Global Access to the Internet for All J. Saldana, Ed.
Internet-Draft University of Zaragoza
Intended status: Informational A. Arcia-Moret
Expires: May 16, 2016 University of Cambridge
B. Braem
E. Pietrosemoli
The Abdus Salam ICTP
A. Sathiaseelan
University of Cambridge
M. Zennaro
The Abdus Salam ICTP
November 13, 2015

Alternative Network Deployments. Taxonomy, characterization, technologies and architectures


This document presents a taxonomy of "Alternative Network deployments", and a set of definitions and shared properties. It also surveys the technologies employed in these network deployments, and their differing architectural characteristics.

The term "Alternative Network Deployments" includes a set of network access models that have emerged in the last decade with the aim of bringing Internet connectivity to people, using topological, architectural and business models different from the so-called "traditional" ones, where a company deploys or leases the network infrastructure for connecting the users, who pay a subscription fee to be connected and make use of it.

Several initiatives throughout the world have built large scale Alternative Networks, using predominantly wireless technologies (including long distance) due to the reduced cost of using the unlicensed spectrum. Wired technologies such as fiber are also used in some of these alternate networks.

The emergence of these networks can be motivated by different causes such as the reluctance, or the impossibility, of network operators to provide wired and cellular infrastructures to rural/remote areas. In these cases, the networks have self sustainable business models that provide more localized communication services as well as Internet backhaul support through peering agreements with traditional network operators. Some other times, networks are built as a complement and an alternative to commercial Internet access provided by "traditional" network operators.

The present classification considers different existing network models such as Community Networks, which are self-organized and decentralized networks wholly owned by the community; networks owned by individuals who act as Wireless Internet Service Providers (WISPs); networks owned by individuals but leased out to network operators who use them as a low-cost medium to reach the underserved population, and finally there are networks that provide connectivity by sharing wireless resources of the users.

Different criteria are used in order to build a classification as e.g., the ownership of the equipment, the way the network is organized, the participatory model, the extensibility, if they are driven by a community, a company or a local stakeholder (public or private), etc.

According to the developed taxonomy, a characterization of each kind of network is presented in terms of specific network characteristics related to architecture, organization, etc.

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Table of Contents

1. Introduction

Several initiatives throughout the world have built large scale networks, using predominantly wireless technologies (including long distance) due to the reduced cost of using the unlicensed spectrum. Wired technologies such as fiber are also used in some of these alternate networks. These networks constitute an alternative to the traditional network operator deployments.

There are several types of alternate deployments: Community Networks are self-organized and decentralized networks wholly owned by the community; networks owned by individuals who act as Wireless Internet Service Providers (WISPs); networks owned by individuals but leased out to network operators who use such networks as a low cost medium to reach the underserved population, and finally there are networks that provide connectivity by sharing wireless resources of the users.

The emergence of these networks can be motivated by different causes, as the reluctance, or the impossibility, of network operators to provide wired and cellular infrastructures to rural/remote areas [Pietrosemoli]. In these cases, the networks have self sustainable business models that provide more localized communication services as well as Internet backhaul support (i.e. uplink connection) through peering agreements with traditional network operators. Some other times, they are built as a complement and an alternative to commercial Internet access provided by "traditional" network operators.

One of the aims of the Global Access to the Internet for All (GAIA) IRTF initiative is "to document and share deployment experiences and research results to the wider community through scholarly publications, white papers, Informational and Experimental RFCs, etc." In line with this objective, this document is intended to propose a classification of these "Alternative Network Deployments". This term includes a set of network access models that have emerged in the last decade with the aim of bringing Internet connectivity to people, following topological, architectural and business models different from the so-called "traditional" ones, where a company deploys the infrastructure connecting the users, who pay a subscription fee to be connected and make use of it. The present document is intended to provide a broad overview of initiatives, technologies and approaches employed in these networks. Research references describing each kind of network are also provided.

1.1. Traditional networks

In this document we will use the term "traditional networks" to denote those sharing these characteristics:

- Regarding scale, they are usually large networks spanning entire regions.

- Top-down control of the network and centralized approaches are used.

- They require a substantial investment in infrastructure.

- Users in traditional networks tend to be passive consumers, as opposed to active stakeholders, in the network design, deployment, operation and maintenance.

1.2. Alternative networks

The definition of an "alternative network" in this document is negative: a network not following the characteristics of "traditional networks".

2. General ideas about Alternative Networks

Alternative Network Deployments are present in every part of the world. Even in some high-income countries, these networks have been built as an alternative to commercial ones managed by traditional network operators. This section discusses the scenarios where Alternative Networks are deployed.

