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Run idnits with the --verbose option for more detailed information about the items above. -------------------------------------------------------------------------------- 1 6LoWPAN Working Group J. Nieminen, Ed. 2 Internet-Draft B. Patil 3 Intended status: Standards Track T. Savolainen 4 Expires: September 7, 2012 M. Isomaki 5 Nokia 6 Z. Shelby 7 Sensinode 8 C. Gomez 9 Universitat Politecnica de 10 Catalunya/i2CAT 11 March 6, 2012 13 Transmission of IPv6 Packets over Bluetooth Low Energy 14 draft-ietf-6lowpan-btle-06 16 Abstract 18 Bluetooth Low Energy is a low power air interface technology defined 19 by the Bluetooth Special Interest Group (BT SIG). The standard 20 Bluetooth radio has been widely implemented and available in mobile 21 phones, notebook computers, audio headsets and many other devices. 22 The low power version of Bluetooth is a new specification and enables 23 the use of this air interface with devices such as sensors, smart 24 meters, appliances, etc. The low power variant of Bluetooth is 25 commonly specified in revision 4.0 of the Bluetooth specifications 26 and commonly refered to as Bluetooth 4.0. This document describes 27 how IPv6 is transported over Bluetooth Low Energy using 6LoWPAN 28 techniques. 30 Status of this Memo 32 This Internet-Draft is submitted in full conformance with the 33 provisions of BCP 78 and BCP 79. 35 Internet-Drafts are working documents of the Internet Engineering 36 Task Force (IETF). Note that other groups may also distribute 37 working documents as Internet-Drafts. The list of current Internet- 38 Drafts is at http://datatracker.ietf.org/drafts/current/. 40 Internet-Drafts are draft documents valid for a maximum of six months 41 and may be updated, replaced, or obsoleted by other documents at any 42 time. It is inappropriate to use Internet-Drafts as reference 43 material or to cite them other than as "work in progress." 45 This Internet-Draft will expire on September 7, 2012. 47 Copyright Notice 48 Copyright (c) 2012 IETF Trust and the persons identified as the 49 document authors. All rights reserved. 51 This document is subject to BCP 78 and the IETF Trust's Legal 52 Provisions Relating to IETF Documents 53 (http://trustee.ietf.org/license-info) in effect on the date of 54 publication of this document. Please review these documents 55 carefully, as they describe your rights and restrictions with respect 56 to this document. Code Components extracted from this document must 57 include Simplified BSD License text as described in Section 4.e of 58 the Trust Legal Provisions and are provided without warranty as 59 described in the Simplified BSD License. 61 Table of Contents 63 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3 64 2. Bluetooth Low Energy . . . . . . . . . . . . . . . . . . . . . 3 65 2.1. Bluetooth Low Energy stack . . . . . . . . . . . . . . . . 4 66 2.2. Link layer roles and topology . . . . . . . . . . . . . . 4 67 2.3. BT-LE device addressing . . . . . . . . . . . . . . . . . 5 68 2.4. BT-LE packets sizes and MTU . . . . . . . . . . . . . . . 5 69 3. Specification of IPv6 over Bluetooth Low Energy . . . . . . . 6 70 3.1. Protocol stack . . . . . . . . . . . . . . . . . . . . . . 6 71 3.2. Link model . . . . . . . . . . . . . . . . . . . . . . . . 7 72 3.2.1. Stateless address autoconfiguration . . . . . . . . . 7 73 3.2.2. Neighbor discovery . . . . . . . . . . . . . . . . . . 8 74 3.2.3. Header compression . . . . . . . . . . . . . . . . . . 9 75 3.2.4. Unicast and Multicast address mapping . . . . . . . . 9 76 3.3. Internet connectivity scenarios . . . . . . . . . . . . . 10 77 4. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 10 78 5. Security Considerations . . . . . . . . . . . . . . . . . . . 11 79 6. Additional contributors . . . . . . . . . . . . . . . . . . . 11 80 7. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . 11 81 8. Normative References . . . . . . . . . . . . . . . . . . . . . 11 82 Appendix A. Bluetooth Low Energy fragmentation and L2CAP Modes . 