ON INTEROPERABILITY BETWEEN WI-FI AND
BLUETOOTH COMMUNICATION SYSTEM
By
T. Pavithra
M. Tech (ES) student
KL University, vaddeswaram, Guntur District, Andhra Pradesh,
India
ABSTRACT
The availability of unlicensed spectrum coupled with the
increasing popularity of wireless communication has given
rise
to
wide
range
of
wireless
technologies.
The
overwhelming success of mobile devices and wireless
communications is stressing the need for the development of
wireless mobile application services. Device mobility
requires services adapting their behavior to sudden context
changes and being aware of handoffs, which introduce
unpredictable delays and intermittent discontinuities.
Heterogeneity of wireless technologies (Wi-Fi, Bluetooth)
and many versions of the same complicate the situation,
since a different treatment of context-awareness and
handoffs is required for each solution. This paper presents
development
of
a
new
integrated
architecture
for
communication between a Master and a slave using different
heterogeneous communication protocols.
All issue which
include dynamic adaptability, heterogeneity, coexistence
and context switching between the wireless technologies have
been addressed.
Keywords:
Wireless
Communication,
Bluetooth,
Heterogeneity, coexistence, intelligent tag.
Wi-
Fi,
Introduction
The widespread use of mobile terminals, today equipped with
multiple wireless communication interfaces, is paving the
way to all-the-time everywhere connectivity view of
pervasive computing. The most adopted wireless technologies
today, such as IEEE 802.11 (Wi-Fi), Bluetooth (BT), have
different characteristics in terms of bandwidth, coverage,
and per-byte transmission cost. The wireless medium is
volatile and addresses the issue of device mobility.
Wireless technologies can introduce sudden variations of
network conditions in terms of delay and bandwidth. Those
unpredictable changes require application services being
able to monitor network conditions. Services are required
to be context-aware, in the sense that they
should be
aware of the possibilities offered by each wireless
technology, should know user location and tracking, and
should have easy access to low-level wireless network
conditions as a first priority within the availability
region.
Although all these standards use the same license free
Industrial, scientific and medical (ISM) band, they cannot
communicate with one another because of the significant
difference in their physical (PHY) and medium access (MAC)
layer design. Thus, to simultaneously use heterogeneous
wireless standards, multiple Access Points (AP) or Network
controllers (NC) are needed, adding considerable management
overhead and cost. Moreover, there is also a complex
coexistence issue among these heterogeneous wireless
standards to avoid mutual interference from one another.
There are many applications in which heterogeneous devices
participate and seamlessly communicate with each other
provided that there is homogeneity among devices with
respect to communication. One of the main problems being
faced today in the IOT field is the issue of interoperability among small device. There is also requirement
of dynamic evolution of selecting a communication protocol
with which one can communicate with other.
There is a need for middleware architecture to be
implemented for having heterogeneous communication with
coexistence. Multiple virtualization architecture, called
Multi- Purpose Access Point (MPAP) and mobility aware
middleware architecture for heterogeneity of communication
protocols which can virtualize multiple heterogeneous
wireless standards based on software radio have been
discussed in literature.
The basic idea is to deploy a wideband radio front-end
to receive wireless signals from all wireless standards
sharing the same spectrum band, and use software basebands
to separate and demodulate information stream for each
coexisting Wireless standard. MPAP consolidates multiple
wireless devices into a single Platform and thus reduces
the maintenance cost. Middleware architecture helps in
handoff management at the mechanism layer and facility
layer. Based on software radio, MPAP enables multiple
wireless standards sharing the same general purpose
computing resource. MPAP is also flexible and extensible to
support future wireless standards. Finally, heterogeneous
software baseband programs along with driver level and MAC
level
switching
with
coexistence
issues
that
can
communicate
and
coordinate
together
provide
better
coexistence and avoid the mutual interference among
heterogeneous wireless communications.
The best features of MPAP, and middleware architectures
which are based on radio have been considered along with
different coexistence mechanisms for making the Master to
communicate effectively with the slave and the combined
model has been implemented.