2.1. Digital Divide and Alternative Networks

Although there is no consensus on a precise definition for the term "developing country", it is generally used to refer to nations with a relatively lower standard of living. Developing countries have also been defined as those which are in transition from traditional lifestyles towards the modern lifestyle which began in the Industrial Revolution. When it comes to quantify to which extent a country is a developing country, the Human Development Index has been proposed by the United Nations in order to consider the Gross National Income (GNI), the life expectancy and the education level of the population in a single indicator. Additionally, the Gini Index (World Bank estimate) may be used to measure the inequality, as it estimates the dispersion of the national income (see

However, at the beginning of the 90's the debates about how to quantify development in a country were shaken by the appearance of Internet and mobile phones, which many authors consider the beginning of the Information Society. With the beginning of this Digital Revolution, defining development based on Industrial Society concepts started to be challenged, and links between digital development and its impact on human development started to flourish. The following dimensions are considered to be meaningful when measuring the digital development state of a country: infrastructures (availability and affordability); ICT (Information and Communications Technology) sector (human capital and technological industry); digital literacy; legal and regulatory framework; and content and services. The lack or less extent of digital development in one or more of these dimensions is what has been referred as Digital Divide. This divide is a new vector of inequality which - as it happened during the Industrial Revolution - may generate progress, but may create economic poverty and exclusion at the same time. The Digital Divide is considered to be a consequence of other socio-economic divides, while, at the same time, a reason for their rise.

In this context, the so-called “developing countries”, in order not to be left behind of this incipient digital revolution, motivated the World Summit of the Information Society which aimed at achieving “a people-centred, inclusive and development-oriented Information Society, where everyone can create, access, utilize and share information and knowledge, enabling individuals, communities and peoples to achieve their full potential in promoting their sustainable development and improving their quality of life” [WSIS], and called upon “governments, private sector, civil society and international organizations” to actively engage to accomplish it [WSIS].

Most efforts from governments and international organizations focused initially on improving and extending the existing infrastructure in order not to leave their population behind. As an example, one of the goals of the Digital Agenda for Europe [DAE] is "to increase regular internet usage from 60% to 75% by 2015, and from 41% to 60% among disadvantaged people."

Universal Access and Service plans have taken different forms in different countries over the years, with very uneven success rates, but in most cases inadequate to the scale of the problem. Given its incapacity to solve the problem, some governments included Universal Service and Access obligations to mobile network operators when liberalizing the telecommunications market. In combination with the overwhelming and unexpected uptake of mobile phones by poor people, this has mitigated the low access indicators existing in many developing countries at the beginning of the 90s [Rendon].

Although the contribution made by mobile network operators in decreasing the access gap is undeniable, their model presents some constraints that limit the development outcomes that increased connectivity promises to bring. Prices, tailored for the more affluent part of the population, remain unaffordable to many, who invest large percentages of their disposable income in communications. Additionally, the cost of prepaid packages, the only option available for the informal economies existing throughout developing countries, is high compared with the rate longer-term subscribers pay.

The consolidation of many Alternative Networks (e.g. Community Networks) in high income countries sets a precedent for civil society members from the so-called developing countries to become more active in the search for alternatives to provide themselves with affordable access. Furthermore, Alternative Networks could contribute to other dimensions of the digital development like increased human capital and the creation of contents and services targeting the locality of each network.

2.2. Urban vs. rural areas

The Digital Divide presented in the previous section is not only present between countries, but within them too. This is specially the case for rural inhabitants, which represents approximately 55% of the world's population, from which 78% inhabit in developing countries. Although it is impossible to generalize among them, there exist some common features that have determined the availability of ICT infrastructure in these regions. The disposable income of their dwellers is lower than those inhabiting urban areas, with many surviving on a subsistence economy. Many of them are located in geographies difficult to access and exposed to extreme weather conditions. This has resulted in the almost complete lack of electrical infrastructure. This context, together with their low population density, discourages telecommunications operators to provide similar services to those provided to urban dwellers, since they do not deem them profitable.

The cost of the wireless infrastructure required to set up a network, including powering it (e.g. via solar energy), is within the range of availability if not of individuals at least of entire communities. The social capital existing in these areas can allow for Alternative Network set-ups where a reduced number of nodes may cover communities whose dwellers share the cost of the infrastructure and the gateway and access it via inexpensive wireless devices. Some examples are presented in [Pietrosemoli] and [Bernardi].

