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Performance Evaluation of USB WiFi Bridge Based On Embedded System by editorijettcs


International Journal of Emerging Trends & Technology in Computer Science (IJETTCS) is an online Journal in English published bimonthly for scientists, Engineers and Research Scholars involved in computer science, Information Technology and its applications to publish high quality and refereed papers. Papers reporting original research and innovative applications from all parts of the world are welcome. Papers for publication in the IJETTCS are selected through rigid peer review to ensure originality, timeliness, relevance and readability. The aim of IJETTCS is to publish peer reviewed research and review articles in rapidly developing field of computer science engineering and technology. This journal is an online journal having full access to the research and review paper. The journal also seeks clearly written survey and review articles from experts in the field, to promote intuitive understanding of the state-of-the-art and application trends. The journal aims to cover the latest outstanding developments in the field of Computer Science and engineering Technology.

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									   International Journal of Emerging Trends & Technology in Computer Science (IJETTCS)
       Web Site: Email:,
Volume 1, Issue 2, July – August 2012                                          ISSN 2278-6856

        Performance Evaluation of USB WiFi Bridge
               Based On Embedded System
                                     Deepali Javale, 2Neelam Joshi, 3Supriya Pansare
                                                       University of Pune,
                                                     Computer Department,
                                                       MITCOE, Pune

Abstract: Data transfer between two devices, one with USB        The basic idea of the product is to transfer the data
port but no WiFi connectivity and another device with WiFi       between a USB device and a WiFi device (the devices are
connectivity but no USB port, is not possible as two devices     not compatible) through the embedded kit. This will
cannot be connected directly. Our aim is to transfer data from   reduce a 3 step process in 1 step process. Thereby,
the USB device to the WiFi device or vice-versa. To overcome     reducing the efforts for data transfer and making the
this shortcoming, we program an embedded system using            transmission between two non-compatible devices
S3C2440A ARM9 processor acts as a bridge between the two
devices enabling the transmission of data between the two.
Results were generated for after the analysis was done to
                                                                    1.2 SPECIFIC REQUIREMENT
check the factors that would affect the speed of transmission       1.2.1 User Interfaces
of files. Four factors were considered File Size, File Format,   GUI is designed using java and installed on both the
Network Strength and Distance                                    devices or at least on the device at the receiving end. The
Keywords: Real Time System, Wireless networking,                 role of the interface is to display the list of files of the
ARM9 processor, S3C2440                                          sending device on to the device at receiving end. The user
                                                                 is required to select the files to be transferred.The
                                                                 interface provides additional options to select the type of
1. INTRODUCTION                                                  file to be transmitted, the listing of file is provided and
                                                                 filtered on the basis of the size, extension, etc.
Many times we feel a need to transfer data from one                 1.2.2 Hardware Interfaces
device to another which have different connection                Hardware interfaces included in the project are the usb
mechanisms, making them incompatible. It seems to be             interface, wifi interface, the embedded kit to be used as
impossible to transfer data between two non-compatible           the bridge.
devices. Like a device has a WiFi interface but not the             1.2.3 Software Interfaces
USB interface, and another device has USB but not WiFi.          The software interfaces included in the project are the
So how will you transmit data between these two devices?         USB and WiFi drivers installed on the kit as well as the
The data could be transmitted through a third device (like       devices. The operating system on the kit, that is, Linux.
laptop) which has both WiFi as well as USB connectivity.            1.2.4 Communications Protocols
But the task becomes lengthy, as you first have to copy          The wireless transmission protocols are used for the
data from USB to your laptop and then transfer if to the         transfer of data between the bridge and the WiFi device.
other device through WiFi.                                       TCP/IP is used for the transmission of data over the USB
For latest development in the direction of embedded              interface.
system and wireless network, this technology proposes a
new idea in which data can be transferred from a USB                1.3 Product Features
device to a WiFi enabled device through an embedded kit.            1.3.1 Product perspective
Hence a 3-step process is optimized to a 1-step process.         The software being developed is an independent and self-
Due to the USB device having no WiFi connectivity and            contained one. It is not a stand-alone application. The
WiFi device having no USB port, the embedded system is           presence of two terminal devices is mandatory for the
used to bridge the devices and transfer the data between         execution. In this process, it will make use of several
the two. The Linux operating system can load the drivers         modules, such as the terminal devices with WiFi and USB
of WiFi and USB. Based on this model, we can                     interfaces, the embedded kit with required interfaces and
implement this USB WiFi Bridge.                                  a reliable buffer used for data storage.
  1.1 Product Overview                                              1.3.2 User characteristics
This USB-to-wireless bridge transfers USB data                   User is not required to have much knowledge about how
wirelessly back and forth, and it can enable the wireless        the data is being transmitted. He is required to have
communication of the WiFi device and the embedded kit.           knowledge of computer system at a very basic level. He
This application is based on ARM9 processor, a product           should be able to attach the USB to the kit and establish
that provides a full/low-speed USB OTG module.                   WiFi connection. He should be aware of what he has to
                                                                 transmit as he has to select the file from the given list.
Volume 1, Issue 2 July-August 2012                                                                                 Page 62
   International Journal of Emerging Trends & Technology in Computer Science (IJETTCS)
       Web Site: Email:,
Volume 1, Issue 2, July – August 2012                                          ISSN 2278-6856

