DMM H. Chan, Ed. Internet-Draft X. Wei Intended status: Informational Huawei Technologies Expires: September 3, 2018 J. Lee Sangmyung University S. Jeon Sungkyunkwan University CJ. Bernardos, Ed. UC3M March 2, 2018 Distributed Mobility Anchoring draft-ietf-dmm-distributed-mobility-anchoring-08 Abstract This document defines distributed mobility anchoring in terms of the different configurations and functions to provide IP mobility support. A network may be configured with distributed mobility anchoring functions for both network-based or host-based mobility support according to the needs of mobility support. In the distributed mobility anchoring environment, multiple anchors are available for mid-session switching of an IP prefix anchor. To start a new flow or to handle a flow not requiring IP session continuity as a mobile node moves to a new network, the flow can be started or re- started using a new IP address configured from the new IP prefix which is anchored to the new network. The mobility functions and their operations and parameters are general for different configurations. Status of This Memo This Internet-Draft is submitted in full conformance with the provisions of BCP 78 and BCP 79. Internet-Drafts are working documents of the Internet Engineering Task Force (IETF). Note that other groups may also distribute working documents as Internet-Drafts. The list of current Internet- Drafts is at https://datatracker.ietf.org/drafts/current/. Internet-Drafts are draft documents valid for a maximum of six months and may be updated, replaced, or obsoleted by other documents at any time. It is inappropriate to use Internet-Drafts as reference material or to cite them other than as "work in progress." This Internet-Draft will expire on September 3, 2018. Chan, et al. Expires September 3, 2018 [Page 1] Internet-Draft distributed mobility anchoring March 2018 Copyright Notice Copyright (c) 2018 IETF Trust and the persons identified as the document authors. All rights reserved. This document is subject to BCP 78 and the IETF Trust's Legal Provisions Relating to IETF Documents (https://trustee.ietf.org/license-info) in effect on the date of publication of this document. Please review these documents carefully, as they describe your rights and restrictions with respect to this document. Code Components extracted from this document must include Simplified BSD License text as described in Section 4.e of the Trust Legal Provisions and are provided without warranty as described in the Simplified BSD License. Table of Contents 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2 2. Conventions and Terminology . . . . . . . . . . . . . . . . . 3 3. Distributed Mobility Anchoring . . . . . . . . . . . . . . . 5 3.1. Configurations for Different Networks . . . . . . . . . . 5 3.1.1. Network-based DMM . . . . . . . . . . . . . . . . . . 5 3.1.2. Client-based DMM . . . . . . . . . . . . . . . . . . 6 4. IP Mobility Handling in Distributed Anchoring Environments - Mobility Support Only When Needed . . . . . . . . . . . . . . 7 4.1. No Need of IP Mobility: Changing to New IP Prefix/Address 8 4.2. Need of IP Mobility . . . . . . . . . . . . . . . . . . . 9 5. IP Mobility Handling in Distributed Mobility Anchoring Environments - Anchor Switching to the New Network . . . . . 11 5.1. IP Prefix/Address Anchor Switching for Flat Network . . . 11 6. Security Considerations . . . . . . . . . . . . . . . . . . . 12 7. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 12 8. Contributors . . . . . . . . . . . . . . . . . . . . . . . . 12 9. References . . . . . . . . . . . . . . . . . . . . . . . . . 12 9.1. Normative References . . . . . . . . . . . . . . . . . . 12 9.2. Informative References . . . . . . . . . . . . . . . . . 14 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 15 1. Introduction A key requirement in distributed mobility management [RFC7333] is to enable traffic to avoid traversing a single mobility anchor far from an optimal route. This document defines different configurations, functional operations and parameters for distributed mobility anchoring and explains how to use them to make the route changes to avoid unnecessarily long routes. Chan, et al. Expires September 3, 2018 [Page 2] Internet-Draft distributed mobility anchoring March 2018 Companion distributed mobility management documents are already addressing the architecture and deployment [I-D.ietf-dmm-deployment-models], source address selection [I-D.ietf-dmm-ondemand-mobility], and control-plane data-plane signaling [I-D.ietf-dmm-fpc-cpdp]. A