4G TECHNOLOGY

 

NAME: B.OBULIRAJ

BRANCH: B. E COMPUTER SCIENCE AND ENGINEERING

E-MAIL: obuliraj.avl@gmail.com

 

4G TECHNOLOGY

 Abstract

     The main aim of our paper is to bring forth the detail about the low cost wireless internet access for rural area through the 4G technology wi-fi (IEEE 802.11n).

    

    Although a large number of Internet users now enjoy high-speed access, there are still vast geographic regions where broadband services are either prohibitively expensive or simply unavailable at any price. Researches and technology are more needed for rural areas where the development is lacking.  

     Hence our paper analyses the cost and effectiveness of all possible technologies such as Cisco Aeronet Bridge based system, tethered Aerostat based network, and mesh network to find the suitable broadband access technology for rural people in a bearable cost.

Introduction

       The 4G technologies are all about improving the performance of today’s mobile networks, and also revolutionizing the model to create a truly ultra-broadband mobile experience.

The international telecommunications regulatory and standardization bodies are working for commercial deployment of 4G networks roughly in the 2012-2015 time scale.

Why move towards 4G

    

• Limitation to meet expectations of applications like multimedia, full motion video, wireless teleconferencing

–        Wider Bandwidth

• Difficult to move and interoperate due to different standards hampering global mobility and service portability
• Primarily Cellular (WAN) with distinct LANs’; need a new integrated network
• Limitations in applying recent advances in spectrally more efficient modulation schemes
• Need all  digital network to fully utilize IP and converged video and data

What is 4G?

       4G is a term used to describe the next complete evolution in wireless communications. A 4G system will be able to provide a comprehensive IP solution where voice, data and streamed multimedia can be given to users on an "Anytime, Anywhere" basis, and at higher data rates than previous generations.

 Objectives of 4G

 1.4G will be a fully IP-based integrated system.

2. 4G will be capable of providing between 100 Mbit/s and 1 Gbit/s speeds both indoors and outdoors, with premium quality and high security.

3. 4G will use smart antennas.

4. It will be multiple inputs and multiple outputs (MIMO) system based

5.Dynamic packet asignment

6. Wideband orthogonal frequency division multiple access (OFDM)

Key 4G Technologies

     Some of the key technologies required for 4G are described below:

1. OFDM technology

     Orthogonal frequency division multiplexing (OFDM) is a modulation technique that divides the communication channel into a number of equally spaced frequency bands. A subcarrier carrying a portion of user information is transmitted in each Band. Each subcarrier is independent of each other.

  OFDM transmits data simultaneously over a large number of channels at different frequency, enables to send a large data. Hence high speed information transmission occurs.

 

Fig.1 : OFDM  subcarriers

     OFDM not only provides clear advantages for physical layer performance, but also a frame work for improving layer 2 performance by proposing an additional degree of freedom. Using OFDM, it is possible to exploit the time domain, the space domain, the frequency domain, even the code domain to optimize radio channel usage. It ensures very robust transmission in multi-path environments with reduced receiver complexity.

 

Fig .2: OFDM in frequency domain

     As shown in the fig. 2 the signal is split into orthogonal subcarriers, on each of which the signal is “narrowband” (a few kHz) and therefore immune to multi-path effects, providing a guard intervals is inserted between each OFDM symbol. OFDM also provides a frequency diversity gain, improving the physical layer performance. It is also compatible with other enhancement technologies, such as smart antennas and MIMO.

     It can also be employed as a multi access technology (OFDMA). In this case, each OFDM symbol can transmit information to/from several users using a different set of flexibility for resource allocation (increasing the capacity) but also enables cross-layer optimization of radio link usage.

     OFDMA has being modulation technique for WLAN, digital audio broad cost systems, digital video broad cost systems and a candidate for future mobile systems.

2. MIMO system

     The multiple input multiple output (MIMO) technology was decided to add to IEEE802.11n standards. MIMO is a family of technologies for multi antenna wireless transmission and reception that increases the achievable data throughput within the same occupied bandwidth, increases quality of communication, and allowing dramatically increased spectral efficiency, while offering sustainable benefits to system performance, it also increases the challenges in design and system evaluation and validation.

     Multiple antennas at both the base station and terminal can significantly increases data rates with sufficient multipath. It uses signals multiplexing between multiple transmitting antennas (space multiplex) and time or frequency.

     MIMO is well suited for OFDM, as it is    possible to process independent time symbols as soon as the OFDM waveform is correctly designed for the channel. This process of OFDM greatly simplifies the process. The signal transmitted by m antennas is received by n antennas. Processing of received signals may deliver several performance improvements: range ,quality of received signals and spectrum efficiency

Fig. 3: MIMO strategy

3. Smart antenna

    

     Smart antennas are base station antennas that use digital signal processing to cancel interference. It provides sustainable interference suppression for enhanced performance.

