MANET Working Group Y.F. Zhang
Internet Draft China Mobile
Intended status: Informational JW. Wang
Expires: Feb. 5, 2009 Tsinghua University
D.P. Liu
China Mobile
July 5, 2008

Cellular-based Central Control (CCC) Mechanism for Mobile Ad hoc
Networks
draft-zhang-manet-ccc-00.txt

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Abstract

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This document discusses a cellular based central control
mechanism(CCC) for middle/small scale mobile Ad hoc networks. The
proposed mechanism can be used for the mobile operators to build a
central-controlled and manageable mobile Ad hoc network.

Table of Contents

1. Introduction................................................2
1.1. Terminology............................................3
2. Scenarios of MANET in Mobile Operator's Network..............3
3. System architecture.........................................3
3.1. System overview.........................................4
3.1.1. Control Network....................................4
3.1.2. Transport Networks.................................5
4. Control Network.............................................6
4.1. Overview...............................................6
4.2. MANET node configuration................................6
4.2.1. MANET node IP address configuration................6
4.2.2. MANET node routing table construction..............7
4.3. Maintenance of the MANET................................7
4.4. Demolition of the MANET.................................8
4.5. Establishment of Multicast MANET........................8
4.6. Session Control.........................................8
4.7. Control Sequences of the Formation of a Connection.......8
5. Details of the Control Network...............................9
5.1. Client and Server.......................................9
5.2. Structure of Control Message in Terminal and Relay Nodes.9
5.2.1. Structure of Control Message in Terminal Nodes......9
5.2.2. Structure of Control Message in Relay Nodes........10
5.3. Interface between Control Network & Transportation Network11
5.4 Interface between Control network and APP...............11
6. Security Considerations.....................................12
7. IANA Considerations........................................12
8. Conclusions................................................12
9. Acknowledgments............................................12
10. References................................................13
10.1. Normative References..................................13
10.2. Informative References................................13
Author's Addresses............................................13
Intellectual Property Statement................................13
Disclaimer of Validity........................................14

1. Introduction

Currently, mobile Ad hoc network (MANET) is more and more popularly
used in many civil scenarios. MANET has its advantages in that it
does not need any network infrastructure and can be deployed fast.
But the lack of control and management mechanism of MANET obstructs

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mobile operators to widely deploy MANET. In this document, we explore
CCC, a cellular based central control mechanism to make MANET
controllable and manageable by mobile operators to some extent. The
proposed mechanism includes IP address configuration, routing table
construction and QoS control of MANET.

1.1. Terminology

In this document, the key words "MUST", "MUST NOT", "REQUIRED",
"SHALL", "SHALL NOT", "SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT
RECOMMENDED", "MAY", and "OPTIONAL" are to be interpreted as
described RFC 2119 [1].

This section defines some key concepts using in this document.

AP: Access Point.

CID: Control Identification.

PCT: Power Consumption Table.

TDT: Time Delay Table.

CCC: Cellular-Based Control.

2. Scenarios of MANET in Mobile Operator's Network

The typical scenario to deploy MANET in Mobile operator's network is
a middle/small scale MANET applications (e.g. including some tens of
Ad hoc nodes) used by multi-mode mobile terminals (including current
operating mobile system GSM/3G and Ad hoc network). The reasons why
the scale is limited to a middle/small are as follows:

First, the operator views MANET as the supplement and of stretch of
reach. So it is suitable to keep a middle/small scale for the MANET
in mobile operator's network.

Second, the operator can control the MANET more easily by current
centralized cellular system with a middle/small scale. The tasks may
include IP address allocation, node management, MANET topology probe
and control and session management.

Last, the operator can easily execute charging and billing centrally
in a MANET of such scale.

3. System architecture

This section describes the system architecture of the cellular based
MANET.

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3.1. System overview

The proposed mechanism requires that the MANET node work in dual mode.
For example, a cell phone which has a 900/1800MHz GSM network
interface and a 2.4GHz IEEE 802.11 interface [2] can be used in the
above scenario. We use this GSM/802.11 dual mode cell phone as the
example in the following discussion. The GSM/3G network interface of
the MANET node enables it to access to the mobile operator's network
which controls and manages the MANET. We call this GSM/3G network
control network. And the 802.11 network that forms ad hoc connections
is called transport network.