number of distributed mobility solutions have also been proposed, for example, in [I-D.seite-dmm-dma], [I-D.bernardos-dmm-pmipv6-dlif], [I-D.sarikaya-dmm-for-wifi], [I-D.yhkim-dmm-enhanced-anchoring], and [I-D.matsushima-stateless-uplane-vepc]. Distributed mobility anchoring employs multiple anchors in the data plane. In general, control plane functions may be separated from data plane functions and be centralized but may also be co-located with the data plane functions at the distributed anchors. Different configurations of distributed mobility anchoring are described in Section 3.1. As an MN attaches to an access router and establishes a link between them, a /64 IPv6 prefix anchored to the router may be assigned to the link for exclusive use by the MN [RFC6459]. The MN may then configure a global IPv6 address from this prefix and use it as the source IP address in a flow to communicate with its correspondent node (CN). When there are multiple mobility anchors, an address selection for a given flow is first required before the flow is initiated. Using an anchor in an MN's network of attachment has the advantage that the packets can simply be forwarded according to the forwarding table. However, after the flow has been initiated, the MN may later move to another network, so that the IP address no longer belongs to the current network of attachment of the MN. The IP session continuity needs of a flow (application) determines the how the IP address used by the traffic of this flow has to be anchored. If the ongoing IP flow can cope with an IP prefix/address change, the flow can be reinitiated with a new IP address anchored in the new network. On the other hand, if the ongoing IP flow cannot cope with such change, mobility support is needed. A network supporting a mix of flows both requiring and not requiring IP mobility support will need to distinguish these flows. 2. Conventions and Terminology All general mobility-related terms and their acronyms used in this document are to be interpreted as defined in the Mobile IPv6 (MIPv6) base specification [RFC6275], the Proxy Mobile IPv6 (PMIPv6) specification [RFC5213], the "Mobility Related Terminologies" [RFC3753], and the DMM current practices and gap analysis [RFC7429]. These include terms such as mobile node (MN), correspondent node Chan, et al. Expires September 3, 2018 [Page 3] Internet-Draft distributed mobility anchoring March 2018 (CN), home agent (HA), home address (HoA), care-of-address (CoA), local mobility anchor (LMA), and mobile access gateway (MAG). In addition, this document uses the following terms: Home network of an application session or a home address: the network that has assigned the HoA used as the session identifier by the application running in an MN. The MN may be running multiple application sessions, and each of these sessions can have a different home network. Anchoring (an IP prefix/address): An IP prefix, i.e., Home Network Prefix (HNP), or address, i.e., HoA, assigned for use by an MN is topologically anchored to an anchor node when the anchor node is able to advertise a connected route into the routing infrastructure for the assigned IP prefix. Location Management (LM) function: that keeps and manages the network location information of an MN. The location information may be a binding of the advertised IP address/prefix, e.g., HoA or HNP, to the IP routing address of the MN or of a node that can forward packets destined to the MN. When the MN is a mobile router (MR) carrying a mobile network of mobile network nodes (MNN), the location information will also include the mobile network prefix (MNP), which is the aggregate IP prefix delegated to the MR to assign IP prefixes for use by the MNNs in the mobile network. In a client-server protocol model, location query and update messages may be exchanged between a Location Management client (LMc) and a Location Management server (LMs), where the location information can be updated to or queried from the LMs. Optionally, there may be a Location Management proxy (LMp) between LMc and LMs. With separation of control plane and data plane, the LM function is in the control plane. It may be a logical function at the control plane node, control plane anchor, or mobility controller. It may be distributed or centralized. Forwarding Management (FM) function: packet interception and forwarding to/from the IP address/prefix assigned for use by the MN, based on the internetwork location information, either to the Chan, et al. Expires September 3, 2018 [Page 4] Internet-Draft distributed mobility anchoring March 2018 destination or to some other network element that knows how to forward the packets to their destination. This function may be used to achieve traffic indirection. With separation of control plane and data plane, the FM function may split into a FM function in the data plane (FM-DP) and a FM function in the control plane (FM-CP). FM-DP may be distributed with distributed mobility management. It may be a function in a data plane anchor or data plane node. FM-CP may be distributed or centralized. It may be a function in a control plane node, control plane anchor or mobility controller. 