                                                             wireless card and USB camera through the USB Hub.
   1.3.3 Constraints                                         USB camera captures images and USB wireless card
The proper execution of the product depends on various       sends images.
constraints like: transmission speed, size of file to be     The other side is the PC which is responsible for
transmitted, range of transmission.                          receiving images under the Redhat9.0 operating system.
                                                             As they have used UDP, it abolishes the rechecking and
   1.3.4 Assumptions & dependencies                          re-sending process. Hence, there will be some dropped
We are assuming that the user has adequate                   frames. And the use of TCP will slow down the
understanding of the connection establishment. It is         transmission.
assumed the proper bandwidth is available for the            Ni and Liu have proposed a system for Image
transmission of data over the wireless media. The noise      acquirement in embedded Linux. The file is transmitted
interference is negligible.                                  between embedded Linux platform and Bluetooth mobile
It is fully dependent on the kit. The kit has to perform     phone by Bluetooth OBEX protocol and Object PUSH
efficiently throughout the transmission process.             service [2]. They have made use of the Bluetooth. The
                                                             Bluetooth has its limitations like, range of transmission,
   1.4 System Attributes                                     speed of transmission, etc.
   1.4.1 Reliability                                         Thus, all the above techniques were based on different
The system has to be very reliable due to the importance     approaches of transfer of images on Embedded System.
of data and the damages incorrect or incomplete data can     But they all have their own limitations. In this proposed
do.                                                          work the main focus is on transfer of any type of file on
   1.4.2 Availability                                        an embedded system and the technology used here is Wi-
The system has to be available throughout the                Fi as it has an upper hand over the other technologies.
transmission process. As the data is to be transmitted
through 3 phases USB  buffer  WiFi, the                    3. EMBEDDED         SYSTEM        FOR      USB      WI-FI
transmission is time consuming. Therefore, the device        BRIDGE
should be available throughout the transmission.
   1.4.3 Security
The data is required to be transmitted securely. As the         3.1 IEEE 802.11g 2003
data is transmitted over the wireless connection, the        IEEE 802.11g is an amendment to the IEEE 802.11
possibility of connection with an unauthorized device is     specification that extended throughput to up to 54 Mbit/s
more. Hence, the devices should be connected by the          using the same 2.4 GHz band as 802.11b. This
proper identification of the node.                           specification under the marketing name of Wi-Fi has been
   1.4.4 Maintainability                                     implemented all over the world. The 802.11g protocol is
The system is easily maintainable as there is no database    now Clause 19 of the published IEEE 802.11-2007
to be maintained or modified frequently. The only            standard
maintenance required to check the buffer at the time of
transmission. Proper functioning of the buffer is              3.2 Proposed System
                                                              - USB Device : It is the device on one end with the
   1.4.5 Portability                                         USB interface and without WiFi interface.
The system is portable since the size of the bridge is
small. Hence it can be carried or installed on mobile
                                                               -USB Connector : It is the hardware port in the kit
                                                             through which the USB device is attached to the
   1.4.6 Performance
                                                             embedded kit.
Performance depends on following factors:
     - Size of data to be transmitted
                                                             Embedded System:
     - Noise in the wireless connection
     - Speed of transmission
                                                             USB Driver: It is the USB driver installed on the device
                                                             which passes the data to the buffer.
Huo and Liu have proposed the system for wireless image      Buffer: It is the data storage area which collects the data
transmission based on the embedded system in [1]. The        from one end and transfers to the other end.
system is using the wireless network card with the
transmission rate of 54Mbps that will greatly increase the   WiFi Driver: It is the WiFi driver which establishes the
access capacity of the embedded system and make the          wireless connection with the WiFi device and transfers
system more competitive. system is divided into the          data.
embedded system and the PC connected wireless card.
Hardware development board connects external USB

