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Voice Over WiFi: On Fabricating an Open Access Neighbourhood Wireless Local Loop for Telecommunication

February, $2007$


Background to the study

In developing nations, the telephone service is available only in large cities at a price few can afford and the more widely available mobile phone service remains expensive. As a result, at least 1.5 million villages in poor nations lack basic telephone services.Peter Lurie and Chris Sprigman quote countries like Guatemala which has just 65 telephones for every 1,000 people; Pakistan, 23; Nigeria, 5; and Burma, 4 and when compared to the United States which has 667 telephones per 1,000 people, one can see how wide the communication access divide is between the developed and developing nations[1].

But during the past 5 years, two enabling technologies have become commercially available that hold significant promise for expanding connectivity in developing countries at a substantially reduced cost- VoIP and WiFi. Fortunately these technologies are such that their demand in more developed markets are such that pricing is already showing the result of competition with a lowering of prices continuing to take place. Some of the newer components just now reaching the market will also experience significant price drops within this next few years[2]. The core technology upon which this dynamic is taking place is the Internet. But specifically it is the Internet Protocol (IP), the packet switching component of the Internet. The fundamental change brought about by the IP is that telecommunications can now take place through a packet-switched network, rather than a circuit-switched network which dominated communications up until the Internet. This factor alone provides for substantially lower costs simply due to the fact that the costs associated with delivering the network infrastructure is significantly reduced and the capacity is increased. Further, this IP network is capable of delivering both voice and data services through a single network, again realizing significant efficiencies.

Upon this IP-based infrastructure, two more recent technology advancemnts now make it possible to;

  • deliver connectivity to more impoverished areas at a substantially lower cost through wireless technologies, specifically WiFi(IEEE 802.11) and

  • deliver voice services through lower cost Voice over Internet Protocol (VoIP) switching, including the deployment of software-based switching that runs on lower-cost commodity servers, including PCs. These VoIP soft-switches include the ability to provide VoIP-PSTN gateways such that calling to/from existing phone systems is totally transparent to the user.

Darell Owen [2] points on an idea of combining of WiFi and VoIP as being a current dynamic that is just now gaining momentum and being implemented in selected locations in developed countries and could be a dream come true for developing countries. It should be noted that Internet access through WiFi HotSpots and wireless community networks is becoming increasingly common. As to WiFi, the techniques to improve its range and data rate are already beginning to be implemented on some large scale using mesh technology and the recent IEEE 802.11n standard. Wi-Fi expanded into the wide-area when it became evident that the technology can operate beyond its original intended use. Researchers and enthusiasts experimenting with Wi-Fi in ad-hoc mode, began setting up Wi-Fi mesh networks, with the aid of intelligent mesh routing protocols. Protocols such as OLSR and AODV dynamically maintain routing information between Wi-Fi nodes, thus making it possible to send information across the mesh regardless of the constantly changing environment. This is the basis of wireless community networks.

Wireless community networks or wireless community projects are developments of interlinked computer networks using wireless LAN technologies, taking advantage of the recent development of cheap, standardised 802.11 (Wi-Fi) devices to build growing clusters of linked networks. Such networks have a distributed topography and have the potential to replace wired internet in most places [3]. These projects are coordinated by citywide user groups who freely share information and help using the Internet. They often spring up as a grassroots movement offering free, anonymous Internet access to anyone with Wi-Fi capability. The community networks are different from wireless hotspots, which are usually put up for commercial purposes, often offering paid-for internet.

As voice-over-Wi-Fi (Telephony over IEEE 802.11) emerges as a productivity-enhancing wireless application and its offer as a possibility for these wireless community projects to bypass the incumbents' local loop to deliver voice services there is a growing expectation that these networks should also be able to provide voice and multimedia services as well. However a strong argument against using the technology for many operators is that, although capable of meeting the requirements for a widespread VoIP access technology; this was not intended in the original 802.11 specification. Equipment therefore needs to be enhanced with customized proprietary solutions to improve QoS, Mobility, security and availability. But there are significant benefits of mixing telephone traffic with data on a WLAN as is done on wired networks.

Therefore, this project begins to explore IEEE 802.11 wireless technologies in Uganda vis-Ã -vis provision of IP telephony over this infrastructure, examining briefly the legislation surrounding both the technology and the application of it. It documents the deployment of a neighborhood community Wi-Fi local loop communication network to provide open access voice services, and investigates guaranteeing mechanisms in order to ensure Quality of Service (QoS) for VoIP applications on these networks.