3. Distributed Mobility Anchoring 3.1. Configurations for Different Networks We next describe some configurations with multiple distributed anchors. To cover the widest possible spectrum of scenarios, we consider architectures in which the control and data planes are separated, as described in [I-D.ietf-dmm-deployment-models]. 3.1.1. Network-based DMM Figure 1 shows a general scenario for network-based distributed mobility management. The main characteristics of a network-based DMM solution are: There are multiple data plane anchors (i.e., DPA instances), each with an FM-DP function. The control plane may either be distributed (not shown in the figure) or centralized (as shown in the figure). The control plane and the data plane (Control Plane Anchor -- CPA -- and Data Plane Anchor -- DPA) may be co-located or not. If the CPA is co-located with the distributed DPAs, then there are multiple co-located CPA-DPA instances (not shown in the figure). An IP prefix/address IP1 (anchored to the DPA with IP address IPa1) is assigned for use by an MN. The MN uses this IP1 address to communicate with CNs (not shown in the figure). The location management (LM) function may be co-located or split (as shown in the figure) into a separate server (LMs) and a client (LMc). In this case, the LMs may be centralized whereas the LMc may be distributed or centralized, according to whether the CPA is distributed or centralized. Chan, et al. Expires September 3, 2018 [Page 5] Internet-Draft distributed mobility anchoring March 2018 ____________ Network ___/ \___________ / +-----+ \___ ( |LMs | Control \ / +-.---+ plane \ / +--------.---+ functions \ ( |CPA: . | in the ) ( |FM-CP, LMc | network ) ( +------------+ \ / . . \ ( . . ) ( . . ) ( . . \ \ +------------+ +------------+Distributed ) ( |DPA(IPa1): | |DPA(IPa2): |DPAs ) ( |anchors IP1 | |anchors IP2 | _/ \ |FM-DP | |FM-DP | etc. / \ +------------+ +------------+ / \___ Data plane _____/ \______ functions / \__________________/ +------------+ |MN(IP1) | Mobile node attached |flow(IP1,..)| to the network +------------+ Figure 1: Network-based DMM configuration 3.1.2. Client-based DMM Figure 2 shows a general scenario for client-based distributed mobility management. In this configuration, the mobile node performs Control Plane Node (CPN) and Data Plane Node (DPN) mobility functions, namely the forwarding management and location management (client role) ones. Chan, et al. Expires September 3, 2018 [Page 6] Internet-Draft distributed mobility anchoring March 2018 +-----+ |LMs | +-.---+ +--------.---+ |CPA: . | |FM-CP, LMp | +------------+ . . . . . . . . +------------+ +------------+ Distributed |DPA(IPa1): | |DPA(IPa2): | DPAs |anchors IP1 | |anchors IP2 | |FM-DP | |FM-DP | etc. +------------+ +------------+ +------------+ |MN(IP1) |Mobile node |flow(IP1,..)|using IP1 |FM, LMc |anchored to +------------+DPA(IPa1) Figure 2: Client-based DMM configuration 4. IP Mobility Handling in Distributed Anchoring Environments - Mobility Support Only When Needed IP mobility support may be provided only when needed instead of being provided by default. A straightforward choice of mobility anchoring is for a flow to use the IP prefix of the network to which the MN is attached when the flow is initiated [I-D.seite-dmm-dma] [I-D.bernardos-dmm-pmipv6-dlif]. The IP prefix/address at the MN's side of a flow may be anchored at the access router to which the MN is attached. For example, when an MN attaches to a network (Net1) or moves to a new network (Net2), an IP prefix from the attached network is assigned to the MN's interface. In addition to configuring new link-local addresses, the MN configures from this prefix an IP address which is typically a dynamic IP address. It then uses this IP address when a flow is initiated. Packets to the MN in this flow are simply forwarded according to the forwarding table. There may be multiple IP prefixes/addresses that an MN can select when initiating a flow. They may be from the same access network or Chan, et al. Expires September 3, 2018 [Page 7] Internet-Draft distributed mobility anchoring March 2018 different access networks. The network may advertise these prefixes with cost options [I-D.mccann-dmm-prefixcost] so that the mobile node may choose the one with the least cost. In addition, these IP prefixes/addresses may be of different types regarding whether mobility support is needed [I-D.ietf-dmm-ondemand-mobility]. A flow will need to choose the appropriate one according to whether it needs IP mobility support. 