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Hop reservation multiple access (HRMA) for multichannel packet radio networks

Hop reservation multiple access (HRMA) for multichannel packet radio networks. Zhenyu Tang; Garcia-Luna-Aceves, J.J. Computer Communications and Networks, 1998. Proceedings. 7th International Conference on , 1998. Outline. Introduction HRMA Protocol Comparative Throughput Analysis

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Hop reservation multiple access (HRMA) for multichannel packet radio networks

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  1. Hop reservation multiple access (HRMA) for multichannel packet radio networks Zhenyu Tang; Garcia-Luna-Aceves, J.J. Computer Communications and Networks, 1998. Proceedings. 7th International Conference on , 1998

  2. Outline • Introduction • HRMA Protocol • Comparative Throughput Analysis • Numerical Results • Conclusions

  3. Introduction(1) • radios operate using two spread spectrum • direct-sequence spread spectrum (DSSS) • frequency-hopping spread spectrum (FHSS) • focuses on an efficient MAC protocol based on FHSS radios operating • prior examples of MAC protocols • ALOHA • slotted ALOHA • sender- or receiver-oriented code assignments

  4. Introduction(2) • proposed paper • based on very slow frequency hopping • allows to reserve a frequency hop (channel) • provides a baseline to offer QoS in ad hoc networks • based on simple half-duplex slow FHSS radios

  5. HRMA Protocol(1) • based on common hopping sequence • no carrier sensing • L available channel • Denote by f0 the synchronization channel • exchange synchronization information • synchronization period • beginning of a frequency hop and the current hop • the rest channels

  6. HRMA Protocol(2) • the rest channels • frequency pairs (fi,fi*),i=1,2…….M • frequency hop fi • HR packet, RTS, CTS, data packet • frequency hop fi* • ACK packet • HRMA slot • synchronization period • HR period (Hop Reservation) • RTS period • CTS period

  7. HRMA Protocol(3)

  8. HRMA Protocol(4) • new node • to join with HRMA • create one-node system

  9. backoff t7 during CTS preiod S_RTS WF_CTS t12 t5 t2 t11 t9 t4 WF_HR t10 more data t8 WF_DATA idle S_DATA t1 end of transmission t6 t3 t13 S_HR HRMA Protocol(5) • t1:receive RTS, send CTS in CTS period • t2:receive CTS, send data • t3:more data, send HR in the next HR period • t4:LD before RTS period and , send RTS in RTS period • t5:the reserved slot starts and HR, send RTS immediately • t6:data received or timeout and • t7:timeout and , send RTS in RTS period • t8:more data , send HR in the reserved slot of next HR frame • t9: timeout and LD • t10:end of transmission and no more data • t11: and receive RTS, send CTS in CTS period • t12:after CTS period of the reserved slot • t13:end of HR packet transmission no synchr. infor. , send synchr. packet join start synchr. infor.

  10. HRMA Protocol(6) • t1:receive RTS, send CTS in CTS period • t2:receive CTS, send data • t3:more data, send HR in the next HR period • t4:LD before RTS period and , send RTS in RTS period • t5:the reserved slot starts and HR, send RTS immediately • t6:data received or timeout and • t7:timeout and , send RTS in RTS period • t8:more data , send HR in the reserved slot of next HR frame • t9: timeout and LD • t10:end of transmission and no more data • t11: and receive RTS, send CTS in CTS period • t12:after CTS period of the reserved slot • t13:end of HR packet transmission

  11. Comparative Throughput Analysis(1) • assumption • a fully-connected network • Radios are half-duplex • N nodes, M frequency hops • M>N • a typical multi-hop packet radio network • compared protocol • ideal protocol with ROCA • ALOHA with ROCA

  12. Comparative Throughput Analysis(2) • ROCA (receiver-oriented channel assignment) • unique channel to receive • tunes its radio to the channel of the intended receiver to transmit a packet • two possible types of conflict • two or more nodes try to start sending packets to the same receiver at the same slot. • the destination is transmitting or receiving

  13. Comparative Throughput Analysis(3) • ideal protocol with ROCA • there is no the two conflicts of ROCA • when the first conflict happens, the ideal protocol can randomly pick one competing sender • block all the attempting senders when the second case happens • The only issue that affects the throughput is the pair-up of nodes

  14. Comparative Throughput Analysis(4) • ALOHA with ROCA • consider here a slotted ALOHA • assumption • transmitting has the highest priority • transmitting preempts any receiving

  15. Numerical Results(1) • network parameters • M : frequency hops available • N : the number of nodes • APL : value of average packet length • depict the throughput per node (S) as a function of offered load (G)

  16. Numerical Results(2) • Throughput of HRMA with different values of APL

  17. Numerical Results(3) • Throughput of HRMA with different numbers of nodes

  18. Numerical Results(4) • Throughput of HRMA with different numbers of channels

  19. Numerical Results(5) • Throughput of Ideal protocol with different populationand APL’s

  20. Numerical Results(6) • Throughput of ALOHA with different population andAPL’s 2 4 10

  21. Numerical Results(7) • Throughput comparison: HRMA, Ideal and ALOHA

  22. Conclusion • offer QoS in ad hoc networks • reserve a frequency hop • better with large data packet • continues to develop multi-hop packet-radio networks

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