Study About Wireless Internet For Rural Areas Computer Science Essay

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Even though the world population amasses around in metropolitan areas, yet there is over 40\% of global population lives in rural and remote areas of developing countries. Full broadband coverage is highly important for bridging the digital divide. The major issue is that wired based solutions cannot get through to their neighborhood due to the geographical restrictions.

We need to find a solution which serves best to the people in the remote places in the world. In other words we need to come up with some practical and cost effective wireless based solutions to help them in this scenario. This literature review report will discuss how overcome this problem using a satellite and the wireless incorporated technology.

\section {Introduction}

\subsection {Rise \& growth of the Internet}

\normalsize As the Internet evolved from the ARPA\footnote{ARPA - Advanced Research Projects Agency Network \cite{1}} project which has commenced in 1960s, it has been facing a lot of revolutions within these five decades. The very first ARPA link was born in between the University of California and the Stanford Research Institute in USA. Afterwards there has been so many innovative networking technologies were embedded into in to the ARPA concept. X.25\cite{1} was the very first public network which was powered by the Packet Switching technology. That was the first time where this global computer network used in business perspective. After the RFC \footnote{RFC - Request for Comments} process introduced the RFC 675- \textbf{TCP/IP} standard in to the world, this global network was known as "\textbf{Internet}" as we call it today.

\subsection{Inaccessible Last Mile}

\textbf{Last Mile} \cite{2} is the portion of a wide area network that runs from a user to the nearest aggregation point or hub. Most often that is the telephone company's local loop running from homes and businesses to a central switching office or exchange.

So with the conventional PSTN\footnote{PSTN - Public Switched Telephone Network} will not give any solution for this situation. Rural areas are defined to have a scattered population pattern including small villages or towns. Thus the DSL Internet providers extensively faced with the coverage limitation that they can reach. In other words DSL wire line providers do not have an intention to provide Last Mile connectivity within their region. To overcome the situation, some new alternatives should be innovated and developed for the commercial use.

\noindent\subsection {Motivation and Outline}

\noindent \normalsize According to the definition in Wikipedia, \textit{"\textbf{wireless communication is the transfer of information over a distance without the use of enhanced electrical conductors or wire}".} Wireless network technology allows us to offer various kinds of services to the remote areas, such as long range voice and data communications, where it seems to be virtually impossible to reach by the wired technology.

\normalsize There are plenty of networking technologies are out there to be examined and conforming to this domain problem. However some of those has started to get more attention when the IEEE\footnote{IEEE-Institute of Electrical and Electronics Engineers} was standardizing them. From Chapter three onwards of this document, we can have a more deep look on a chosen wireless solution for this domain problem. To get more information regarding the contents of this document you can browse through the original refernce pages which are available at the end of the document.



\section {Explored Solution}

\indent \large \textbf{Hybrid Satellite and Wireless LAN architecture}

\subsection {Satellite Approach}

\noindent \normalsize In the areas where there is no wire line (optical fiber or POTS) available, satellite connectivity seems to be a viable option for serving the rurals with telecommunication and Internet facility. Satellite communication can be divided into two broad categories as unidirectional (i.e. Television Streams) and Bi-directional. In this context (of accessing the Internet), it must be a Bi-Directional one.

Satellite systems are usually configured as VSAT\footnote{VSAT - Very Small Aperture Terminal \cite{3}(\textit{Very Small} term refers to the satellite dish which is used by the VSAT system)} or DVB-RCS\footnote{DVB RCS - Digital Video Broadcast Return Channel System \cite{3}} standard in order to send and receive the data signals with the satellite. VSAT system consists with main three components.





\caption{Componenets in a VSAT system \cite{3}}

\label{hybrid satellite approach }


As the above figure depicts, there are three main components required to establish a regular VSAT station.


\item \textbf{Satellite -- }Geostationary satellite.

\item \textbf{Master Earth Station (MES)} - It works as the network control center for the entire VSAT network. It is responsible for the configuration monitoring and management of the VSAT network.

\item \textbf{VSAT remote earth station} \textbf{--} This is the end user's hardware utilization. It includes the outdoor unit (ODU) indoor unit (IDU) and the inter-facility link (IFL)the


With today's technolgy, Star network topology and Mesh network topology have been using for implementing a VSAT system.