RELATED WORK
The effect of interference will depend on the relative
location of the two transceivers, the frequency with which
they transmit and also the type of data that is being
transmitted. Bluetooth employs a frequency hopping scheme,
where a burst of data is contained within a segment of
spectrum 1MHz wide, which randomly changes to a different
frequency 1,600 times every second. 802.11 transmitters do
not hop, but transmit at a static frequency, using 22 MHz
of spectrum. Both have mechanisms to deal with interference
from another similar system, although in each case steady
degraded of performance is noticed. However, when they are
mixed together, the opportunity for disruption increases
[11].
Today’s wireless networks are highly heterogeneous, with
mobile devices consisting of multiple wireless network
interfaces (WNICs). Since battery lifetime is limited,
power management of the interfaces has become essential
have developed an integrated approach for the management of
power and performance of mobile devices in heterogeneous
wireless environments. Our policy decides which WNIC to
employ for a given application and optimizes its usage
based on the current power and performance needs of the
system. The policy dynamically switches between WNICs
during program execution if data communication requirements
and/or network conditions change [3].
“Coexistence,” the ability for multiple protocols to
operate in the same frequency band without significant
degradation to either’s operation, has recently become a
significant topic of analysis and discussion throughout the
industry. This is due to several factors. Both protocols
are expecting rapid growth, and because they both operate
in the 2.4 GHz frequency band,
the potential for
interference between them is high. Also, Bluetooth and WLAN
are complementary rather than competing technologies.
Consequently, more and more usage models are being
discovered in which it is desirable and necessary for both
Bluetooth and Wi-Fi to operate simultaneously and in close
proximity [13].
They have shown novel virtualization architecture,
called Multi-Purpose Access Point (MPAP), which can
virtualize multiple heterogeneous wireless standards based
on software radio. The basic idea is to deploy a wide-band
radio front-end to receive wireless signals from all
wireless standards sharing the same spectrum band, and uses
separate software basebands to demodulate information
stream for each wireless standard. Based on software radio,
MPAP consolidates multiple wireless devices into single
hardware platform, and allows them to share the same
general purpose computing resource. Different software
basebands can easily communicate and coordinate with one
another. Thus, it also provides better coexistence among
heterogeneous wireless standards. As an example, they have
demonstrated to use non-contiguous OFDMin802.11gPHY to
avoid the mutual interference with narrow band Zig bee
communication [10].
However while many advantages exists with each of the
architecture proposed in the literature, real heterogeneous
implementation can only be achieved by using dynamically
configurable virtual network interfacing (VNIC).
In this paper a new architecture has been proposed that
incorporates VNIC thereby addressing the heterogeneous
issues related effecting communication by using varieties
of communication protocols that are actively coexisting at
any given point of time.
EXISTING
COMMUNICATION
HETEROGENEOUS COMMUNICATION
ARCHITECTURES
FOR
The survey of literature reveals the existence of
architectures which deals with heterogeneous communication
which
include
MPAP,
Middleware,
and
co-existence
architecture. However each of the architecture suffers from
draw backs such as communication through access points
only, non- adaptability of the co-existence, non-addressing
the communication issues that both relate to Wi-Fi and Blue
tooth
at
different
layers.
Combining
all
of
the
architectures into single one helps effective heterogeneous
communication system. MPAP Architecture:
The MPAP architecture is designed considering the
state-of-the-art software radio technique and wide-band RF
front end hardware. MPAP uses a wide-band RF front-end that
can receive heterogeneous wireless signals with different
standards in the same spectrum band (i.e. 2.4GHz ISM band).
The received signals are transferred into a HOSTS main
memory using Sora Radio Control Board (RCB).
Then, the
Sora SDR Service will distribute these raw digital samples
to various virtual network card interface (VNIC) for
further processing. VNIC is a software program that
implements both PHY and MAC of a wireless standard [5].
Since in MPAP, a much wider band signal is sampled, it is
essential for each software baseband to perform filtering
on the incoming samples to match their own wireless channel
definition. Then, the matched digital samples are fed into
demodulator and the corresponding frames are sent to upper
layer of the network stack [18].
