Blue star seminar report dated 18 march


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Blue star seminar report dated 18 march

  1. 1. BLUESTARCHAPTER-1 INTRODUCTION Bluetooth is a wireless communication technology that provides short-range, semi-autonomous radio network connections, and offers the ability to establish ad hoc networks,called piconets. It has also been chosen to serve as the baseline of the IEEE 802.15.1 standard forwireless personal area networks (WPANs). WPAN can be integrated with large wide areanetworks (WANs) to provide Internet connectivity in addition to access among these devices. Itis much likely that Bluetooth devices and wireless local area networks (WLANs) stationsoperating in the 2.4 GHz frequency band should be able to coexist as well as cooperate with eachother, and access each other’s resources. These cooperative requirements have encouraged anintuitive architecture, called Bluestar, whereby few selected Bluetooth devices, called Bluetoothwireless gateways (BWG), are also members of a WLAN, empowering low-cost, short-rangedevices to access the global Internet infrastructure through the use of WLAN basedhigh-poweredtransmitters [1]. Bluetooth Wireless Gateways (BWGs), are also IEEE 802.11 enabled so thatthese BWGs could serve as egress/ingress points to/from the IEEE 802.11 wireless network. An important challenge in defining the Bluestar architecture is that both Bluetooth andWLANs employ the same 2.4 GHz ISM band and can possibly impact the performance. Theinterference generated by WLAN devices over the Bluetooth channel called as persistentinterference, while the presence of multiple piconets in the vicinity creates interference referredto as intermittent interference. To combat both of these interference sources and provideeffective coexistence, authors proposed a unique hybridapproach of adaptive frequency hopping(AFH) and a new mechanism called Bluetooth carrier sense (BCS) in Blue-Star. AFH seeks tomitigate persistent interference by scanning the channels during a monitoring period. BCS takescare of the intermittent interference by sensing channel before transmission. Bluestar takes advantage of the widely available WLAN installed base as it is advantageousto use pre-existing WLAN infrastructure. This can easily support long-range, large-scalemobility as well as provide uninterrupted access to Bluetooth devices.Dept. of Electronics and Communication Page 1
  2. 2. BLUESTARCHAPTER-2 BLUETOOTH Ad hoc networks such as Bluetooth are networks designed to dynamically connect remotedevices such as cell phones, laptops, and PDAs. These networks are termed “ad hoc” because oftheir shifting network topologies. Whereas WLANs use a fixed network infrastructure, ad hocnetworks maintain random network configurations, relying on a master-slave system connectedby wireless links to enable devices to communicate. In a Bluetooth network, the master of thepiconet controls the changing network topologiesof these networks. It also controls the flow ofdata between devices that are capable of supporting direct links to each other. Bluetooth was designed as a low-cost, low-power wireless networking technology to be usedin a person’s operating space,i.e. the space that typically extends up to 10m. Bluetooth is a short-range (up to 10 m) wireless technology aimed at replacing cables that connect phones, laptops,and other portable devices [3]. Bluetooth operates in the ISM frequency band 2.4 GHz. TheBluetooth radio transmission uses a slotted protocol with a FHSS (Frequency Hopping SpreadSpectrum) technique. A total of 79 RF channels of 1 MHz width are defined, where the raw datarate is 1 Mbit/s. Channel is divided into 625 µs slots and, with a 1 Mbit/s symbol rate, a slot cancarry up to 625 bits. Transmission occurs in packets that occupy 1, 3 and 5 slots. Each packet istransmitted on a different hop frequency with a maximum frequency hopping rate of 1600hops/s. Fig-1 Packet transmission in BluetoothDept. of Electronics and Communication Page 2
  3. 3. BLUESTAR Communication of Bluetooth devices follows a strict master-slave scheme, i.e. there is noway for slave devices to communicate directly with each other. Master periodically polls theSlave devices and only after receiving such a poll is a Slave allowed to transmit. The Master fora particular set of connections is defined as the device that initiated the connections. A Masterdevice can directly control up to seven active Slave devices. The Bluetooth network supportsboth point-to-point and point-to-multi-point connections. In order to fulfill this function, twoterms are defined:2.1 Piconet The Bluetooth devices which have been setup using the same frequency hopping channeland clock form a Piconet. In every Piconet, one Bluetooth device is in charge of setting thecommunications, deciding the queue of frequency hopping and synchronizing the network. It isso-called Master. Other devices are joined to this piconet