In this case, the lack of awareness and confidence of rural communities to embark themselves in such tasks can become major barriers to their deployment. Scarce technical skills in these regions have also been pointed as a challenge for their success, but the proliferation of urban Community Networks, where scarcity of spectrum, scale, and heterogeneity of devices pose tremendous challenges to their stability and the services they aim to provide, has fuelled the creation of robust low-cost low-consumption low-complexity off-the-shelf wireless devices which make much easier the deployment and maintenance of these alternative infrastructures in rural areas.

2.3. Gap between demanded and provided communications services

Beyond the Digital Divide, either international or domestic, there are many situations in which the market fails to provide the information and communications services demanded by the population. When this happens permanently in an area, citizens may be compelled to take a more active part in the design and implementation of ICT solutions, hence promoting Alternative Networks.

2.4. Topology patterns followed by Alternative Networks

Alternative Networks, considered self-managed and self-sustained, follow different topology patterns [Vega]. Generally, these networks grow spontaneously and organically, that is, the network grows without specific planning and deployment strategy and the routing core of the network fits fairly well a power law distribution. Moreover, the network is composed of a high number of heterogeneous devices with the common objective of freely connecting and increasing the network coverage. Although these characteristics increase the entropy (e.g., by increasing the number of routing protocols), they have resulted in an inexpensive solution to effectively increase the network size. One example corresponds to [Vega] with an exponential grow rate in the number of operating nodes during the last decade.

Regularly rural areas in these networks are connected through long-distance links (the so-called community mesh approach) which in turn convey the Internet connection to relevant organisations or institutions. In contrast, in urban areas, users tend to share and require mobile access. Since these areas are also likely to be covered by commercial ISPs, the provision of wireless access by Virtual Operators like [Fon] may constitute a way to extend the user capacity (or gain connection) to the network. Other proposals like Virtual Public Networks [Sathiaseelan_a] can also extend the service.

3. Classification criteria

The classification of Alternative Network Deployments, presented in this document, is based on the next criteria:

3.1. Commercial model / promoter

The entity (or entities) or individuals promoting an Alternative Network can be:

3.2. Goals and motivation

Alternative networks can also be classified according to the underlying motivation for them, i.e., addressing deployment and usage hurdles:

3.3. Administrative model

3.4. Technologies employed

3.5. Typical scenarios

The scenarios where Alternative Networks are usually deployed can be:

4. Classification of Alternative Networks

This section classifies Alternative Networks according to the criteria explained previously. Each of them has different incentive structures, maybe common technological challenges, but most importantly interesting usage challenges which feeds into the incentives as well as the technological challenges.

At the beginning of each subsection, a table is presented including a classification of each network according to the criteria listed in the "Classification criteria" subsection.

In some cases, real examples of Alternative Networks are cited.

4.1. Community Networks

Community Networks' characteristics summary
Commercial model/promoter community
Goals and motivation reducing hurdles; to serve underserved areas; network neutrality
Administration distributed
Technologies Wi-Fi, optical fiber
Typical scenarios urban and rural

Community Networks are large-scale, distributed, self-managed networks sharing these characteristics:

- They are built and organized in a decentralized and open manner.

- They start and grow organically, they are open to participation from everyone, sometimes sharing an open peering agreement. Community members directly contribute active (not just passive) network infrastructure.

- Knowledge about building and maintaining the network and ownership of the network itself is decentralized and open. Community members have an obvious and direct form of organizational control over the overall operation of the network in their community (not just their own participation in the network).

- The network can serve as a backhaul for providing a whole range of services and applications, from completely free to even commercial services.

Hardware and software used in Community Networks can be very diverse, even inside one network. A Community Network can have both wired and wireless links. Multiple routing protocols or network topology management systems may coexist in the network.

These networks grow organically, since they are formed by the aggregation of nodes belonging to different users. A minimum governance infrastructure is required in order to coordinate IP addressing, routing, etc. An example of this kind of Community Network is described in [Braem]. These networks follow a participatory model, which has been shown effective in connecting geographically dispersed people, thus enhancing and extending digital Internet rights.

The fact of the users adding new infrastructure (i.e. extensibility) can be used to formulate another definition: A Community Network is a network in which any participant in the system may add link segments to the network in such a way that the new segments can support multiple nodes and adopt the same overall characteristics as those of the joined network, including the capacity to further extend the network. Once these link segments are joined to the network, there is no longer a meaningful distinction between the previous and the new extent of the network.

In Community Networks, the profit can only be made by offering services and not simply by supplying the infrastructure, because the infrastructure is neutral, free, and open (traditional Internet Service Providers base their business on the control of the infrastructure). In Community Networks, everybody keeps the ownership of what he/she has contributed.

