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Implementation of Mobile Terminal in a Wireless Mobile Networks
SUN-MI JUN NAM-HOON PARK
Electronics and Telecommunications Research Institute
161 Gajeong-Dong, Yuseong-Gu, Daejeon
Republic of Korea
Abstract: - Nowadays, there are many efforts to develop wireless mobile networks in which the existing Internet
services can be applicable. However, the existing Windows based PC is not suitable to support the seamless
service in the wireless mobile network. To support the seamless Internet, the terminal should change its network
configuration and update location whenever handoff procedures. We develop an appropriate mobile terminal
based on Windows. In our developing wireless mobile network, there are two types of packets delivered to the
terminal. One type is traffic packets loaded on IP protocol. The other is control packet which takes a part of
controlling the terminal such as initiating , terminating sessions, and management. The terminal should monitor
the radio states and diagnose the terminal states. We propose to modify the NDIS library, which is Windows
network adaptation library, to receive and process the control packets for our developing network. We also
introduce the additional software blocks to control the terminal such as the radio states monitor, debug monitor,
and the Mobile IP client.
Key-Words: - Wireless mobile network, mobile terminal, NDIS
1 Introduction
The fast growth of the Internet users and the rapid
development of the wireless technologies are
increasing the needs of the Internet service on the
wireless mobile network such as WiBro in Korea [1].
The various kinds of service based on the Internet are
tried to adapt on the wireless mobile network. There
are many efforts to adapt the IP based service to the
wireless mobile network.
HA
packets
Edge Router
Internet
Server
AAA
PAR 1
BS0
BS1
PAR 2
packets
BS2
MT
Move to new BS
Move to new PAR
Fig. 1 A Service example in Wireless Mobile Network
The seamless service for a mobile terminal requires
the pre-negotiated QoS between a server and a
terminal. But the mobile terminal should implement
the handoff procedures during its moving and these
cause the handoff latency which is a factor of
transmission delay.
Fig. 1 presents an example of the architecture of
wireless mobile network, WiBro [1]. Terminals are
connected to a BS (Base Station) through a wireless
interface and an aggregation of BSs is connected to a
PAR (Packet Access Router or Mobile switch Center)
through a wired interface. PAR manages BSs and
terminals and also allows them to access the public
Internet. A mobile terminal implements handoff
operations from a BS to another BS while moving
[1][2][3].
The existing applications and management suites
of the notebook or PDA are not suitable to the wireless
mobile network. The terminal control programs for
mobility should be required and the modification of
the existing TCP/IP protocol suite should be also
required.
This paper presnets a design of the mobile mobile
terminal based on Windows PC or PDA and the
implementation result. Chapter2 shows some
considerations of the mobile terminal suitable to
wireless mobile environment, Chapter3 describes our
design feature of the mobile terminal, Chapter 4 shows
the implementation result.
2 Considerations
The based on the general purpose OS has limitation to
support the seamless service, because the general
purpose platform has insufficiecy in terminal mobility.
The terminal also should be compatible with the
existing application program and service. If the
terminal platform is based on the x86 processor and
Windows OS, the off-the-shelf services and
applications should be adapted to the wireless mobile
network. As a result, we modify the existing platform
of the terminal suitable to the wireless mobile
environment.
This chapter introduces some considerations to
develop the mobile terminal platform.
-
-
-
Wireless modem and RF interface are located in
a NIC(Network Interface Card) which can be
connected with the various types of terminals
easily.
The terminal should imform the user of the radio
rx/tx states.
The terminal also should have the Terminal
Control Process which controls the entire
signalling procedure of the wireless internet
networking such as Mobile IP, initiating and
terminating wireless service.
The adaptation layer is required between the NIC
driver and the TCP/IP protocol suite. This layer
analyzes the packets from the NIC, classifies
them into appropriate TCP/IP queues and the
Terminal Control Process.
The terminal is divided into two parts. One is MTS
(Mobile Terminal Subsystem), which has RF device,
the modem, and MAC protocol layer, and located in
PCMCIA card. The other is TES (Terminal
Equipment Subsystem) with the Terminal Control
Process, the mobile IP client and the Internet protocol,
which is located in the portable PC or PDA. The
design of the TES is detailed in Chapter 3.
3 Design of the Mobile Terminal
We implement the TES based on the Windows XP
notebook PC. TES should have some function blocks
presented in Fig. 3. Especially, the following two
blocks, the modified NDIS and RSMB should be
created and developled newly. The other blocks are
implemented using the existing standards or
recommendations .
3.1 IP adaptation and NDIS modification
User
space
We design the structure of the mobile terminal as
the following Fig. 2.
TES
Fig. 3 IP Adaptation layer and NDIS layer
Use
Ap
A. The original NDIS
Windows-based operating systems support several
types of kernel-mode network drivers. The Network
Driver Interface Specification (NDIS) library abstracts
the network hardware from network drivers. NDIS
also specifies a standard interface between layered
network drivers, thereby abstracting lower-level
drivers that manage hardware from upper-level drivers
such as network transports. NDIS also maintains state
information and parameters for network drivers,
including pointers to functions, handles, and
parameter blocks for linkage, and other system values.
Kernel Equipm
TES (Terminal
space
Windows
Application
Programs
Fig. 2 The structure of the mobile terminal
T
Mobile
A NDIS miniport driver (also called a miniport
driver) has two basic functions: Managing a network
interface card (NIC), including sending and receiving
data through the NIC. Interfacing with higher-level
drivers, such as intermediate drivers and transport
protocol drivers, a miniport driver communicates with
its NIC and with higher-level drivers through the
NDIS library[7].
