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Checking references for intended status: Informational ---------------------------------------------------------------------------- No issues found here. Summary: 0 errors (**), 0 flaws (~~), 1 warning (==), 1 comment (--). Run idnits with the --verbose option for more detailed information about the items above. -------------------------------------------------------------------------------- 2 Global Access to the Internet for All J. Saldana, Ed. 3 Internet-Draft University of Zaragoza 4 Intended status: Informational A. Arcia-Moret 5 Expires: July 25, 2015 Universidad de Los Andes 6 B. Braem 7 iMinds 8 L. Navarro 9 U. Politecnica Catalunya 10 E. Pietrosemoli 11 ICTP 12 C. Rey-Moreno 13 University of the Western Cape 14 A. Sathiaseelan 15 University of Cambridge 16 M. Zennaro 17 Abdus Salam ICTP 18 January 21, 2015 20 Alternative Network Deployments. Taxonomy and characterization 21 draft-manyfolks-gaia-community-networks-02 23 Abstract 25 This document presents a taxonomy of "Alternative Network 26 deployments", and a set of definitions and shared characteristics. 27 This term includes a set of network access models emerged in the last 28 decade with the aim of bringing Internet connectivity to people, 29 using topological, architectural and business models different from 30 the so-called "traditional" ones, where a company deploys the network 31 infrastructure for connecting the users, who pay for it. 33 Several initiatives throughout the world have built large scale 34 networks that are alternative to the traditional network operator 35 deployments using predominately wireless technologies (including long 36 distance) due to the reduced cost of using the unlicensed spectrum. 37 Wired technologies such as Fiber are also used in some of these 38 alternate networks. There are several types of such alternate 39 network: networks such as community networks are self-organized and 40 decentralized networks wholly owned by the community; networks owned 41 by individuals who act as wireless internet service providers 42 (WISPs), networks owned by individuals but leased out to network 43 operators who use such networks as a low-cost medium to reach the 44 underserved population and finally there are networks that provide 45 connectivity by sharing wireless resources of the users. 47 The emergence of these networks can be motivated by different causes 48 such as the reluctance, or the impossibility, of network operators to 49 provide wired and cellular infrastructures to rural/remote areas. In 50 these cases, the networks have self sustainable business models that 51 provide more localised communication services as well as Internet 52 backhaul support through peering agreements with traditional network 53 operators. Some other times, networks are built as a complement and 54 an alternative to commercial Internet access provided by 55 "traditional" network operators. 57 The present classification considers different existing network 58 models such as Community Networks, open wireless services, user- 59 extensible services, traditional local Internet Service Providers 60 (ISPs), new global ISPs, etc. Different criteria are used in order 61 to build a classification as e.g., the ownership of the equipment, 62 the way the network is organized, the participatory model, the 63 extensibility, if they are driven by a community, a company or a 64 local (public or private) stakeholder, etc. 66 According to the developed taxonomy, a characterization of each kind 67 of network is presented, in terms of specific network characteristics 68 related to architecture, organization, etc. 70 Status of This Memo 72 This Internet-Draft is submitted in full conformance with the 73 provisions of BCP 78 and BCP 79. 75 Internet-Drafts are working documents of the Internet Engineering 76 Task Force (IETF). Note that other groups may also distribute 77 working documents as Internet-Drafts. The list of current Internet- 78 Drafts is at http://datatracker.ietf.org/drafts/current/. 80 Internet-Drafts are draft documents valid for a maximum of six months 81 and may be updated, replaced, or obsoleted by other documents at any 82 time. It is inappropriate to use Internet-Drafts as reference 83 material or to cite them other than as "work in progress." 85 This Internet-Draft will expire on July 25, 2015. 87 Copyright Notice 89 Copyright (c) 2015 IETF Trust and the persons identified as the 90 document authors. All rights reserved. 92 This document is subject to BCP 78 and the IETF Trust's Legal 93 Provisions Relating to IETF Documents 94 (http://trustee.ietf.org/license-info) in effect on the date of 95 publication of this document. Please review these documents 96 carefully, as they describe your rights and restrictions with respect 97 to this document. Code Components extracted from this document must 98 include Simplified BSD License text as described in Section 4.e of 99 the Trust Legal Provisions and are provided without warranty as 100 described in the Simplified BSD License. 102 Table of Contents 104 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 4 105 1.1. Requirements Language . . . . . . . . . . . . . . . . . . 5 106 2. Classification . . . . . . . . . . . . . . . . . . . . . . . 5 107 2.1. Community Networks . . . . . . . . . . . . . . . . . . . 5 108 2.1.1. Free Networks . . . . . . . . . . . . . . . . . . . . 6 109 2.2. Wireless Internet Service Providers WISPs . . . . . . . . 7 110 2.3. Shared infrastructure model . . . . . . . . . . . . . . . 7 111 2.4. Crowdshared approaches, led by the people and third party 112 stakeholders . . . . . . . . . . . . . . . . . . . . . . 8 113 2.5. Testbeds for research purposes . . . . . . . . . . . . . 9 114 3. Scenarios where Alternative Networks are deployed . . . . . . 9 115 3.1. Digital Divide and Alternative Networks . . . . . . . . . 9 116 3.2. Urban vs. rural areas . . . . . . . . . . . . . . . . . . 11 117 4. Technologies employed . . . . . . . . . . . . . . . . . . . . 12 118 4.1. Wired . . . . . . . . . . . . . . . . . . . . . . . . . . 12 119 4.2. Wireless . . . . . . . . . . . . . . . . . . . . . . . . 12 120 4.2.1. Antennas . . . . . . . . . . . . . . . . . . . . . . 13 121 4.2.2. Link length . . . . . . . . . . . . . . . . . . . . . 14 122 4.2.2.1. Line-of-Sight . . . . . . . . . . . . . . . . . . 14 123 4.2.2.2. Transmitted and Received Power . . . . . . . . . 15 124 4.2.2.3. Medium Access Protocol . . . . . . . . . . . . . 16 125 4.2.3. Layer 2 . . . . . . . . . . . . . . . . . . . . . . . 16 126 4.2.3.1. 802.11 (Wi-Fi) . . . . . . . . . . . . . . . . . 16 127 4.2.3.2. GSM . . . . . . . . . . . . . . . . . . . . . . . 18 128 4.2.3.3. Dynamic Spectrum . . . . . . . . . . . . . . . . 18 129 5. Network and architecture issues . . . . . . . . . . . . . . . 20 130 5.1. Layer 3 . . . . . . . . . . . . . . . . . . . . . . . . . 20 131 5.1.1. IP addressing . . . . . . . . . . . . . . . . . . . . 20 132 5.1.2. Routing protocols . . . . . . . . . . . . . . . . . . 20 133 5.1.2.1. Traditional routing protocols . . . . . . . . . . 21 134 5.1.2.2. Mesh routing protocols . . . . . . . . . . . . . 21 135 5.2. Upper layers . . . . . . . . . . . . . . . . . . . . . . 21 136 5.2.1. Services provided by Alternative Networks . . . . . . 22 137 5.2.1.1. Intranet services . . . . . . . . . . . . . . . . 22 138 5.2.1.2. Access to the Internet . . . . . . . . . . . . . 23 139 5.3. Topology . . . . . . . . . . . . . . . . . . . . . . . . 23 140 6. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 24 141 7. Contributing Authors . . . . . . . . . . . . . . . . . . . . 24 142 8. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 25 143 9. Security Considerations . . . . . . . . . . . . . . . . . . . 25 144 10. References . . . . . . . . . . . . . . . . . . . . . . . . . 25 145 10.1. Normative References . . . . . . . . . . . . . . . . . . 25 146 10.2. Informative References . . . . . . . . . . . . . . . . . 28 147 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 32 149 1. Introduction 151 Several initiatives throughout the world have built large scale 152 networks that are alternative to the traditional network operator 153 deployments using predominately wireless technologies (including long 154 distance) due to the reduced cost of using the unlicensed spectrum. 