireless network, such as satellite, cellular wireless, WLAN, PAN and system for wireless access to the fixed network. It ability to roam between multiple wireless and mobile standards. Due to the interoperability of different mobile and wireless network through the same terminal we can identify the three possible configuration. There are

Multimode terminals:-this is obviously achieved by incorporating multiple interfaces to the terminal, one for the access methods of every different kind of wireless network. The ability to use many access methods will enable users to use a single device to access the 4G network irrespective of the particular access method used.
Overlay network:- In this architecture user will access the 4G network through the Access Points of an overall network. The AP will perform protocol translation and Qos negotiation for the connections. Since APs can monitor the resource used by a user, this architecture supports single billing and subscription.
Common access protocol:-this choice calls for use one or two standard access protocol by the wireless networks. A possible option is for the wireless networks to use either ATM cells with additional headers or WATM cells.

Terminal bandwidth and battery life:-
Future generation network will be covering a large range of banwidths from about a couple of kbps to about 100 Mbps or above. The battery life is expected to be about a week. This will happen with a reduction of the size of the battery.
Packet-switched fixed network.:-
This 4G technology will use wireless IP based fixed networks which will be able to connect the mobiles with the wireless networks effectively.
Varying quality of bandwidth for wireless access:-
Having a range of networks together will cause it to overlap with other networks. Due to where they are, the user will be abl to use different qualities of wireless by the change of bandwidth.
Distribution layer:
This layer of the network will be able to help with digital video as well as broadcasting and due to a good coverage will cover all areas.
Cellular layer:
This layer of the wireless network will give a load of capacity providing many users as well as provide good coverage in highly populated areas. It will allow data sizes of over 2 Mbps. The cell size will also be small compared to the distribution layer, and will support good mobility.
Hot-spot layer:
This layer will help with good service over a short distance. It will include WLAN systems like IEEE 802.11 and HIPERLAN. This layer will not provide great coverage in particular as it is a short distance however roaming should be available.
Personal network layer:
This layer will include wireless connection however in short ranges say through the use of Bluetooth. Mobility will be less but roaming should be available.
Fixed layers:
This layer uses an access system which is fixed.
Advanced base stations:
In the future for networks, the new smart antennas will make the capacity bigger as well as base stations having self-configuration not needing the need for employment. This would reduce costs. They will include a good range of terminals.
High data rates:
The 3G system will be changed using what it has already to form the new 4G generation. The 4G generation will offer higher speed than the 3G generation.
The introduction of 4G needs specific targets which are named above. To get to these targets, 4G needs the basis on how to achieve this which is explained in detail below.[1].
How 4G works:
In the networks which have the 4G wireless technology, each one will be given an IP address which will have a home IP address and an address which represents its real location. When the computer in the Internet wants to communicate with another device perhaps a mobile phone in the wireless network. The computer will be able to send packets to the IP address of the 4G technology getting to know the home address too.
To the phone’s address, the directory will send the packet through a tunnel, or a mobile IP, whilst on the meantime the directory server would also let the computer know that the phone’s address is correct. After this the other packets can be sent. The use of4G-IP address (IPv6) is that it will be able to carry more info than in the past with the IP address (IPv4). In this IP address, software can use them to tell the differences between services and to communicate with network areas of different sorts. This could be with the computer and the phones network. An example includes Moreover which uses 4G technology not only has this transmission way but also uses OFDM, MC-CDMA, LAS-CDMA, UWB *7 and Network-LMDS.[4]
Orthogonal Frequency Division Multiplexing abbreviated as OFDM, passes on figures on a great quantity through a radio wave. Changing the radio signal into many small signals then transferred at the same time through different frequencies to the receiver is the method in which this is carried out. OFDM is a digital technology through modulation which increase strength of these signal; this is good for high digital data transition. This is a great digital technology method in which through the process of modulation increases the strength of the signal and is good for a transition of high quality digital data.[2]
In this time, users might have a good question about how theses waves targeted the correct destination. A OFDM makes the radio wave target the right place though a couple of devices which are wireless, which make a connection tunnel when they start communication. After connecting the target, the radio wave splits into smaller signals which have the correct direction towards the target.
MS-CDMA stands for Multi-Carrier Code Division Multiple Access, which is actually OFDM with a CDMA overlay. The users are multiplexed with orthogonal codes to differentiate users in MS-CDMA and single-carrier CDMA systems. It allows flexible system design between cellular system and signal cell system. However, in MC-CDMA, each user can be allocated several codes, where the data is spread in time or frequency.
LAS-CDMA the shortened form for Large Area Synchronized Code Division Multiple Access, is made through by LinkAir Communication which is basically wireless technology through the developed 4G technology. LAS-CDMA makes voice capacity better, with high speed and the latest original solution called Code-Division Duplex (CDD) which combines the LAS-CDMA technology with the greater data transmission type of Time-Division Duplex (TDD).
This combination makes Code-Division Duplex to be very spectrally efficient as well as having high speed available today as a great system. LAS-CDMA is seen as being the great 4G technology’s ‘World Cell’. If two wireless devices for instance are a quite big distance apart then using this protocol which has IPv6 to create the connection.
In the 4G world, UWB radio which solves the multi-path weakening matters through its clever use of electrical impulses which has all frequencies at one time. Due to its low-power condition though, this UWB cannot be used outside of being indoors or underground. UWB should be used however with OFDM which cal transfer digital data on a large scale. This is positive though as the UWB would be running insides equally as the OFDM runs outside which means that the signal can stay strong. UWB also needs to be used in small distances inside the buildings through 4G technology. The broadband technology which is wireless used to carry video, data Internet as well as voice in 25 GHz is the Network-LMDS Local Multipoint distribution system. This method makes sure all these things are carried together at once, and this can be the result in the fading issue locally. [4]
Differences between 3G and 4G:
The main factors in which 3G and 4G technologies vary is due to their services, their ways of transmission, access to the web, the rates of transfer, security as well as quality. 3G technology can only carry upto the speed of about and up to 2 Mbps however 4G technology can go much higher to a better speed. 4G technologies can provide global connection whereas for 3G markets it is difficult to roam globally. Technology which uses 4G can provide global roaming at a lower price. 3g is based on the notion through circuits and packets through things like WCDMA, CDMA and TD-SDMA. However 4G uses the use of packets.
As mentioned above about the differentiation between the 3G and 4G, this has been broadened in the tab le below.