4.1. No Need of IP Mobility: Changing to New IP Prefix/Address When IP mobility support is not needed for a flow, the LM and FM functions are not utilized so that the configurations in Section 3.1 are simplified as shown in Figure 3. Net1 Net2 +---------------+ +---------------+ |AR1 | AR is changed |AR2 | +---------------+ -------> +---------------+ |CPA: | |CPA: | |---------------| |---------------| |DPA(IPa1): | |DPA(IPa2): | |anchors IP1 | |anchors IP2 | +---------------+ +---------------+ +...............+ +---------------+ .MN(IP1) . MN moves |MN(IP2) | .flow(IP1,...) . =======> |flow(IP2,...) | +...............+ +---------------+ Figure 3: Changing to a new IP address/prefix When there is no need to provide IP mobility to a flow, the flow may use a new IP address acquired from a new network as the MN moves to the new network. Regardless of whether IP mobility is needed, if the flow has terminated before the MN moves to a new network, the flow may subsequently restart using the new IP address assigned from the new network. When IP session continuity is needed, even if a flow is ongoing as the MN moves, it may still be desirable for the flow to change to using the new IP prefix configured in the new network. The flow may then close and then restart using a new IP address configured in the new network. Such a change in the IP address of the flow may be enabled using a higher layer mobility support which is not in the scope of this document. Chan, et al. Expires September 3, 2018 [Page 8] Internet-Draft distributed mobility anchoring March 2018 In Figure 3, a flow initiated while the MN was using the IP prefix IP1 anchored to a previous access router AR1 in network Net1 has terminated before the MN moves to a new network Net2. After moving to Net2, the MN uses the new IP prefix IP2 anchored to a new access router AR2 in network Net2 to start a new flow. The packets may then be forwarded without requiring IP layer mobility support. An example call flow is outlined in Figure 4 MN AR1 AR2 CN |MN attaches to AR1: | | | |acquire MN-ID and profile | | |--RS---------------->| | | | | | | |<----------RA(IP1)---| | | | | | | Assigned prefix IP1 | | | IP1 address configuration | | | | | | |<-Flow(IP1,IPcn,...)-+------------------------------------------>| | | | | |MN detaches from AR1 | | | |MN attaches to AR2 | | | | | | | |--RS------------------------------>| | | | | | |<--------------RA(IP2)-------------| | | | | | Assigned prefix IP2 | | | IP2 address configuration | | | | | | |<-new Flow(IP2,IPcn,...)-----------+---------------------------->| | | | | Figure 4: Re-starting a flow with new IP prefix/address 4.2. Need of IP Mobility When IP mobility is needed for a flow, the LM and FM functions in Section 3.1 are utilized. The mobility support may be provided by IP prefix anchor switching to the new network to be described in Section 5 or by using other mobility management methods ([Paper-Distributed.Mobility], [Paper-Distributed.Mobility.PMIP] and [Paper-Distributed.Mobility.Review]). Then the flow may continue to use the IP prefix from the prior network of attachment. Yet some time later, the user application for the flow may be closed. If the application is started again, the new flow may not need to use the prior network's IP address to avoid having to invoke IP mobility Chan, et al. Expires September 3, 2018 [Page 9] Internet-Draft distributed mobility anchoring March 2018 support. This may be the case where a dynamic IP prefix/address rather than a permanent one is used. The flow may then use the new IP prefix in the network where the flow is being initiated. Routing is again kept simpler without employing IP mobility and will remain so as long as the MN which is now in the new network has not moved again and left to another new network. An example call flow in this case is outlined in Figure 5. MN AR1 AR2 CN |MN attaches to AR1: | | | |acquire MN-ID and profile | | |--RS---------------->| | | | | | | |<----------RA(IP1)---| | | | | | | Assigned prefix IP1 | | | IP1 address configuration | | | | | | |<-Flow(IP1,IPcn,...)