MPAP also deploys a coordination module to ensure the
friendly coexistence among multiple heterogeneous VNICs;
one key function of this coordinator is to synchronize the
transmitting/receiving behavior of each VNIC. This is
because MPAP uses only a single wide- band RF front-end,
which can only transmit or receive at a time. Thus, in
MPAP, if a VNIC is transmitting/receiving, all other VNICs
should transmit/receive as well. Moreover, MPAP coordinator
also facilitates to mitigate mutual interference among
heterogeneous wireless standards. It is because MPAP can
jointly sense the usage of a wide spectrum band and compute
a best configuration based on the knowledge for each VNIC
(and its corresponding network) adaptively. However this
architecture
has
no
provision
of
availability
of
communication module at the target side. This architecture
is also not addressing the coexistence issues.
Several technical differences exists when communication
between various protocol standards have to be carried. The
technical differences are the handoff mechanisms and to
deal with them the need for middleware architecture to ease
mobility-aware services development via a uniform and
simple API is needed. The architecture is capable of
handling heterogeneous handoff procedures by exploiting all
the possibilities offered by underlying communication
technologies. Technological aspects are hidden in the
application level and the middleware provides service
developers with uniform and easy to use interfaces.
Moreover, the middleware is able to provide a wide
visibility
of
underlying
events,
such
as
horizontal/vertical handoff, user
location
change,
and
network
failure e v e n t s .
The middleware architecture consists of two layers: the
Mechanisms Layer and the Facilities Layer. Mechanism layer
modules depend on the specific technology and encapsulate
all
the
logic/knowledge
necessary
to
control/monitor
particular wireless technology at data link/ network
layers.
The
facility
layer
instead,
offers
to
the
application level a set of common facilities, such as the
NCSOCKS and the Mobility Awareness & Management presented
to develop general purpose applications without specific
needs, and a set of domain specific facilities such as the
Multimedia Streaming. It is worth noting that services can
use the Mobility Awareness & Management facility to gather
information about the current channel status and to perform
vertical handoff. Thus, a service can undertake vertical
handoffs once it verifies that its requirements are not
met. That highlights the tight coupling between context
awareness and handoff management [14].
The coexistence mechanism approach simply entails coallocating the two wireless devices in a single form factor
without any attempt to avoid the potential interference.
Collocating
Bluetooth
and
Wi-Fi
without
using
any
coexistence mitigation techniques increases the likelihood
of significant interference. Performance is likely to be
significantly degraded for both protocols in this scenario.
Conceptual
wireless
architecture
specifies
the
techniques for switching between Bluetooth and Wi-Fi base
band, driver level switching exposes the interference
problem and have un predictable latencies where that can be
overcome by having adaptive hopping and MAC level switching
but exacerbate long development cycle, where all this
techniques can be adopted as alternate techniques for
making Bluetooth and Wi-Fi to communicate effectively
without interference. Therefore there is a need of
architecture which emphasis on the key issues like
Heterogeneity of communication protocols with coexistence
without interference.
The Idea and the related innovation
The
literature
survey
of
existing
presented suffers from the following issues:
architectures
1. MPAP architecture is independent of the HOSTS that are
connected to the access point, where interference and
coexistence issues are not taken into consideration.
2. Middle ware architecture best suits for handoff
management but the architecture have not addressed
collision issues, delay time for heterogeneity and
network failure issues.
3. Wireless
communication
architecture
specifies
hierarchy for various coexistence techniques depending
upon the application specific coexistence mechanism.
Taking
into
consideration
the
time
factor
for
coexistence and communicate without interference and
making both the heterogeneous communication protocols
to work at any given instant of time.
An efficient architecture that covers all the above
mentioned drawbacks is shown in the figure 1. Here a design
of new architecture is done since intelligence in making
heterogeneous communication without interference is the key
issue. The overall architecture specifies about the hand
off mechanisms and the coexistence of Bluetooth and Wi-Fi
by
making
the
architecture
advantageous
over
past
architectures.
