Paper (2006 - 2007)

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    Next Generation Wireless For Rural Areas

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    Wireless For Rural Areas
    Ashok Jhujhunwala
    Professor, Department of Electrical Engineering ,
    Indian Institute of Technology, Chennai 6000036.
    ashok @tenet. res. in

    1. Introduction:

    India has emerged as a significant force around the world, fueled by its rapid growth over the last decade. The economic growth has taken place concurrent to its explosive growth in communications and to significant extent, fueled by it. India used to add less than one million Telephones a year in early nineties. Now it adds six million per month. It is the wireless technology (both fixed wireless as well as mobiles), which has made telecom affordable in India, fueling the growth. This has helped business in all kinds of ways, propelling the Indian economy. The economic growth in India however is limited to urban areas. So is the telecom boom. 700 million people living in 637,000 villages have seen little change in their lives; even the Telephony has barely reached them. This is the challenge in India over the next decade. In a paper, .Role of wireless technologies in connecting rural India.1, the emerging technologies and business models with the promise to connect rural India were examined in detail. In another paper, .Broad band wireless technology for rural India .2, published in the issue, some of the innovations in the form of micro-GSM and satellite communication system for sparse areas are presented, which promises to flood rural India with mobile Telephony. But these will be primarily Voice and SMS connectivity. In this paper, we would review four emerging Broadband wireless efforts, which could provide Broadband connectivity in villages creating the potential for massive transformation of rural India.

    2. Emerging Broadband Wireless Efforts:

    As narrowband voice communication system reaches rural India, the need for Broadband Internet connectivity is felt even more. Such Internet connectivity in villages has the transformation ability, as it may enable rural India to leap-frog and fuel economic growth in these areas. Such a growth is essential for two reasons. The first is because the 700 million people live in these areas in a relatively deprived situation. Most have seen very little benefits to them arising out of the recent economic growth. At the same time, the reach of televisions in rural area has enabled them to see the transformations taking place in urban India. Fortunately, in a vibrant democracy that India is, they all have a vote and can not accept a political leadership, which allows rural areas to stagnate and not get the share of the growth. The second reason requiring urgent attention to rural growth is absolutely essential simply because that a large number of people continue to live in rural India. Even though, denied of opportunities, many would migrate to urban areas. But the population growth will ensure that rural population does not fall below 700 million people. Such large number of people cannot be left behind. A paper, .Rural connectivity in India: The n-logue Example. By Sangamitra Ramachandran included in this issue, shows the transformative capability of Internet. Rural India therefore needs the broadband connections at the earliest. Four technological solutions in the wireless domain, that may meet the requirement, are on the horizon. They include: (a) Broadband corDECT (b) IEEE 802.16 m (c) 3GPP . LTE (d) 3GPP2 . UMB We present each of these efforts in brief.
    2.1 Broadband corDECT:1
    The Broadband corDECT solution has emerged from India and is an advancement of DECT standard. Here the modulation used is 8-QAM as opposed to BPSK used in DECT. Using this higher-level modulation and line of sight communication and two DECT time slots a user. Circuit switched bi-directional time slot, a dedicated 256 kbps bi-directional connectivity can be provided to each user. Also, taking advantage of line of sight, horizontal and vertical polarization is used to double the bit-rate that can be transmitted for a given spectrum. Further, careful design of antenna and deployments in all fixed environment, implies that one can use 12 sectors in a cell, enabling significant spectrum reuse. The designers claim that they can thus getan efficiency of as much as 10 bits per cell per Hz, whereas most other systems do not even get 50% of it. The systems are being widely deployed today in small towns and villages of India today.
    2.2 IEEE 802.16 m3
    This is a OFDMA based standard emerging out of efforts of IEEE. The earlier version of the standard is IEEE 802.16 e which was finalized last year and is popularly known as WiMAX. This broadband wireless standard, using state of art modulation, coding, scheduling and multiplexing would use multiple smart antennas at least at the base station side, to enable peak data rates of 100 Mbpsec for mobile users in 20 MHz spectrum. The working group finalizing the standard aims to finalize the requirements, channel model and evaluation methodology by May 2007 and make a proposal to ITU-R Working Party 8F (WP8F) for IMT-advanced requirements by March 2008. The principle stakeholders driving this effort are vendors developing 802.16 products, licensed carriers using 802.16 products and members of WiMAX ForumTM.
    2.3 3GPP LTE4
    A Third Generation (wireless) Partnership Project (3GPP) Long Term Evolution (LTE) was started with feasibility study on evolution of Universal Terrestrial Radio Access Network (UTRAN) in 2004 and grew with the recommendations for delivery of mobile broadband services by Next generation Mobile Networks (NGMN) initiative in 2006. A Technical Report (TR 25.913) provides detailed requirements, which include downlink peak date rate of 100 Mbps within a downlink spectrum of 20 MHz using the OFDMA technique. The uplink peak data rate is expected to be 50 Mbps with a 20 MHz uplink spectrum using SC-FDMA technique. It is proposed to support at 200 users in active state in each cell for a spectrum of upto 5 MHz. The users are expected to get high performance with mobility as high as 120 kms / hr. MIMO is expected to be used and an enhanced multimedia service is expected to be a part of the standard.
    2.4 3G-PP25
    The CDMA Development group (CDG) is collaborating with Third generation Partnership Project 2 (3GPP2) to define an Ultra Mobile Broadband (UMB) standard as an evolution of CDMA 2000. The systems requirement document was approved in May 2006 and uses scalable bandwidth up to 20 MHz. The forward direction peak data rate is expected to be as high as 500 Mbps in fixed and 10 Mbps in mobile environment using OFDMA. The reverse direction data rate is to be 150 Mbps in fixed and 50 Mbps in mobile environment using qusi-orthogonal transmission based on OFDMA, together with non-orthogonal user multiplexing with layered superposed OFDMA (LS-OFDMA). The reverse link also supports CDMA for control and low-rate, low latency traffic. The advanced air interface agreement has been reached by Technical specification group C (TSG-C) based on a consolidated framework proposal submitted by China Unicom, Huwei Technologies, KDDI, LG Electronics, Lucent Technologies, Motorola, Nortel, Qualcomm, RITT, Samsung Electronics and ZTE Corporation. The detailed technical specification of air interface framework is expected by end of second quarter of 2007 and the Technological Evolution Framework (TEF) outlines the evolution strategy beyond the 2010 time frame.

    3. Implications for India

    These next generation broadband wireless standards are important for India, as it would enable broadband wireless to reach urban as well as rural India, pretty much like GSM / CDMA mobiles do so today. A broadband Wireless Consortium of India (BWCI) has been formed between operators, equipment manufacturers, component suppliers, academia and contribute the standardization efforts described in sections 2.2, 2.3 and 2.4. While these technologies would be available in 2008, the operators are starting to use Broadband corDECT in small towns and rural India. The next generation wireless would have the capability required to get broadband to all villages. The bit-pipes would be there. The challenge would be use the bit-pipes to transform rural economy.

    References


    1. Jhunjhunwala Ashok and Ramachander Sangamitra, Commentary: The Role of Wireless Technologies in Connecting Rural India, Indian Journal of Radio and Space Physics, Vol. 34, and October 2005.
    2.Bhasker Ramamurthi, Broad band wireless technology for rural India to be published in this issue
    3.http://www.ieee802.org/16/tgm/index.html
    4. http://www.3gpp.org/ftp/PCG/PCG/PCG Beijing workshop Presentations/3GPP Beijing workshop Corau TSG RAN Chairman .ppt
    5. www. 3G- PP2/CDG Press Release (August15, 2006)