155 Wired technologies such as Fiber are also used in some of these 156 alternate networks. There are several types of such alternate 157 network: networks such as community networks are self-organized and 158 decentralized networks wholly owned by the community; networks owned 159 by individuals who act as wireless internet service providers 160 (WISPs), networks owned by individuals but leased out to network 161 operators who use such networks as a low cost medium to reach the 162 underserved population and finally there are networks that provide 163 connectivity by sharing wireless resources of the users. 165 The emergence of these networks can be motivated by different causes, 166 as the reluctance, or the impossibility, of network operators to 167 provide wired and cellular infrastructures to rural/remote areas 168 [Pietrosemoli]. In these cases, the networks have self sustainable 169 business models that provide more localised communication services as 170 well as Internet backhaul support through peering agreements with 171 traditional network operators. Some other times, they are built as a 172 complement and an alternative to commercial Internet access provided 173 by "traditional" network operators. 175 One of the aims of the Global Access to the Internet for All (GAIA) 176 IRTF initiative is "to document and share deployment experiences and 177 research results to the wider community through scholarly 178 publications, white papers, Informational and Experimental RFCs, 179 etc." In line with this objective, this document is intended to 180 propose a classification of these "Alternative Network deployments". 181 This term includes a set of network access models emerged in the last 182 decade with the aim of bringing Internet connectivity to people, 183 following topological, architectural and business models different 184 from the so-called "traditional" ones, where a company deploys the 185 infrastructure connecting the users, who pay for it. The document is 186 intended to be largely descriptive providing a broad overview of 187 initiatives, technologies and approaches employed in these networks. 188 Research references describing each kind of network are also 189 provided. 191 1.1. Requirements Language 193 The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", 194 "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this 195 document are to be interpreted as described in RFC 2119 [RFC2119]. 197 2. Classification 199 This section classifies Alternative Networks (ANs) according to their 200 intended usage. Each of them has different incentive structures, 201 maybe common technological challenges, but most importantly 202 interesting usage challenges which feeds into the incentives as well 203 as the technological challenges. 205 This classification is agnostic from the technical point of view. 206 Technology in this case must be taken as implementation. Moreover, 207 many of these networks are implemented in a way that several 208 technologies (Ad-Hoc Wi-Fi, Infrastructure Wi-Fi, Optical Fiber, 209 IPv4, IPv6, RFC1918, OLSR, BMX6, etc.) coexist. 211 2.1. Community Networks 213 Community Networks are large-scale, distributed, self-managed 214 networks sharing these characteristics: 216 - They are built and organized in a decentralized and open manner. 218 - They start and grow organically, they are open to participation 219 from everyone, sometimes agreeing to an open peering agreement. 220 Community members directly contribute active network infrastructure 221 (not just passive infrastructure). 223 - Knowledge about building and maintaining the network and ownership 224 of the network itself is decentralized and open. Community members 225 have an obvious and direct form of organizational control over the 226 overall operation of the network in their community (not just their 227 own participation in the network). 229 - The network CAN serve as a backhaul for providing a whole range of 230 services and applications, from completely free to even commercial 231 services. 233 Hardware and software used in Community Networks CAN be very diverse, 234 even inside one network. A Community Network CAN have both wired and 235 wireless links. The network CAN be managed by multiple routing 236 protocols or network topology management systems. 238 These networks grow organically, since they are formed by the 239 aggregation of nodes belonging to different users. A minimum 240 governance infrastructure is required in order to coordinate IP 241 addressing, routing, etc. A clear example of this kind of Community 242 Network is described in [Braem]. These networks are effective in 243 enhancing and extending digital Internet rights following a 244 participatory model. 246 The fact of the users adding new infrastructure (i.e. extensibility) 247 can be used to formulate another definition: A Community Network is a 248 network in which any participant in the system may add link segments 249 to the network in such a way that the new network segments can 250 support multiple nodes and adopt the same overall characteristics as 251 those of the joined network, including the capacity to further extend 252 the network. Once these link segments are joined to the network, 253 there is no longer a meaningful distinction between the previous 254 extent of the network and the new extent of the network. 256 In Community Networks, the profit can only be made by services and 257 not by the infrastructure itself, because the infrastructure is 258 neutral, free, and open (traditional Internet Service Providers, 259 ISPs, base their business on the control of the infrastructure). In 260 Community Networks, everybody keeps the ownership of what he/she has 261 contributed. 263 Community Networks MAY also be called "Free Networks" or even 264 "Network Commons". [FNF]. The majority of Community Networks 265 accomplishes the definition of Free Network, included in the next 266 subsection. 268 2.1.1. Free Networks 270 A definition of Free Network (which MAY be the same as Community 271 Network) is proposed by the Free Network Foundation (see 272 http://thefnf.org) as: 274 "A free network equitably grants the following freedoms to all: 276 Freedom 0 - The freedom to communicate for any purpose, without 277 discrimination, interference, or interception. 279 Freedom 1 - The freedom to grow, improve, communicate across, and 280 connect to the whole network. 282 Freedom 2- The freedom to study, use, remix, and share any network 283 communication mechanisms, in their most reusable forms." 284 The principles of Free, Open and Neutral Networks have also been 285 summarized (see http://guifi.net/en/FONCC) this way: 287 - You have the freedom to use the network for any purpose as long as 288 you do not harm the operation of the network itself, the rights of 289 other users, or the principles of neutrality that allow contents and 290 services to flow without deliberate interference. 292 - You have the right to understand the network, to know its 293 components, and to spread knowledge of its mechanisms and principles. 295 - You have the right to offer services and content to the network on 296 your own terms. 298 - You have the right to join the network, and the responsibility to 299 extend this set of rights to anyone according to these same terms. 301 2.2. Wireless Internet Service Providers WISPs 303 WISPs are commercially-operated wireless Internet networks that 304 provide Internet and/or Voice Over Internet (VoIP) services. They 305 are most common in areas not covered by incumbent telcos or ISPs. 306 WISPs often use wireless point-to-point or point-to-multipoint in the 307 unlicensed frequencies but licensed frequency use is common too 308 especially in regions where unlicensed spectrum is either perceived 309 as crowded or where unlicensed spectrum may have regulatory barriers 310 impeding its use. 312 Most WISPs are operated by local companies responding to a perceived 313 market gap. There is a small but growing number of WISPs, such as 314 AirJaldi [Airjaldi] in India that have expanded from local service 315 into multiple locations. 