List of Acronyms

  • AODV: Ad-hoc On-demand Distance Vector (AODV) routing algorithm
  • DECT: Digital Enhanced Cordless Telecommunications
  • IAX2: Inter­Asterisk eXchange protocol (version 2)
  • IETF: Internet Engineering Task Force
  • IEEE: Institute of Electrical and Electronics Engineers
  • ITU: International Telecommunications Union
  • OLSR: Optimized Link State Routing Protocol for wireless ad-hoc networks
  • PBX(PABX): Private (Automatic) Branch Exchange
  • QoS: Quality of Service
  • RFC: Request For CommentÂ
  • RTP: Real­time Transport ProtocolÂ
  • SIP: Session Initiation Protocol
  • UDP: User Data Protocol
  • VoIP: Voice over IP
  • VSAT: Very Small Aperture Terminal
  • WLAN: Wireless Local Area Network

Statement of the problem

There is justified concern that the ICT revolution underway is bypassing the poor especially the rural poor. The explosion of mobile telephony, and the widespread emergence of internet cafes and telecentres have begun to extend beyond urban areas and towards poorer communities. Yet the majority of poor across the world are still beyond affordable reach of ICTs [4]. ICTs are considered to be promising technologies that can facilitate and perhaps even kick start African social and economic development and therefore there is an impetus from the Uganada Communication Commission through its Rural Communication Development Policy, the United nations, and many other non-governmental organisations for investigation and research in the area of rural communication technology development, to bridge the so called digital divide. The digital divide is characterised as the gap that exists in both the availability of electronic technologies to rural, underprivileged, and previously disadvantaged groups, as well as the availability of skills to operate the said technologies. This body of research is growing, with many practical case studies already in existence with a growing number of experimental and exploratory works in progress.

Therefore the focus of this study is a community-driven solutions for both network extension and service provision and indeed applications and content development and deployment of a communication system (specifically voice transmission tools) built in the open source environment, in conjunction with easily custom built infrastructural elements to be used in a test network by communities as an exploratory testbed for providing low cost voice services.


General Objective

This project aims to explore what current technologies can be applied to places with inadequate telecommunication infrastructure to provide voice telephony, using a wireless infrastructure which can be used at a later stage to provide data services.

Specific objectives

This project will focus on the use of open source, community developed software and tools to accomplish the task, and hopefully create a utility that is free of hindrances and uses current technologies to provide;

  1. A wireless telecommunications infrastructure using IEEE 802.11 mass produced devices and open source software to terminate voice communications

  2. Consumer access to community members

  3. An infrastructure environment that encourages community involment to provide sustainbale telecommunications

  4. Means for reduced overall cost of telecommunication system deployment in general and telephony service as a whole.

The challenging questions facing the researcher are:

  1. Can a wireless telecommunications infrastructure be built using mass produced devices and open source software to terminate voice communications?

  2. Will provisioning consumer access to community members make a contribution to current paradigms of ICT development in the developing world?

  3. Can consumer telecommunications be provided sustainably to a community using a community involvement model?

Scope of the study

Based on works by Mansell 1998; Burgelman, Nulens, and Van Audenhove 1999, Conradie, Morris and Jacobs [5] cite the following three key focus areas to successfully start bridging the digital divide in affected areas;

  1. Establish an ICT infrastructure or network that is reliable and affordable.

  2. Introduce/develop ICT applications that are responsive to local needs. Also ensure local capacity to adapt ICT applications to local conditions.

  3. Introduce relevant and supporting regulation or measures (ICT-related and other) such as steps to enable and support the first two actions mentioned above.

These three recommended actions can be seen as prerequisites for any kind of intervention aimed at using ICTs to reduce the digital divide or to foster development. Burgelman, Nulens and Van Audenhove add that, from a policy perspective, a new tolerant culture of political governance also needs to develop in order to make it possible for these actions to materialize and be successful.

Cost of Deployment

By using standards based, mass produced devices and open source software, the result should be a cheaply deployable network. Cost of deployment will be measured per capita, and must consider initial costs of deployment, cost of powering the devices and cost of network maintenance.

Key Technologies

The study will focus on the use of WiFi (IEEE 802.11) [6] as the core network infrastructure, contrasted with other current wireless networking technologies i.e.

  • ArrayComm's iBurst(HC-SDMA High Capacity Spatial Division Multiple Access)
  • Cellular/UMTS/GPRS/CDMA
  • DECT (Digital Enhanced Cordless Technologies)
  • Motorola Canopy
  • Software Radio Technologies
  • WiMAX (IEEE 802.16)

Power Considerations

Since the deployment of this network could possibly be done in an arena that promises little in the way of infrastructure this study will examine sustainable and affordable methods of powering network and user devices. The choice of technology used will be strongly influenced by how the devices can be powered, and if they can be powered without formal power infrastructure. The study will examine current solar and battery technologies as possible candidates for power provision.

The Community

The test network will be provided around the Makerere - Mulago Hill area. Makerere university has a relationship with the community in question, notable through provision of housing and academic related services.This region is a very good starting point for testing out information and communication technologies development research since it has a large community in need of telecommunication services and an established sudo dialogue with Makerere University.

Legislative issues

Since no study is done in a vacuum, and there are a number of legislative issues surrounding provision of communication access (especially wireless and VoIP), this study will position any developments relative to current issues surrounding provision of communication in this instance, and briefly consider the legal viability of a deployment.