12 83 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 13 85 1. Introduction 87 Bluetooth Low Energy (BT-LE) is a radio technology targeted for 88 devices that operate with coin cell batteries or minimalistic power 89 sources, which means that low power consumption is essential. BT-LE 90 is an especially attractive technology for Internet of Things 91 applications, such as health monitors, environmental sensing, 92 proximity applications and many others. 94 Considering the potential for the exponential growth in the number of 95 sensors and Internet connected devices and things, IPv6 is an ideal 96 protocol due to the large address space it provides. In addition, 97 IPv6 provides tools for autoconfiguration, which is particularly 98 suitable for sensor network applications and nodes which have very 99 limited processing power or a full-fledged operating system. 101 [RFC4944] specifies the transmission of IPv6 over IEEE 802.15.4. The 102 Bluetooth Low Energy link in many respects has similar 103 characteristics to that of IEEE 802.15.4. Many of the mechanisms 104 defined in [RFC4944] can be applied to the transmission of IPv6 on 105 Bluetooth Low Energy links. This document specifies the details of 106 IPv6 transmission over Bluetooth Low Energy links. 108 The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", 109 "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this 110 document are to be interpreted as described in RFC 2119 [RFC2119]. 112 The terms 6LN, 6LR and 6LBR are defined as in [I-D.ietf-6lowpan-nd]. 114 2. Bluetooth Low Energy 116 BT-LE is designed for transferring small amounts of data infrequently 117 at modest data rates at a very low cost per bit. Bluetooth SIG has 118 introduced two trademarks, Bluetooth Smart for single-mode devices (a 119 device that only supports BT-LE) and Bluetooth Smart Ready for dual- 120 mode devices. In the rest of the draft, the term BT-LE refers to 121 both types of devices. 123 BT-LE is an integral part of the BT 4.0 specification [BTCorev4.0]. 124 Devices such as mobile phones, notebooks, tablets and other handheld 125 computing devices which include BT 4.0 chipsets also have the low- 126 energy functionality of Bluetooth. BT-LE is also included in many 127 different types of accessories that collaborate with mobile devices 128 such as phones, tablets and notebook computers. An example of a use 129 case for a BT-LE accessory is a heart rate monitor that sends data 130 via the mobile phone to a server on the Internet. 132 2.1. Bluetooth Low Energy stack 134 The lower layer of the BT-LE stack consists of the Physical (PHY) and 135 the Link Layer (LL). The Physical Layer transmits and receives the 136 actual packets. The Link Layer is responsible for providing medium 137 access, connection establishment, error control and flow control. 138 The upper layer consists of the Logical Link Control and Adaptation 139 Protocol (L2CAP), Generic Attribute protocol (GATT) and Generic 140 Access Profile (GAP) as shown in Figure 1. GATT and BT-LE profiles 141 together enable the creation of applications in a standardized way 142 without using IP. L2CAP provides multiplexing capability by 143 multiplexing the data channels from the above layers. L2CAP also 144 provides fragmentation and reassembly for large data packets. 146 +----------------------------------------+------------------+ 147 | Applications | 148 +----------------------------------------+------------------+ 149 | Generic Attribute Profile | Generic Access | 150 +----------------------------------------+ Profile | 151 | Attribute Protocol |Security Manager | | 152 +--------------------+-------------------+------------------+ 153 | Logical Link Control and Adaptation | 154 +--------------------+-------------------+------------------+ 155 | Host Controller Interface | 156 +--------------------+-------------------+------------------+ 157 | Link Layer | Direct Test Mode | 158 +--------------------+-------------------+------------------+ 159 | Physical Layer | 160 +--------------------+-------------------+------------------+ 162 Figure 1: BT-LE Protocol Stack 164 2.2. Link layer roles and topology 166 BT-LE defines two Link Layer roles: the Master Role and the Slave 167 Role. A device in the Master Role, which is called master, can 168 manage multiple simultaneous connections with a number of devices in 169 the Slave Role, called slaves. A slave can only be connected to a 170 single master. Hence, a BT-LE network (i.e. a BT-LE piconet) follows 171 a star topology. 