as slave.2.2 Scatternet Agroup of Piconet in which connections consists between different Piconet is called aScatternet. Between two Piconet in a Scatternet, at least one Bluetooth device is acting as abridge to connect two Piconet. Each piconet is established by a different frequency hoppingchannel. All users participating on the same piconet are synchronized to this channel. The Bluetooth specification defines two distinct types of links for the support of voiceand data applications, namely, SCO (synchronous connection-oriented) andACL (asynchronousconnectionless). The first link type supports point to point voice switched circuits while the lattersupports symmetric as well as asymmetric data transmission. The frequency hopping scheme iscombined with fast ARQ (Automatic Repeat Request), CRC (Cyclic Redundancy Check) andFEC (Forward Error Correction) to achieve appropriate reliability on the wireless link.Dept. of Electronics and Communication Page 3
  4. 4. BLUESTAR2.3 Bluetooth Stack Bluetooth is a lower-layer specification by the view of OSI. Figure below shows themain protocols of Bluetooth. The key parts of it are radio (RF) layer, baseband and linklayer(link manager and L2CAP). Fig-2: Bluetooth protocol Radio or RF part of Bluetooth is the lowest layer that defines the frequency bands and channel arrangement, transmitter and receiver characteristics. Baseband define packet format, physical and logical channels, channel control, hop selection etc. It establishes the Bluetooth physical link between devices forming a piconet. Link Manager Protocol (LMP) is used for link set-up and control. Other functions of the link manager include security, negotiation of Baseband packet sizes, power mode and duty cycle control of the Bluetooth device, and the connection states of a Bluetooth device in a piconet..Dept. of Electronics and Communication Page 4
  5. 5. BLUESTAR The interfaces between the hardware and software are such common ones as USB and UART which are include in Host Controller Interface (HCI) to make them universal to the different vendor. L2CAP supports higher-level protocol multiplexing, packet segmentation and reassembly, and the conveying of quality of service information. It provides the upper layer protocols with connectionless and connection-oriented services. Bluetooth also includes other important protocols, such as service discovery protocol (SDI), audio and some Bluetooth-specific adaptation protocol (RFCOMM). RFCOMM protocol, which allows for the emulation of serial ports over the L2CAP. It is a transport protocol that provides serial data transfer. In other words, it enables legacy software applications to operate on a Bluetooth device. The Service Discovery Protocol (SDP) provides the means for Bluetooth applications to discover the services and the characteristics of the available services that are unique to Bluetooth.SDPprovides service discovery specific to Bluetooth. That is, one device can determine the services available in another connected device by implementing the SDP.Dept. of Electronics and Communication Page 5
  6. 6. BLUESTARCHAPTER-3 Wireless LAN WLANs allow greater flexibility and portability than do traditional wired local area networks(LAN). Unlike a traditional LAN, which requires a wire to connect a user’s computer to thenetwork, a WLAN connects computers and other components to the network using an accesspoint device[5]. An access point communicates with devices equipped with wireless networkadaptors; it connects to a wired Ethernet LAN via an RJ-45 port. Access point devices typicallyhave coverage areas of up 100 meters. This coverage area is called a cell or range. Users movefreely within the cell with their laptop or other network device. Access point cells can be linkedtogether. WLANs are based on the IEEE 802.11 standard, which the IEEE first developed in 1997.The IEEE designed 802.11 to support medium-range, higher data rate applications, such asEthernet networks, and to address mobile and portable stations. 802.11 is the original WLANstandard, designed for 1 Mbps to 2 Mbps wireless transmissions. 802.11b standard wascompleted in 1999, which operates in the 2.4 - 2.48 GHz band and supports 11 Mbps. The802.11b standard is currently the dominant standard for WLANs, providing sufficient speeds formost of today’s applications. Fig-3 wireless LANDept. of Electronics and Communication Page 6
  7. 7. BLUESTARCHAPTER-4 The proposed Bluestar architecture BlueStars produces a mesh-like connected scatternet with multiple routes between pairsof nodes. It is a distributed solution. That is, all the nodes participate in the formation of thescatternet. But they do so with minimal, local topology knowledge (nodes only knowabout theirone-hop neighbors). BlueStars, a new scatternet formation protocol for multi-hop Bluetoothnetworks, that overcomes the drawbacks of previous solutions in that it is fully distributed, doesnot require each node to be in the transmission range of each othernode and generates ascatternet whose topology is a mesh[4].The protocol proceeds in three phases: 1. The first phase, topology discovery, concerns the discovery of neighboring devices. This phase allows each device to become aware of its one hop neighbors’ ID and weight.By the end of this phase, neighboring devices acquire a “symmetric” knowledge of each other. Fig-4 First Phase TopologyDept. of Electronics and Communication Page 7