-+------------------------------------------>| | | | | |MN detach from AR1 | | | |MN attach to AR2 | | | | | | | |--RS------------------------------>| | IP mobility support such as that described in next sub-section |<--------------RA(IP2,IP1)---------| | | | | | |<-Flow(IP1,IPcn,...)---------------+---------------------------->| | | | | Assigned prefix IP2 | | | IP2 address configuration | | | | | | Flow(IP1,IPcn) terminates | | | | | | |<-new Flow(IP2,IPcn,...)-----------+---------------------------->| | | | | Figure 5: A flow continues to use the IP prefix from its home network after MN has moved to a new network Multiple instances of DPAs (at access routers), which are providing IP prefix to the MNs, are needed to provide distributed mobility anchoring in an appropriate configuration such as those described in Figure 1 (Section 3.1.1) for network-based distributed mobility or in Figure 2 (Section 3.1.2) for client-based distributed mobility. Chan, et al. Expires September 3, 2018 [Page 10] Internet-Draft distributed mobility anchoring March 2018 5. IP Mobility Handling in Distributed Mobility Anchoring Environments - Anchor Switching to the New Network IP mobility is invoked to enable IP session continuity for an ongoing flow as the MN moves to a new network. Here the anchoring of the IP address of the flow is in the home network of the flow, which is not in the current network of attachment. A centralized mobility management mechanism may employ indirection from the anchor in the home network to the current network of attachment. Yet it may be difficult to avoid unnecessarily long route when the route between the MN and the CN via the anchor in the home network is significantly longer than the direct route between them. An alternative is to switch the IP prefix/address anchoring to the new network. 5.1. IP Prefix/Address Anchor Switching for Flat Network The IP prefix/address anchoring may move without changing the IP prefix/address of the flow. Here the LM and FM functions in Figure 1 in Section 3.1 are implemented as shown in Figure 6. Net1 Net2 +---------------+ +---------------+ |AR1 | |AR2 | +---------------+ +---------------+ |CPA: | |CPA: | |LM:IP1 at IPa1 | |LM:IP1 at IPa2 | | changes to | | | | IP1 at IPa2 | | | |---------------| |---------------| |DPA(IPa1): | IP1 anchoring is effectively moved|DPA(IPa2): | |anchored IP1 | =======> |anchors IP2,IP1| +---------------+ +---------------+ +...............+ +---------------+ .MN(IP1) . MN moves |MN(IP2,IP1) | .flow(IP1,...) . =======> |flow(IP1,...) | +...............+ +---------------+ Figure 6: Anchor mobility As an MN with an ongoing session moves to a new network, the flow may preserve IP session continuity by moving the anchoring of the original IP prefix/address of the flow to the new network. One way to accomplish such move is to use a centralized routing protocol, but note that this solution presents some scalability Chan, et al. Expires September 3, 2018 [Page 11] Internet-Draft distributed mobility anchoring March 2018 concerns and its applicability is typically limited to small networks. 6. Security Considerations Security protocols and mechanisms are employed to secure the network and to make continuous security improvements, and a DMM solution is required to support them [RFC7333]. In a DMM deployment [I-D.ietf-dmm-deployment-models] various attacks such as impersonation, denial of service, man-in-the-middle attacks need to be prevented. 7. IANA Considerations This document presents no IANA considerations. 8. Contributors Alexandre Petrescu and Fred L. Templin had contributed to earlier versions of this document regarding distributed anchoring for hierarchical network and for network mobility, although these extensions were removed to keep the document within reasonable length. This document has benefited from other work on mobility support in SDN network, on providing mobility support only when needed, and on mobility support in enterprise network. These works have been referenced. While some of these authors have taken the work to jointly write this document, others have contributed at least indirectly by writing these drafts. The latter include Philippe Bertin, Dapeng Liu, Satoru Matushima, Pierrick Seite, Jouni Korhonen, and Sri Gundavelli. Valuable comments have been received from John Kaippallimalil, ChunShan Xiong, and Dapeng Liu. Dirk von Hugo, Byju Pularikkal, Pierrick Seite have generously provided careful review with helpful corrections and suggestions. 