Community Networks may also be called "Free Networks" or even "Network Commons" [FNF]. The majority of Community Networks comply with the definition of Free Network, included in the next subsection.

4.1.1. Free Networks

A definition of Free Network (which may be the same as Community Network) is proposed by the Free Network Foundation (see as:

"A free network equitably grants the following freedoms to all:

Freedom 0 - The freedom to communicate for any purpose, without discrimination, interference, or interception.

Freedom 1 - The freedom to grow, improve, communicate across, and connect to the whole network.

Freedom 2- The freedom to study, use, remix, and share any network communication mechanisms, in their most reusable forms."

The principles of Free, Open and Neutral Networks have also been summarized (see this way:

- You have the freedom to use the network for any purpose as long as you do not harm the operation of the network itself, the rights of other users, or the principles of neutrality that allow contents and services to flow without deliberate interference.

- You have the right to understand the network, to know its components, and to spread knowledge of its mechanisms and principles.

- You have the right to offer services and content to the network on your own terms.

- You have the right to join the network, and the responsibility to extend this set of rights to anyone according to these same terms.

4.2. Wireless Internet Service Providers WISPs

WISPs' characteristics summary
Commercial model/promoter company
Goals and motivation to serve underserved areas; to reduce CAPEX in Internet access
Administration centralized
Technologies wireless, unlicensed frequencies
Typical scenarios rural

WISPs are commercially-operated wireless Internet networks that provide Internet and/or Voice Over Internet (VoIP) services. They are most common in areas not covered by traditional telcos or ISPs. WISPs mostly use wireless point-to-multipoint links using unlicensed spectrum but often must resort to licensed frequencies, which use is common in regions where unlicensed spectrum is either perceived as crowded, or too unreliable to offer commercial services, or where unlicensed spectrum faces regulatory barriers impeding its use.

Most WISPs are operated by local companies responding to a perceived market gap. There is a small but growing number of WISPs, such as AirJaldi [Airjaldi] in India that have expanded from local service into multiple locations.

Since 2006, the deployment of cloud-managed WISPs has been possible with hardware from companies as Meraki and later OpenMesh and others. Until recently, however, most of these services have been aimed at industrialized markets. Everylayer [Everylayer], launched in 2014, is the first cloud-managed WISP service aimed at emerging markets.

4.3. Shared infrastructure model

Shared infrastructure characteristics summary
Commercial model/promoter shared: companies and users
Goals and motivation to eliminate a CAPEX barrier (to operators); lower the OPEX (supported by the community); to extend coverage to underserved areas
Administration distributed
Technologies wireless in non-licensed bands and/or low-cost fiber
Typical scenarios rural areas, and more particularly rural areas in developing regions

In conventional networks, the operator usually owns the telecommunications infrastructures required for the service, or sometimes rents these infrastructures to/from other companies. The problem arises in large areas with low population density, in which neither the operator nor other companies have deployed infrastructure and such deployments are not likely to happen due to the low potential return of investment.

When users already own a deployed infrastructure, either individually or as a community, sharing that infrastructure with an operator represents an interesting win-win solution that starts to be exploited in some contexts. For the operator, this supposes a significant reduction of the initial investment needed to provide services in small rural localities because the CAPEX is only associated to the access network, as renting capacity in the users' network for backhauling supposes only an increment in the OPEX. This approach also benefits the users in two ways: they obtain improved access to telecommunications services that would not be otherwise accessible, and they can get some income from the operator that helps to afford the network's OPEX, particularly for network maintenance.

One clear example of the potential of the “shared infrastructure model” nowadays is the deployment of 3G services in rural areas in which there is a broadband rural community network. Since the inception of femtocells, there are complete technical solutions for low-cost 3G coverage using the Internet as a backhaul. If a user or community of users has an IP network connected to the Internet with some capacity in excess, placing a femtocell in the user premises benefits both the user and the operator, as the user obtains better coverage and the operator does not have to support the cost of the infrastructure. Although this paradigm was conceived for improved indoor coverage, the solution is feasible for 3G coverage in underserved rural areas with low population density (i.e. villages), where the number of simultaneous users and the servicing area are small enough to use low-cost femtocells. Also, the amount of traffic produced by these cells can be easily transported by most community broadband rural networks.

Some real examples can be referenced in the European Commission FP7 TUCAN3G project, (see which deployed demonstrative networks in two regions in the Amazon forest in Peru. In these networks [Simo_a], the operator and several rural communities have cooperated to provide services through rural networks built up with WiLD links [WiLD]. In these cases, the networks belong to the public health authorities and were deployed with funds come from international cooperation for telemedicine purposes. Publications that justify the feasibility of this approach can also be found in that website.