  8. 8. BLUESTAR 2. The second phase takes care of BlueStar (piconet) formation. Given that each piconet is formed by one master and a limited number of slaves that form a star-like topology, we call this phase of the protocol BlueStars formation phase. Based on the information gathered in the previous phase, namely, the ID, the weight, and synchronization information of the discovered neighbors, each device performs the protocol locally. A device decides whether it is going to be a master or a slave depending on the decision made by the neighbors with bigger weight. By the end of this phase, the whole network is covered by disjoint piconets. Fig-5 Second phase TopologyDept. of Electronics and Communication Page 8
  9. 9. BLUESTAR3. The final phase The final phase concerns the selection of gateway devices to connect multiple BlueStars.The purpose of the third phase of our protocol is to interconnect neighboring BlueStars byselecting inter-piconet gateway devices so that the resulting scatternet is connected wheneverphysically possible. The main task accomplished by this phase of the protocol is gatewayselection and interconnection. Fig-6 Third Phase TopologyDept. of Electronics and Communication Page 9
  10. 10. BLUESTAR This noval architecture is expected to be capable of accessing networked information,especially through a WAN such as the Internet. This allows dynamic content to be delivered tothe piconets and to the devices that may not otherwise have such WAN access, but cancommunicate with other Bluetooth devices that do have access, either within the piconet orscatternet. Bluetooth access to the WAN and take advantage of the existing IEEE 802.11WLANs by using bluetooth selected devices – which possess botha WLAN interface and aBluetooth interface – as Bluetooth wireless gateways (BWGs). The interaction between theBluetooth network and the outside world is managed by the BWGs[1]. Figure below illustratesthe BlueStar architecture with a scatternet, composed of total of four piconet, where each piconethas several slaves (indicated by the letter Si,j) and one master (indicated by the letter Mi ). In thisfigure, two BWGs provide the scatternet Bluetooth devices access to the local WLAN which, inturn, provides communication to the local LAN, MAN, or WAN, and possibly the Internet. Fig-7 Bluestar proposed architectureDept. of Electronics and Communication Page 10
  11. 11. BLUESTAR The interaction between the Bluetooth network and the outside world is managed by theBWGs. The possible protocol stacks to carry IP packets over Bluetooth could be employedwithin BWGs. the Bluetooth SIG has published a native way for carrying IP traffic overBluetooth by a protocol called Bluetooth network encapsulation protocol(BNEP) wherein IPpackets are encapsulated in Ethernet packets which are then carried over Bluetooth links. Fig-8 Protocol stack for each entity In order for Bluetooth devices to be directly addressed, authors assumed that everyBluetooth device possesses an IP address and any of the well-known routing algorithms isavailable A crucial challenge in the design of BlueStar is to enable an efficient and concurrentoperation of both Bluetooth and WLANs as they both employ the same 2.4 GHz ISM band. Tocombat the interference sources, BlueStar employs a unique hybrid approach of an adaptivefrequency hopping (AFH) and the Bluetooth carrier sense (BCS).Dept. of Electronics and Communication Page 11
  12. 12. BLUESTAR4.1.Bluetooth carrier sense (BCS) BlueStar employs carrier sense so that intermittent-like interference can be avoided.Carrier sensing is fundamental to any efficient interference mitigation with other technologiesusing the same ISM frequency band, and among Bluetooth piconets Themselves[1]. Author hasincorporated BCS into Bluetooth without any modifications to the current slot structure. Carriersensing is shown in figure : Fig-9 Carrier sensing mechanism in Bluetooth In figure the dashed block denotes the sense window of size WBCS. Before startingpacket transmission, the next channel is checked (i.e., sense) in the turn around time of thecurrent slot. If the next channel is busy or becomes busy during the sense window, the sendersimply withholds any attempt for packet transmission, skips the channel, and waits for the nextchance. Otherwise, packet transmission is carried out. A direct consequence of this approach isthat, eventually, an ARQ (automatic retransmission request) packet will be sent when the slot isclear and the communication is carried out.Dept. of Electronics and Communication Page 12