Volume 1, Issue 2 July-August 2012                                                                              Page 63
   International Journal of Emerging Trends & Technology in Computer Science (IJETTCS)
       Web Site: Email:,
Volume 1, Issue 2, July – August 2012                                          ISSN 2278-6856

WiFi Device: It is the device on the other end with the        the Wi-Fi end, the driver will take the data from buffer
WiFi connectivity. It doesn’t have the USB connectivity.       and will send it to the destination device after verifying
                                                               the Wi-Fi device is present and connection is established.
                                                               On the receiving end device, a User Interface is present
                                                               which will actually initialize the connection and prompt
                                                               user to select the files to be transmitted. This transmission
                                                               is from USB to Wi-Fi end. Similarly transmission in
                                                               opposite direction will take place, each entity playing its
                                                               role in reverse order. After the transmission of a file, an
                                                               acknowledgement will be sent prompting the driver to
                                                               empty the buffer for next transmission.

                                                               4. RESULT
                                                               An analysis was done to check the factors that would
                                                               affect the speed of transmission of files. The following
                                                               Four factors were considered:
                                                                    1. File Size
                                                                    2. File Format
    Figure 1: Block Diagram of the Proposed System
                                                                    3. Network Strength
                                                                    4. Distance
   3.3 Hardware Description
The proposed system is to be implemented on a Single           The following graphs give a detailed analysis based on
Board Computer (SBC) having the features like WiFi             the above factors.
adapter and USB ports like Technologic systems’ TS-                 1. Here, we have considered different files with
7553board. Along with it, we will need a ARM9 CPU for                   different sizes.
embedding the drivers which we are coding, on the SBC.
The TS-7553 features a 250MHz Cavium ARM9 CPU
and a 5000 LUT Lattice FPGA. With 64MB RAM and a
bootable 256MB on-board flash drive with our new                                              .jpg files
XNAND technology, the TS-7553 is a powerful and
extremely reliable embedded solution. External devices                                    0
                                                                         Speed (kbps)