317 Since 2006, the deployment of cloud-managed WISPs has been possible 318 with companies like Meraki and later OpenMesh and others. Until 319 recently, however, most of these services have been aimed at 320 industrialised markets. Everylayer [Everylayer], launched in 2014, 321 is the first cloud-managed WISP service aimed at emerging markets. 323 2.3. Shared infrastructure model 325 These networks are owned by individuals but leased out to network 326 operators who use them as a low cost medium to reach the underserved 327 population. 329 2.4. Crowdshared approaches, led by the people and third party 330 stakeholders 332 These networks can be defined as a set of nodes whose owners share 333 common interests (e.g. sharing connectivity; resources; peripherals) 334 regardless of their physical location. The node location exhibits a 335 space and time correlation which is the basis to establish a robust 336 connectivity model over time. 338 These networks conform to the following approach: the home router 339 creates two wireless networks: one of them is normally used by the 340 owner, and the other one is public. A small fraction of the 341 bandwidth is allocated to the public network, to be employed by any 342 user of the service in the immediate area. Some examples are 343 described in [PAWS] and [Sathiaseelan_c]. Other example is 344 constituted by the networks created and managed by City Councils 345 (e.g., [Heer]). 347 In the same way, some companies [Fon] develop and sell Wi-Fi routers 348 with a dual access: a Wi-Fi network for the user, and a shared one. 349 A user community is created, and people can join the network in 350 different ways: they can buy a router, so they share their connection 351 and in turn they get access to all the routers associated to the 352 community. Some users can even get some revenue every time another 353 user connects to their Wi-Fi spot. Other users can just buy some 354 passes in order to use the network. Some telecommunications 355 operators can collaborate with the community, including in their 356 routers the possibility of creating these two networks. 358 A Virtual Private Network (VPN) is created for public traffic, so it 359 is completely secure and separated from the owner's connection. The 360 network capacity shared may employ a low priority, a less-than-best- 361 effort or scavenger approach, so as not to harm the traffic of the 362 owner of the connection [Sathiaseelan_a]. 364 The elements involved in a crowd-shared network are summarised below: 366 - Interest: a parameter capable of providing a measure (cost) of the 367 attractiveness of a node towards a specific location, in a specific 368 instance in time. 370 - Resources: A physical or virtual element of a global system. For 371 instance, bandwidth; energy; data; devices. 373 - The owner: End users who sign up for the service and share their 374 network capacity. As a counterpart, they can access another owners' 375 home access for free. The owner can be an end user or an entity 376 (e.g. operator; virtual operator; municipality) that is to be made 377 responsible for any actions concerning his/her device. 379 - The user: a legal entity or an individual using or requesting a 380 publicly available electronic communications' service for private or 381 business purposes, without necessarily having subscribed to such 382 service. 384 - The Virtual Network Operator (VNO): An entity that acts in some 385 aspects as a network coordinator. It may provide services such as 386 initial authentication or registering, and eventually, trust 387 relationship storage. A VNO is not an ISP given that it does not 388 provide Internet access (e.g. infrastructure; naming). A VNO is 389 neither an Application Service Provider (ASP) since it does not 390 provide user services. Virtual Operators MAY also be stakeholders 391 with socio-environmental objectives. They CAN be a local government, 392 grass root user communities, charities, or even content operators, 393 smart grid operators, etc. They are the ones who actually run the 394 service. 396 - Network operators, who have a financial incentive to lease out the 397 unused capacity [Sathiaseelan_b] at lower cost to the VNOs. 399 VNOs pay the sharers and the network operators, thus creating an 400 incentive structure for all the actors: the end users get money for 401 sharing their network, the network operators are paid by the VNOs, 402 who in turn accomplish their socio-environmental role. 404 2.5. Testbeds for research purposes 406 In some cases, the initiative to start the network is not from the 407 community, but from a research entity (e.g. a university), with the 408 aim of using it for research purposes [Samanta], [Bernardi]. 410 3. Scenarios where Alternative Networks are deployed 412 Alternative Network deployments are present in every part of the 413 world. Even in some high-income countries, these networks have been 414 built as an alternative to commercial ones managed by traditional 415 network operators. This section discusses the scenarios where 416 Alternative Networks have been deployed. 418 3.1. Digital Divide and Alternative Networks 420 There is no definition for what a developing country represents that 421 has been recognized internationally, but the term is generally used 422 to describe a nation with a low level of material well-being. In 423 this sense, one of the most commonly used classification is the one 424 by the World Bank, who ranks countries according to their Gross 425 National Income (GNI) per Capita: low income, middle income, and high 426 income, being those falling within the low and middle income groups 427 considered developing economies. Developing countries have also been 428 defined as those which are in transition from traditional lifestyles 429 towards the modern lifestyle which began in the Industrial 430 Revolution. Additionally, the Human Development Index, which 431 considers not only the GNI but also life expectancy and education, 432 has been proposed by the United Nations to rank countries according 433 to their well-being and not solely based on economic terms. These 434 classifications are used to give strong signals to the international 435 community about the need of special concessions in support of these 436 countries, implying a correlation between development and increased 437 well-being. 439 However, at the beginning of the 90's the debates about how to 440 quantify development in a country were shaken by the appearance of 441 Internet and mobile phones, which many authors consider the beginning 442 of the Information Society. With the beginning of this Digital 443 Revolution, defining development based on Industrial Society concepts 444 started to be challenged, and links between digital development and 445 its impact on human development started to flourish. The following 446 dimensions are considered to be meaningful when measuring the digital 447 development state of a country: infrastructures (availability and 448 affordability); ICT (Information and Communications Technology) 449 sector (human capital and technological industry); digital literacy; 450 legal and regulatory framework; and content and services. The lack 451 or less extent of digital development in one or more of these 452 dimensions is what has been referred as Digital Divide. This divide 453 is a new vector of inequality which - as it happened during the 454 Industrial Revolution - generates a lot of progress at the expense of 455 creating a lot economic poverty and exclusion. The Digital Divide is 456 considered to be a consequence of other socio-economic divides, 457 while, at the same time, a reason for their rise. 459 In this context, the so-called "developing countries", in order not 460 to be left behind of this incipient digital revolution, motivated the 461 World Summit of the Information Society which aimed at achieving "a 462 people-centred, inclusive and development-oriented Information 463 Society, where everyone can create, access, utilize and share 464 information and knowledge, enabling individuals, communities and 465 peoples to achieve their full potential in promoting their 466 sustainable development and improving their quality of life" [WSIS], 467 and called upon "governments, private sector, civil society and 468 international organisations" to actively engage to accomplish it 469 [WSIS]. 