Significance of the Study

The proposed research has theoretical, practical, and methodological significance:

  1. Since communication is a vital tool in the social and economic development of a country, therefore availability of quality and affordable basic communication services to everyone is critical.

  2. Communication services play a very crucial role in local governance and administration as decentralization takes root in Uganda.

  3. The availability of free/cheap communication services improves access to market information and reduces the cost of general ownership and wide usage.

  4. Access to communication services reduces isolation of communities in remote areas and improves service delivery in the fields of health, education, agriculture etc.

Literature Review


The biggest infrastructure problem found in the Developing countries is the lack of telecommunication networks that can support distributed applications[7]. In their works on Mapping Africa's initiative at building an information and communications infrastructure,Thapisa and Birabwa warn that the world is split between the fast and the slow which creates an imbalance because power shifts from the slow to the fast in terms of transactions and technological innovation.In supporting this view, Mutula contends that Internet has created an information revolution and is exercising an enormous influence in the commercial, education and social sectors of any economy of the world [8].

Julie Zielstra [9]basing on works by the the Banton Foundation quotes that "The design of the communications system through which we will talk to one another, learn from one another, and participate in political and economic life together is too important to be left to the free market alone. Public interest advocates- including representatives of the poor- must play an active role in both the policy arena and the marketplace to ensure that the emerging networks meet the basic economic, social, political and cultural needs of everyone, regardless of their ability to pay or where the live". And this statement in its entirety encompass the vision of community networks which is the basis of this work.

Community Networks

Community networks, information notworks or wireless community networks are locally focused groups of people who provide content on the Internet, Internet access, training, computer centers or volunteer opportunities and advocacy work. Zielstra [9]provides four characteristics of community networks which include;
  1. provision of public space in cyberspace, space for meeting new people, discussing issues and other social interrelations

  2. They recorgnise that communication is more important than information provision

  3. The have to be locally focused, which does not preclude communities of interest that are located within the locality

  4. And they should be comprehensive, covering all aspects of life and all sectors in a community and these sectors need to be involved in the creation of the network

Thomas Keenan and David Mitchell[10] give a detailed view on the changing role of community networks in providing citizen access to the Internet.Their main argument for the need for community networks is that in the past, states and governments through their ownership and regulation of the telecommunications networks were able to effectively guarantee near-universal basic access to telecommunications networks and services. However with the general withdraw of governments from their dominant role in telecommunication through policies such as privatization, universal access to telecommunication networks and services may not be guaranteed.

Though this view is based on telecommunication and governments in the developed world which to some extent differs from the situation for example in african countries like Uganda where it is the private sector that has revived the communication industry, Keenan et al concludes by predicting that community organisations will play a new role in the communication industry by providing services like free access to internet. The also predict that commercial establsihments like ISP will provide free services with new models of business for example advertisement on web pages or kiosk style type of access to communities who can not have access to hardware.

Ivan Horrocks and Christine Bellamy [11] in thier research on Telematics and community governance agree that telematics could be very instrumental in generating enriched information resources especially those needed to support new roles for citizens.The make a conclusion that community governance will depend on the establishment of a more dynamic conception of informatics that embraces focus on information as a resource and community networks act as conducts for dissemination.In regard to access to marketized telecommunication networks, Horrocks raises an issue of access relying on public service obligations of telecommunication providers. The emphasize that to ensure equity in terms of access, community networks which are open in nature are the only antidote mostly in areas with limited access.

Where wireless fits in

In community network evolution, wireless networks with an emphasis on data transfer have a place to fill. Wireless data carrier technology has application in rapid and highly accessible data network deployments. Luiz Dasilva [3]gives three reasons why wireless community networks have evolved as defacto for community networks. She attributes this to the success of the IEEE 802.11 family of standards for wireless local area networks which gave rise to a grass-root level effort that envisioned using this technology to realise the goal of unlimited, inexpensive bandwidth and sometimes internet access to mobile or nomadic user.

Dasilva attributes the success to wireless community network development to spontaneous deployment in the industrialized countries often spearheaded by grassroot hobbyist who share their own resources with others by setting up WLANs with open access and extended range through the use of external antennas. She also mentions low cost of wireless equipment due to the popularity of IEEE.802.11 technology and the the ease to make external antennas for the equipment. She lastly attributes the wide spread success of wireless community networks to the not for profit nature of operation with a goal of free internet access for all where participants make available their resources and time without financial compensation.

Applications of wireless community networks go beyond general access to the Internet, to include e-governance, tele-medicine,radio broadcast within a community, IP telephony, support of non-governmental organizations (NGOs),etc [3]. Rudi et al [12] contends that Although the types of wireless technologies that make wireless community networks viable (IEEE 802.11, in particular) are still not pervasive in some developing countries, we expect this to happen soon. The envisage that wireless communications are an especially promising solution for broader network access in such countries due to the lack of infrastructure (fiber, cable, twisted pair) requirements and rapidly decreasing costs. The conclude that there is a significant potential for adapting the wireless community network model to bring wideband access to under-privileged communities and give some relevant issues which include:

  1. Access to broadband “last mile” links where community networks can make broadband access available to a larger portion of the population, by creating a multiplicative effect because Broadband access can be supplied to a few points, and then distributed within a limited geographic area by forming overlapping wireless local area networks.