Feature

3G wireless technology

4G Wireless technology

Speed

Up to 2Mbps

Full-mobility: up to 100Mbps
Low-mobility:up to 1Gbps

Service

1. Difficult of global roaming
2. Expensive
3. good for voice transmission

1. roaming smoothly
2. inexpensive
3. good for any type of transmission

Core Network

1. Wide-area concept
2. Circuit and packet switching

1. broadband IP-based
2. Entirely packet switching

Technologies

1. WCDMA
2. CDMA
3. TD-SDMA

All access convergence
Main:
1. OFDM
2. MC-CDMA
3. LAS-CDMA
4. UWB
5. Network-LMPS

Wimax
Wimax which stands for Worldwide Interoperability for Microwave Access was made to give a ordinary structure for wireless connectivity in permanent, moveable, and mobile environments. WiMAX is a wireless technology intended to give high throughput over a distance.
It gives the quick broadband of link. It also provides wireless access which reduces costs which involves the fibre and making buildings. It has a range that goes beyond WiFi.
A WiMAX uses two hardware components — a WiMAX tower as well as WiMAX receiver. This tower covers a 30 mile radius. The tower joins to the Internet using a wide connection through a wireline, or it offers a wireless link to other WiMAX towers with Line Of Site (LOS for short) microwave links. The receiver could be anything.
NLOS (non-line of sight in full) connections join devices to the tower using a frequency range of 2-11 GHz as low wavelength signals are strong. LOS connections however do not cover as large area but covers and area of 4-6 miles.
QoS is the aspect in a technology to deliver high bandwidth services. Examples of such include VoIP and IP video services as well as other services as such. To provide such QoS service, the WiMax need to make sure they have a low latency.[4]
WiMAX security is defined in the Privacy Sub-layer in the MAC Layer, as specified by WiMAX standards. Fixed WiMAX (802.16-2004) typically uses X.509 certificates for authentication and 56-bit Digital Encryption System (DES), while Mobile WiMAX (802.16e-2005) uses EAP for authentication and Advanced Encryption System (AES) for encryption. Both employ Privacy Key Management (PKM) for authentication between base station and subscriber station.[5][9].
LTE
Long Term Evolution (LTE) is a 4G wireless broadband technology made by the Third Generation Partnership Project.
LTE has many benefits for not only the consumer but also the workers too:
Performance and capacity – one request that the LTE is to provide downlink rates of a minimum of 100Mbit/s and needs the technology to allow for speeds that are over 200Mbit/s.
Simplicity

From below 5MHz up to 20MHz, LTE supports carrier bandwidths. LTE also supports both FDD (Frequency Division Duplex) and TDD (Time Division Duplex). Ten paired and four unpaired spectrum bands have so far been identified by 3GPP for LTE. it is easiest to deploy 10MHz or 20MHz carriers, and eventually deploy LTE in all bands.
plug-and-play, self-configuration and self-optimization will simplify and reduce the cost of network roll-out and management.
LTE will be deployed in parallel with simplified, IP-based core and transport networks that are easier to build, maintain and introduce services on.