471 Most efforts from governments and international organizations focused 472 initially on improving and extending the existing infrastructure in 473 order not to leave their population behind. As an example, one of 474 the goals of the Digital Agenda for Europe [DAE] is "to increase 475 regular internet usage from 60% to 75% by 2015, and from 41% to 60% 476 among disadvantaged people." 478 Universal Access and Service plans have taken different forms in 479 different countries over the years, with very uneven success rates, 480 but in most cases inadequate to the scale of the problem. Given its 481 incapacity to solve the problem, some governments included Universal 482 Service and Access obligations to mobile network operators when 483 liberalizing the telecommunications market. In combination with the 484 overwhelming and unexpected uptake of mobile phones by poor people, 485 this has mitigated the low access indicators existing in many 486 developing countries at the beginning of the 90s [Rendon]. 488 Although the contribution made by mobile network operators in 489 decreasing the access gap is undeniable, their model presents some 490 constraints that limit the development outcomes that increased 491 connectivity promises to bring. Prices, tailored for the more 492 affluent part of the population, remain unaffordable to many, who 493 invest large percentages of their disposable income in 494 communications. Additionally, the cost of prepaid packages, the only 495 option available for the informal economies existing throughout 496 developing countries, is high compared with the rate longer-term 497 subscribers pay. 499 The consolidation of many Alternative Networks (e.g. Community 500 Networks) in high income countries sets a precedent for civil society 501 members from the so-called developing countries to become more active 502 in the search for alternatives to provide themselves with affordable 503 access. Furthermore, Alternative Networks could contribute to other 504 dimensions of the digital development like increased human capital 505 and the creation of contents and services targeting the locality of 506 each network. 508 3.2. Urban vs. rural areas 510 The Digital Divide presented in the previous section is not only 511 present between countries, but within them too. This is specially 512 the case for rural inhabitants, which represents approximately 55% of 513 the world's population, from which 78% inhabit in developing 514 countries. Although it is impossible to generalize among them, there 515 exist some common features that have determined the availability of 516 ICT infrastructure in these regions. The disposable income of their 517 dwellers is lower than those inhabiting urban areas, with many 518 surviving on a subsistence economy. Many of them are located in 519 geographies difficult to access and exposed to extreme weather 520 conditions. This has resulted in the almost complete lack of 521 electrical infrastructure. This context, together with their low 522 population density, discourages telecommunications operators to 523 provide similar services to those provided to urban dwellers, since 524 they do not deem them profitable. 526 The cost of the wireless infrastructure required to set up a network, 527 including powering it via solar energy, is within the range of 528 availability if not of individuals at least of entire communities. 529 The social capital existing in these areas can allow for Alternative 530 Network set-ups where a reduced number of nodes may cover communities 531 whose dwellers share the cost of the infrastructure and the gateway 532 and access it via inexpensive wireless devices. Some examples are 533 presented in [Pietrosemoli] and [Bernardi]. 535 In this case, the lack of awareness and confidence of rural 536 communities to embark themselves in such tasks can become major 537 barriers to their deployment. Scarce technical skills in these 538 regions have been also pointed as a challenge for their success, but 539 the proliferation of urban Community Networks, where scarcity of 540 spectrum, scale, and heterogeneity of devices pose tremendous 541 challenges to their stability and the services they aim to provide, 542 has fuelled the creation of robust low-cost low-consumption low- 543 complexity off-the-shelf wireless devices which make much easier the 544 deployment and maintenance of these alternative infrastructures in 545 rural areas. 547 4. Technologies employed 549 4.1. Wired 551 In many (developed or developing) countries it may happen that 552 national service providers may decline to provide connectivity to 553 tiny and isolated villages. So in some cases the villagers have 554 created their own optical fiber networks. It is the case of 555 Lowenstedt in Germany [Lowenstedt]. 557 4.2. Wireless 559 Different wireless technologies [WNDW] can be employed in Alternative 560 Network deployments. Below we summarise topics to be considered in 561 such deployments: 563 4.2.1. Antennas 565 Three kinds of antennas are suitable to be used in these networks: 566 omnidirectional, directional and high gain antennas. 568 For local access, omnidirectional antennas are the most useful, since 569 they provide the same coverage in all directions of the plane in 570 which they are located. Above and below this plane, the received 571 signal will diminish, so the maximum benefits are obtained when the 572 client is at approximately the same height as the Access Point. 574 When using an omnidirectional antenna outdoors to provide 575 connectivity to a large area, people often select high gain antennas 576 located at the highest structure available to extend the coverage. 577 In many cases this is counterproductive, since a high gain 578 omnidirectional antenna will have a very narrow beamwidth in the 579 vertical plane, meaning that clients that are below the plane of the 580 antenna will receive a very weak signal (and by the reciprocity 581 property of all antennas, the antenna will also receive a feeble 582 signal from the client). A moderate gain omnidirectional of about 8 583 to 10 dBi is normally preferable. Higher gain omnidirectional 584 antennas are only advisable when the farthest way client is roughly 585 in the same plane. 587 For indoor clients, omnidirectional antennas are generally fine, 588 because the numerous reflections normally found in indoor 589 environments negate the advantage of using directional antennas. 591 For outdoor clients, directional antennas can be quite useful to 592 extend coverage to an Access Point fitted with an omnidirectional 593 one. 595 When building point-to-point links, the highest gain antennas are the 596 best choice, since their narrow beamwidth mitigates interference from 597 other users and can provide the longest links [Flickenger], 598 [Zennaro]. 600 24 to 34 dBi antennas are commercially available at both the 601 unlicensed 2.4 GHz and 5 GHz bands, and even higher gain antennas can 602 be found in the newer unlicensed bands at 17 GHz and 24 GHz. 604 Despite the fact that the free space loss is directly proportional to 605 the square of the frequency, it is normally advisable to use higher 606 frequencies for point-to-point links when there is a clear line of 607 sight, because it is normally easier to get higher gain antennas at 5 608 GHz. Deploying high gain antennas at both ends will more than 609 compensate for the additional free space loss. Furthermore, higher 610 frequencies can make do with lower altitude antenna placement since 611 the Fresnel ellipsoid (the volume around the optical line occuppied 612 by radio waves, which should be free from obstacles), is inversely 613 proportional to the square root of the frequency. 615 On the contrary, lower frequencies offer advantages when the line of 616 sight is blocked because they can leverage diffraction to reach the 617 intended receiver. 619 It is common to find dual radio Access Points, at two different 620 frequency bands. One way of benefiting from this arrangement is to 621 attach a directional antenna to the high frequency radio for 622 connection to the backbone and an omnidirectional one to the lower 623 frequency to provide local access. 