  2. Role of government and NGOs in some countries, where it is not realistic to expect the private sector to take the lead in the deployment of wireless community networks. Local governments, international donors,and NGOs may need to play an active role in the funding and viability of these projects.

  3. Coverage planning where the give an example in developed countries, where wireless community networks have evolved in a mostly un-coordinated fashion with an objective to provide uniform coverage to a community though the contend that some planning for the location of access points is desirable and the encourage the usage of techniques applied in cellular network dimensioning and planning.

  4. Regulatory issues in most countries and the enphasize that IEEE 802.11 technology works in unlicensed bands of the spectrum though the acknowledge that licensing and regulation can limit the rapid spread of this technology.The gave an example of China which imposes limits on the use of WiFi technology, mandating a Chinese version of the WLAN specifications.

  5. Rate of penetration of the technology where the rate of penetration of IEEE 802.11 access points and network interface cards (and, related, laptops and palmtops) is lower in developing countries though the rapidly falling prices make it likely that this will change in the near future.

In analyzing the views of the above researchers, the success of wireless community networks which are largely hobbyist-led developments of interlinked computer networks can not be under estimated due to the large size of web presence the community organizations have.[13].And the success of these networks has been mainly due to reasons Luiz Dasilva [3] gives as the major driving forces for wireless community network evolution

VoIP as a value added service in wireless community networks

In his research with the USAID Last Mile Initiative, Darell Owen [2]in his research on Rural telecommunication and technical business model notes that when one takes into account the literacy rates of those living in the rural areas of the world, combined with the very nature of their practical needs, it does not take much of an imagination to anticipate that voice will trump data as to highest demand within almost all rural communities across the globe. He goes further to say that it is a fact that in the most advanced developed countries in the world today and has been consistently for over a hundred years! even with the sophisticated potential of the Internet, the “killer application” for the last 20 years has been for basic person-to-person communications. He goes on to predict that the next Internet killer application? Oddly enough will be voice. In his research, he goes to emphasize that the message is not in any way to stop the expansion of data services off of the Internet but the need to refocus on the highest demand first and make sure voice is delivered to rural areas along with, or even ahead of the data services. And recognizing that VoIP is technically a data service over the Internet both voice and data services can now be delivered over one convergent and lower cost network.

As cited earlier [3]during the past 5 years, two enabling technologies have become commercially-available that hold significant promise for expanding connectivity in developing countries at a substantially reduced cost. Fortunately these technologies are such that their demand in more developed markets are such that pricing is already showing the result of competition with a lowering of prices continuing to take place. Some of the newer components just now reaching the market will also experience significant price drops within this next few years.

The core technology upon which this dynamic is taking place is the Internet. But specifically it is the Internet Protocol (IP), the packet switching component of the Internet, not necessarily all the additional value-added components we frequently think of when we refer to the Internet. The fundamental change brought about by the IP is that telecommunications can now take place through a packet-switched network, rather than a circuit-switched network which dominated communications up until the Internet. This factor alone provides for substantially lower costs simply due to the fact that the costs associated with delivering the network infrastructure is significantly reduced and the capacity is increased. Further, this IP network is capable of delivering both voice and data services through a single network, again realizing significant efficiencies. Upon this IP-based infrastructure, two more recent technology advancemnts now make it possible to;

  • deliver connectivity to more impoverished areas at a substantially lower cost through wireless technologies, specifically WiFi(IEEE 802.11) and

  • deliver voice services through lower cost Voice over Internet Protocol (VoIP) switching,including the deployment of software-based switching that runs on lower-cost commodity servers, including PCs. These VoIP soft-switches include the ability to provide VoIP-PSTN gateways such that calling to/from existing phone systems is totally transparent to the user.

Darell Owen [2] points on an idea of combining of WiFi and VoIP as being a current dynamic that is just now gaining momentum and being implemented in selected locations in developed countries and could be a dream come true for developing countries. It should be noted that Internet access through WiFi HotSpots and wireless community networks are becoming increasingly common. As to WiFi, the techniques to improve its range and data rate are already beginning to be implemented on some large scale using mesh technology and the recent IEEE 802.11n standard, primarily as a component in Wireless ISPs or community networks. The VoIP technologies have seen a very rapid adoption through firms such as SKYPE (computer-to-computer based), Vonage (the first large scale adopted phone-to-phone service), and more recently AT&T's Advantage plan. VoIP is also being rapidly deployed in the office setting where it is rapidly replacing more expensive specialty-hardware based PBXs.