173 [BTLE-Slave]-----\ /-----[BTLE-Slave] 174 \ / 175 [BTLE-Slave]-----/[BTLE-Master]/-----[BTLE-Slave] 176 / \ 177 [BTLE-Slave]-----/ \-----[BTLE-Slave] 179 Figure 2: BT-LE Star Topology 181 A master is assumed to be less constrained than a slave. Hence, 182 master and slave can correspond with 6LoWPAN Border Router (6LBR) and 183 host, respectively. 185 In BT-LE, communication only takes place between a master and a 186 slave. Hence, in a BT-LE network using IP, a radio hop is equivalent 187 to an IP link and vice versa. 189 2.3. BT-LE device addressing 191 Every BT-LE device is identified by a unique 48 bit Bluetooth Device 192 Address (BD_ADDR). A Bluetooth Smart device such as a sensor may use 193 a public (obtained from IEEE Registration Authority) or a random 194 device address (generated internally). The public address is created 195 according to the IEEE 802-2001 standard [IEEE802-2001] and using a 196 valid Organizationally Unique Identifier (OUI) obtained from the IEEE 197 Registration Authority. This specification mandates that the 198 Bluetooth Device Address MUST be a public address. 200 2.4. BT-LE packets sizes and MTU 202 Maximum size of the payload in the BT-LE data channel PDU is 27 203 bytes. Depending on the L2CAP mode in use, the amount of data 204 available for transporting IP bytes in the single BT-LE data channel 205 PDU ranges between 19 and 27 octets. For power efficient 206 communication between two BT-LE devices, data and its header should 207 fit in a single BT-LE data channel PDU. MTU larger than 27 bytes can 208 be supported by the L2CAP specification. The Basic L2CAP Mode allows 209 a maximum payload size (i.e. IP datagram size) of 65535 bytes per 210 L2CAP PDU. The rest of the L2CAP modes allow a maximum payload size 211 that ranges between 65527 and 65533 bytes per L2CAP PDU. 213 The maximum payload size of a BT-LE data channel PDU is 27 bytes, 214 from which L2CAP headers may consume additional bytes. However, data 215 packets may be much larger (e.g. IPv6 requires support for an MTU of 216 1280 bytes). Fragmentation and Recombination (FAR) functionality is 217 an inherent function of the BT-LE L2CAP layer. Larger L2CAP packets 218 can be transferred with the assistance of the FAR functionality. 220 Appendix A describes FAR operation and five L2CAP Modes. This 221 specification requires that FAR functionality MUST be provided in the 222 L2CAP layer up to the IPv6 minimum MTU of 1280 bytes. The 223 corresponding L2CAP Mode MUST be Basic Mode. Since FAR in BT-LE is a 224 function of the L2CAP layer, fragmentation functionality as defined 225 in [RFC4944] MUST NOT be used in BT-LE networks. 227 3. Specification of IPv6 over Bluetooth Low Energy 229 BT-LE technology sets strict requirements for low power consumption 230 and thus limits the allowed protocol overhead. 6LoWPAN standard 231 [RFC4944], [I-D.ietf-6lowpan-nd] and [RFC6282] provides useful 232 generic functionality like header compression, link-local IPv6 233 addresses, Neighbor Discovery and stateless IP-address 234 autoconfiguration for reducing the overhead in 802.15.4 networks. 235 This functionality can be partly applied to BT-LE. 237 A significant difference between IEEE 802.15.4 and BT-LE is that the 238 former supports both star and mesh topology (and requires a routing 239 protocol), whereas BT-LE does not currently support the formation of 240 multihop networks. In consequence, the mesh header defined in 241 [RFC4944] for mesh under routing MUST NOT be used in BT-LE networks. 242 In addition, a BT-LE device MUST NOT play the role of a 6LoWPAN 243 Router (6LR). 245 3.1. Protocol stack 247 In order to enable transmission of IPv6 packets over BT-LE, a new 248 fixed L2CAP channel ID MUST be reserved for IPv6 traffic by the BT- 249 SIG. A request for allocation of a new fixed channel ID for IPv6 250 traffic by the BT-SIG should be submitted through the liaison process 251 or formal communique from the 6lowpan chairs and respective area 252 directors. Until a channel ID is allocated by BT-SIG, the channel ID 253 0x0007 is recommended for experimentation. Once the channel ID is 254 allocated, the allocated value MUST be used. Figure 3 illustrates 255 IPv6 over BT-LE stack. 