The Performance Evaluation of Qos in Wireless Personal Area Network (WPAN) on Impact of Bluetooth Worms

The Bluetooth technology is the convergence of Mobile Communication and Computing Applications. The set of Mobile Devices ”Laptops, Notebook Computers,PDA’s,Mobile Smart Phones etc” connected by Bluetooth protocol forms a Bluetooth Network or Bluetooth Piconet or WPAN.Even through the devices have numerous benefits its open nature increases the threats and risks being posed on them. The wired network faces challenging problems because of internet worms, similiarly the Bluetooth Network or WPAN faces serious problems because of Bluetooth Worms. This paper gives a comparative study of WPAN performance on impact of Bluetooth Worms in Bluetooth Piconet (symmetric) and Bluetooth Piconet(asymmetric) and derives the result how the degree of homogeneity increases the infection rate.


Bluetooth Technolog y
Bluetooth technology is the low power, low cost technology used in short range radiofrequency (RF) communicat ion. It is a protocol used for connecting a set of wireless devices, ranging fro m PDAs, Smart phones , Notebook computers, Laptops etc,. Bluetooth radio operates in the 2.4 GHz unlicensed ISM band(Industrial, Scientific and Medical).Bluetooth supports both point to point and point to multipoint connections. In point to multipoint connection , the channel is shared among several Bluetooth devices. The channel is divided into time slots each 625µs in length, where each slot corresponds to RF hop frequency. Two or more devices sharing the same channel fo rms a piconet [Figure1]and multip le piconets with overlapping coverage area forms a scatternet. A device wh ich is a member in more that one Piconet is called bridge. Bluetooth protocol uses asynchronous connectionless link for (A CL) for data transfer and synchronous connection oriented link (SCO) for voice or co mb ination of voice and data transfer.[1] [7].
Speed , storage capacity and hence the uploading and downloading rates are increasing rapidly. [1] [9] This paper is organized as follows. Sect ion 2 focuses on Bluetooth Secu rity issues . Sect ion 3 d iscuss on t raffic scheduling algorith m to evaluate QOS in the piconet and S-Slave , M -Mast er

Bluetooth Security and Security Issues
Bluetooth is designed to run in a peer to peer short range wireless network. All Bluetooth enabled devices imp lements the Generic Access Profile. The profile defines a security model that includes three security modes .Security Mode1, is an in secured mode. Security Mode2 , enforces security at service level after the channel has been established. Security The earliest versions of worms are harmless and they didn't spread fro m device to device. The recent worms are capable of spreading to nearby device via Bluetooth and pose serious threats on Enterprise networks. The Bluetooth worm uses proximity scanning process to infect the nearby device. The worm infection cycle has three phases-inquiry, paging and probing. In the inquiry phase it identifies and collects the list of neighboring devices which is within its vicin ity area. In the paging process it establishes connection and in the probing phase it probes for infection. Once probing is completed it d isconnects from the victim device and move back to the inquiry list to select the next victim. Now a days all business transactions, banking transactions, accessing web resources are made ease through mobile phones. Additional security concerns are for Bluetooth mobile phones. Mobile phone worms take advantage of the Bluetooth technology to propagate to other Bluetooth devices. The attack beco mes more severe in fore co ming days which may be in the form of handset downtime, service discrepancies due to DoS(Den ial of service) attacks, physical damages to hardware device and theft of sensitive data from the device.
The service providers and mobile phone vendors currently do not have any mechanism to integrate in the Bluetooth stack to detect a worm infect ion in mobile hand sets. However the antivirus software for mobile handsets partially helps to defend against such exp loits. These tools do not identify or detect exp loits in the mobile OS or in Bluetooth stack, they try only to heal the in fected files or d irectories fro m the handsets. So antivirus software is not a complete solution. [

Analysis of QOS in WPAN
When the devices are infected in the WPAN, the performance of the entire network gets affected. A complete performance study is simu lated in NS-2. The simu lation environ ment is set for 8 devices connected by Bluetooth technology, which otherwise called as Piconet. Piconet having similar devices are called symmetric Piconet and non-similar devices are called asymmetric Piconet.
A Master and slave send and receive packets alternatively, slave is allowed to communicate only when it is polled by the master.At most a single packet is sent in each direction(uplink / downlink).Whenever a master, slave queue pair is served. If the master has nothing to send to a specific slave, one slot called POLL has to be send during downlink co mmunicat ion. If the slave has nothing to send, one slot called NULL has to be sent during uplink communicat ion.
Always the master is subject to higher traffic co mpared with slaves. The master uses intra scheduling algorithm to schedule the traffic in downlink. Limited or Pure Round Robin algorith m is imp lemented Master commun icates with a slave in a fixed cyclic o rder. Each node is assumed to have infinite buffers and the packets generated at the uplink queues and downlink queues is assumed to be an independent Poisson arrival processes. The arrival rate in symmetric Piconet is same all the time and the arrival rate is not same at all the time in asymmetric Piconet, it may be zero some times.
The Queuing Model forms the base for service distribution in Piconet or WPAN. Table 1 shows the distribution parameters Normal flow o f trans mission in the uplink and the downlink in the Piconet is monitored first and then the a node is infected in the Piconet and then the uplink and downlink transmission is monitored. The impact of worm affects the QOS in any WPAN.
The QOS of any network can be measured by the standard parameters.

Graphical Results and Discussions
The graphs (Fig 2, Fig 3, Fig 4, Fig 5, Fig 6 Fig 7 ,Fig 8   Fig 9) g iven below co mpares initial in fection , infection in symmetric Piconet, asymmetric Piconet . In all the cases the infection rate is higher for symmetric Piconets (homogeneous devices) .The above results derive that WPAN having similar devices are are prone to have higher degree of attack as well as degradation of QOS .

Conclusions & Future Work
The devices of WPAN or Bluetooth Network are Vu lnerable to worm attack. Its a serious problem faced by the wireless network. Enhanced security model for worm detection and prevention is required.To meet the security risks and and to improve the QOS in WPAN a new model called Pattern Dependent Model is proposed and it's discussed in future work.