Underprivileged communities and the needs for telecommunications

Most underprivileged communities in developing countries live in rural areas and have limited telecommunications assets to exploit for development. There is lack of telephones generally to provide voice communications. A number of the advanced telephone services available to modern urban residents, including call waiting, call forwarding, three-way calling, caller identification and voice mail, are very expensive for rural residents.

For some disadvantaged communities in developing countries, the first and most urgent telecommunications need is to provide them with basic local telephone service up to current minimum acceptable standards, with single-party, touch-tone service provided with digital switching, and line quality sufficient for voice mainly for local communication.

Gwen Wolford and Ann Hollifield [14] out of their intensive literature review in rural communication note that rural communities and rural residents pay in several ways the rural penalty that results from the greater distances and lower population densities that are the defining characteristic of rural areas. One of the prices they pay that is harmful to rural economic development is a universal countrywide flat rate of per minute billing, which does not differentiate rural and urban subscribers plus local and long-distance calling. In Uganda for example The Uganda Communication Commission studies have shown that rural residents pay a higher proportion of their income for telephone service than do urban residents. Most of that difference results from the higher per minute charges rural residents pay because needed services that would be a local call are charged uniformly despite the low cost incurred in routing local voice [15].

In urban locations, telephone companies routinely offer a wide variety of optional services, including voice-mail and caller identification. Voice-mail is important to small businesses because, unlike answering machines, voice-mail can record messages from incoming callers when the phone line is busy. Caller identification is an important business productivity tool for many computerized businesses. The caller ID feature permits the business to have the computer records of the calling customer or vendor retrieved from the computer database and available on the computer screen of the person answering the phone almost as fast as they can pick up the phone. This improves quality of service and saves costs. It should be noted that rural businesses could take advantage of these and other advanced optional services like broadband Internet if they were available locally but many telephone companies are reluctant to make the investment needed to provide advanced optional services on their rural telephone switches.

Relating telecommunication to Economic growth

Many researchers have studied the effects of telecommunications investment. They have consistently found that investment in telecommunications infrastructure and the resulting improvement in telecommunications services have consistently led to economic growth. Improved telecommunications has helped both urban and rural communities achieve their dreams of economic success. Recent books have reported or summarized many of the studies on the subject of telecommunications and rural development.

Cronin and others, in a landmark study published in 1991, conducted a detailed economic analysis of the US economy from 1958 to 1988 [16]. They found a cyclical, positive feedback process in which telecommunications investment in any year led to growth in the US economy in later years, which in turn led to more demand for and investment in telecommunications infrastructure. A related study found that the mechanism by which this telecommunications-induced economic growth took place was productivity gains in other sectors of the economy that were able to operate more efficiently with improved telecommunications. The research team extended the analysis they had done on US national economic statistics by replicating the study in a single state, Pennsylvania, and in rural counties within Pennsylvania. They found that the significant causal relationship between telecommunications investment and economic growth evident in national statistics was also seen in rural counties.

Several different types of telecommunications applications can help improve the economy and quality of life in underprivileged communities. Networks that electronically link the parts of an organization together, including computer local area networks (LANs) and wide area networks (WANs), improve productivity in the businesses and other organizations so connected. External electronic networks connecting businesses to their suppliers and customers permit cost reductions and service quality improvements.

Distance learning networks may be an ideal way for rural schools to pool their resources and to draw on outside talents not available locally, in order to provide their students with the best education available anywhere. It is hard to offer advanced placement courses or a wide variety of math and science courses in small rural schools. With appropriate distance learning networks, these options are all possible. Distance learning networks may also permit lifelong continuing education for rural residents who cannot afford the relocation or the long drive time required to attend courses in distant locations.

Tele-medicine networks can improve the quality of rural health care by permitting medical specialists in distant urban medical centers to consult with rural patients and primary health care providers. Improved remote diagnostic and monitoring capabilities may improve home health care services for rural residents. Improved computer networking may help local governments improve the quality and reduce the costs of their services while making government information more accessible to their citizens.

These and other specific telecommunications-intensive applications will be the way underprivileged communities use improved telecommunications to improve their economies and their quality of life. The relationship between telecommunications investment and rural development is not some distant, abstract concept. It is the practical business of installing in rural communities the networking capabilities that will make a difference to the lives and work of underprivileged residents.

Problems of Voice transmission on 802.11 networks

Voice over IP (VoIP) is an area of research and development that has been reported on extensively. This area as created to leverage the current wired computer networks to transmit multimedia. In particular, the transmission of voice has been a very important area. Wired networks can provide all the necessary functions to transmit voice traffic. However, there are inherent problems with voice over wired IP networks. An example of such a problem can be seen with the TCP/IP protocol. This protocol does not have any quality of service guarantees. Such guarantees are important with multimedia. With voice a caller and the called would prefer little to no delay.