B. The modified NDIS
In WiBro, there are two types of packets delivered to
the terminal. One type is the traffic packets loaded on
IP protocol. The other is the control packet which
takes a part of controlling the terminal such as
initiating and terminating sessions, and authenticating.
They also monitor the radio states and diagnose the
terminal states. However, the original NDIS cannot
process the control packets of WiBro and deliver them
to the Terminal Control Process. We modify the
original NDIS layer so that it processes not the IP
traffic packets, but also the control packets. This NDIS
layer classifies the packets from NIC into the IP
packets and the control packets. The IP packets are
delivered to the TCP/IP protocol suite, and the control
packets are delivered to the predefined file shared with
the Terminal Control Process. The following picture is
the proposed software architecture of the mobile
terminal, which has the modified NDIS layer and the
additional file I/O system shared with Terminal
Control Process.
Terminal Control Process initiates and terminates
WiBro service. This process authenticates the device
or the user and also monitors the radio states and
diagnoses the terminal execution states.
Terminal Control
Process
NIC Initilization
Service
Authentication/RSM/
DM Initiation
Mobile IP Release
Mobile IP Initiation
Terimnation
Fig. 5 The sequence of the Terminal Control Process
Fig. 5 is the sequence of the operations of Terminal
Control Process. This process is an application
program located in TES, initializes the Network
Interface Card and the WiBro service. This process
executes the Mobile IP transaction which initiates the
Internet service through the public network. This
process terminates the service by doing the Mobile IP
release operation. This process monitors the radio
states and the terminal execution or debug messages.
These additional blocks are detailed in the next
sections.
3.3 Radio States Monitoring Block
For the purpose of Radio States Management, there are
The details of the modified NDIS layer are
introduced the following picture, Fig. 4.
User
App
Fig. 4 The modification of the NDIS layer
3.2
Terminal Control Process
some parameters concerning wireless environment to
be monitored, and user can change the connection
modes manually or automatically.
The required radio parameters are shown as below,
Signal strength (dBM)
Tx rate (Kbit/s)
Tx Packet Amount (Kbyte)
Tx Packet Error rate (%)
Rx rate (Kbit/s)
Rx Packet Amount (Kbyte)
Rx Packet Error rate (%)
User
App
This block polls and receives the radio states from
the wireless modem periodically to update its
monitoring tasks. The updated results are displayed in
a near real-time delay with a maximum delay in the
TES (host computer) equal to the polling interval to
reflect the current radio environment states.
Socket Interfa
When it finished to prepare the service start, by
RSMRequest signal from the host main process, the
state transition takes place for all processes to ready to
working state from Null state. Then, by sending
CIBDataReq primitive, RSM entity is able to receive
data frame from the Modem (NIC). CIBDataReq
primitive is used to request that an upper layer PDU be
sent using the procedures for the information transfer
service. CIBDataInd primitive indicates the arrival of
Radio state parameters received within one
transmission time interval by means of the information
transfer periodically.
Terminal
Control
Process
RSMB
NIC
NDIS
Fig. 8 The dialog for user information
(Authentication, AAA Key, Mobile IP)
(Service Start)
StartRSMRequest
Selectively
CIBDataReq
RSMB Message
CIBDataReq
RSMB Message
CIBDataInd
RSMB Message
StartRSMResponse
CIBDataInd
RSMB Message
CIBDataInd
RSMB Message
Periodically
CIBDataInd
RSMB Message
Fig. 9 The Radio States Monitor Dialog
5 Conclusion
Fig. 6 Message sequences chart of RSMB
4 Implementation
The mobile termianl is implemented using Visual
Studio, Windows DDK and SDK based on Windows
XP. The following features are the presentation of the
mobile termianl.
Fig. 7 The Terminal Control Process
This paper shows a design and implementation of the
mobile terminal suitable to wireless mobile network.
This terminal is implemented using the existing
platform such as x86 notebook PC and Windows XP
OS. There is no network development package or
protocol suite for wireless mobile environment. As a
result, we show the development of some additional
controlling process for networking signaling and the
radio states monitor, and we mention the need of the
modification of the existing NDIS library of Windows
XP. We are now developing WiBro, wireless mobile
network, using the mobile terminal introduced in this
paper.
References:
[1] ETRI, TTA, Specifications for 2.3GHz band
Highspeed Portable Internet Service, 2004. 4.
[2] IEEE, Part16: Air Interface for Fixed Broadband
Wireless Access Systems, IEEE Standards, 2001
[3] IEEE 802.16 TGe Working Document : Part 16 :
Air Interface for Broadband Wireless Access
Systems, Amendment 4-Mobility Enhancements
[4] J.S. Kim, “Design of Radio Status Management
System for Highspeed Wireless Mobile Terminal”,
WWC,Vol1, 2004
[5] C. Eklund, R. B. Marks et al.: “IEEE Standard
802.16:A
Tech-nical
Overview
of
the
TM
WirelessMAN
Air Interface for Broad-band
Wireless Access”, IEEE Comm. Mag., June, 2002,
pp.98-107.
[6] A. Rubini, J. Corbet, Linux Device Drivers - The
2nd Edition, O’Reilly.
[7] Network Devices and Protocols: Windows DDK,
MS Press