Design architecture with context awareness
module which encapsulates all the logic/knowledge necessary
to control/monitor needs to be done on the slave side as
much as possible.
Wireless technology at data link/ network layers for
heterogeneous
communication
along
with
driver
level
switching approach which potentially transmit at the same
time the wireless system is receiving, which reduces the
setup time and hold time for making the device to be
heterogeneous.
Since issue arises when Bluetooth at one side must be
able to communicate with having Wi-Fi at the other side,
there should be a conversion mechanism for MAC standard to
the other; a Modified Multipurpose Access Point (MPAP) has
been designed. In this case, MPAP consists of wide band RF
front end IN 2.4G ISM band which receives the data that has
been sent from various Intelligent Tags that are designed
for our application and the Remote hosts independent of the
communication protocol from which the device data has been
send. The SORA RCB (Software Radio Control Board) essential
to perform filtering on the incoming samples to match their
own wireless channel definition at the destination end.
SORA RCB will distribute these raw digital samples which
are converted to PHY and MAC of a wireless standard to
various virtual network card interface (VNIC) for further
processing.
VNIC is a software program that implements both PHY and
MAC of a wireless standard are controlled by coordinator
node which makes intelligence in distributing the protocol
standard formats to corresponding destination. The MMPAP
architecture accepts information that has been sent from
multiple Tags for communicating with the remote Host,
intelligence is made in making at the MMPAP by scheduling
of the priority of the Tags, since the authenticated Host
is only one which has to be communicating with multiple
Tags. Here in the proposed MMPAP architecture MAC-level
switching is performed before baseband and basically
performs the same functionality as driver-level switching,
but at a much faster rate and with predictable latency.
Consequently, it is able to mitigate many of the
interference factors that driver-level switching cannot at
the TAG side or HOST side.
Figure 1 Architecture of Modified Multipurpose Access point
protocol
MMPAP also performs Adaptive hopping mechanism where the
Bluetooth device transmits a “test” pattern of packets
across the entire spectrum, observes the ratio of lost
packets across available channels and locates its adapted
piconet in the least active or interference prone channel,
and the Bluetooth device is collocated with a Wi-Fi device,
and can receive the Wi-Fi pass band location from the Wi-Fi
device, so it simply avoids operating within the Wi-Fi pass
band.
At the Master side since there is a need of peer to peer
communication and ad-hoc network communication, HOST must
be capable of handoff management detection and search
phases are performed adopting the Last Second Soft Handoff
(LSSH) scheme. The handoff detection is based on the
Receiver Signal Strength Indicator (RSSI) with a proper
tuning of its parameters; this scheme allows each AP to
cover a well-defined zone. During the search phase,
multiple connections are established in order to implement
the soft handoff scheme. To reduce the number of monitored
APs, a topology-based solution is adopted that allows a
mobile device to choose the next AP to use only among AP
neighbors. Context awareness being the same as if at the
TAG side where as the Mobility awareness management at the
facility layer exploit the underlying context- awareness
mechanisms and make the context information available to
services according to a uniform representation format .If
the current perceived bandwidth is low, a mobility-aware
file transfer service can switch to another available
wireless technology with the hope to achieve better
bandwidth .Intelligent application at the API level looks
out for the readily available communication interfaces and
establishes the communication with proper authentication,
and the driver level switching and hand off management
will run in the background making
the host to be
Intelligent.
Implementation of MMPAP
Hardware has been designed for an Embedded that
includes Wi-Fi and Bluetooth Interfaces required for
effecting communication with the mobile device. Figure 2
shows the layout and interfacing various devices with micro
controller. ARM 7 acts as main controller to which most of
the devices are interfaced directly through various busses.
To the main bus which is AHP Bus, VLSI Peripheral bus and
Local bus are connected. To the VLSI bus GPIO bus and I2C
bus are connected. All the devices are connected to one of
the busses.
EEPROM is connected as external memory via I2C Bus.