  13. 13. BLUESTARThe nature of intermittent interference : As packet transmission in different piconets are asynchronous and are transmitted withperiod Tp, which depends upon the Bluetooth packet type p. For instance, if p is equal to DH1 orDM1 we have that Tp= 2 · slotsize, where slotsizeis the size of a Bluetooth slot, and is equal to625 µsec. Figure 4 illustrates the timing of two Bluetooth packets p and z generated at piconetsiand j with sizes Sp,iand Sz,j, respectively. Fig-10 Timing of two Bluetooth pockets on different piconets The probability of packet collision between piconetsI and j is : pc(i, j ) = (Sp,i+ Sz,j ) /((max _slotsperpacket(p),slotsperpacket(z)) + 1)* slotsize)*1/C whereC is the number of available frequency channels slotsperpacket(X) gives the number of slots occupied by a Bluetooth packet X The packet collision probability with a packet originated at the ithpiconet is given by (N piconets) : pc(i) = 1 − (1 - pc(i, j ))N−1.Dept. of Electronics and Communication Page 13
  14. 14. BLUESTAR Fig-11 Packet collision and withdrawal probabilities for different slot length packets As we can see from figure 5, even though both packet probabilities increase with thenumber of piconets, the packet withdrawal probability increases at a slower rate, indicating that alarge fraction of packet collisions are being avoided with the adoption of BCS. Moreover, therate of increase is also distinct for different slot length packets. Bluetooth with BCS not onlysignificantly increases the overall throughput but alsonables a larger number of nearby piconetsto operate efficiently.Dept. of Electronics and Communication Page 14
  15. 15. BLUESTAR4.2. Bluetooth adaptive frequency hopping (AFH) Given that a IEEE 802.11 DATA frame has a maximum size of up to 2346 octets and aBluetooth slot occupies 625 bits , in the worst case, so a IEEE 802.11 DATA frame can overlapwith up to 30 Bluetooth slots[1]. Figure 7 shows two potential cases of packet collisions. Fig-12 Potential packet collisions between IEEE 802.11 and Bluetooth Although the IEEE 802.11WLAN senses the channel before transmission, it cannotsense the Bluetooth activities, since the Bluetooth signal is narrowband and low power ascompared to WLANs. Therefore, when the Bluetooth packet (from piconeti) is ahead of theWLAN, packet collision (with the next IEEE 802.11 packet) takes place even after employingBCS. On the other hand, when the WLAN packet is ahead of the Bluetooth packet BCSsuccessfully senses activity in the medium and withdraws packet transmission. Bluetooth devices scan every T SCAN seconds for each of the 79 channels used byBluetooth and collect PER statistics. If the PER is above a threshold PERTHRES, it is labeledas “bad”; otherwise it is labeled as “good”. All devices within a piconet carry out this procedureand when the piconet master request this, the slaves send their measured “good” and “bad”channel marks. The master, in turn, conducts a referendum process based on informationcollected by itself and provided by the slaves. The final mapping sequence is then determinedand sent back to each slave device, which follow this new sequence thereafter. Authors haveimplemented this scheme by a bitmap comprising of 79 bits where a one indicates that afrequency can be used while a zero indicates otherwise. The overall effect on Bluetooth is thatthe total number of available channels C decreases as some channels may be labeled as “bad”.Dept. of Electronics and Communication Page 15
  16. 16. BLUESTAR4.3 Capacity allocation scheme In the BlueStar architecture, theBWGs have to act as forwarding units between thewireless systems besides serving as source or destination for their own applications. Thus, aBWG must spend a proportional amount of time in receiving data as in forwarding it[1].Obviously, because of mismatch in packet sizes and the eventual segmentation and reassemblyoverheads, the time spent in one network may not be exactly the time spent in the other. Since aBWG can be present only in one piconet at a time, the total capacity a BWG can provide to theusers it serves is bounded by half the piconet capacity. This prevents the fair distribution of thecapacity when a BWG serves more than half the total number of users in the scatternet.Dept. of Electronics and Communication Page 16