 

Fig. 4: smart antenna

   

 

Fig .5: smart antenna in side & top view

      A smart antenna combines multiple antenna elements with a signal-processing capability to optimize its radiation and/or reception pattern automatically in response to the signal environment .it amplifies the frequency to user who wants to communicate and it can be adopted to OFDM and SDR

 

Fig .6: radiation pattern of smart antenna

4. Software Defined Radio

     SDR technology is enabling frequencies and communication methods and to be changed flexible by means of software. It responses to internet protocol version 6 (IPV6). SDR benefits from today’s high processing to develop multi-band, multi-standard base stations and terminals.

     Although in future the terminals will adapt the air interface to the available radio access technology, at present this is done by the infrastructure. Several infrastructure gains are expected from SDR.

     For example to increase the network capacity at a specific time (eg. During sports event), an operator will reconfigure its network adding several modes at a given transceiver station (BTS). SDR makes this reconfiguration easy.

    

     In the context of 4G systems, SDR will become an enabler for the aggregation of multi-standard Pico/micro cells. For the manufacture, this can be a powerful aid to providing multi-standard, multi-band equipment with reduced development effort and costs through simultaneous multi-channel processing.

Interlayer optimization

    

     The most obvious interaction is the one between MIMO and the MAC layer. Other interactions have been identified in fig.7

•          OFDMA

•          Smart antenna

•          MIMO

•          Optimized MAC scheduling algorithm

•          Robust and scalable transformation

•          Network selection

•          Usage cache

•          Pico station associated deployment

•          IP mobility

•          Meshed networks and ad hoc routing

Emerging 4G technologies

1. wi-fi( IEEE.802.11n)
2. wi-max (IEEE 802.16e)
3. 3GGP LTE

      4.    UMB

Low cost wireless Internet access through wi-fi for rural area    

  

                Fig. 8: A Look at Access Technologies in India

    

  The condition of the Rural Area

  

      Researches and Technologies are more needed where development is lacking, that is, in the developing regions of the world .however technology meant for developed telecom economics are often too cost, or otherwise   unsuitable for use in rural regions of the third  world. Thus, despite the enormous benefits enjoyed through the cellular revolution by people in metropolitan areas of developing countries like India, penetration of the technology in rural areas is poor or non-existent.     

Why the Penetration of Technology is less in Rural Area?

     The reasons for this are the low population density in rural (in comparison with cities) and the low paying capacity of users there. The cost of technology is important factor in deciding its applicability for rural use.

Issues with current approach

1.      Tower cost is very high

2.      The cost of directional antennas is very high. But to some extent directional antennas is unavoidable.

3.      Alignment of villages based client directional antenna is an expensive proposition.

corDECT(IIT-madras, TeNeT Group)

     corDECT is a wireless local loop standard developed in India by IIT Madras and Midas Communications at Chennai, under leadership of Prof Ashok Jhunjhunwala, based on the DECT digital cordless phone standard.

     The technology is a Fixed Wireless Option, which has extremely low capital costs and is ideal for small start ups to scale, as well as for sparse rural areas. It is very suitable for ICT4D projects and India has one such organization, n-Logue Communications that has aptly done this.

     The full form of DECT is Digital EnhancedCordless Telecommunications, which is useful in designing small capacity WLL (wireless in local loop) systems. These systems are operative only on LOS Conditions and are very much affected by weather conditions.System is designed for rural and sub urban areas where subscriber density is medium or low.

     "corDECT" system provides simultaneous voice and Internet access.The new generation corDECT technology is called Broadband corDECT which supports & provides broadband Internet access over wireless local loop.

     It is low cost technology designed for rural accesses. however the bandwidth achievable with corDECT are much lower .BB corDECT is a new version from TeNeT Group. It is commercially deployed in few thousand villages and it has also been deployed in Egypt, some African countries

     Wi-Max (IEEE 802.16 d/e) does the same and it promises broadband speeds but at much higher price – points.

Fig. 9: corDECT system

Cisco Aeronet Bridge Based System

  

     The Cisco aironet wireless bridge enables high speed (11 mbps), long-range outdoor lines up to 25 miles (40.2 km).

 

Fig.10:connectivity using Cisco                          wireless   Bridge

Installation amount in US$

Base station                        client side

Tower	5000
Cisco bridge	2000
3-D antenna	900
Total	$7900

Pole	100
Cisco bridge	2000
1-D antenna	300
Total	$2400

Tethered Aerostat approach

     An aerostat is a lighter than air object that can stay stationary in the air. The main envelope is filled with helium. It serves as a tower to hold omni directional antenna at the base station. It consists of antenna, router, and power over Ethernet cables. Its height is about 50 to 100 m.