625 In the case of mesh networking, where the antenna should connect to 626 several other nodes, it is better to use omnidirectional antennas. 628 The same type of polarisation must be used at both ends of any radio 629 link. For point-to-point links, some vendors use two radios 630 operating at the same frequency but with orthogonal polarisations, 631 thus doubling the achievable throughput, and also offering added 632 protection to multipath and other transmission impairments. 634 4.2.2. Link length 636 4.2.2.1. Line-of-Sight 638 For short distance transmission, there is no strict requirement of 639 line of sight between the transmitter and the receiver, and multipath 640 can guarantee communication despite the existence of obstacles in the 641 direct path. 643 For longer distances, the first requirement is the existence of an 644 unobstructed line of sight between the transmitter and the receiver. 645 For very long path the earth curvature is an obstacle that must be 646 cleared, but the trajectory of the radio beam is not strictly a 647 straight line due to the bending of the rays as a consequence of non- 648 uniformities of the atmosphere. Most of the time this bending will 649 mean that the radio horizon extends further than the optical horizon. 651 Another factor to be considered is that the Fresnel zone (the volume 652 around the optical line) must be unencumbered from obstacles for the 653 maximum signal to be captured at the receiver. The size of the 654 Fresnel ellipsoid grows with the distance between the end points and 655 with the wavelength of the signal, which in turn is inversely 656 proportional to the frequency. 658 For optimum signal reception the end points must be high enough to 659 clear any obstacle in the path and leave extra "elbow room" for the 660 Fresnel zone. This can be achieved by using suitable masts at either 661 end, or by taking advantage of existing structures or hills. 663 4.2.2.2. Transmitted and Received Power 665 Once a clear radio-electric line of sight (including the Fresnel zone 666 clearance) is obtained, one must ascertain that the received power is 667 well above the sensitivity of the receiver, by what is known as the 668 "link margin". The greater the link margin, the more reliable the 669 link. For mission critical applications 20 dB margin is suggested, 670 but for non critical ones 10 dB might suffice. 672 The sensitivity of the receiver decreases with the transmission 673 speed, so more power is needed at greater transmission speeds. 675 The received power is determined by the transmitted power, the gain 676 of the transmitting and receiving antennas and the propagation loss. 678 The propagation loss is the sum of the free space loss (proportional 679 to the square of the the frequency and the square of the distance), 680 plus additional factors like attenuation in the atmosphere by gases 681 or meteorological effects (which are strongly frequency dependent), 682 multipath and diffraction losses. 684 Multipath is more pronounced in trajectories over water. If they 685 cannot be avoided special countermeasures should be taken. 687 In order to achieve a given link margin (also called "fade margin"), 688 one can: 690 a) Increase the output power.The maximum transmitted power is 691 specified by each country's regulation, and for unlicensed 692 frequencies is much lower than for licensed frequencies. 694 b) Increase the antenna gain. There is no limit in the gain of the 695 receiving antenna, but high gain antennas are bulkier, present more 696 wind resistance and require sturdy mounts to comply with tighter 697 alignment requirements. The transmitter antenna gain is also 698 regulated and can be different for point-to-point as for point-to- 699 multipoint links. Many countries impose a limit in the combination 700 of transmitted power and antenna gain, EIRP (Equivalent Isotropically 701 Irradiated Power) which can be different for point-to- point or 702 point-to-multipoint links. 704 c) Reduce the propagation loss, by using a more favorable frequency 705 or a shorter path. 707 d) Use a more sensitive receiver. Receiver sensitivity can be 708 improved by using better circuits, but it is ultimately limited by 709 the thermal noise, which is proportional to temperature and 710 bandwidth. One can increase the sensitivity by using a smaller 711 receiving bandwidth, or by settling to lower throughput even in the 712 same receiver bandwidth. This step is often done automatically in 713 many protocols, in which the transmission speed can be reduced from 714 150 Mbit/s to 6 Mbit/s if the receiver power is not enough to sustain 715 the maximum throughput. 717 4.2.2.3. Medium Access Protocol 719 A completely different limiting factor is related to the medium 720 access protocol. Wi-Fi was designed for short distance, and the 721 transmitter expects the reception of an acknowledgment for each 722 transmitted packet in a certain amount of time; if the waiting time 723 is exceeded, the packet is retransmitted. This will significantly 724 reduce the throughput at long distance, so for long distance 725 applications it is better to use a different medium access technique, 726 in which the receiver does not wait for an acknowledgement of the 727 transited packet. This strategy of TDMA (Time Domain Multiple 728 Access) has been adopted by many equipment vendors who offer 729 proprietary protocols alongside the standard Wi-Fi in order to 730 increase the throughput at longer distances. Low cost equipment 731 using TDMA can offer high throughput at distances over 100 732 kilometers. 734 4.2.3. Layer 2 736 4.2.3.1. 802.11 (Wi-Fi) 738 Wireless standards ensure interoperability and usability to those who 739 design, deploy and manage wireless networks. The standards used in 740 the vast majority of Community Networks come from the IEEE Standard 741 Association's IEEE 802 Working Group. 743 The standard we are most interested in is 802.11 a/b/g/n, 744 [IEEE.802-11A.1999], [IEEE.802-11B.1999], [IEEE.802-11G.2003], 745 [IEEE.802-11N.2009] as it defines the protocol for Wireless LAN. 746 Different 802.11 amendments have been released, as shown in the table 747 below, also including their frequencies and approximate ranges. 749 |802.11| Release | Freq |BWdth | Data Rate per | Approx range (m) | 750 |prot | date | (GHz)|(MHz) |stream (Mbit/s) | indoor | outdoor | 751 +------+---------+------+------+----------------+--------+----------+ 752 | a |Sep 1999 | 5 | 20 | 6,9,12, 18, 24,| 35 | 120 | 753 | | | | | 36, 48, 54 | | | 754 | b |Sep 1999 | 2.4 | 20 | 1, 2, 5.5, 11 | 35 | 140 | 755 | g |Jun 2003 | 2.4 | 20 | 6,9,12, 18, 24,| 38 | 140 | 756 | | | | | 36, 48, 54 | | | 757 | n |Oct 2009 | 2.4/5| 20 | 7.2, 14.4, 21.7| 70 | 250 | 758 | | | | | 28.9, 43.3, | | | 759 | | | | | 57.8, 65, 72.2 | | | 760 | n |Oct 2009 | 2.4/5| 40 | 15, 30, 45, 60,| 70 | 250 | 761 | | | | | 90, 120, | | | 762 | | | | | 135, 150 | | | 763 | ac |Nov 2011 | 5 | 20 | Up to 87.6 | | | 764 | ac |Nov 2011 | 5 | 40 | Up to 200 | | | 765 | ac |Nov 2011 | 5 | 80 | Up to 433.3 | | | 766 | ac |Nov 2011 | 5 | 160 | Up to 866.7 | | | 768 In 2012 IEEE issued the 802.11-2012 Standard that consolidates all 769 the previous amendments. The document is freely downloadable from 770 IEEE Standards [IEEE]. 772 4.2.3.1.1. Deployment planning for 802.11 wireless networks 774 Before packets can be forwarded and routed to the Internet, layers 775 one (the physical) and two (the data link) need to be connected. 776 Without link local connectivity, network nodes cannot talk to each 777 other and route packets. 779 To provide physical connectivity, wireless network devices MUST 780 operate in the same part of the radio spectrum. This means that 781 802.11a radios will talk to 802.11a radios at around 5 GHz, and 782 802.11b/g radios will talk to other 802.11b/g radios at around 2.4 783 GHz. But an 802.11a device cannot interoperate with an 802.11b/g 784 device, since they use completely different parts of the 785 electromagnetic spectrum. More specifically, wireless interfaces 786 must agree on a common channel. If one 802.11b radio card is set to 787 channel 2 while another is set to channel 11, then the radios cannot 788 communicate with each other. 