can connect to the TS-7553 via Ethernet, 802.11g WiFi,
                                                                                                    111.5 kb34.1 kb
                                                                                              53.1 kb      3     1463.9 kb
XBee radio socket (point to point), USB host, USB
device, or I2C ports, as well as DIO, UARTs, CAN Bus,                                                  Size (kb)
DMX, and SPI which are implemented in the standard
FPGA load.
                                                                               Figure2: Speed Graph for jpg files
ARM is         a 32-bit reduced        instruction       set
computer (RISC) instruction       set    architecture (ISA)
                                                                              Table 1: Speed in kbps for jpg files
developed by ARM Holdings. It was known as the
Advanced      RISC      Machine.      ARM9 is      an ARM           SIZE [kb]                    TIME [ms]         SPEED [kbps]
architecture 32-bit RISC CPU family. With this design                  53.1                         396               134.11
generation, ARM moved from a von Neumann                               111.5                        598               186.53
architecture (Princeton architecture) to a Harvard
                                                                       334.1                        1936              204.22
architecture with separate instruction and data buses (and
caches), significantly increasing its potential speed. Most           1463.9                        5996              244.15
silicon chips integrating these cores will package them
as modified Harvard architecture chips, combining the
                                                                               AVERAGE SPEED: 192.25 kbps
two address buses on the other side of separated CPU
caches and tightly coupled memories.
   3.4 Software Description
The entire system is composed in three parts. First is, we                                    .jpg files
will need a software to extract data from the USB device                                500
at the USB end. This will mount the USB device onto the                                   0
                                                                         Speed (kbps)

board, get the files and pass the reference to the next                                             111.5 kb34.1 kb
                                                                                              53.1 kb      3     1463.9 kb
software. When the connection establishment and files to
be transmitted has completed, the same software will                                                   Size (kb)
transfer the files to the buffer memory for the Wi-Fi
driver to pick up the data. Secondly, inside the bridge, at                 Figure 3: Speed Graph for png files

Volume 1, Issue 2 July-August 2012                                                                                       Page 64
      International Journal of Emerging Trends & Technology in Computer Science (IJETTCS)
       Web Site: Email:,
Volume 1, Issue 2, July – August 2012                                          ISSN 2278-6856

                                Table 2: Speed in kbps for png files               Table 5: Speed and time for different file sizes with
           SIZE                                                                                 and without packet loss
                                      TIME [ms]       SPEED [kbps]
            50.4                        336               150                                                       WITH PACKET            WITHOUT
           403.7                        2548             158.46                             SIZE [kb]               LOSS [30-50%]        PACKET LOSS
           947.8                        4281             221.40                                                     TIME     SPEED       TIME    SPEED
           1471.9                       6489             226.83
                                                                                                        53.1        1060       50.1      396     134.11
                                 AVERAGE SPEED: 189.17 kbps
                                                                                                        111.5       2161      51.61      598     186.53
  2. Here, we have considered files of different format                                                 334.1       5711      58.51      1636    204.22
    but with approximately same size.
                                                                                                   1463.9           18508     79.16      5996    244.15

                                Comparison based                                         AVERAGE SPEED [WITH PACKET LOSS] : 59.84 kbps

                                on diff. file formats                                AVERAGE SPEED[WITHOUT PACKET LOSS] : 192 kbps

                                                                                 4. Here, we have considered the transmission of same
                                500                                              file and varying the distances between the terminal
                 Speed (kbps)

                                               Type and Size (kb)
                                                                                                        Comparison based on distance
 Figure4: Comparison of Speed for different file formats                                                           [.mp3 ]
                                                                                                    300       size = 6173.5 kb
                                                                                         Speed (kbps)