257 +-------------------+ 258 | UDP/TCP | 259 +-------------------+ 260 | IPv6 | 261 +-------------------+ 262 | 6LoWPAN adapted | 263 | to BT-LE | 264 +-------------------+ 265 | BT-LE L2CAP | 266 +-------------------+ 267 | BT-LE Link Layer | 268 +-------------------+ 269 | BT-LE Physical | 270 +-------------------+ 272 Figure 3: IPv6 over BT-LE Stack 274 3.2. Link model 276 The concept of IP link (layer 3) and the physical link (combination 277 of PHY and MAC) needs to be clear and the relationship has to be well 278 understood in order to specify the addressing scheme for transmitting 279 IPv6 packets over the BT-LE link. [RFC4861] defines a link as "a 280 communication facility or medium over which nodes can communicate at 281 the link layer, i.e., the layer immediately below IP." 283 In the case of BT-LE, L2CAP is an adaptation layer that supports the 284 transmission of IPv6 packets. L2CAP also provides multiplexing 285 capability in addition to FAR functionality. This draft assumes the 286 same common IPv6 header values as those assumed in [RFC 6282]. It is 287 also assumed that the IPv6 payload length can be inferred from the 288 L2CAP header length and also assumes that IPv6 addresses assigned to 289 6LoWPAN interfaces are formed with an IID derived directly from the 290 48-bit Bluetooth device addresses, as described in subsection 3.2.1. 292 The BT-LE link between two communicating nodes can be considered to 293 be a point-to-point or point-to-multipoint link. When one of the 294 communicating nodes is in the role of a master, then the link can be 295 viewed as a point-to-multipoint link. 297 When a host connects to another BT-LE device the link is up and IP 298 address configuration and transmission can occur. 300 3.2.1. Stateless address autoconfiguration 302 A BT-LE 6LN performs stateless address autoconfiguration as per 303 [RFC4862]. The 64 bit Interface Identifier (IID) for a BT-LE 304 interface is formed from the 48-bit unique public Bluetooth device 305 address [REF Sec 2.3] as per the "IPv6 over Ethernet" specification 306 [RFC2464]. A BT-LE 6LN SHOULD utilize this EUI-64 address for 307 stateless address autoconfiguration. The 48-bit public bluetooth 308 address is globally unique and provided by the IEEE registration 309 authority. Hence the "Universal/Local" (U/L) bit MUST be set to 0. 311 The IPv6 link-local address [RFC4291] for a BT-LE node is formed by 312 appending the IID, as defined above, to the prefix FE80::/64, as 313 depicted in Figure 4. 315 The tool for a gateway to obtain an IPv6 prefix for numbering the 316 BT-LE network is out of scope of this document, but can for example 317 be accomplished via DHCPv6 Prefix Delegation. The used IPv6 prefix 318 may change due to the gateway^1s movement. 320 3.2.2. Neighbor discovery 322 [I-D.draft-ietf-6lowpan-nd] describes the neighbor discovery approach 323 for 6loWPAN nodes. BT-LE does not support mesh networks and hence 324 only those aspects of the [I-D.draft-ietf-6lowpan-nd] that apply to a 325 star topology are considered. 327 The following aspects of 6lowpan-nd are applicable to BT-LE 6LNS: 329 1. A BT-LE 6LN MUST register its address with the router by sending 330 a NS message with the ARO option and process the NA accordingly. The 331 NA with the ARO option SHOULD be sent irrespective of whether the IID 332 is derived from the unique 48 bit BT-LE device address or the IID is 333 a random value that is generated as per the privacy extensions for 334 stateless address autoconfiguration [RFC4941]. 336 2. Sending a Router solicitation (RS) and processing Router 337 advertisements by BT-LE 6LNs MUST follow Sections 5.3 and 5.4 338 respectvely of [I-D.draft-ietf-6lowpan-nd]. 