Wide range of terminals- LTE supports hand-over and roaming to existing mobile networks, all devices can have ubiquitous mobile broadband coverage from day one[6].[9]
COMPARSION BETWEEN WIMAX AND LTE

Aspect

Wimax

LTE

 
 
 

Access technology
Downlink(DL)
Uplink(UL)

OFDMA
OFDMA

OFDMA
SC-FDMA

Frequency band

2.3-2.4GHz,2.496-2.69GHz

~2GHz

Bit-rate:
DL
UL

75Mbps(MIMO 2TX 2RX)
25Mbps

100Mbps(MIMO 2TX 2RX)
50Mbps

Channnel bandwidth

5,8.75,10MHz

1.25-20MHz

Cell radius

2-7km

5km

Cell capacity

100-200 users

>200 users in 5MHz
>400 users for large BW

Spectral efficiency

3.75[bits/sec/Hz]

5[bits/sec/hz]

Mobility:
Speed
Handovers

Up to 120km/h
Optimized hard handovers supported

Up to 250km/h
Inter-cell soft handovers supported

Legacy

IEEE802.16a through 16d

GSM/GPRS/EGPRS/UMTS/HSPA

MIMO
DL
UL
No. of code words

2Tx X 2Rx
1Tx X NRx(Collaborative SM)
1

2Tx X 2RX
2Tx X 2Rx
2

Standardization coverage

IEEE 802.16e-2005 PHY and MAC CN standardization in Wimax

RAN(PHY+MAC)+CN

Roaming framework

Wimax forum

Auto through existing GSM/UMTS

 
 
 

[7].Verizon has devoted to using Long Term Evolution starting by soon, ensuring to deliver ten times the data throughput of 3G technologies in the current time. Others, including NTT DoCoMo in Japan, France Telecom, Vodafone in the UK, AT&T, and T-Mobile have said also they will use LTE rather than WiMAX.
Meanwhile, Sprint, Clearwire, and Comcast in the U.S., UQ Communications in Japan, and Yota in Russia are all competitively using 4G networks suitable for mobile networks using todays edition of WiMAX, 802.16e (2 to 10 Mbps), in inner-city markets where they will without doubt compete with 3G (and later, LTE) sources.
The WiMAX Forum declares that 504 operators in 145 countries have organized WiMAX, but many use older 802.16d technology that however cannot provide mobile services, and many are small operators in developing countries or pastoral areas.[8]
Conclusion:-
In every generation, when there is a default, the next following generation gets rid of this and a new idea or notion is found as a result. However at some points this may be difficult to happen due to several reasons. The world is looking forward for the most intellectual technology that would bond the full earth. New ideas are being introduced by researchers throughout the world, but new ideas introduce new challenges. There are several issues yet to be solved like integrating the mobile world to the IP based core network, resourceful billing system, and smooth hand off mechanisms.
Reference:

Future mobile networks 3G and beyond Edited by Alan Clapton published by : the Institution of Electrical Engineers, London, United kingdom
Convergence Technologies for 3G Networks IP,UMTS,EGPRS and ATM Jeffrey banister, Paul Mather and Sebastian Coope at Orbitage Consultants.
http://docs.google.com/viewer?a=v&q=cache:suYVNKca06YJ:www.habits.in/hab_files_007_822/files/3G%2520TO%25204G%25205G.pdf+limitations+of+4G&hl=en&gl=uk&pid=bl&srcid=ADGEESgduPdmeqSL9dwRiGnFJ0JOIktrJxjYXI8_5x7PWdeg7eQwcmvkJGDQE-N6lFOL62qsTZW4So4iJ9oIZIeb3tSr6X8xD35e3gjxiI_g6tL4XcJMY3MYFWZyjtnclDWgFCAA8S6R&sig=AHIEtbSPBQflncP4szu1MI5tLZL4tX8Y9g
Wimax taking wireless to the max Deepak Pareek published in 2006 by Auerbach publications
http://4g-wirelessevolution.tmcnet.com/topics/4g-wirelessevolution/articles/what-is-wimax.htm 15/03/2010 19.00
http://4g-wirelessevolution.tmcnet.com/topics/4g-wirelessevolution/articles/lte-ericsson.htm 15/03/2010 20.00
http://www.comsysmobile.com/pdf/LTEvsWiMax.pdf 15/03/2010 19.00
http://www.wi-fiplanet.com/news/article.php/3845111 15/03/2010 19.00
http://www.cs.york.ac.uk/rts/docs/CODES-EMSOFT-CASES-2006/codes/p266.pdf 15/03/2010