790 When two wireless interfaces are configured to use the same protocol 791 on the same radio channel, then they are ready to negotiate data link 792 layer connectivity. Each 802.11a/b/g device can operate in one of 793 four possible modes: 795 1. Master mode (also called AP or infrastructure mode) is used to 796 create a service that looks like a traditional Access Point. The 797 wireless interface creates a network with a specified name (called 798 the SSID, Service Set IDentifier) and channel, and offers network 799 services on it. While in master mode, wireless interfaces manage all 800 communications related to the network (authenticating wireless 801 clients, handling channel contention, repeating packets, etc.) 802 Wireless interfaces in master mode can only communicate with 803 interfaces that are associated with them in managed mode. 805 2. Managed mode is sometimes also referred to as client mode. 806 Wireless interfaces in managed mode will join a network created by a 807 master, and will automatically change their channel to match it. 808 They then present any necessary credentials to the master, and if 809 those credentials are accepted, they are associated with the master. 810 Managed mode interfaces do not communicate with each other directly, 811 and only communicate with an associated master. 813 3. Ad-hoc mode creates a multipoint-to-multipoint network where 814 there is no single master node or AP. In ad-hoc mode, each wireless 815 interface communicates directly with its neighbours. Nodes must be 816 in range of each other to communicate, and must agree on a network 817 name and channel. Ad-hoc mode is often also called Mesh Networking. 819 4. Monitor mode is used by some tools (such as Kismet) to passively 820 listen to all radio traffic on a given channel. When in monitor 821 mode, wireless interfaces transmit no data. This is useful for 822 analysing problems on a wireless link or observing spectrum usage in 823 the local area. Monitor mode is not used for normal communications. 825 When implementing a point-to-point or point-to-multipoint link, one 826 radio will typically operate in master mode, while the other(s) 827 operate in managed mode. In a multipoint-to-multipoint mesh, the 828 radios all operate in ad-hoc mode so that they can communicate with 829 each other directly. Managed mode clients cannot communicate with 830 each other directly, so a high repeater site is required in master or 831 ad-hoc mode. Ad-hoc is more flexible but has a number of performance 832 issues as compared to using the master / managed modes. 834 4.2.3.2. GSM 836 GSM has also been used in Alternative Networks as Layer 2 option, as 837 explained in [Mexican]. 839 4.2.3.3. Dynamic Spectrum 841 Some Alternative Networks make use of TV White Spaces - a set of UHF 842 and VHF television frequencies that can be utilized by secondary 843 users in locations where it is unused by licensed primary users such 844 as television broadcasters. Equipment that makes use of TV White 845 Spaces is required to detect the presence of existing unused TV 846 channels by means of a spectrum database and/or spectrum sensing in 847 order to ensure that no harmful interference is caused to primary 848 users. In order to smartly allocate interference-free channels to 849 the devices, cognitive radios are used which are able to modify their 850 frequency, power and modulation techniques to meet the strict 851 operating conditions required for secondary users. 853 The use of the term "White Spaces" is often used to describe "TV 854 White Spaces" as the VHF and UHF television frequencies were the 855 first to be exploited on a secondary use basis. There are two 856 dominant standards for TV white space communication: (i) the 802.11af 857 standard [IEEE.802-11AF.2013] - an adaptation of the 802.11 standard 858 for TV white space bands and (ii) the IEEE 802.22 standard 859 [IEEE.802-22.2011] for long-range rural communication. 861 4.2.3.3.1. 802.11af 863 802.11af [IEEE.802-11AF.2013] is a modified version of the 802.11 864 standard operating in TV White Space bands using Cognitive Radios to 865 avoid interference with primary users. The standard is often 866 referred to as White-Fi or Super WiFi and was approved in February 867 2014. 802.11af contains much of the advances of all the 802.11 868 standards including recent advances in 802.11ac such as up to four 869 bonded channels, four spatial streams and very high rate 256-QAM 870 modulation but with improved in-building penetration and outdoor 871 coverage. The maximum data rate achievable is 426.7 Mbps for 872 countries with 6/7 MHz channels and 568.9 Mbps for countries with 8 873 MHz channels. Coverage is typically limited to 1km although longer 874 range at lower throughput and using high gain antennas will be 875 possible. 877 Devices are designated as enabling stations (access points) or 878 dependent stations (clients). Enabling stations are authorized to 879 control the operation of a dependent station and securely access a 880 geolocation database. Once the enabling station has received a list 881 of available white space channels it can announce a chosen channel to 882 the dependent stations for them to communicate with the enabling 883 station. 802.11af also makes use of a registered location server - a 884 local database that organizes the geographic location and operating 885 parameters of all enabling stations. 887 4.2.3.3.2. 802.22 889 802.22 [IEEE.802-22.2011] is a standard developed specifically for 890 long range rural communications in TV white space frequencies and 891 first approved in July 2011. The standard is similar to the 802.16 892 (WiMax) [IEEE.802-16.2008] standard with an added cognitive radio 893 ability. The maximum throughput of 802.22 is 22.6 Mbps for a single 894 8 MHz channel using 64-QAM modulation. The achievable range using 895 the default MAC scheme is 30 km, however 100 km is possible with 896 special scheduling techniques. The MAC of 802.22 is specifically 897 customized for long distances - for example, slots in a frame 898 destined for more distant CPEs are sent before slots destined for 899 nearby CPEs. 901 Base stations are required to have a GPS and a connection to the 902 Internet in order to query a geolocation spectrum database. Once the 903 base station receives the allowed TV channels, it communicates a 904 preferred operating white space TV channel with the Client Premises 905 Equipment (CPE) devices. The standard also has a co-existence 906 mechanism that uses beacons to make other 802.22 base stations aware 907 of the presence of a base station that is not part of the same 908 network. 910 5. Network and architecture issues 912 5.1. Layer 3 914 5.1.1. IP addressing 916 Most known Alternative Networks started in or around the year 2000. 917 IPv6 was fully specified by then, but almost all Alternative Networks 918 still use IPv4. A survey [Avonts] indicated that IPv6 rollout 919 presents a challenge to Community Networks. 921 Most Community Networks use private IPv4 address ranges, as defined 922 by RFC 1918 [RFC1918]. The motivation for this was the lower cost 923 and the simplified IP allocation because of the large available 924 address ranges. 926 5.1.2. Routing protocols 928 Alternative Networks are composed of possibly different layer 2 929 devices, resulting in a mesh of nodes. Connection between different 930 nodes is not guaranteed and the link stability can vary strongly over 931 time. To tackle this, some Alternative Networks use mesh network 932 routing protocols while other networks use more traditional routing 933 protocols. Some networks operate multiple routing protocols in 934 parallel. For example, they use a mesh protocol inside different 935 islands and use traditional routing protocols to connect islands. 937 5.1.2.1. Traditional routing protocols 939 The BGP protocol, as defined by RFC 4271 [RFC4271] is used by a 940 number of Community Networks, because of its well-studied behavior 941 and scalability. 943 For similar reasons, smaller networks opt to run the OSPF protocol, 944 as defined by RFC 2328 [RFC2328]. 