Resolving Data Collision in CSMA via Protocols<br />Presented by: <br />                                                  ...
Wireless LAN configuration<br />2<br />
3<br />The 802.11 CSMA	 Sublayer Protocol<br />(a) The hidden station problem.<br />(b) The exposed station problem.<br />
RESEARCH  PAPER 1 By Fouad A. Tobagi & Leonard <br />A busy tone solution for hidden terminal problem in CSMA. <br />When ...
RESEARCH  PAPER 2 by HossamHassanein and Chi-Hsiang Yeh<br />It assign priority for packets.<br />it can enable different ...
RASEARCH PAPER 3 BY Tiantong You AND HossamHassanein<br />An Adaptive Distributed ID Assignment Scheme for CSMA/IC.<br />A...
RESEARCH PAPER 4 BY Zhenyu Tang and J. J. Garcia-Luna-Aceves<br />Hop reservation multiple access protocol (HRMA)  introdu...
RESEARCH PAPER 5 BY by J. D. Angelopoulos, N. Leligou, Th. Orphanoudakis, G. Pikrammenos<br />MACA with Piggy-Backed Reser...
10<br />Solution by RTS-CTS protocol<br />The CSMA protocol.  (a) A sending an RTS to B.<br />(b) B responding with a CTS ...
11<br />CSMAW<br />Variants of this method can be found in IEEE 802.11 as DFWCSMA (Distributed Foundation Wireless CSMA),<...
12<br />CSMA variant: DFWCSMA in IEEE802.11<br />sender<br />receiver<br />idle<br />idle<br />packet ready to send; RTS<b...
13<br />Examples <br />A<br />C<br />A<br />C<br />CSMA  avoids the problem of hidden terminals<br />A and C want to send ...
References<br />[1] 1st Research Paper:The Institute of Electrical and Electronics Engineers, Inc. IEEE Std 802.11 - Wirel...
[5] 5th  Research Paper:; J. D. Angelopoulos, N. I. Lepidas, E. K. Fragoulopoulos, I.S. Venieris,“TDMA multiplexing of  AT...
ANY <br />
THANK YOU<br />
Resolving data collision in csma via protocols
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Resolving data collision in csma via protocols

  1. 1. Resolving Data Collision in CSMA via Protocols<br />Presented by: <br /> Anurag Pratap Singh<br /> CS -64<br /> 2912210001<br />
  2. 2. Wireless LAN configuration<br />2<br />
  3. 3. 3<br />The 802.11 CSMA Sublayer Protocol<br />(a) The hidden station problem.<br />(b) The exposed station problem.<br />
  4. 4. RESEARCH PAPER 1 By Fouad A. Tobagi & Leonard <br />A busy tone solution for hidden terminal problem in CSMA. <br />When a node is ready for transmission, it senses the channel to check whether the busy tone is active. <br />If not, it turns on the busy tone signal and starts data transmissions<br />Otherwise, it reschedules the packet for transmission after some random rescheduling delay.<br />Any other node which senses the carrier on the incoming data channel also transmits the busy tone signal on the control channel, thus, prevent two neighboring nodes from transmitting at the same time.<br /> IEEE802i:http://www.cedt.iisc.ernet.in/WEP<br />
  5. 5. RESEARCH PAPER 2 by HossamHassanein and Chi-Hsiang Yeh<br />It assign priority for packets.<br />it can enable different packets with different priority to access the media and thus gain QoS.<br />http://www.isaac.cs.berkeley.edu/isaac/wep-faq.html <br />
  6. 6. RASEARCH PAPER 3 BY Tiantong You AND HossamHassanein<br />An Adaptive Distributed ID Assignment Scheme for CSMA/IC.<br />Achieving collision free medium access in CSMA/IC only requires that the nodal ID is unique in its preventing range, while the nodal MAC ID (48 bits long) could guarantee uniqueness in the entire<br /> network.<br />IEEE 802.15.4. Part 15.4 :Wireless medium access control (MAC) and physical layer (PHY) specifications for low-rate wireless personal area networks (LR-WPANs).<br />
  7. 7. RESEARCH PAPER 4 BY Zhenyu Tang and J. J. Garcia-Luna-Aceves<br />Hop reservation multiple access protocol (HRMA) introduced<br />a multichannel MAC protocol which is based on half-duplex, very slow frequency-hopping spread spectrum (FHSS) radios<br />uses a reservation and handshake mechanism to enable a pair of communicating nodes to reserve a frequency hop, thereby guaranteeing collision-free data transmission.<br />can be viewed as a time slot reservation protocol where each time slot is assigned a separate frequency channel.<br />IEEE: http://www.ieee802.org/1/files/public/docs2000/P8021XOverview.PDFORiNOCO security paper v2.2 <6> Copyright© 2003<br />