340 10 bits 54 bits 64 bits 341 +----------+-----------------+----------------------+ 342 |1111111010| zeros | Interface Identifier | 343 +----------+-----------------+----------------------+ 345 Figure 4: IPv6 link-local address in BT-LE 347 3.2.3. Header compression 349 This document assumes [RFC6282], which specifies the compression 350 format for IPv6 datagrams on top of IEEE 802.15.4, as the basis for 351 IPv6 header compression on top of BT-LE. It is required that all 352 headers MUST be compressed according to HC base encoding. In BT-LE 353 the star topology structure can be exploited in order to provide a 354 mechanism for IID compression. The following text describes the 355 principles of IPv6 address compression on top of BT-LE. 357 In a link-local communication, both the IPv6 source and destination 358 addresses MUST be elided, since the device knows that the packet is 359 destined for it even if the packet does not have destination IPv6 360 address. On the other hand, a node SHALL learn the IID of the other 361 endpoint of each L2CAP connection it participates in. By exploiting 362 this information, a node that receives a data channel PDU containing 363 an IPv6 packet (or a part of it) can infer the corresponding IPv6 364 source address. The device MUST maintain a Neighbor Cache, in which 365 the entries include both the IID of the neighbor and the Device 366 Address that identifies the neighbor. 368 When a BT-LE slave transmits an IPv6 packet to a remote destination 369 using global IPv6 addresses, the slave MUST elide the IPv6 source 370 address, if a context is defined for the prefix of the IPv6 source 371 address. In this case, the 6LBR/master can infer the elided IPv6 372 source address since 1) the master/6LBR has previously assigned the 373 prefix to the slaves; and 2) the master/6LBR maintains a Neighbor 374 Cache that relates the Device Address and the IID of the 375 corresponding slave. If a context is defined for the IPv6 376 destination address, the slave MUST also elide the prefix of the 377 destination IPv6 address. In that case, the 6LBR/master can infer 378 the elided destination prefix by using the context. 380 When a master/6LBR receives an IPv6 packet sent by a remote node 381 outside the BT-LE network, and the destination of the packet is a 382 slave, the master/6LBR MUST elide the IPv6 destination address of the 383 packet before forwarding it to the slave. The slave can infer that 384 the IPv6 destination address of the packet is its own IPv6 address. 385 If a context is defined for the prefix of the IPv6 source address, 386 the master/6LBR MUST elide that prefix as well. 388 3.2.4. Unicast and Multicast address mapping 390 The BT-LE link layer does not support multicast. Hence traffic is 391 always unicast between two BT-LE devices. Even in the case where a 392 master is attached to multiple slave BT-LE devices, the master device 393 cannot do a multicast to all the connected slave devices. If the 394 master device needs to send a multicast packet to all its slave 395 devices, it has to replicate the packet and unicast it on each link. 396 However, this may not be energy-efficient and particular care must be 397 taken if the master is battery-powered. In the opposite direction, a 398 slave can only transmit data to a single destination (i.e. the 399 master). Hence, if a slave transmits an IPv6 multicast packet, the 400 slave can unicast the corresponding BT-LE packet to the master. It 401 is required that the master MUST provide a table for mapping 402 different types of multicast addresses (all-nodes, all-routers and 403 solicited-node multicast addresses) to the corresponding IIDs and 404 Device Addresses. 406 3.3. Internet connectivity scenarios 408 In a typical scenario, BT-LE network is connected to the Internet. 410 h ____________ 411 \ / \ 412 h ---- 6LBR --- | Internet | 413 / \____________/ 414 h 415 h: host 416 <-- BT-LE --> 6LBR: 6LoWPAN Border Router 418 Figure 5: BT-LE network connected to the Internet 420 In some scenarios, the BT-LE network may transiently or permanently 421 be an isolated network. 423 h h h: host 424 \ / 6LBR: 6LoWPAN Border Router 425 h --- 6LBR -- h 426 / \ 427 h h 429 Figure 6: Isolated BT-LE network 431 Host-to-master and master-to-host communication MUST use the same 432 mechanisms as would be used in global IPv6 communications. The 433 gateway is used to route the packets to one of its slaves. 435 4. IANA Considerations 437 While there are no actions for IANA, we do expect BT SIG to allocate 438 an L2CAP channel ID (see Section 3.1). 440 5. Security Considerations 442 The transmission of IPv6 over BT-LE links has similar requirements 443 and concerns for security as for IEEE 802.15.4. IPv6 over BT-LE 444 SHOULD be protected by using BT-LE Link Layer security. 