The function of control network includes: IP address allocation, node
management, MANET topology probe and control, session management as
well as charging and billing. We shall discuss the charging and
billing mechanisms in the future draft.The transport network provides
civil MANET services, such as text transportation, audio
transportation and video transportation.

In the following sections the architecture and the functions of these
two kinds of networks a explored and we take GSM as the control
network.

3.1.1. Control Network

The following picture demonstrates the architecture of the control
network.

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+------------------------------------------------+
| |
| +-----------+ +-----------+ |
| |Cellphone1 | |Cellphone2 | |
| +-----------+ +-----------+ |
| \ GSM link / |
| \ / |
| +--------------+ |
| |Control Server| |
| +--------------+ |
| / \ |
| / \ |
| +-----------+ +-----------+ |
| |Cellphone3 | |Cellphone4 | |
| +-----------+ +-----------+ |
| |
| |
| |
+------------------------------------------------+
Figure 1: Control Network Architecture

MANET nodes connect to the control server using GSM link. The control
server is located in the mobile operator's network and it takes the
responsibility of IP address allocation and configuration of the
MANET node. Meanwhile the MANET nodes send their transport network's
link status to the control server which uses this link status
information to form a routing path that can satisfy the QoS
requirement of the user. The control serve also calculates and
forming routing table for each MANET node and send the routing table
to the MANET node using GSM link. Session Control can also be
executed by this control network.

3.1.2. Transport Networks

The MANET nodes use their 802.11 wireless interfaces to form ad hoc
transport connections with each other. The transport network is used
for application data such as text file, audio and video
transportation. In our scenario there are two kinds of routing tables,
primary routing table and secondary routing table. For the
convenience of management, different form conventional ad hoc network,
the primary routing tables of the MANET nodes is received from the
control server. The MANET nodes also maintain ad hoc routing table as
the secondary routing table from ad hoc routing protocol (such as
AODV) which can be used in the case of GSM link failure.

The following figure is an example of the transport network.

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+------------------------------------------------+
| |
| +-----------+ +-----------+ |
| |Cellphone1 | |Cellphone2 | |
| +-----------+ +-----------+ |
| \ / |
| \ / |
| +------------+ / |
| |Cellphone3 | / |
| +------------+ / |
| / \ / |
| / \ / |
| +-----------+ +-----------+ |
| |Cellphone4 | |Cellphone5 | |
| +-----------+ +-----------+ |
| |
| |
| |
+------------------------------------------------+
Figure 2: Transport Network Architecture

4. Control Network

The transport network is same as the typical MANET. In this section we
focus on the control network functions[3].

4.1. Overview

Every MANET node has a Control Identification, CID (i.e. cell phone
number). The control server maintains a MANET node's neighboring CIDs
table, a Power Consumption Table, PCT and Time Delay Table,TDT by the
reports which are periodically sent by the MANET nodes.

4.2. MANET node configuration

This section describes in details about the MANET node configuration and
ad hoc network construction.

4.2.1. MANET node IP address configuration

The MANET node IP address is configured by the control server. The
control server has an IP address pool that can be dynamically allocated
to the MANET node. The IP address used can be IPv4 or IPv6 address. The
control server sends the IP address configuration information to the
MANET node and the MANET node then uses this IP address to configure its
MANET interface (802.11 wireless interface in this example). The IP
address configuration policy can be configured by the mobile operator.

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4.2.2. MANET node routing table construction

When a MANET node wants to establish an ad hoc connection with another
MANET node, it sends a request message to the control server. The
control server then calculates a shortest path using Dijkstra algorithm
[4] for that MANET node. In the routing table construction process, the
QoS requirement is guaranteed according to the TDT. After forming the
routing table, the control server sends it to the MANET nodes by the
control network using GPRS link. Then the MANET node can use this IP
address and routing table to communicate with its destination node in an
ad hoc fashion.

As demonstrated in figure 3, when node A wants to establish a connection
with B, it sends a request to the control server. Before the connection
is established, the control server calculates the shortest path by
Dijkstra Algorithm, and allocates all the related node's IP address and
routing table. In figure 3, node A and B are the session nodes, node 2
is the relay node, and node 3 and 5 are backup nodes in case of node 2
fails. They agree to participate the session. However, the shortest path
does not include them.