946 5.1.2.2. Mesh routing protocols 948 A large number of Alternative Networks use the OLSR routing protocol 949 as defined in RFC 3626 [RFC3626]. The pro-active link state routing 950 protocol is a good match with Alternative Networks because it has 951 good performance in mesh networks where nodes have multiple 952 interfaces. 954 The Better Approach To Mobile Adhoc Networking (BATMAN) [Abolhasan] 955 protocol was developed by members of the Freifunk community. The 956 protocol handles all routing at layer 2, creating one bridged 957 network. 959 Parallel to BGP, some networks also run the BMX6 protocol [Neumann]. 960 This is an advanced version of the BATMAN protocol which is based on 961 IPv6 and tries to exploit the social structure of Alternative 962 Networks. 964 5.2. Upper layers 966 From crowdshared perspective, and considering just regular TCP 967 connections during the critical sharing time, the Access Point 968 offering the service is likely to be the bottleneck of the 969 connection. This is the main concern of sharers, having several 970 implications. There should be an adequate Active Queue Management 971 (AQM) mechanism that implements a Less than Best Effort (LBE) policy 972 for the user and protects the sharer. Achieving LBE behaviour 973 requires the appropriate tuning of the well known mechanisms such as 974 ECN, or RED, or others more recent AQM mechanisms such as CoDel and 975 PIE that aid on keeping low latency RFC 6297 [RFC6297]. 977 The user traffic should not interfere with the sharer's traffic. 978 However, other bottlenecks besides client's access bottleneck may not 979 be controlled by the previously mentioned protocols. Therefore, 980 recently proposed transport protocols like LEDBAT [Ros], [Komnios] 981 with the purpose of transporting scavenger traffic may be a solution. 982 LEDBAT requires the cooperation of both the client and the server to 983 achieve certain target delay, therefore controlling the impact of the 984 user along all the path. 986 There are applications that manage aspects of the network from the 987 sharer side and from the client side. From sharer's side, there are 988 applications to centralise the management of the APs conforming the 989 network that have been recently proposed by means of SDN 990 [Sathiaseelan_a], [Suresh]. There are also other proposals such as 991 Wi2Me [Lampropulos] that manage the connection to several Community 992 Networks from the client's side. These applications have shown to 993 improve the client performance compared to a single-Community Network 994 client. 996 On the other hand, transport protocols inside a multiple hop wireless 997 mesh network are likely to suffer performance degradation for 998 multiple reasons, e.g., hidden terminal problem, unnecessary delays 999 on the TCP ACK clocking that decrease the throughout or route 1000 changing [Hanbali]. There are some options for network 1001 configuration. The implementation of an easy-to-adopt solution for 1002 TCP over mesh networks may be implemented from two different 1003 perspectives. One way is to use a TCP-proxy to transparently deal 1004 with the different impairments (RFC 3135 [RFC3135]). Another way is 1005 to adopt end-to-end solutions for monitoring the connection delay so 1006 that the receiver adapts the TCP reception window (rwnd) 1007 [Castignani_c]. Similarly, the ACK Congestion Control (ACKCC) 1008 mechanism RFC 5690 [RFC5690] could deal with TCP-ACK clocking 1009 impairments due to inappropriate delay on ACK packets. ACKCC 1010 compensates in an end-to-end fashion the throughput degradation due 1011 to the effect of media contention as well as the unfairness 1012 experienced by multiple uplink TCP flows in a congested Wi-Fi access. 1014 5.2.1. Services provided by Alternative Networks 1016 This section provides an overview of the services between hosts 1017 inside the network. They can be divided into Intranet services, 1018 connecting hosts between them, and Internet services, connecting to 1019 nodes outside the network. 1021 5.2.1.1. Intranet services 1023 Intranet services can include, but are not limited to: 1025 - VoIP (e.g. with SIP) 1027 - Remote desktop (e.g. using my home computer and my Internet 1028 connection when I am on holidays in a village). 1030 - FTP file sharing (e.g. distribution of Linux software). 1032 - P2P file sharing. 1034 - Public video cameras. 1036 - DNS. 1038 - Online games servers. 1040 - Jabber instant messaging. 1042 - IRC chat. 1044 - Weather stations. 1046 - NTP. 1048 - Network monitoring. 1050 - Videoconferencing / streaming. 1052 - Radio streaming. 1054 5.2.1.2. Access to the Internet 1056 5.2.1.2.1. Web browsing proxies 1058 A number of federated proxies MAY provide web browsing service for 1059 the users. Other services (file sharing, skype, etc.) are not 1060 usually allowed in many Alternative Networks due to bandwidth 1061 limitations. 1063 5.2.1.2.2. Use of VPNs 1065 Some "micro-ISPs" may use the network as a backhaul for providing 1066 Internet access, setting up VPNs from the client to a machine with 1067 Internet access. 1069 5.3. Topology 1071 Alternative Networks follow different topology patterns, as studied 1072 in [Vega]. 1074 Regularly rural areas in these networks are connected through long- 1075 distance links (the so-called community mesh approach) which in turn 1076 convey the Internet connection to relevant organisations or 1077 institutions. In contrast, in urban areas, users tend to share and 1078 require mobile access. Since these areas are also likely to be 1079 covered by commercial ISPs, the provision of wireless access by 1080 Virtual Operators like [Fon] may constitute a way to extend the user 1081 capacity (or gain connection) to the network. Other proposals like 1082 Virtual Public Networks [Sathiaseelan_a] can also extend the service. 1084 As in the case of main Internet Service Providers in France, 1085 Community Networks for urban areas are conceived as a set of APs 1086 sharing a common SSID among the clients favouring the nomadic access. 1087 For users in France, ISPs promise to cause a little impact on their 1088 service agreement when the shared network service is activated on 1089 clients' APs. Nowadays, millions of APs are deployed around the 1090 country performing services of nomadism and 3G offloading, however as 1091 some studies demonstrate, at walking speed, there is a fair chance of 1092 performing file transfers [Castignani_a], [Castignani_b]. Scenarios 1093 studied in France and Luxembourg show that the density of APs in 1094 urban areas (mainly in downtown and residential areas) is quite big 1095 and from different ISPs. Moreover, performed studies reveal that 1096 aggregating available networks can be beneficial to the client by 1097 using an application that manages the best connection among the 1098 different networks. For improving the scanning process (or topology 1099 recognition), which consumes the 90% of the connection/reconnection 1100 process to the Community Network, the client may implement several 1101 techniques for selecting the best AP [Castignani_c]. 1103 6. Acknowledgements 1105 This work has been partially funded by the CONFINE European 1106 Commission Project (FP7 - 288535). 1108 The editor and the authors of this document wish to thank the 1109 following individuals who have participated in the drafting, review, 1110 and discussion of this memo: 1112 Paul M. Aoki, Roger Baig, Jaume Barcelo, Steven G. Huter, Rohan 1113 Mahy, Rute Sofia, Dirk Trossen. 1115 A special thanks to the GAIA Working Group chairs Matt Ford and 1116 Arjuna Sathiaseelan for their support and guidance. 1118 7. Contributing Authors 1119 Ioannis Komnios 1120 Democritus University of Thrace 1121 Department of Electrical and Computer Engineering 1122 Kimmeria University Campus 1123 Xanthi 67100 1124 Greece 1126 Phone: +306945406585 1127 Email: ikomnios@ee.duth.gr 1129 Steve Song 1130 Village Telco Limited 1132 Halifax 1133 Canada 1135 Phone: 1136 Email: stevesong@nsrc.org 1138 David Lloyd Johnson 1139 Meraka, CSIR 1140 15 Lower Hope St 1141 Rosebank 7700 1142 South Africa 1144 Phone: +27 (0)21 658 2740 1145 Email: djohnson@csir.co.za 1147 8. IANA Considerations 1149 This memo includes no request to IANA. 1151 9. Security Considerations 1153 No security issues have been identified for this document. 