  17. 17. BLUESTARCHAPTER-5 Simulation of BlueStar Authors have implemented all functionalities of BlueStar in the network simulator (ns-2)andBlueHoc. In addition, authors consider that the interfering range of Bluetooth devices isabout two times larger than the transmission range and an IEEE 802.11b DSSS running at 11Mbps for all simulations[1]. Authors have developed a hybrid Bluetooth-802.11 model that hasbeen incorporated into the BWGs.5.1Bluetooth-only simulation environment Initial experiment employs an environment comprised of only Bluetooth devices withoutany external sources of interference. Therefore, since we are mainly concerned with intermittentinterference and BCS, AFH is not employed. Figure 8 illustrates the topology used for thisevaluation. Within a total area of 500 m × 500 m, we have considered a network composedinitially of 10 piconets. For each of the twenty simulation runs, we increase the number ofpiconets by 10 up to a total of 200 piconets, where each piconet comprises of four devices. Fig-13 Bluetooth only network topology modelBluetooth with BCS greatly reduces the number of collisions and defers packet transmissionuntil a safe channel is found and BCS can drastically increase throughput..Dept. of Electronics and Communication Page 17
  18. 18. BLUESTAR5.2 Combined Bluetooth and WLAN simulation environment In this section authors carried out experiments with both intermittent and persistentinterferences. For that, we utilize the implementations of both BCS and AFH[1].TCP/IP traffic simulation Similar to earlier simulations, we have considered a network initially comprising of 10piconets, and increase the number of piconets in steps of 10 till 200 piconets. As for the WLANaxis, it is composed of an AP, located at (0, 200) m, which has a radio range of 250 m. Fig-14 WLAN and Bluetooth network simulation model The traffic between the WLAN AP and Bluetooth network also consists of FTP traffic.The WLAN packet is of total size of approximately 1.5 KByte. Authors had set the offered loadin each piconet to 30% of its total capacity, and assume Bluetooth stations to be stationary ascurrently assumed by BlueHoc.Dept. of Electronics and Communication Page 18
  19. 19. BLUESTARFour possible scenarios as follows:Scenario A: The flow of data packets is from the WLAN AP to the BWG, reflecting an applicationwhere Bluetooth devices downloading contents from the WAN.Scenario B: This scenario is the opposite of the previous one with the Bluetooth devices uploadinginformation to the WAN, i.e., the flow of data packets is from the BWG to the WLAN AP.Scenario C: A BWG might find itself in a situation where it simultaneously receives data packetsfrom both the WLAN AP and the Bluetooth devices in order to synchronize information in theBWG.Scenario D: This scenario models the opposite situation as described in scenario C. In other words, itis the case where the BWG simultaneously transmits data packets to both the Bluetooth devicesand the WLAN AP.Dept. of Electronics and Communication Page 19
  20. 20. BLUESTARResults obtained for different scenarios after Simulation are:Scenarios B and D: scenarios B and D experience a sizeable degradation in throughput as compared toscenarios A and C, with scenario B having the largest impact. This is particularly true in thesescenarios because when the BWG is transmitting data packets towards the AP, there is a highpersistent interference in the Bluetooth network causing a high PER. On the other hand, inscenarios A and C the BWG is sending acknowledgments (ACKs) to the AP, therefore reducingthe probability of packets being corrupted. The reason why scenario B suffers a higherperformance drop (and higher PER) than scenario D is because the WLAN transmissions corruptthe Bluetooth data packets in scenario B, while in scenario D only Bluetooth ACK packets aresusceptible to be corrupted by WLAN transmissions.Since these scenarios are more impacted by persistent interference, AFH is effective for a largernumber of piconets until it reaches a point where the intermittent interference levels becomessignificant. At these points, BCS performs better by effectively mitigating intermittentinterference sources. Despite the high interference levels, BlueStar, employing both AFH andBCS, accomplishes enhanced performance by achieving the highest throughput and lowest PER.Scenarios A and C : AFH is now effective only for a smaller number of piconets as the larger impact comesfrom intermittent interference. In scenarios A and C (especially in scenario A) the regularBluetooth implementation shows performance sometimes comparable to that of the AFHscheme, which is primarily due to the TCP congestion control mechanisms employed in theWLAN interface. When collisions in the WLAN traffic occur, the frame has to be completelyretransmitted as IEEE 802.11 WLANs do not employ any kind of FEC (forward errorcorrection). In scenario A the WLAN transmissions have been corrupting the Bluetooth ACKpackets, while in scenario C Bluetooth data packets are more impacted. Therefore, scenario Aperforms slightly better due to the shorter and less frequent duration of the ACK packets.Dept. of Electronics and Communication Page 20