+------------------------------------------------+
| The shortest path |
| +-----------+ +-----------+ |
| |Node A |==============|Node 2 | |
| +-----------+ +-----------+ |
| | \ / || |
| | \ / ||The |
| | +--------------+ ||shortest |
| | | Node 5 | ||path |
| | +--------------+ || |
| | || |
| | || |
| +-----------+ +-----------+ |
| |Node 3 |--------------|Node B | |
| +-----------+ +-----------+ |
| |
| |
| |
+------------------------------------------------+
Figure 3: Routing Management

4.3. Maintenance of the MANET

In the case of MANET topology changing, the control server will find the
PCT changes, so it applies Dijkstra algorithm again and forming a new
routing table. This procedure may include new IP address configuration
and old IP address withdrawal. If the control network cannot be used due

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to poor signal power, the MANET node will use its default ad hoc routing
protocol to construct a new routing table. And when the control network
can be used, the MANET node then send the network changes to the control
server, the control server then updates its PCT and TDT.

4.4. Demolition of the MANET

When a MANET node wants to leave from a MANET, it sends a demolition
request to the control server. The control serve then withdraws the IP
address and updates its PCT and TDT.

4.5. Establishment of Multicast MANET

The control server uses the topology information of the MANET to first
calculate the shortest path using Dijkstra algorithm in each pair of
MANET nodes and then calculate a minimum weight sub-graph[4].

4.6. Session Control

The control network can also interact with the application in session
control. The details are illustrated in Section 5.4.

4.7. Control Sequences of the Formation of a Connection

The following figure demonstrated the control sequence of the process of
a connection establishment.

+-------------------------------------------------------------------+
| |
| +-------+ +-------+ +--------+ +------+ |
| |Node A | |Node 1 | |Node B | |Server| |
| +-------+ +-------+ +--------+ +------+ |
| | | | | |
| |------------|--------------|-----------|A want to connect |
| | | | | |
| | | | |Server calculate |
| | | | |the shortest path |
| | | | |and routing tables |
| |<-----------|<-------------|<------------| |
| | | | |Server allocate IP |
| | | | |address and routing|
| | | | |tables |
| |<--------- |<----------- |<----------- |NodeA,NodeB,Node1 |
| | | | |transfer data |
| | | | | |
+-------------------------------------------------------------------+

Figure 4: Control Sequence of Connection Establishment

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5. Details of the Control Network

5.1. Client and Server

There are two kinds of terminals, client and server in a control
network. Client is installed on the cell phone while the server
resides in the mobile operator's network. The clients and server
communicate by the GPRS channel. Basically, Client sends the
information of nodes up to the server and communicates with transport
networks and the server calculates the routing table and send back
Control Messages.

5.2. Structure of Control Message in Terminal and Relay Nodes

5.2.1. Structure of Control Message in Terminal Nodes

The structure of control message includes header and body. The header is
4 bytes long and the body structure is decided by the header.

The first Byte of the header is defined as the following:

EstablishS 00000000 establish an ad hoc connection
EstablishM 10000000 establish a network with multi-points
Delete 11000000 delete the connection
Refresh 11100000 request of renew the routing table
Leave 11110000 request of leaving the network
MyNeighbor 11111000 tell center the neighbouring points
AckSNet 11111100 agree to join a ad hoc connection
nAckSnet 11111110 disagree to join a ad hoc connection
AckMNet 11111111 agree to join a multi-points connection
nAckMNet 00000001 disagree to join a multi-points connection
NetFlow 00000011 report the netflow of the point
ParticipateNet 00000111 request of paricipation
AllowIn 00001111 agree of the join of the CID
nAllowIn 00011111 disagree of the join of the CID

The second Byte is verification,which can be calculated by suming all
bytes in the control message and using modular arithmetic with modulus
11111111.The third Byte is the length of the control message except the
header. The fourth Byte is the CID.

The body definition is as follows.

EstablishS CID of the supposed opposite point
EstablishM number of CID and the CIDs

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Delete the ID supposed to be deleted
Refresh null
Leave null
MyNeighbor number of CIDs and all the neighbouring CIDs
AckSNet ID established
nAckSNet ID established
AckMNet ID established
nAckMNet ID established
NetFlow flow of the net(by k)
ParticipateNetID established
AllowIn ID established and CIDs permitted
nAllowIn ID established and CIDs not permitted

5.2.2. Structure of Control Message in Relay Nodes

The structure of control message in relay nodes is similar to that of
terminal nodes.