9. References 9.1. Normative References [I-D.bernardos-dmm-pmipv6-dlif] Bernardos, C., Oliva, A., Giust, F., and J. Zuniga, "Proxy Mobile IPv6 extensions for Distributed Mobility Management", draft-bernardos-dmm-pmipv6-dlif-00 (work in progress), October 2017. Chan, et al. Expires September 3, 2018 [Page 12] Internet-Draft distributed mobility anchoring March 2018 [I-D.ietf-dmm-deployment-models] Gundavelli, S. and S. Jeon, "DMM Deployment Models and Architectural Considerations", draft-ietf-dmm-deployment- models-03 (work in progress), November 2017. [I-D.ietf-dmm-fpc-cpdp] Matsushima, S., Bertz, L., Liebsch, M., Gundavelli, S., Moses, D., and C. Perkins, "Protocol for Forwarding Policy Configuration (FPC) in DMM", draft-ietf-dmm-fpc-cpdp-09 (work in progress), October 2017. [I-D.ietf-dmm-ondemand-mobility] Yegin, A., Moses, D., Kweon, K., Lee, J., Park, J., and S. Jeon, "On Demand Mobility Management", draft-ietf-dmm- ondemand-mobility-13 (work in progress), January 2018. [I-D.matsushima-stateless-uplane-vepc] Matsushima, S. and R. Wakikawa, "Stateless user-plane architecture for virtualized EPC (vEPC)", draft- matsushima-stateless-uplane-vepc-06 (work in progress), March 2016. [I-D.mccann-dmm-prefixcost] McCann, P. and J. Kaippallimalil, "Communicating Prefix Cost to Mobile Nodes", draft-mccann-dmm-prefixcost-03 (work in progress), April 2016. [I-D.sarikaya-dmm-for-wifi] Sarikaya, B. and L. Li, "Distributed Mobility Management Protocol for WiFi Users in Fixed Network", draft-sarikaya- dmm-for-wifi-05 (work in progress), October 2017. [I-D.seite-dmm-dma] Seite, P., Bertin, P., and J. Lee, "Distributed Mobility Anchoring", draft-seite-dmm-dma-07 (work in progress), February 2014. [I-D.yhkim-dmm-enhanced-anchoring] Kim, Y. and S. Jeon, "Enhanced Mobility Anchoring in Distributed Mobility Management", draft-yhkim-dmm- enhanced-anchoring-05 (work in progress), July 2016. [RFC3753] Manner, J., Ed. and M. Kojo, Ed., "Mobility Related Terminology", RFC 3753, DOI 10.17487/RFC3753, June 2004, . Chan, et al. Expires September 3, 2018 [Page 13] Internet-Draft distributed mobility anchoring March 2018 [RFC5213] Gundavelli, S., Ed., Leung, K., Devarapalli, V., Chowdhury, K., and B. Patil, "Proxy Mobile IPv6", RFC 5213, DOI 10.17487/RFC5213, August 2008, . [RFC6275] Perkins, C., Ed., Johnson, D., and J. Arkko, "Mobility Support in IPv6", RFC 6275, DOI 10.17487/RFC6275, July 2011, . [RFC6459] Korhonen, J., Ed., Soininen, J., Patil, B., Savolainen, T., Bajko, G., and K. Iisakkila, "IPv6 in 3rd Generation Partnership Project (3GPP) Evolved Packet System (EPS)", RFC 6459, DOI 10.17487/RFC6459, January 2012, . [RFC7333] Chan, H., Ed., Liu, D., Seite, P., Yokota, H., and J. Korhonen, "Requirements for Distributed Mobility Management", RFC 7333, DOI 10.17487/RFC7333, August 2014, . [RFC7429] Liu, D., Ed., Zuniga, JC., Ed., Seite, P., Chan, H., and CJ. Bernardos, "Distributed Mobility Management: Current Practices and Gap Analysis", RFC 7429, DOI 10.17487/RFC7429, January 2015, . 9.2. Informative References [Paper-Distributed.Mobility] Lee, J., Bonnin, J., Seite, P., and H. Chan, "Distributed IP Mobility Management from the Perspective of the IETF: Motivations, Requirements, Approaches, Comparison, and Challenges", IEEE Wireless Communications, October 2013. [Paper-Distributed.Mobility.PMIP] Chan, H., "Proxy Mobile IP with Distributed Mobility Anchors", Proceedings of GlobeCom Workshop on Seamless Wireless Mobility, December 2010. [Paper-Distributed.Mobility.Review] Chan, H., Yokota, H., Xie, J., Seite, P., and D. Liu, "Distributed and Dynamic Mobility Management in Mobile Internet: Current Approaches and Issues", February 2011. Chan, et al. Expires September 3, 2018 [Page 14] Internet-Draft distributed mobility anchoring March 2018 Authors' Addresses H. Anthony Chan (editor) Huawei Technologies 5340 Legacy Dr. Building 3 Plano, TX 75024 USA Email: h.a.chan@ieee.org Xinpeng Wei Huawei Technologies Xin-Xi Rd. No. 3, Haidian District Beijing, 100095 P. R. China Email: weixinpeng@huawei.com Jong-Hyouk Lee Sangmyung University 31, Sangmyeongdae-gil, Dongnam-gu Cheonan 31066 Republic of Korea Email: jonghyouk@smu.ac.kr Seil Jeon Sungkyunkwan University 2066 Seobu-ro, Jangan-gu Suwon, Gyeonggi-do Republic of Korea Email: seiljeon@skku.edu Carlos J. Bernardos (editor) Universidad Carlos III de Madrid Av. Universidad, 30 Leganes, Madrid 28911 Spain Phone: +34 91624 6236 Email: cjbc@it.uc3m.es URI: http://www.it.uc3m.es/cjbc/ Chan, et al. Expires September 3, 2018 [Page 15]