  21. 21. BLUESTARScenarios C and D: A higher drop in throughput for scenario D, especially for the ordinary Bluetoothimplementation. As expected, AFH outperforms BCS when most of the interference is ofpersistent type, however degrades nearly at the same rate as the ordinary Bluetoothimplementation when the number of piconets become larger than 50 and 65 for scenarios C andD, respectively. Likewise, BlueStar approximately doublesthe throughput achieved in Bluetoothby combining AFH and BCS. Moreover, it is also important to highlight the performance of AFH as it outperformsBCS under a small number of piconets, since most of the interference is of persistent type.However, as the number of piconets increase, and hence the intermittent interference level, theperformance of AFH degrades and BCS becomes more efficient both in terms of PER andthroughput. More specifically, in scenarios B and D AFH is more efficient than BCS up to 90and 72 piconets respectively, whereas in scenarios A and C AFH performs better when thenumber of piconets is approximately less than 55. In all scenarios, BlueStar achieves the best throughput and the lowest PER by takingadvantage of both AFH and BCS.5.3 Placement and number of BWGs in bluestarThis section deals with number of BWGs are needed to provide adequate and uninterruptedcoverage to all devices in a Bluetooth scatternet, as well as where to place these BWGs. Authorsrefer to these as the placement and the number problems. The topology of interconnection hasinfluence on the number of resulting BWGs. Authors has proposed a model in which a BWGserve as bridge node between exactly two neighboring piconets and piconets have a circularshape and are centered on the master[1]. BWG between two piconet While in figure A the addition of a piconet resulted in the addition of only one moreBWG, the same piconet might also result in the addition of two more BWGs as shown in figureDept. of Electronics and Communication Page 21
  22. 22. BLUESTAR However, since major interest is in an upper bound (worst-case) on the number ofBWGs, this task is simplified by considering only the topology which results in the highestinterconnection, as exemplified in the sketch of figure C. In Bluetooth, it is possible to have alleight devices of a piconet working as bridge nodes. Fig D Fig.A Fig. B Fig. C Fig-15 Placement and number of BWGs in BluestarDept. of Electronics and Communication Page 22
  23. 23. BLUESTAR For mathematical simplicity, we impose a restriction that only the master device is notallowed to work as a BWG. Thus, among seven BWGs of a piconet, each BWG is shared by twopiconets. It is clear that we can have at most [7n/2] BWGs in a scatternet composed of npiconets. In fact, the total number of BWGs required will be fewer than these as there is no needto have a BWG on non-bridge devices as shown in the outer parts of figures .Proposition 1. For a scatternet comprised of n (n >0) piconets, where piconets have a circular (or near-circular) shape (figure B), the number of BWGs needed is at most [7n/2] − 2[4√n − 4] .Proposition 2. For a scatternet comprised of n (n >0) piconets, the maximum number of BWGs neededis [7n/2] − 2[4√n − 4] .Dept. of Electronics and Communication Page 23
  24. 24. BLUESTARCHAPTER-6 ConclusionThis paper introduces a novel architecture called BlueStar, which employs a combinationofadaptive frequency hopping and Bluetooth carrier sensing to efficiently provide advanced widearea services to Bluetooth devices. BlueStar can take advantage of the existing installed base ofIEEE 802.11 wireless networks by assigning selected Bluetooth devices, called Bluetoothwireless gateways (BWG), with IEEE 802.11 capabilities. These BWG are responsible forproviding uninterrupted access to the WAN, such as the Internet, to the entire Bluetooth network(piconet or scatternet). BlueStar is observed to greatly outperform existing Bluetooth underdifferent traffic condition. The incorporation of BlueStar into Bluetooth is simple, does not incurmuch overhead, and hence is an excellent enabler for co-existence and cooperation of Bluetoothand IEEE 802.11.Future work in BlueStar includes defining a more elaborate capacity allocation algorithm. Inaddition, we plan to investigate the correlation amongst the various simulation parameters inorder to assess their impact on BCS and AFH. Mobility of both IEEE 802.11 and Bluetoothdevices and its impact on both systems are also part of our future research.Dept. of Electronics and Communication Page 24
  25. 25. BLUESTARCHAPTER-7 References [1] Bluestar: enabling efficient integration between Bluetooth WPANs and IEEE 802.11 WLANs Mobile Networks and Applications archive Volume 9 , Issue 4 (August 2004) ,Pages: 409 – 422 Carlos De M. Cordeiro, SachinAbhyankar, Rishi Toshiwal, Dharma P. Agrawal [2] Ascatternet operation protocol for Bluetooth ad hoc networks Wireless Personal Multimedia Communications, 2002 27-30 Oct. 2002,pages: 223 – 227, Volume: 1 Tadashi Sato, KenichiMase [3] Bluetooth - The Fastest Developing Wireless Technology May 2000 , pages: 1657 – 1664 ZhangPei, Li Weidong, Wang Jing, Wang Yotizhen [4] Bluetooth scatternet models December 2004/ January 2005, pages : 36 – 39 Patricia McDermott-WellsDept. of Electronics and Communication Page 25