\noindent Three Identified frequency ranges\cite{4} are using for the satellite links.


\item Ku-band: 12 - 18 GHz. Using for TV \& Radio broadcast as well as Internet down link.

\item Ka-band: 20 -- 30 GHz. However this is more vulnerable to environmental changes like rain.

\item V-band: 40- 74 GHz. Still in experimental age.


\noindent \normalsize It is highly costly if you are using a one to one mapping in between the satellite terminal and the end user. To overcome that issue we need to have a affordable terrestrial (broadband) solution which can serve many end-users with a single satellite terminal with a return channel. However these type of networks usually suffers from high end-to-end network latency. There are some alternative Transport Layer techniques available to improve the efficiency over terretrial wireless and satellite networks.

\subsubsection{Enhanced TCP methodologies for Wireless networks}


\item \textbf{I-TCP Approach} \cite{5} - In this method, it splits the main TCP connection into two separated connections at the base station. One between the fixed host and the base station, and another between the base station and the mobile host. The latter one is connected by one-hop wirelss link and there is no need of using TCP on that link.

\item \textbf{Fast-Retransmit} \cite{5}- Mobile host Sends certain threshold number of duplicate acknowledgments to the sender. Because of that TCP at the sender to immediately reduce its window size and retransmit packets starting from the first missing one.

\item \textbf{Snoop Module} \cite{6} - While sending data from mobile host to a fixed host, it detect missing packets at the base station and generate negative acknowledgments for them. These negative acknowledgments are sent to the mobile host (the sender).It will processes them and retransmits the corresponding missing packets.


Among the hundreds of wireless lan designs which are still in the research level, we can concentrate on more reliable and well studied and tested architectures which are meant for this purpose.


\subsection{Wireless LAN plans}

\subsubsection{IEEE 801.16 (WiMax) approach.}

\noindent WiMax\footnote{WIMAX - Worldwide Interoperability for Microwave Access} support high speed data communication, but it also has the ability to maintain dedicated links and VoIP (Voice over IP) services can be very reliable and of high quality. Currently for a service provider, deploying a DSL to a relatively remote location can take several months and the cost involved can be significant. With the help of WiMax, a service provider will be able to provision that service in a few days and in a very cost effective manner.

WiMax is based on the IEEE 802.16 standard, which enables high speed packet data access on a mobile terminal (laptop, smart phone.. etc) without any access point dependency. \textbf{Fixed WiMax} and \textbf{Mobile WiMax} can be identified as the main two categories of WiMax technology. Because of the Mobile WiMax (IEEE 802.16e standard) end users can gain access with only a USB dongle which attached to a computer.

\noindent A WiMax system consists of two parts:


\item \textbf{WiMax tower}- Which is similar in concept to a cell-phone tower

\item \textbf{WiMax receiver} - The receiver and antenna could be a small box or PCMCIA card, or they could be built into a laptop the way Wi-Fi access is today.


\noindent The important thing about WiMax is it supports both line-of-sight service and non line-of-sight service. When the implementation complies with the line-of-sight it uses higher frequencies around 12 - 66GHz\cite{7}. Thus it can serve very high bandwidth with less interference.


some Internet service provider establish a WiMax base within a village subscribers may need to pay for the base station. This should not be misunderstood with the Wi-Fi technology. With Wi-Fi, it put some a bunch of Wi-Fi covered areas called "hot spots" that cover a few hundred square yards, and users may access the Internet when they can reach those hot spots.


\noindent WiFiRe \cite{8} stands for WiFi Rural Extension. It uses licence free 2.4 GHz spectrum and cheap

802.11b RF chipset as physical layer. WiFiRe is a star topology - a Base Station (BS) at the fiber Point of Presence (PoP) and Subscriber Stations in the villages nearby with 6 directional and sectorised antennas at the System.

Design of the Wi-FiRe is very much similar to WiMAX which has several advantages. Mistakes done by WiMAX will not be repeated in case of WiFiRe (like complexity and expensivness of equipments). Both have similar layering approach. Modularity and abstraction in those layers is also same. WiMAX is closely 'talking' with hardware while WiFiRe will keep modular approach and 'minimum talk' with the hardware.


