1. IEEE 802.21 MEDIA INDEPENDENT HANDOVER DCN: 21-07-0382-00-0000
Title: MIH in Multi-hop Networks
Date Submitted: October, 8, 2007
Authors or Source(s):
 P. Stupar T. Melia A. de la Oliva A. Banchs C.J. Bernardos I. Soto A. Vidal
Abstract: This document is a problem statement for a future Study Group proposal on IEEE adaptation for multi-hop access networks
21-07-xxxx

2. IEEE 802.21 presentation release statements
This document has been prepared to assist the IEEE Working Group. It is offered as a basis for discussion and is not binding on the contributing individual(s) or organization(s). The material in this document is subject to change in form and content after further study. The contributor(s) reserve(s) the right to add, amend or withdraw material contained herein.
The contributor grants a free, irrevocable license to the IEEE to incorporate material contained in this contribution, and any modifications thereof, in the creation of an IEEE Standards publication; to copyright in the IEEE’s name any IEEE Standards publication even though it may include portions of this contribution; and at the IEEE’s sole discretion to permit others to reproduce in whole or in part the resulting IEEE Standards publication. The contributor also acknowledges and accepts that this contribution may be made public by IEEE
The contributor is familiar with IEEE patent policy, as stated in Section 6 of the IEEE-SA Standards Board bylaws < and in Understanding Patent Issues During IEEE Standards Development
IEEE presentation release statements
This document has been prepared to assist the IEEE Working Group. It is offered as a basis for discussion and is not binding on the contributing individual(s) or organization(s). The material in this document is subject to change in form and content after further study. The contributor(s) reserve(s) the right to add, amend or withdraw material contained herein.
The contributor grants a free, irrevocable license to the IEEE to incorporate material contained in this contribution, and any modifications thereof, in the creation of an IEEE Standards publication; to copyright in the IEEE’s name any IEEE Standards publication even though it may include portions of this contribution; and at the IEEE’s sole discretion to permit others to reproduce in whole or in part the resulting IEEE Standards publication. The contributor also acknowledges and accepts that this contribution may be made public by IEEE
The contributor is familiar with IEEE patent policy, as outlined in Section 6.3 of the IEEE-SA Standards Board Operations Manual < and in Understanding Patent Issues During IEEE Standards Development
21-07-xxxx

3. MIH in Multi-hop Networks

4. Introduction
Legacy specification is based on infrastructure alike operator’s access networks.
Terminal mobility
1 wireless hop

5. Introduction
Operators might include multi-hop networks of multiple technologies as extension to their infrastructure access networks
PoS mobility
2 or more wireless hops

6. New Reference Scenario
21-07-xxxx

7. Current WG PAR
PAR says: “The purpose is to improve the user experience of mobile devices by facilitating handover between 802 networks whether or not they are of different media types, including both wired and wireless, where handover is not otherwise defined and to make it possible for mobile devices to perform seamless handover where the network environment supports it. These mechanisms may also be useable for handovers between 802 networks and non 802 networks.”
IEEE WG 5 Criteria Document states:
“This standard will provide services both across an 802 link and to upper layers to
Facilitate the optimization of detection and selection of networks
Provide a source of extensible and semantically defined information to facilitate optimized handover decision making
Provide a mechanism to access this information over an 802 link.
Provide triggers to upper layers”
Currently there are no methods defined to handover to multi-hop networks connecting to the infrastructure such as mobile networks, or ad-hoc networks 7 7

8. Problem Scope
General Problem: IEEE does not provide mechanisms to handle multi-hop networks formed by multiple wireless nodes.
Sub-problem 1: The information required to successfully handover in multi-hop networks has not been defined.
Sub-problem 2: Mechanisms to handle the possible changes on the topology of multi-hop networks and handover according to it have not been defined.

9. Previous Contributions
Previous related contributions:
IS multi-hop operation (J.Guo, Y. Peng)‏
IS%20multi-hop%20operation.ppt
Multi-Hop Issues (Y. Ohba)‏
03_meeting_docs/AdHoc_Feb07/ Multi-Hop- Issues.ppt
Multitechnology mesh scenario (A. Vidal, T. Melia, A. de la Oliva, A. Banchs)‏
Multitechnology_mesh_scenario.doc
Ambient Networks (E. Hepworth, R. Giaffreda, R. Hancock)‏
Ambient-Networks.ppt

10. General Problem:
IEEE does not provide mechanisms to handle multi-hop networks formed by multiple wireless nodes.

11. What is the problem
So far IEEE scope is focused on the relation between a MN and operator’s networks.
The reference model does not cover communications that involve multiple wireless nodes. Only infrastructure mode is supported.
There are no primitives defined for this kind of communication.

12. Usage scenario
Example: Extension of operator network through the use of nodes as relays. The node hands over to the WiFi link that works as an extension of the infrastructure network.
Problems:
Which is the PoS of the MN?
How can the information, events and commands be relayed to and from the MN?
How does the MN know a new candidate PoS is another MN?

13. Possible Solution
Modification of the reference model to include communications between different MN entities.
New component in the reference communication model to be included:
PoF: Point of forwarding, a wireless node (may be a MN) that is used as a PoS for other MNs, forwarding MIH packets and providing services to them.

14. Possible Solution
Extended communication model:
21-07-xxxx

15. Subproblem 1: The information required to successfully handover in multi-hop networks has not been defined.

16. What is the problem
Given the special nature of networks formed by multiple wireless nodes, new Information Elements may be created.
If a MN detects a multi-hop or mobile network it should know its nature to help on handover decision.
Information such as Number of Hops to infrastructure, power levels at the different nodes, etc… should be provided by MIH.

17. Usage Scenario A
Example: A MN wants to handover, it detects two multihop networks. Which network should it select?
Problems:
In this case information regarding the number of hops to Internet, the quality of the links, etc. would be useful.
There are no IEs defined providing this information.
The MNs forming the multi-hop network should be able to process the information and provide it to other nodes.

18. Possible Solution Provide extensions to MIIS
MNs should be able to provide information regarding their status and the status of other nodes.
Wireless Nodes should be able to process the information and provide this processed information to nodes attached to them.

19. Usage Scenario B
Example: A MN wants to perform a handover, it detects a mobile network and other network.
Problems:
The MN cannot know that one of the candidate PoAs is a mobile network.
The mobile network cannot provide information to the MN.

20. Possible Solution
New IEs to handle scenarios regarding new network paradigms should be created.
The communication of MNs, PoAs and PoSs with mobile networks must be studied.

21. Subproblem 2: Mechanisms to handle the possible changes on the topology of multi-hop networks and handover according to it have not been defined.

22. What is the problem
On an multihop network formed by multiple wireless nodes, the topology may vary. Nodes can disappear from the network, the gateway to the infrastructure may change or disappear, etc…
Primitives indicating such situations should be supported.

23. Usage scenario Problems:
Example: a MN uses a multihop network to access internet. One of the nodes integrating the network moves out of it. Other of the nodes turns off due to power shortage.
Problems:
The MN should know there are changes on the network. Perhaps a handover to other network is recommended.
Changes on the topology may produce changes on the QoS etc.. The MN must be notified.

24. Possible Solution
Extension to MIES in order to allow MN2MN events indicating changes on topology, quality of service, bandwidth, etc.
Extension to MICS in order to optimize handover preparation to multi-hop networks.

25. Pre-SG Objectives
Make sure that all work identified is within the scope of WG and does not attempt to solve a problem that is being solved by other standards
Perform a further study to identify other issues that need to be solved
Build a consistent piece of work for a further Study Group proposal 25 25