4.4. Crowdshared approaches, led by the people and third party stakeholders

Crowdshared approaches characteristics summary
Commercial model/promoter community, public stakeholders, private companies
Goals and motivation sharing connectivity and resources
Administration distributed
Technologies wireless
Typical scenarios urban and rural

These networks can be defined as a set of nodes whose owners share common interests (e.g. sharing connectivity; resources; peripherals) regardless of their physical location. They conform to the following approach: the home router creates two wireless networks: one of them is normally used by the owner, and the other one is public. A small fraction of the bandwidth is allocated to the public network, to be employed by any user of the service in the immediate area. Some examples are described in [PAWS] and [Sathiaseelan_c]. Other example is constituted by the networks created and managed by City Councils (e.g., [Heer]).

In the same way, some companies [Fon] develop and sell Wi-Fi routers with a dual access: a Wi-Fi network for the user, and a shared one. A user community is created, and people can join the network in different ways: they can buy a router, so they share their connection and in turn they get access to all the routers associated to the community. Some users can even get some revenue every time another user connects to their Wi-Fi spot. Other users can just buy some passes in order to use the network. Some telecommunications operators can collaborate with the community, including in their routers the possibility of creating these two networks.

The elements involved in a crowd-shared network are summarized below:

- Interest: a parameter capable of providing a measure (cost) of the attractiveness of a node towards a specific location, in a specific instance in time.

- Resources: A physical or virtual element of a global system. For instance, bandwidth; energy; data; devices.

- The owner: End users who sign up for the service and share their network capacity. As a counterpart, they can access another owners' home access for free. The owner can be an end user or an entity (e.g. operator; virtual operator; municipality) that is to be made responsible for any actions concerning his/her device.

- The user: a legal entity or an individual using or requesting a publicly available electronic communications' service for private or business purposes, without necessarily having subscribed to such service.

- The Virtual Network Operator (VNO): An entity that acts in some aspects as a network coordinator. It may provide services such as initial authentication or registering, and eventually, trust relationship storage. A VNO is not an ISP given that it does not provide Internet access (e.g. infrastructure; naming). A VNO is neither an Application Service Provider (ASP) since it does not provide user services. Virtual Operators may also be stakeholders with socio-environmental objectives. They can be a local government, grass root user communities, charities, or even content operators, smart grid operators, etc. They are the ones who actually run the service.

- Network operators, who have a financial incentive to lease out the unused capacity [Sathiaseelan_b] at lower cost to the VNOs.

VNOs pay the sharers and the network operators, thus creating an incentive structure for all the actors: the end users get money for sharing their network, the network operators are paid by the VNOs, who in turn accomplish their socio-environmental role.

4.5. Testbeds for research purposes

Testbeds' characteristics summary
Commercial model/promoter research / academic entity
Goals and motivation research
Administration centralized initially, but it may end up in a distributed model.
Technologies wired and wireless
Typical scenarios urban and rural

In some cases, the initiative to start the network is not from the community, but from a research entity (e.g. a university), with the aim of using it for research purposes [Samanta], [Bernardi].

The administration of these networks may start being centralized in most cases (administered by the academic entity) and may end up in a distributed model in which other local stakeholders assume part of the network administration [Rey].

5. Technologies employed

5.1. Wired

In many (developed or developing) countries it may happen that national service providers may decline to provide connectivity to tiny and isolated villages. So in some cases the villagers have created their own optical fiber networks. It is the case of Lowenstedt in Germany [Lowenstedt], or some parts of [Cerda-Alabern].

5.2. Wireless

The vast majority of the Alternative Network Deployments are based on different wireless technologies [WNDW]. Below we summarize the options and trends when using these features in Alternative Networks.

5.2.1. Media Access Control (MAC) Protocols for Wireless Links

Different protocols for Media Access Control, which also include physical layer (PHY) recommendations, are widely used in Alternative Network Deployments. Wireless standards ensure interoperability and usability to those who design, deploy and manage wireless networks.

The standards used in the vast majority of Alternative Networks come from the IEEE Standard Association's IEEE 802 Working Group. Standards developed by other international entities can also be used, as e.g. the European Telecommunications Standards Institute (ETSI). 802.11 (Wi-Fi)

The standard we are most interested in is 802.11 a/b/g/n/ac, as it defines the protocol for Wireless LAN. It is also known as "Wi-Fi". The original release (a/b) was issued in 1999 and allowed for rates up to 54 Mbit/s. The latest release (802.11ac) approved in 2013 reaches up to 866.7 Mbit/s. In 2012, the IEEE issued the 802.11-2012 Standard that consolidates all the previous amendments. The document is freely downloadable from IEEE Standards [IEEE].