\subsubsection{Mesh Network concept.}

\noindent \normalsize Wireless mesh networks are a special case of ad-hoc networks. Since they are easy to setup and maintain, and have good scalability. In this concept users' devices are an active part of the mesh. They dynamically join the network acting as both user terminals and routers for other devices, consequently further extending network coverage.





\caption{Wireless Mesh Concept \cite{9}}

\label{Wireless Mesh }


As the above figure depicts, there are three main components required to establish a regular VSAT station. However (not like in the above figure) in this scenario we are discussing about a wireless mesh with a satellite VSAT backbone.

This type of networks can be categorized into two main categories as \textbf{off-the-shelf} and \textbf{proprietary} solutions. This interesting concept is a still very hot topic among the researchers who are seeking for new revolutions in networking world.

Mesh network differs from flat ad hoc networks because it introduces a hierarchy in the network architecture with the implementation of dedicated nodes (known as \textbf{wireless routers}) communicating among each other. Also it provides a wireless transport services to data traveling from users to either other users or access points (access points are special wireless routers with a high-bandwidth wired connection to the Internet backbone). The network of wireless routers forms a wireless backbone (tightly integrated into the mesh network), which provide multi hop connectivity between mobile (nomadic) users and Internet gateways.


\noindent \subsubsection{Advantages of Wireless Mesh}


\item Reduction of installation cost -- Because of the few connection to the Internet backbone this reduces a enormous amount of cost rather than the typical Wi-Fi hot spot concept. Even the user nodes it selves becomes the part of the network and they also support to expand the network by acting as the repeaters.

\item Reliable -- Wireless backbone provides redundant paths between each pair of the end points, significantly increasing communications reliability. Failure of a single point does not affect the overall performance of the network.

\item Self Manage -- As the user nodes are adding to the mesh it keeps growing and growing infinitely. Thus there are new routing paths will born and nodes will be configured to detect them automatically.

\item Community and neighborhood networking support - Information can be shared easily within the community without flow through the Internet.

\item Large scale of coverage

\item Multiple paths are available for one home to access the Internet or communicate with neighbors.


\noindent \subsubsection{Challenges in Wireless Mesh}


\item Provisioning - Provisioning WLANs in multi access point deployments is far from trivial. Usually, the main

provisioning problem is to determine how much bandwidth each subscriber can receive, given a WMN topology and the offered loads.

\item Authentication - Before allowing a user to join the network, each client (stationary or mobile) should be authenticated. This can prevent access of the unauthorized users.

\item Privacy - Where user data travels through multiple wireless hops, there should be an end to end encryption mechanism to avoid the data sniffing.


\noindent \subsubsection{Mesh routing algorithms}

\noindent There are various kind of mesh routing algorithms\cite{10} under the research and development of various institutes.


\item Mobile Mesh Routing Protocol

\item Layer 2 wireless mesh routing protocol

\item Associativity Based Routing





\noindent This literature review comprise of exploration about new internet solutions that can reached to the last mile rural areas. In present various institutes and Universities are doing so many research and developments on this topic. However this article has mainly focused on Hybrid satellite and Wireless combination solution for this issue. When you implementing this type of solution in the real world you need to have a proper wireless network plan which suits the best to the terrain. Due to the geographic variance in the world there is no such solution exists that we can call as a "best wireless solution ".


However comparing with the WiMAX or Wi-FiRe , Mesh networks can be much more affordable and reliable solution for the rural client. For example If you build a WiMAX / Wi-FiRe solution within a village, subscribers' montly bill might also be added with the initial construction cost of broadcasting station.


Now a days Mesh Networking has a huge community support by researching new routing alogrithms, optimizing the network span... etc. As the name speaks itself mesh network span by adding new nodes to the network. It is not only by the broadcasting routers but also by user nodes (computers, PDA.. etc ).Even if we implement such wireless solution though we need to optimize the Transport layer communication. Otherwise it will all ended up with a congested network because of the end-to-end latency.