The header is defined as follows:

AckEstablishS 00000000 agree to establish a ad hoc connection
nAckEstablishS 10000000 fail to establish a connection
AckEstablishM 11000000 agree to establish a multi-points connection
nAckEstablishM 11100000 fail to establish a multi-points connection
AckDelete 11110000 agree to delete the connection
nAckDelete 11111000 fail to delete the connection
DistributeRoute 11111100 give a routing table to the point
AckLeave 11111110 allow the point to leave
IsPartiSNet 11111111 ask the point if it likes to join the
connection
IsPartiMNet 00000001 ask the point if it likes to join the
multi-points connection
AckNetFlow 00000011 infos of flow
AckMyNeighbor 00000111 neighbouring CIDs
ToBeDeleted 00001111 the ID to be deleted
AckParticipate 00011111 agree to join the network
nAckParticiapte 00111111 disagree to join the network
IsAllow 01111111 wether agree the CID's join

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The body definition is as follows.
st nd rd AckEstablishS ConnectionID in 1 byte, request/answer CID in 2 /3
byte st nd nAckEstablishS request/answer CID in 1 /2 byte st AckEstablishM ConnectionID in 1 byte, Participants CID in following
byte
NAckEstablishM Initiator's CID
AckDelete ConnectionID
nAckDelete ConnectionID
DistributeRoute Routing Table Information
AckLeave Leaving node CID st nd IsPartiSNet ConnectionID in 1 byte, request CID in 2 byte st IsPartiMNet ConnectionID in 1 byte, Participants CID in following
byte
AckNetFlow null
AckMyNeighbor null
ToBeDeleted ConnectionID to be deleted
AckParticipate ConnectionID
NAckParticipate ConnectionID st nd IsAllow ConnectionID in 1 byte, Joining node CID in 2 byte
5.3. Interface between Control Network & Transportation Network

The senders receive the IP address of gateway from the control network,
all the other messages received will be discarded except that from the
right IP address.

5.4 Interface between Control network and APP

The message that control network sends to the APP is defined as follows.

AckEstablishS a connection's established
nAckEstablishS a connection's not established
AckEstablishM a connection's established
nAckEstablishM a connection's not established
AckDelete a connection's deleted
nAckDelete a connection's not deleted
AckLeave allow to leave
IsPartiSNet ask whether to join
IsPartiMNet ask whether to join
ToBeDeleted the connection will be deleted
IsAllow answer allow to join or not

The message that the APP sends to the control network is defined as

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follows.

EstablishS establish a ad hoc connection
EstablishM establish a multi-points connection
Delete delete the connection
Leave leave
AckSNet acknoledge to join a connection
nAckSNet disacknoledge to join a connection
AckMNet acknoledge to join a multi-points connection
nAckMNet disacknoledge to join a multi-points connection
ParticipateNet participate a net of the ID
AllowIn allow a CID to join
nAllowIn not allow a CID to join

6. Security Considerations

The security mechanism of Control Network depend on the security
mechanism that provided by the mobile operator's network.

The control server takes the responsibility to authenticate and
authorize the MANET node.

The inter MANET node's data transportation should be protected by shared
key and the data should be encrypted.

7. IANA Considerations

This document makes no requests to IANA.

8. Conclusions

This document discusses a cellular base central control system that
can be used for the mobile operator to control and mange a MANET
network.

9. Acknowledgments

The authors would like to thank the following individuals for their
review, comments, and suggestions to improve the content of this
document.

Lin Zhang, Guijin Wang, Zhisheng Niu, Peng Kang, Wenxin Ning, Han
Wang.

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10. References

10.1. Normative References

[1] Bradner, S., "Key words for use in RFCs to Indicate Requirement
Levels", BCP 14, RFC 2119, March 1997.

[2] http://ieee802.org/11/

10.2. Informative References

[3] Wang Jingwu,''Design and implementation Operational Wireless Ad
hoc Control Server'', Tech. Report,Tsinghua University,May 2008.

[4] Thomas H.Cormen et al,''Introduction to Algorithms'', Second
Edition. MIT Press and McGraw-Hill, 2001. Section 24.3: Dijkstra's
algorithm, pp.595- -601

Author's Addresses

Yunfei Zhang
China Mobile Communications Corporation

Phone: +86 10 66006688
Email: zhangyunfei@chinamobile.com

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