1155 10. References 1157 10.1. Normative References 1159 [IEEE.802-11A.1999] 1160 "Information technology - Telecommunications and 1161 information exchange between systems - Local and 1162 metropolitan area networks - Specific requirements - Part 1163 11: Wireless LAN Medium Access Control (MAC) and Physical 1164 Layer (PHY) specifications - High-speed Physical Layer in 1165 the 5 GHZ Band", IEEE Standard 802.11a, Sept 1999, 1166 . 1169 [IEEE.802-11AF.2013] 1170 "Information technology - Telecommunications and 1171 information exchange between systems - Local and 1172 metropolitan area networks - Specific requirements - Part 1173 11: Wireless LAN Medium Access Control (MAC) and Physical 1174 Layer (PHY) specifications - Amendment 5: Television White 1175 Spaces (TVWS) Operation", IEEE Standard 802.11af, Oct 1176 2009, . 1179 [IEEE.802-11B.1999] 1180 "Information technology - Telecommunications and 1181 information exchange between systems - Local and 1182 metropolitan area networks - Specific requirements - Part 1183 11: Wireless LAN Medium Access Control (MAC) and Physical 1184 Layer (PHY) specifications - Higher-Speed Physical Layer 1185 Extension in the 2.4 GHz Band", IEEE Standard 802.11b, 1186 Sept 1999, . 1189 [IEEE.802-11G.2003] 1190 "Information technology - Telecommunications and 1191 information exchange between systems - Local and 1192 metropolitan area networks - Specific requirements - Part 1193 11: Wireless LAN Medium Access Control (MAC) and Physical 1194 Layer (PHY) specifications - Amendment 4: Further Higher 1195 Data Rate Extension in the 2.4 GHz Band", IEEE Standard 1196 802.11g, Jun 2003, . 1199 [IEEE.802-11N.2009] 1200 "Information technology - Telecommunications and 1201 information exchange between systems - Local and 1202 metropolitan area networks - Specific requirements - Part 1203 11: Wireless LAN Medium Access Control (MAC) and Physical 1204 Layer (PHY) specifications - Amendment 5: Enhancements for 1205 Higher Throughput", IEEE Standard 802.11n, Oct 2009, 1206 . 1209 [IEEE.802-16.2008] 1210 "Information technology - Telecommunications and 1211 information exchange between systems - Broadband wireless 1212 metropolitan area networks (MANs) - IEEE Standard for Air 1213 Interface for Broadband Wireless Access Systems", IEEE 1214 Standard 802.16, Jun 2008, 1215 . 1218 [IEEE.802-22.2011] 1219 "Information technology - Telecommunications and 1220 information exchange between systems - Local and 1221 metropolitan area networks - Specific requirements - Part 1222 22: Cognitive Wireless RAN Medium Access Control (MAC) and 1223 Physical Layer (PHY) specifications: Policies and 1224 procedures for operation in the TV Bands", IEEE Standard 1225 802.22, Jul 2011, . 1228 [RFC1918] Rekhter, Y., Moskowitz, R., Karrenberg, D., Groot, G., and 1229 E. Lear, "Address Allocation for Private Internets", BCP 1230 5, RFC 1918, February 1996. 1232 [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate 1233 Requirement Levels", BCP 14, RFC 2119, March 1997. 1235 [RFC2328] Moy, J., "OSPF Version 2", STD 54, RFC 2328, April 1998. 1237 [RFC3135] Border, J., Kojo, M., Griner, J., Montenegro, G., and Z. 1238 Shelby, "Performance Enhancing Proxies Intended to 1239 Mitigate Link-Related Degradations", RFC 3135, June 2001. 1241 [RFC3626] Clausen, T. and P. Jacquet, "Optimized Link State Routing 1242 Protocol (OLSR)", RFC 3626, October 2003. 1244 [RFC4271] Rekhter, Y., Li, T., and S. Hares, "A Border Gateway 1245 Protocol 4 (BGP-4)", RFC 4271, January 2006. 1247 [RFC5690] Floyd, S., Arcia, A., Ros, D., and J. Iyengar, "Adding 1248 Acknowledgement Congestion Control to TCP", RFC 5690, 1249 February 2010. 1251 [RFC6297] Welzl, M. and D. Ros, "A Survey of Lower-than-Best-Effort 1252 Transport Protocols", RFC 6297, June 2011. 1254 10.2. Informative References 1256 [Abolhasan] 1257 Abolhasan, M., Hagelstein, B., and J. Wang, "Real-world 1258 performance of current proactive multi-hop mesh 1259 protocols", In Communications, 2009. APCC 2009. 15th Asia- 1260 Pacific Conference on (pp. 44-47). IEEE. , 2009. 1262 [Airjaldi] 1263 Rural Broadband (RBB) Pvt. Ltd., Airjaldi., "Airjaldi 1264 service", Airjaldi web page, www.airjaldi.net , 2015. 1266 [Avonts] Avonts, J., Braem, B., and C. Blondia, "A Questionnaire 1267 based Examination of Community Networks", Proceedings 1268 Wireless and Mobile Computing, Networking and 1269 Communications (WiMob), 2013 IEEE 8th International 1270 Conference on (pp. 8-15) , 2013. 1272 [Bernardi] 1273 Bernardi, B., Buneman, P., and M. Marina, "Tegola tiered 1274 mesh network testbed in rural Scotland", Proceedings of 1275 the 2008 ACM workshop on Wireless networks and systems for 1276 developing regions (WiNS-DR '08). ACM, New York, NY, USA, 1277 9-16 , 2008. 1279 [Braem] Braem, B., Baig Vinas, R., Kaplan, A., Neumann, A., Vilata 1280 i Balaguer, I., Tatum, B., Matson, M., Blondia, C., Barz, 1281 C., Rogge, H., Freitag, F., Navarro, L., Bonicioli, J., 1282 Papathanasiou, S., and P. Escrich, "A case for research 1283 with and on community networks", ACM SIGCOMM Computer 1284 Communication Review vol. 43, no. 3, pp. 68-73, 2013. 1286 [Castignani_a] 1287 Castignani, G., Loiseau, L., and N. Montavont, "An 1288 Evaluation of IEEE 802.11 Community Networks Deployments", 1289 Information Networking (ICOIN), 2011 International 1290 Conference on , vol., no., pp.498,503, 26-28 , 2011. 1292 [Castignani_b] 1293 Castignani, G., Monetti, J., Montavont, N., Arcia-Moret, 1294 A., Frank, R., and T. Engel, "A Study of Urban IEEE 802.11 1295 Hotspot Networks: Towards a Community Access Network", 1296 Wireless Days (WD), 2013 IFIP , pp.1,8, 13-15 , 2013. 1298 [Castignani_c] 1299 Castignani, G., Arcia-Moret, A., and N. Montavont, "A 1300 study of the discovery process in 802.11 networks", 1301 SIGMOBILE Mob. Comput. Commun. Rev., vol. 15, no. 1, p. 25 1302 , 2011. 1304 [DAE] European Commission, EC., "A Digital Agenda for Europe", 1305 Communication from the Commission of 19 May 2010 to the 1306 European Parliament, the Council, the European Economic 1307 and Social Committee and the Committee of the Regions - A 1308 Digital Agenda for Europe , 2010. 1310 [Everylayer] 1311 former Volo Broadband, Everylayer., "Everylayer", 1312 Everylayer web page, http://www.everylayer.com/ , 2015. 1314 [FNF] The Free Network Foundation, FNF., "The Free Network 1315 Foundation", The Free Network Foundation web page, 1316 https://thefnf.org/ , 2014. 1318 [Flickenger] 1319 Flickenger, R., Okay, S., Pietrosemoli, E., Zennaro, M., 1320 and C. Fonda, "Very Long Distance Wi-Fi Networks", NSDR 1321 2008, The Second ACM SIGCOMM Workshop on Networked Systems 1322 for Developing Regions. 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Radicella, "On a long 1441 wireless link for rural telemedicine in Malawi", 6th 1442 International Conference on Open Access, Lilongwe, Malawi 1443 , Nov 2008. 1445 Authors' Addresses 1447 Jose Saldana (editor) 1448 University of Zaragoza 1449 Dpt. IEC Ada Byron Building 1450 Zaragoza 50018 1451 Spain 1453 Phone: +34 976 762 698 1454 Email: jsaldana@unizar.es 1456 Andres Arcia-Moret 1457 Universidad de Los Andes 1458 Facultad de Ingenieria. Sector La Hechicera 1459 Merida 5101 1460 Venezuela 1462 Phone: +58 274 2402811 1463 Email: andres.arcia@ula.ve 1465 Bart Braem 1466 iMinds 1467 Gaston Crommenlaan 8 (bus 102) 1468 Gent 9050 1469 Belgium 1471 Phone: +32 3 265 38 64 1472 Email: bart.braem@iminds.be 1473 Leandro Navarro 1474 U. Politecnica Catalunya 1475 Jordi Girona, 1-3, D6 1476 Barcelona 08034 1477 Spain 1479 Phone: +34 934016807 1480 Email: leandro@ac.upc.edu 1482 Ermanno Pietrosemoli 1483 ICTP 1484 Via Beirut 7 1485 Trieste 34151 1486 Italy 1488 Phone: +39 040 2240 471 1489 Email: ermanno@ictp.it 1491 Carlos Rey-Moreno 1492 University of the Western Cape 1493 Robert Sobukwe road 1494 Bellville 7535 1495 South Africa 1497 Phone: 0027219592562 1498 Email: crey-moreno@uwc.ac.za 1500 Arjuna Sathiaseelan 1501 University of Cambridge 1502 15 JJ Thomson Avenue 1503 Cambridge CB30FD 1504 United Kingdom 1506 Phone: +44 (0)1223 763781 1507 Email: arjuna.sathiaseelan@cl.cam.ac.uk 1509 Marco Zennaro 1510 Abdus Salam ICTP 1511 Strada Costiera 11 1512 Trieste 34100 1513 Italy 1515 Phone: +39 040 2240 406 1516 Email: mzennaro@ictp.it