The MAC protocol in 802.11 is called CSMA/CA (Carrier Sense Multiple Access with Collision Avoidance) and was designed for short distances; the transmitter expects the reception of an acknowledgment for each transmitted unicast packet; if a certain waiting time is exceeded, the packet is retransmitted. This behavior makes necessary the adaptation of several MAC parameters when 802.11 is used in long links [Simo_b]. Even with this adaptation, the distance has a significant negative impact on the performance. For this reason, many vendors implement alternative medium access techniques that are offered alongside the standard CSMA/CA in their outdoor 802.11 products. These alternative proprietary MAC protocols usually employ some type of TDMA (Time Division Multiple Access). Low cost equipment using these techniques can offer high throughput at distances above 100 kilometers. GSM

GSM (Global System for Mobile Communications), from ETSI, has also been used in Alternative Networks as Layer 2 option, as explained in [Mexican], [Village], [Heimerl] . Dynamic Spectrum

Some Alternative Networks make use of TV White Spaces – a set of UHF and VHF television frequencies that can be utilized by secondary users in locations where it is unused by licensed primary users such as television broadcasters. Equipment that makes use of TV White Spaces is required to detect the presence of existing unused TV channels by means of a spectrum database and/or spectrum sensing in order to ensure that no harmful interference is caused to primary users. In order to smartly allocate interference-free channels to the devices, cognitive radios are used which are able to modify their frequency, power and modulation techniques to meet the strict operating conditions required for secondary users.

The use of the term “White Spaces” is often used to describe “TV White Spaces” as the VHF and UHF television frequencies were the first to be exploited on a secondary use basis. There are two dominant standards for TV white space communication: (i) the 802.11af standard [IEEE.802-11AF.2013] – an adaptation of the 802.11 standard for TV white space bands and (ii) the IEEE 802.22 standard [IEEE.802-22.2011] for long-range rural communication. 802.11af

802.11af [IEEE.802-11AF.2013] is a modified version of the 802.11 standard operating in TV White Space bands using Cognitive Radios to avoid interference with primary users. The standard is often referred to as White-Fi or "Super Wi-Fi" and was approved in February 2014. 802.11af contains much of the advances of all the 802.11 standards including recent advances in 802.11ac such as up to four bonded channels, four spatial streams and very high rate 256-QAM modulation but with improved in-building penetration and outdoor coverage. The maximum data rate achievable is 426.7 Mbps for countries with 6/7 MHz channels and 568.9 Mbps for countries with 8 MHz channels. Coverage is typically limited to 1km although longer range at lower throughput and using high gain antennas will be possible.

Devices are designated as enabling stations (Access Points) or dependent stations (clients). Enabling stations are authorized to control the operation of a dependent station and securely access a geolocation database. Once the enabling station has received a list of available white space channels it can announce a chosen channel to the dependent stations for them to communicate with the enabling station. 802.11af also makes use of a registered location server – a local database that organizes the geographic location and operating parameters of all enabling stations. 802.22

802.22 [IEEE.802-22.2011] is a standard developed specifically for long range rural communications in TV white space frequencies and first approved in July 2011. The standard is similar to the 802.16 (WiMax) [IEEE.802-16.2008] standard with an added cognitive radio ability. The maximum throughput of 802.22 is 22.6 Mbps for a single 8 MHz channel using 64-QAM modulation. The achievable range using the default MAC scheme is 30 km, however 100 km is possible with special scheduling techniques. The MAC of 802.22 is specifically customized for long distances – for example, slots in a frame destined for more distant Consumer Premises Equipment (CPEs) are sent before slots destined for nearby CPEs.

Base stations are required to have a Global Positioning System (GPS) and a connection to the Internet in order to query a geolocation spectrum database. Once the base station receives the allowed TV channels, it communicates a preferred operating white space TV channel with the CPE devices. The standard also includes a co-existence mechanism that uses beacons to make other 802.22 base stations aware of the presence of a base station that is not part of the same network.

6. Upper layers

6.1. Layer 3

6.1.1. IP addressing

Most known Alternative Networks started in or around the year 2000. IPv6 was fully specified by then, but almost all Alternative Networks still use IPv4. A survey [Avonts] indicated that IPv6 rollout presents a challenge to Community Networks.