  Table 3: Speed in kbps for different file formats with
              approximate same file size
                                                          TIME         SPEED                        100
                        TYPE              SIZE [kb]
                                                           [ms]        [kbps]
                             .jpg           1463.9         5996        244.15                             0
                            .mp3            1713.8         7639        224.35
                             .pdf           1471.9         6489        226.83                                   1-2 m     Distances m
                                                                                                                        5-6 m 10-12(m)
                             .doc           1030.8         3693        279.12
                                                                                 Figure 6: Comparison of Speed for same file with varying
                                                                                              distance between terminals
3. Here, we have considered the transmission of the
    same files under two conditions :
                                                                                 5. CONCLUSION
Without packet loss                                                              There are various methods to transfer the information
With packet loss(30-50%)
                                                                                 between two different independent connections like USB
  Table 4: Speed for same file with Varying distance                             and Wi-Fi. Because the system adopts high- powered
                  between terminals                                              ARM9 processor and Linux operation system, it has
DISTANCE                                                                         expansibility. The system has characteristics such as
                                        TIME [ms]        SPEED [kbps]
   [m]                                                                           strong function, high reliability, good stability and
          1-2                             34230              180.35              expansibility. The device is built using embedded arm
          5-6                             21884              282.12
                                                                                 processor and single board computer for initial
                                                                                 deployment. However for mass production the entire kit
    10-12                                 29298              210.71              can be replaced by hardware developed solely for this
                                                                                 purpose. The results show, that the file size, file format
      500                                                                        and the distance between the terminal devices do not play
                                Comparison based on                      witho   an important role in deciding the quality of transmission.
                                                                         ut      Whereas, the network strength is has strong impact on
                                  network strength
  Speed (kbps)

                                                                         pack    the speed of transmission.
                 0                                                               References
                    Size (kb)                                                      [1]  Wireless image transmission based on the
         53.1 kb 111.5 kb 334.1 kb1463.9 kb
                                                                                       Embedded System by Huo Chunbao, Gao Liduo,
 Figure 5: Comparison of Speed for different files with                                Liu Yuwei
                and without packet loss                                            [2] Image Acquirement with Bluetooth Technique
                                                                                       under Embedded Linux Environment by Yuanping

Volume 1, Issue 2 July-August 2012                                                                                                              Page 65
   International Journal of Emerging Trends & Technology in Computer Science (IJETTCS)
       Web Site: Email:,
Volume 1, Issue 2, July – August 2012                                          ISSN 2278-6856

       Ni, Jing Liu in 3rd International Conference on
       Biomedical Engineering and Informatics (BMEI
  [3] Evaluation of Wireless Home Automation
       Technologies by A. J. Dinusha Rathnayaka,
       Vidyasagar M. Potdar, Samitha J. Kuruppu in 5th
       IEEE International Conference on Digital
       Ecosystems and Technologies (IEEE DEST 2011),
       31 May -3 June 2011, Daejeon, Korea.
  [4] Embedded USB Homecare Internet System, Circuits
       and Systems (APCCAS), 2010 IEEE Asia Pacific
       Conference on 6-9 Dec. 2010
   [5] An embedded converter from RS232 to Universal
       Serial Bus,     Integrated Circuits and Systems
       Design, 2001, 14th Symposium, 2001
  [6] Evolutionary trends of embedded systems, Industrial
       Technology, 2003 IEEE International Conference
       on 10-12 Dec. 2003
  [7] WiFi: What's Next? Communications Magazine,
       IEEE, Dec 2002
  [8] Robust video broadcasting over 802.11a/g in time-
       correlated fading channels, Consumer Electronics,
       2009. ICCE'09. Digest of Technical Papers
       International Conference on 10-14 Jan. 2009
  [9] Connection Time for Strange Devices, Mobile
       Computing Systems and Applications, 2006.
       WMCSA '06 proceedings. 7th IEEE Workshop on
       1-1 Aug. 2005.

                 Prof. Deepali Javale, Assistant
                 Professor, MIT College of Engineering,
                 holds Bachelors Degree in Computer
                 Engg. and recently Pursuing Master of
                 Information Technology from Pune
                 University. She is having 6 years of
                 teaching experience. Her expertise is in
the field of Embedded Systems and Data Mining

                 Mrs. Neelam Joshi, holds Bachelors
                 Degree in Electronics Engg. and
                 recently Pursuing Master of Electronics
                 and Tele-communication from Pune
                 University. She is having 4 years of
                 Industrial experience. Her expertise is in
                 the field of Embedded Systems and
Signal Processing.

Volume 1, Issue 2 July-August 2012                                                    Page 66

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