Three devices are used for establishing communication in
different communication modes. While Bluetooth module is
connected through USB (Universal serial bus) to the
microcontroller through VLSI bus, Wi-Fi is connected to the
microcontroller through UART01 and VLSI bus. GPS is
connected to microcontroller through UART02 and VLSI bus.
LCD, LED’s, Keypad, Buzzer, Beeper, reset gate are
connected to the Micro controller through GPIO and VLSI
Bus.
LCD is used for displaying the environmental changes
taking place in and around the intelligent TAG with the
mobile phone. LCD, LED’s are used to alert local operator
about the identification status between the Tag and a Host
through Wi-Fi or Bluetooth communication modules.
The microcontroller is loaded with ES application that
has application modules which facilitates communication
with remote Tag. The ES application keeps tracking of the
devices that are related to the HOST and provides proper
identification and authentication with the HOST. The ES
software keeps updating the status of the TAG and happening
of various events through communication modules. Both the
Communication devices have been connected to other embedded
systems which acts as a middleware containing all versions
of Bluetooth and Wi-Fi communication protocols. The
embedded system which acts as middleware communicates with
a access point
ARM7 PRIMER BOARD
POWER
SUPPLY
P0[31 – 28]
and P0[25 – 0]
P1[31 – 16]
Fast
GPIO
ARM7
LPC2148
/RST
Power on
Reset
XTAL2
POWER
REGULATOR
XTAL1
BATTERY
SYSTEM
FUNCTIONS
ARM7 TDMI–S
AHB BRIDGE
ARM7 LOCAL BUS
AHB BUS
WI-FI
802.11a
802.11b
802.11g
AHB TO VPB
BRIDGE
BLUETOOH
M
M
P
A
P
802.11n
VER-1
WI - FI
VER-2
VER-3
GPS
VER-4
BLUETOOTH
RX0
TX0
UART0
CTS,DSR,DTR,RTS,DC
D,RI
RX1
TX1
HAND
OFF
ADC
ACCESS POINT CONTROL LOGIC
SCL
SDA
P0.7
BUZZER
P0.16 – P0.22
LCD
P1.24 – P1.31
KEYPAD
P0.16 – P0.22
LEDs
UART1
CTS,DSR,DTR,RTS,DC
D,RI
D+
USB
Dcontroller
EEPROM
P1.22
VLSI
peripheral
bus
GPIO
2
IC1
Bus
Figure 2 Hardware Layout diagram for Implementing MMPAP
Experimentation and Results
For simulating the working of the methods using the
Hardware design, processes have been added into mobile and
the TAG. Active and inactive nature of the ports has been
simulated at either end of the TAG and the Mobile phone and
the status of the ports have been communicated to MMPAP
device. Even the assignment of the protocols versions to
different ports has also been simulated and the same have
been communicated to the MMPAP device. Many of the TAGs
have been put into operation and the simulation software
loaded into them configures the ports with Inactive/Active,
Protocol versions randomly. Experiment is initiated by way
commencing the execution of ES software on all the TAGS and
the Mobile Phone. The Data transmitted or received at the
Mobile phone is displayed on LCD, even the configurations
data set at the mobile phone has also been displayed on the
LCD of the Mobile Phone. Similarly the configuration data
and the actual data communicated through the TAG have also
been displayed on its LCD. The data displayed is tabulated
and shown in the Table 7.1. From the Table it could be seen
that
all
issues
of
Heterogeneity,
Interference
and
Active/Inactive statuses of the ports have been taken care
of properly by the MMPAP implementation within the Access
device.
The proposed algorithm for tag Communication system is
implemented through embedded C under integrated KEIL
development tool kit.
Figure 3 show the Bluetooth module
interfaced to UART0 of ARM LPC 2148. The data Tx and Rx is
routed through UART0 for Bluetooth.
Figure 3 Hardware Bluetooth Interface to ARM LPC 2148
The Figure 4 show the secure wireless communication
between the Tag and Mobile Device and the data sent through
Bluetooth from the mobile device is transmitted and
received by the Bluetooth module that has been interfaced
with ARM LPC 2148 and displayed on the Dot Matrix LCD
connected to Controller GPIO Pins.
