Study Of Multiple Access Protocols In Microcellular And Low-Earth-Orbit Satellite Communications

ABSTRACTMicrocellular communications and Iow Earth orbit satellite communications wiIl be playinga key role in forming the fiJtUre Personal communications netWork. Multiaccess protocol,which principaIIy constrUcts the air intedece of microcellular communications and LEOsatellite communications is one of key technologies of wireless netWorking.The introduction and development of celluIar and microcelIuIar communications areconcisely described in Chapter One. The multiple access protocol for microcelluIar systemsand reeent progress of Personal communication netWork are outlined as well.In ChaPter Two, Packe Reservation Multiple Access protOCol (PRMA) is introduced at first.Based on the idea of the Pus, a new protocol, referred to Frame-based PRMA, isproposed for the microceIlular communications working with time-division dupIex. Theperformance analysis demonstraes that the FPRMA achieves a throughput very close to thatof the PRMA with frequency-division duplex. To further increase the capacity and overcomethe instability of PIwt-like prOtocols under heaVy load, an advanced Non-Collision PRMAprotocol is developed. A mathematical model is created by using birth-death process theoryfor the Perfbrmance analysis of the NC-PIM. The analytical and simulation result showthat the NC-PareA improves the performance to some extent, and meanwhile may producean upPer lAnit of the perfOrmance PIwt-like protocols can reach. The upper limit isconsequently very significan for the performance eva1uation of diverse PRMA protocols.In ChaPter Three, after the original proposal of data-sPeech integration over the Prmbeing concisely' depicted, a more efficient ddsspeech integration protocol is proposed,which is based on the FPbo. The proposal makes use of a movable border to maximise thethroughput of dds packetS under the requirement to meet the QoS of speech communicationa1l the time. The idea of horizontally reserving slotS created a new way tO efficient[yintegrate dare and speech. Based on this idea and the NC-PIwt, a more advanced data-speech integration protocol, called NC-IPIwt, is proposed. The NC-IPanA increases thechannel throughput up to 90%, and also comp1etely protectS speech service from beingaffected by the burstiness of data service.In Chapter Four, some application background of LEO store-and-forward satellitecommunications is intrOduced first, then a Peculiar slotted ALOHA protocol based on ACK-liSt and local event-synchronisation is presented for the UoSAT microsatellite scenario. Theprotocol both benefitS frOm channel-slotting (doubled throughput) and avoids the costlyimplementation requirement of it (strict netWork synchronisation). The prOtocol also can beseamlessly integrated into TD-SRMA protocoI of PACSAT protocol suite, which is currentIy3functioning in al1 the in-orbit UoSAT sateIlite. More important is that the protocol canemploy captUre effect (commonly existing in fading channels) to substantially increase thechannel throughput. Considering alI the above advantages, the protocol is one of the mostsuitabIe muItiaccess protocoIs for short message transmission in the LEO sateIlitecommunications netWorks.In Chapter Five, the caPtUre effect in fading channels is investigaed in depth. Based on themechanism resulting in the capture effect and the fearere of the LEO channel, Brand-newenhancement measures of capture effeCt, referred tO ring-shaped division of a footprint plusextra power assignInent, are presented. It turns out to be effective and can further remarkablyimProve the channel thrOughput. The evaluation of caPtUre probability is dePendent uPOn theavailability of an accurate evaluation model. To do so, tWo sophisticated models aredeveloPed for Coherent BPSK and Non-Coherent FSK demodulation resPectively. The C-BPSK model takes the carriersynchronisation margin requirement of a praCtical narrow-band radio receiver into accounL and consequently is more reaIistic and more...