  8. 8. RESEARCH PAPER 5 BY by J. D. Angelopoulos, N. Leligou, Th. Orphanoudakis, G. Pikrammenos<br />MACA with Piggy-Backed Reservation (MACA/PR)<br />Provide real-time traffic support in multi-hop wireless networks<br />Based on the MACAW protocol with non-persistent CSMA<br /><ul><li>http://www.blackhat.com/html/bh-usa-02/bh-usa-02 speakers.html#Bruce%20Potter</li></li></ul><li>Problem domain<br />Continuous checking <br />More wait for low priority data<br />ID assignment deals only with hidden surface problem.<br />HRMA have problem of low efficiency and throughput.<br />
  9. 9. 10<br />Solution by RTS-CTS protocol<br />The CSMA protocol. (a) A sending an RTS to B.<br />(b) B responding with a CTS to A. <br />
  10. 10. 11<br />CSMAW<br />Variants of this method can be found in IEEE 802.11 as DFWCSMA (Distributed Foundation Wireless CSMA),<br />CSMAW (CSMA for Wireless) is a revision of CSMA.<br />The sender senses the carrier to see and transmits a RTS (Request To Send) frame if no nearby station transmits a RTS.<br />The receiver replies with a CTS (Clear To Send) frame.<br />Neighbors<br />see CTS, then keep quiet.<br />see RTS but not CTS, then keep quiet until the CTS is back to the sender.<br />The receiver sends an ACK when receiving an frame.<br />Neighbors keep silent until see ACK.<br />Collisions<br />There is no collision detection.<br />The senders know collision when they don’t receive CTS.<br />They each wait for the exponential backoff time.<br />
  11. 11. 12<br />CSMA variant: DFWCSMA in IEEE802.11<br />sender<br />receiver<br />idle<br />idle<br />packet ready to send; RTS<br />data; <br />ACK<br />time-out; <br />RTS<br />RxBusy<br />wait for the <br />right to send<br />RTS; <br />CTS<br />time-out  <br />data; <br />NAK<br />ACK<br />time-out  <br />NAK;<br />RTS<br />CTS; data<br />wait for<br />data<br />wait for ACK<br />RTS; RxBusy<br />ACK: positive acknowledgement<br />NAK: negative acknowledgement<br />RxBusy: receiver busy<br />
  12. 12. 13<br />Examples <br />A<br />C<br />A<br />C<br />CSMA avoids the problem of hidden terminals<br />A and C want to send to B<br />A sends RTS first<br />C waits after receiving CTS from B<br />CSMA avoids the problem of exposed terminals<br />B wants to send to A, C to another terminal<br />now C does not have to wait for it cannot receive CTS from A<br />RTS<br />CTS<br />CTS<br />B<br />RTS<br />RTS<br />CTS<br />B<br />
  13. 13. References<br />[1] 1st Research Paper:The Institute of Electrical and Electronics Engineers, Inc. IEEE Std 802.11 - Wireless LAN Medium Access Control (MAC) and Physical Layer (PHY) specifications, 1999 edition.<br /> <br />[2] 2nd Research Paper: B. Leiner, D. Nielson, and F. A. Tobagi, Eds.,<br />Proceedings of IEEE GLOBECOM, Special issue on packet radio networks<br /> [3] 3rd Research Paper: T.You, C.-H. Yeh, and H. Hassanein, “CSMA/IC: A New Class of Collision-free MAC Protocols for Ad Hoc Wireless Networks,” Proc. IEEE Int'l Symp Computer Communications (IEEE ISCC'03), June/July 2003<br /> <br />[4] 4th Research Paper : WINGs for the Internet project and SPARROW project. http://www.cse.ucsc.edu/research/ccrg/, Santa Cruz, CA, 1998. <br /> <br />.<br />
  14. 14. [5] 5th Research Paper:; J. D. Angelopoulos, N. I. Lepidas, E. K. Fragoulopoulos, I.S. Venieris,“TDMA multiplexing of ATM cells in a residential access SuperPON”, IEEE Journal on Selected Areas in Comm., Special issue on high capacity optical transport networks, Vol. 16, No. 7, September, 1998<br />[6]www.google.com/lectures/IEEE 802.11 Media Access Control and Network Layer Standards<br />[7]Chapter 6 of EE136 textbook:A. Leon-Garcia, I. Widjaja, “Communication Networks,” McGraw Hill.<br />[8]The IEEE 802.11 specification – posted on my.poly.edu – reference materials<br />[9]P. Brenner, “A Technical Tutorial on the IEEE 802.11 Protocol,” http://www.sss-mag.com/pdf/802_11tut.pdf<br />
  15. 15. ANY <br />
  16. 16. THANK YOU<br />

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