As Wireless technology becomes more popular and implemented in mainstream networks which wireless community networks are part of, it is only natural for applications such as VoIP to be implemented. The new joint area is called Voice over Wireless Data Networks. This area covers Voice over Wi-Fi (VoWiFi) as well as Voice over Wimax, but excludes cellular networks. The idea of VoWiFi is to utilize existing wireless technology that is used for computer networks to transport voice traffic. Such computer networks can be thought of as Data Networks, since the original purpose was to transmit data from computer to computer. This newly merged area of research maintains most, if not all, of the wired network problems with voice traffic. In addition, mobility and security become a bigger problem. With individuals traveling to and from subnetworks, issues of handoff and connectivity become apparent. This research tries to identify problem areas and discuss solutions that are currently under development.

Ping Chung et al [17] in their works on voice over IEEE 802.16 MANs emphasize that conventional VoIP schemes transmit packets to/from each client individually over wireless channel in a WLAN and since each packet is typically 10-30 Bytes, the overhead at the physical and MAC layers become quite significant, substantially reducing the efficiency of wireless networks. The propose a multiplex-multicast enhancement scheme which the claim can improve the VoIP capacity in WLAN operated as an infrastructure basic service set (BSS) by close to 100%. Unfortunately this scheme can not be implemented easily since it advocate a change in the 802.11 standard and hardware design.

Zubey et al [18] cite that packet switched data transmission, such as IP is optimized for data integrity. If a portion of an email or web page is garbled, then the ability to read the communication may be compromised or rendered impossible. However, the transmission of such data is not time dependent and the user can tolerate relatively wide variations in the packet arrival time, as long as all the packets arrive eventually, and all packets are reassembled in the proper order. However contrasting with digitized voice and video which are isochronous or time dependant data, the perceived quality of a call depends on each part of the transmission arriving in order, and within a very narrow time frame relative to previously received packets.

Another drawback of VoIP service is its frequent reliance upon another separate service - an Internet connection. The quality and overall reliability of the phone connection is entirely reliant upon the quality, reliability, and speed of the internet connection which it is using. Higher overall network latencies can lead to significantly reduced call quality and cause certain problems such as echoing. Related to this, because UDP does not provide a mechanism to ensure that data packets are delivered in sequential order, or provide Quality of Service guarantees, VoIP implementations face problems dealing with latency and jitter. This is especially true when long round trip propagation delays are involved. The receiving node must restructure IP packets that may be out of order, delayed or missing, while ensuring that the audio stream maintains a proper time consistency.

Conventional phones are connected directly to telephone company phone lines, which in the event of a power failure are kept functioning by back-up generators or batteries located at the telephone exchange. However, wireless community networks are powered by household electricity, which may be subject to outages dictating the use of an uninterpretable power supply or generator to ensure availability during power outages. Even with local power still available, the servers acting as VoIP nodes themselves may experience outages as well. While the PSTN has been matured over decades and is typically extremely reliable, most community networks are less than 10 years old, and even the best are still subject to intermittent outages.

Some community networks have less than desirable quality most especially when there is interference and long distances involved . Where IP packets are lost or delayed at any point in the network between VoIP users, there will be a momentary drop-out of voice. This is more noticeable in highly congested networks and/or where there is long distances and/or inter-networking between end points.

The nature of IP makes it difficult to geographically locate network users. Emergency calls, therefore, cannot easily be routed to a nearby call center, and are impossible on VoIP systems. Moreover, in the event that the caller is unable to give an address, emergency services may be unable to locate them in any other way. A technical work-around may require the registration of the physical address the VoIP line will be used at. When one dials the emergency numeber they will route it to the appropriate local system. Related to this, wireless networks and IP networks as a whole have a shortcoing in sending faxes due to software and networking restraints in most voip systems. However, an effort is underway by the International Telecommunication Union to define an alternate IP-based solution for delivering Fax-over-IP, namely the T.38 protocol [19].

While the traditional Plain Old Telephone System (POTS) and mobile phone networks share a common global standard (E.164) which allocates and identifies any specific telephone line, there is no widely adopted similar standard for VoIP networks and this is further complicated in wireless community networks which tend to grow organically. This problem may be partially overcome using service discovery protocols for example ENUM and DUNDi but still it does not guarantee uniqueness.

Current attempts to implement QoS on IEEE.8011 Networks

A variety of wireless standards are in the works to address the technical limitations of running voice over wireless. The following are some of the key enabling standards for quality of service, security, radio resource management and fast roaming.


This amendment defines the medium access control (MAC) procedures to support local area network (LAN) applications with quality of service (QoS) requirements. The procedures include the transport of voice, audio, and video over IEEE 802.11 wireless LANs (WLANs).[20]

The 802.11e task group is adding QoS to the wireless standard. The group has come up with two different types of QoS:

  1. Prioritized QoS using priority tagging to place different types of traffic in different queues. Certain applications - such as voice - get priority treatment, but not a reserved or guaranteed bandwidth.

  2. Parameterized QoS effectively reserves a certain amount of bandwidth for a certain stream, much like the use of virtual circuits in TDM-based switching.

The 802.11e standard was approved on the 22 September 2005. To accommodate VoWiFi needs, Wireless Multimedia Extensions (WME)a Wi-Fi Alliance interoperability certification, based on the IEEE 802.11e standard is being enforced by the Wi-Fi Alliance. It provides basic Quality of service (QoS) features to IEEE 802.11 networks. WMM prioritizes traffic according to 4 AC (Access Categories) - voice, video, best effort, and background. However, it does not provide guaranteed throughput. It is suitable for simple applications that require QoS, such as voice over wifi.[20]


Security mechanisms for IEEE 802.11 [21] are defined in this amendment, which includes a definition of WEP for backward compatibility with the original standard, IEEE Std 802.11, 1999 Edition. This amendment defines TKIP and CCMP, which provide more robust data protection mechanisms than WEP affords. It introduces the concept of a security association into IEEE 802.11 and defines security association management protocols called the 4-Way Handshake and the Group Key Handshake. Also, it specifies how IEEE 802.1X may be utilized by IEEE 802.11 LANs to effect authentication. This amendent provides security mechanisms which are stronger and better suited to voice. Data security mechanisms, however robust, often introduce more latency than voice can tolerate - especially if they require re-authenticating to each new access point. Also, voice devices can be used to gain unauthorized data access.

The 802.11i task group has developed two new algorithms - TKIP (Temporal Key Integrity Protocol)and CCMP (Counter mode with Cipher-block chaining with message authentication code Protocol) to provide confidentiality, data integrity, and data source authentication. The group also came up with a protocol for mutual authentication and key management.[21]

TKIP is not as strong as CCMP, but can be implemented on today's existing hardware with a firmware upgrade. The stronger CCMP algorithm is based on the Advanced Encryption Standard (AES) which requires new hardware.


The 802.11k task group is working on radio resource management that will make more efficient use of WLAN resources. Feedback from clients will enable switches and access points to make better roaming decisions, thus providing faster and uninterrupted wireless service. Network elements will be able to determine who is using the RF and what the quality of each RF connection is, among other things.


The standard is in progress at the "Task Group r" level within the IEEE. If approved and ratified as a standard by the IEEE 802.11, the IEEE 802.11r will specify fast BSS ("Basic Service Set") transitions. This will permit connectivity aboard vehicles in motion, with fast handoffs from one base station to another managed in a seamless manner. Handoffs are supported under the "a", "b" and "g" implementations, but only for data (using IEEE 802.11f or Inter-Access Point Protocol commonly known in the wireless circles as IAPP). The handover delay is too long to support applications like voice and video and is problematic for secure 802.11 connections using WPA2 or WPA.

The primary application currently envisioned for the 802.11r standard is VOIP ("voice over IP", or Internet-based telephony) via mobile phones designed to work with wireless Internet networks, instead of (or in addition to) standard cellular networks.


Although wireless community networks may not have been envisioned in the original development of the IEEE 802.11 specification, this is the technology that gave rise to the Wireless Community Network movement. There are still technical hurdles to overcome: the standardization of inter-access point protocols will enable more seamless movement between coverage areas of different access points; stronger encryption will address privacy concerns; and quality of service support will enable real-time applications with acceptable performance.

For security, amendment 802.11i was approved . Mobility should be increased with the hand-off characteristics being developed in 802.11r. Quality of Voice is a complex issue and is being addressed in at least two ways. In the standard 802.11e priority queues are utilized to help ensure the throughput of Voice and other multimedia traffic. Voice quality is also determined by the codec that is chosen and implemented. The codec is important, because the sampling and the compression ratio can drastically decrease the quality.

Research Methodology and Design

There are numerous issues to consider when designing any network to ensure maximum throughput for clients to the network independent of locality. Deploying a Communications system involves a series of several steps. These steps include analysing requirements, designing the system, and implementing the components. This study will follow a step by step based methodology in order to deploy a functioning network.

Requirements Analysis

The first step will involve the determination of requirements and this will involve:

  • Analysing user operations to determine features and functions that need to be included in the system for example;

Table 1: Sample Requirements and Example Considerations
Requirements Example Considerations
Site requirementsWhere are the locations that the system will serve?

How should the system components be distributed across sites?
AvailabilityIs availability needed 24 hours a day?

What is the required recovery time after failure?
CapacityHow many users must be supported?

How many simultaneous calls must be supported?
Deployment scheduleWhen must the system be installed and operating?

How will the system be phased in?

  • Reviewing options and determining the implications of each alternative.
  • Defining the components that meet the user and network requirements.

Network and Infrastructure Assessment

Network and infrastructure assessment will involve the review and audit of all network infrastructure areas that will be affected by the deployment. The assessment will be performed at each site where the deployment of a network component will take place. Aspects like Network design (routing and switching network), Software, Hardware, Power/environment, Network links and Network services will be looked into in this step.