446 BT-LE Link Layer supports encryption and authentication by using the 447 Counter with CBC-MAC (CCM) mechanism [RFC3610] and a 128-bit AES 448 block cipher. Upper layer security mechanisms may exploit this 449 functionality when it is available. (Note: CCM does not consume 450 bytes from the maximum per-packet L2CAP data size, since the link 451 layer data unit has a specific field for them when they are used.) 453 Key management in BT-LE is provided by the Security Manager Protocol 454 (SMP). 456 6. Additional contributors 458 Kanji Kerai, Jari Mutikainen, David Canfeng-Chen and Minjun Xi from 459 Nokia have contributed significantly to this document. 461 7. Acknowledgements 463 Samita Chakrabarti and Erik Nordmark have provided valuable feedback 464 for this draft. 466 8. Normative References 468 [BTCorev4.0] 469 "Bluetooth Core Specification v4.0, http:// 470 www.bluetooth.org/Technical/Specifications/adopted.htm". 472 [I-D.ietf-6lowpan-nd] 473 Shelby, Z., Chakrabarti, S., and E. Nordmark, "Neighbor 474 Discovery Optimization for Low Power and Lossy Networks 475 (6LoWPAN)", draft-ietf-6lowpan-nd-18 (work in progress), 476 October 2011. 478 [IEEE802-2001] 479 "IEEE 802-2001 standard, 480 http://standards.ieee.org/findstds/standard/ 481 802-2001.html". 483 [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate 484 Requirement Levels", BCP 14, RFC 2119, March 1997. 486 [RFC2464] Crawford, M., "Transmission of IPv6 Packets over Ethernet 487 Networks", RFC 2464, December 1998. 489 [RFC3610] Whiting, D., Housley, R., and N. Ferguson, "Counter with 490 CBC-MAC (CCM)", RFC 3610, September 2003. 492 [RFC4291] Hinden, R. and S. Deering, "IP Version 6 Addressing 493 Architecture", RFC 4291, February 2006. 495 [RFC4861] Narten, T., Nordmark, E., Simpson, W., and H. Soliman, 496 "Neighbor Discovery for IP version 6 (IPv6)", RFC 4861, 497 September 2007. 499 [RFC4862] Thomson, S., Narten, T., and T. Jinmei, "IPv6 Stateless 500 Address Autoconfiguration", RFC 4862, September 2007. 502 [RFC4944] Montenegro, G., Kushalnagar, N., Hui, J., and D. Culler, 503 "Transmission of IPv6 Packets over IEEE 802.15.4 504 Networks", RFC 4944, September 2007. 506 [RFC6282] Hui, J. and P. Thubert, "Compression Format for IPv6 507 Datagrams over IEEE 802.15.4-Based Networks", RFC 6282, 508 September 2011. 510 Appendix A. Bluetooth Low Energy fragmentation and L2CAP Modes 512 This section provides an overview of Fragmentation and Recombination 513 (FAR) method and L2CAP modes in Bluetooth Low Energy. FAR is an 514 L2CAP mechanism, in which an L2CAP entity can take the (large) upper 515 layer PDU, prepend the L2CAP header (4 bytes in the Basic L2CAP mode) 516 and break the resulting L2CAP PDU into fragments which can then be 517 directly encapsulated into Data channel PDUs. There are bits in the 518 Data channel PDUs which identify whether the payload is a complete 519 L2CAP PDU or the first of a set of fragments, or one of the rest of 520 the fragments. 522 There are five L2CAP modes defined in the BT 4.0 spec. These modes 523 are: Retransmission Mode (a Go-Back-N mechanism is used), Enhanced 524 Retransmission Mode (includes selective NAK among others), Flow 525 Control Mode (PDUs are numbered, but there are no retransmissions), 526 Streaming Mode (PDUs are numbered, but there are no ACKs of any kind) 527 and Basic L2CAP Mode. 529 Authors' Addresses 531 Johanna Nieminen (editor) 532 Nokia 533 Itaemerenkatu 11-13 534 FI-00180 Helsinki 535 Finland 537 Email: johanna.1.nieminen@nokia.com 539 Basavaraj Patil 540 Nokia 541 6021 Connection drive 542 Irving, TX 75039 543 USA 545 Email: basavaraj.patil@nokia.com 547 Teemu Savolainen 548 Nokia 549 Hermiankatu 12 D 550 FI-33720 Tampere 551 Finland 553 Email: teemu.savolainen@nokia.com 555 Markus Isomaki 556 Nokia 557 Keilalahdentie 2-4 558 FI-02150 Espoo 559 Finland 561 Email: markus.isomaki@nokia.com 563 Zach Shelby 564 Sensinode 565 Hallituskatu 13-17D 566 FI-90100 Oulu 567 Finland 569 Email: zach.shelby@sensinode.com 570 Carles Gomez 571 Universitat Politecnica de Catalunya/i2CAT 572 C/Esteve Terradas, 7 573 Castelldefels 08860 574 Spain 576 Email: carlesgo@entel.upc.edu