Fig . 11: An aerostat

Cost of aerostat assembling

Aerostat	US$
Envelope Tether Winch First time to fill helium	800      80    120    200
Total	1200.00

Running cost: refilling the aerostat once a month - US$ 40.00

Cost of aerostat based assembly

Base station                       client side                                   

Pole	100
Wi-Fi	300
1-D antenna	200
Total	600

Aerostat	1200
Wi-Fi	300
Omni antenna	400
Total	1900

Prices of PC, Printer, power supply etc not included.

Advantages of Aerostat assembly

1. low cost
2.  easy to deploy
3.  portable
4.  Useful for hilly terrain and rapid deployment.

Disadvantages

1. periodic refilling for helium
2.  transportation of helium
3.  may require more maintenance

Wi-Fi using mesh network

Fig . 12 Mesh network

Village node

India has 600million Rural population

                                                                                                                          

     India has total of 6,00,000 villages in India and its population per village is approximately  500  to 1000. The average village area is 6 sq.km and the average distance between each village is 2 to 2.5 km 

Connect each village to the Internet

     Mesh network covers approximately 600 sq.kms. Hence 120 villages will be connected by each access point (AP) of mesh network. Some of village nodes (STA) groped together forms Ad hoc network (multi hop archicture).

 

Fig.13: Ad hoc archicture (without AP)

 

Multi-Hop networking       

  

       In mesh network the multi hop peer-to-peer paths are formed replacing the single hop (from and to the AP) paths. In addition the direct communication between nodes (without any participation of the AP) becomes possible.

     

     The benefits of the adaptation of the peer-to-peer paradigm within a WLAN a include mainly reduced energy consumption and the possibility for multiple simultaneous transmissions over the shared medium, which are expectations to lead to increase bandwidth.

     The AP is the only node capable of providing backbone connectivity. Each Hop is approximately 2 to 2.5 km and the maximum Hop to fiber drop is 6.

 

Fig.14: Mesh network

Cost of Mesh Network in US $

Equipment	Cost
10-15 m mast	100
Access point	100
Omni directional antenna	75
Total	$ 275

Steps to set up mesh AP

1.      mind set

2.      hardware

3.      software

4.      first node

5.      Wiana registration

6.      access controls

7.      more nodes

8.      deployment of nodes

9.      testing mesh connectivity

10.  feed back and routing

11.  contributing to locustworld

DGP project

     It was initiated at the IIT Kanpur (IITK), utter Pradesh, to explore the technical feasibility of establishing long-distance 802.11 links. Fig 1 shows DGP network as it has evolved over time we have a central location called the landline node which has wires internet connectivity.

                                                                                                                   

     In the DGP test bed, this is the IITK location. We have many long-distance (up to several tens of kms) 802.11 links formed using high gain directional antennas. Long-distance links connect various surrounding villages to the land line through a multi-hop mesh network. the DGP network primarily been used as a testbed for aiding various protocol studies , although we do  have developed people using communication  services  at many locations.

Ashwini project

    It is a network deployment effort by the byrraju foundation, to   provide broadband access and services to   a collection   of villages    in    the    west

 

 

Fig . 13: Ashwini project

Godavari district of Andhra Pradesh, India. This is a service –centric deployment and currently a variety of  

Interactive video-based applications such as distance-education, tele-medicine etc are being run on the network. Fig 3 shows the currently active links in the ashwini network. Here the bhimavaram location is the landline node. It is worth noting that a future 17 nodes will be included in the network in the near future.

Advantages of 4G

     As the networks move from generation to generation, more and more services are provided. Here is few of them,

1. seamless mobility
2. efficient support of various services at anytime anywhere basis
3. maintaining Qos as compared with wire-line network
4. higher bit rates from 10 mbps to 100 mbps
5. economic deployment of systems

    

Conclusion

     Wireless  communication is an unending,  undying  field  which  will prosper as long  as  the human  race  exist. To make India a leader in wireless

technology, the awareness and adaptation of the technologies forth coming new generation are needed and there is a need for conducting mission oriented research for 4G technology to give it to the people with low cost.

References

1. Ashok Jhunghunwala, “next generation wireless” TeTeK Group, IIT madras.

2. Dr.Bhasakaran Raman and Kameswari Chebrodu “Experiences in using wi-fi for rural internet in India” Indian Institute of Technology, Kanpur

3. Stephen Mc Laughlin, “Broadband communications” college of Engineering and electronics, University of Edinburgh.

4. IEEE network magazine

5. www.google.com