Most Community Networks use private IPv4 address ranges, as defined by [RFC1918]. The motivation for this was the lower cost and the simplified IP allocation because of the large available address ranges.

6.1.2. Routing protocols

As stated in previous sections, Alternative Networks are composed of possibly different layer 2 devices, resulting in a mesh of nodes. Connection between different nodes is not guaranteed and the link stability can vary strongly over time. To tackle this, some Alternative Networks use mesh network routing protocols while other networks use more traditional routing protocols. Some networks operate multiple routing protocols in parallel. For example, they use a mesh protocol inside different islands and use traditional routing protocols to connect these islands. Traditional routing protocols

The Border Gateway Protocol (BGP), as defined by [RFC4271] is used by a number of Community Networks, because of its well-studied behavior and scalability.

For similar reasons, smaller networks opt to run the Open Shortest Path First (OSPF) protocol, as defined by [RFC2328]. Mesh routing protocols

A large number of Alternative Networks use the Optimized Link State Routing Protocol (OLSR) routing protocol as defined in [RFC3626]. The pro-active link state routing protocol is a good match with Alternative Networks because it has good performance in mesh networks where nodes have multiple interfaces.

The Better Approach To Mobile Adhoc Networking (BATMAN) [Abolhasan] protocol was developed by members of the Freifunk community. The protocol handles all routing at layer 2, creating one bridged network.

Parallel to BGP, some networks also run the BatMan-eXperimental (BMX6) protocol [Neumann]. This is an advanced version of the BATMAN protocol which is based on IPv6 and tries to exploit the social structure of Alternative Networks.

6.2. Transport layer

6.2.1. Traffic Management when sharing network resources

When network resources are shared (as e.g. in the networks explained in "Crowdshared approaches, led by the people and third party stakeholders" subsection), a special care has to be put on the management of the traffic at upper layers. From a crowdshared perspective, and considering just regular TCP connections during the critical sharing time, the Access Point offering the service is likely to be the bottleneck of the connection. This is the main concern of sharers, having several implications. There should be an adequate Active Queue Management (AQM) mechanism that implements a Lower-than-best-effort (LBE) [RFC6297] policy for the user and protects the sharer. Achieving LBE behavior requires the appropriate tuning of the well known mechanisms such as Explicit Congestion Notification (ECN) [RFC3168], or Random Early Detection (RED) [RFC2309], or other more recent AQM mechanisms such as Controlled Delay (CoDel) and [I-D.ietf-aqm-codel] PIE (Proportional Integral controller Enhanced) [I-D.ietf-aqm-pie] that aid on keeping low latency.

6.3. Services provided

This section provides an overview of the services between hosts inside the network. They can be divided into Intranet services, connecting hosts between them, and Internet services, connecting to nodes outside the network.

6.3.1. Intranet services

Intranet services can include, but are not limited to:

- VoIP (e.g. with SIP).

- Remote desktop (e.g. using my home computer and my Internet connection when I am on holidays in a village).

- FTP file sharing (e.g. distribution of Linux software).

- P2P file sharing.

- Public video cameras.

- DNS.

- Online games servers.

- Jabber instant messaging.

- IRC chat.

- Weather stations.

- NTP.

- Network monitoring.

- Videoconferencing / streaming.

- Radio streaming.

6.3.2. Access to the Internet Web browsing proxies

A number of federated proxies may provide web browsing service for the users. Other services (file sharing, VoIP, etc.) are not usually allowed in many Alternative Networks due to bandwidth limitations. Use of VPNs

Some “micro-ISPs” may use the network as a backhaul for providing Internet access, setting up VPNs from the client to a machine with Internet access.

7. Acknowledgements

This work has been partially funded by the CONFINE European Commission Project (FP7 – 288535). Arjuna Sathiaseelan and Andres Arcia Moret were funded by the EU H2020 RIFE project (Grant Agreement no: 644663). Jose Saldana was funded by the EU H2020 Wi-5 project (Grant Agreement no: 644262).

The editor and the authors of this document wish to thank the following individuals who have participated in the drafting, review, and discussion of this memo:

Paul M. Aoki, Roger Baig, Jaume Barcelo, Steven G. Huter, Rohan Mahy, Rute Sofia, Dirk Trossen.

A special thanks to the GAIA Working Group chairs Mat Ford and Arjuna Sathiaseelan for their support and guidance.