After this assessment, it it hoped that we will come up with a design of the system which hopefully will use a decentralized network infrastructure which is relatively inexpensive, and very reliable and resilient, as each nodes will act as a repeater and switch to transmit data from nearby nodes to peers that are too far away to reach. This network design is envisaged to be extremely reliable, as each node will be connected to other nodes.

Site Requirements Development

This stage will involve identifying the hardware, software, and physical and environmental needs that relate to the implementation and operation of the Communications system at each location where a network component will be deployed.

The physical frontiers which face the network will be considered because the network will use radio waves as its transmission medium hence we must delve briefly into a few physical aspects of radio-waves. Antennae enable greater transmission ranges, but we will need to discover which kind of antenna best suits our needs. The access nodes also will need to cover as great an area as possible, so that every antenna will give us the widest area coverage.

In the deployment of the wireless network we will consider which radio channel to run the network on. There are three non-overlapping channels available for use, although there are twelve channels to choose from. As each of the discrete channels are pretty much equivalent there are only two major factors which will impact channel selection;

  1. Channel collisions which can happen where two wireless networks share an area, or overlap each other (including client placements). If two neighbouring networks share the same channel service quality can be degraded heavily. A site survey will be taken to determine if any other wireless networks will impact on our deployment.

  2. Existence of wireless phones or handsets in the deployment area. Unfortunately the researcher is not in position to access tools to test for non IEEE 802.11 devices, and only highly specialised equipment can be used to determine if there is an alternate wireless network in operation. A simple, although time consuming, method to determine the success of a network will be to temporarily deploy a network, and monitor traffic speeds on different channels over a suitable time period (for example a working day).

High-level design documents will be reviewed to understand the component requirements for the solution at each location. Issues for example hardware components, software levels, WAN connectivity, electrical requirements, and environmental/physical space requirements will be considered in this stage to see that site deployment proceeds successfully

Detailed Design Development

The detailed design will address a wide variety of issues regarding the Communications components that will be implemented. These issues include:

  • Network infrastructure
  • Interoperability requirements
  • Call processing system requirements
  • Application software requirements
  • Customer interaction requirements
  • Messaging system architecture and requirements
  • Conferencing requirements

The core technologies to be used for the proposed network will primarily include;

  • an Internet Protocol (IP) network which will imitate a circuit switched network,
  • Voice services that are provided through Voice over IP (VoIP) which will copy a design of custom hardware-based switching, and
  • Wireless distribution based on WiFi acting as PSTN terrestrial land lines.

The core telephone switching system that will allow for calls to be routed between the user community, whether they are within the local community or with those residing on other networks including other similar IP-based community networks, mobile users, or PSTN users will be such that a single VoIP switch can provide support to hundreds of local community phone systems/customers. The core switching system will be based on Asterisk and The GNU gatekeeper which are both open source PBX and H.323 gatekeeper software respectively.

With the VoIP switching in place to handle the routing of traffic between the users relying on the community networks, there is an envisaged need to add an in-country interconnection capability to those wanting to terminate calls to those relying on other networks (fixed or mobile). This will be provided by a main Voip server switch that will provide interconnection with the PSTN and mobile networks within the country, as well as to international destinations.


The processes required to carry out the implementation of the Communications system will be defined in this step. The following elements will be considered:

  • Scheduling of site-specific actions needed prior to implementation
  • Equipment delivery
  • Resource requirements for network and site-specific implementation
  • Project phases and deadlines
  • Acceptance criteria for each project phase
  • Training


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Table 2: Project Budget
No Description Quantity Cost / @ Total Cost
1Linksys WRT54GL Wireless Routers4185,000740,000
2RP TNC to N male Coaxial Cable1027,750277,500
3CounterPath eyeBeam 1.5 license470,000280,000
4ITU g729 license417,50070,000
5Intel Pentium IV 3.2Ghz CPU4500,0002,000,000
6Dell PowerEdge Dual Processor Server1--
7Toshiba Satellite Laptop11,500,0001,500,000
8SuperPass 2.4 GHz 8dBi Omni Antenna3258,667776,000
92.4 GHz 24 dBi Grid Antenna1185,000185,000
10Sipura SPA-2000 ATA 2xFXS4106,375425,500
11Sipura SPA-3000 AT 1xFXS 1xFXO1185,000185,000
12Hauwei CDMA FWT1360,000360,000
13Analogue Desktop Telephones830,000240,000
14Roll of Ethernet cable1150,000150,000


Table 3: Project Time Frame
No Activity Start Date End Date
1Proposal Writing and ApprovalOctober 2006February 2007
2Framework DevelopmentMarch 2007April 2007
3Methodology, Planning, and DesignApril 2007May 2007
4ImplementationsMay 2007June 2007
5Testing and EvaluationJune 2007June 2007
6Report writing and handing inJune 2007July 2007

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Voice Over WiFi:
On Fabricating an Open Access Neighbourhood Wireless Local Loop for Telecommunication

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