Figure 4 Data Sent From Mobile Displayed On LCD of the TAG
Figure 5 demonstrates an acknowledgment to the data
sent from the remote mobile device that has been received
by the Tag.
Figure 5 Acknowledgment to the Data Sent to the TAG
Experiments have been initiated by way commencing the
execution of ES software on all the TAGS and the Mobile
Phone. The Data transmitted or received at the Mobile phone
is displayed on LCD, Even the configurations data set at
the mobile phone has also been displayed on the LCD of the
Mobile Phone. Similarly the configuration data and the
actual data communicated through the TAG have also been
displayed on its LCD. The data displayed is tabulated and
shown in the Table 1. From the Table it could be seen that
all issues of Heterogeneity, Interference have been taken
care of properly by the MMPAP protocol implementation
within the Access device.
Conclusions
Development of an intelligent slave must have quick
adoptability to various wireless technologies, there is a
need for development of architecture that deals with
interfacing with heterogeneous communication protocols,
middleware that converts one protocol standard to other and
the
need
for
coexistence
many
of
the
protocols
architectures at the Master side to receive the data that
has been sent from the Slave independent of communication
standard, coexistence of Bluetooth and Wi-Fi have several
interfacing issues and resolve them various coexistence
mechanisms
have been discussed. The coexistence is used
for making heterogeneous wireless communication with remote
host with coexistence of wireless technologies without
interference.
References
1. Bluetooth
Special
Interest
Group,
Feb,
2001,"Specification of the Bluetooth System 1.1,
Volume 1: Core," http://www.bluetooth.com.
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adaptive
wireless
and
mobile
networking,”
IEEE
Personal Communications, 1996.
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Stoica,
August 17–
22,
2008,”
Predicting
Wi-Fi
Availability
using
Bluetooth and Cellular Signals”, ACM 978-1-60558-1750/08/08.
4. H. Velayos, G. Karlsson, 2004, “Techniques to Reduce
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protocol
for
fine-grained
peer-to-peer
vertical
handoff,” Proc. of PIMRC.
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Integration:
solving
Co-existence
challenges”,
www.rfdesign.com
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Access
Scheduling
Among
Heterogeneous
Wireless Systems.
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in
Wireless Overlay Networks. Kluwer Mobile Networks and
Applications”, Vol.3, No.4.
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versus Wi-Fi Direct”.
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De Micheli, 2003,” Heterogeneous wireless network
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Ankcorn, Venky Krishnan, Givanni De Micheli, December
3rd
, 2003,” Heterogeneous wireless
16. Wi-FiTM
and
BluetoothTM
–
Interference
Issue
“,January 2002.
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ID102
√
SENT
PTEMP
Active
TG101
ID102
√
RECVD
PDOW
Active
TG102
ID102
√
SENT
ATTAC
Active
TG103
ID102
√
RECVD
BEEP
Active
TG104
RECVD
LATT
In
active
TG105
√
RECVD
LATT
Active
-
-
√
SENT
LONG
Active
TG106
-
-
-
-
TG106
ID103
ID103
√
√
ID104
ID104
-
-
-
√
√
√
√
-
-
√
√
-
Active/In
Active
Actual
Message
MSG SENT/
RECVD
Blue Tooth
3.0
Blue Tooth
2.2
Slave Device
Wi-fi
802.11b
Wi-Fi
802.11g
Tag ID
Active
/Inactive
Actual
Message
MSG SENT/
RECVD
Blue Tooth
2.2
Wi-Fi
802.11b
Wi-Fi
802.11g
Blue Tooth
3.0
Table 1 Experimental Data and Results
Master device
Mobile
Device
Code
RECVD
PTEMP
Active
SENT
PDOW
Active
RECVD
ATTAC
Active
SENT
BEEP
Active
SENT
LATT
Active
-
-
-
RECVD
LONG
In
active
RECVD
LONG
Active