8. Contributing Authors

Leandro Navarro
U. Politecnica Catalunya
Jordi Girona, 1-3, D6
Barcelona  08034

Phone: +34 934016807
Carlos Rey-Moreno
University of the Western Cape
Robert Sobukwe road
Bellville  7535
South Africa

Phone: 0027219592562
Ioannis Komnios
Democritus University of Thrace
Department of Electrical and Computer Engineering
Kimmeria University Campus
Xanthi 67100

Phone: +306945406585
Steve Song
Village Telco Limited


David Lloyd Johnson
Meraka, CSIR
15 Lower Hope St
Rosebank 7700
South Africa

Phone: +27 (0)21 658 2740
Javier Simo-Reigadas
Escuela Técnica Superior de Ingeniería de Telecomunicación
Campus de Fuenlabrada
Universidad Rey Juan Carlos

Phone: 91 488 8428 / 7500

9. IANA Considerations

This memo includes no request to IANA.

10. Security Considerations

No security issues have been identified for this document.

11. References

11.1. Normative References

, ", ", "
[IEEE] Institute of Electrical and Electronics Engineers, IEEE, IEEE Standards association", 2012.
[IEEE.802-11AF.2013]Information technology - Telecommunications and information exchange between systems - Local and metropolitan area networks - Specific requirements - Part 11: Wireless LAN Medium Access Control (MAC) and Physical Layer (PHY) specifications - Amendment 5: Television White Spaces (TVWS) Operation", IEEE Standard 802.11af, Oct 2009.
[IEEE.802-16.2008]Information technology - Telecommunications and information exchange between systems - Broadband wireless metropolitan area networks (MANs) - IEEE Standard for Air Interface for Broadband Wireless Access Systems", IEEE Standard 802.16, Jun 2008.
[IEEE.802-22.2011]Information technology - Telecommunications and information exchange between systems - Local and metropolitan area networks - Specific requirements - Part 22: Cognitive Wireless RAN Medium Access Control (MAC) and Physical Layer (PHY) specifications: Policies and procedures for operation in the TV Bands", IEEE Standard 802.22, Jul 2011.
[RFC1918] Rekhter, Y., Moskowitz, B., Karrenberg, D., de Groot, G. and E. Lear, "Address Allocation for Private Internets", BCP 5, RFC 1918, DOI 10.17487/RFC1918, February 1996.
[RFC2309] Braden, B., Clark, D., Crowcroft, J., Davie, B., Deering, S., Estrin, D., Floyd, S., Jacobson, V., Minshall, G., Partridge, C., Peterson, L., Ramakrishnan, K., Shenker, S., Wroclawski, J. and L. Zhang, "Recommendations on Queue Management and Congestion Avoidance in the Internet", RFC 2309, DOI 10.17487/RFC2309, April 1998.
[RFC2328] Moy, J., "OSPF Version 2", STD 54, RFC 2328, DOI 10.17487/RFC2328, April 1998.
[RFC3168] Ramakrishnan, K., Floyd, S. and D. Black, "The Addition of Explicit Congestion Notification (ECN) to IP", RFC 3168, DOI 10.17487/RFC3168, September 2001.
[RFC3626] Clausen, T. and P. Jacquet, "Optimized Link State Routing Protocol (OLSR)", RFC 3626, DOI 10.17487/RFC3626, October 2003.
[RFC4271] Rekhter, Y., Li, T. and S. Hares, "A Border Gateway Protocol 4 (BGP-4)", RFC 4271, DOI 10.17487/RFC4271, January 2006.
[RFC6297] Welzl, M. and D. Ros, "A Survey of Lower-than-Best-Effort Transport Protocols", RFC 6297, DOI 10.17487/RFC6297, June 2011.

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Authors' Addresses

Jose Saldana (editor) University of Zaragoza Dpt. IEC Ada Byron Building Zaragoza, 50018 Spain Phone: +34 976 762 698 EMail:
Andres Arcia-Moret University of Cambridge 15 JJ Thomson Avenue Cambridge, FE04 United Kingdom Phone: +44 (0) 1223 763610 EMail:
Bart Braem iMinds Gaston Crommenlaan 8 (bus 102) Gent, 9050 Belgium Phone: +32 3 265 38 64 EMail:
Ermanno Pietrosemoli The Abdus Salam ICTP Via Beirut 7 Trieste, 34151 Italy Phone: +39 040 2240 471 EMail:
Arjuna Sathiaseelan University of Cambridge 15 JJ Thomson Avenue Cambridge, CB30FD United Kingdom Phone: +44 (0)1223 763781 EMail:
Marco Zennaro The Abdus Salam ICTP Strada Costiera 11 Trieste, 34100 Italy Phone: +39 040 2240 406 EMail: