Reseafch On Spectrum Handoff And Cooperative Communication In Multi-radio Multi-channel Wireless Mesh Network

Multi-radio Multi-channe l wire less mes h network has become a research focusin the ne xt generatio n broadband wire less access networks for its high fle xib ility,robustness, high ba ndwidth and easy ma inte na nce, etc.In one ha nd,spectrum ha ndoffhas attracted the interest of ma ny peo ple as it can reduce inter ference a mongwire less trans miss io ns and optimize the structure o f wire less network. Curre ntstud ies on spectrum ha ndoff ca n’t guara ntee the connectivity a nd high thro ughp ut o fwire less network whe n spectrum ha ndoff happens, because these stud ies ignore thatspectrum ha ndoff order amo ng multip le links can impact perfor ma nce.In the otherhand, more and more attentio n has recently been paid to cooperativecommunications, which are proposed as a distr ib uted way to combat channe l fadingand achie ve space divers ity via d istr ib uted ter mina ls. Recent stud ies ind icate thatus ing multip le cha nne ls can reduce the wire less inter fere nce and thus greatlyimpro ve the overa ll ne twork capacity. Howe ver, most o f these works on cooperativecommunicat ions ha ve been ma inly limited to the wire less network o f s ingle rad ioand single cha nne l, whic h can not make use of the perfor ma nce of multi-radiomulti-cha nne l.To ma ximize network capacity, we tr y to study the techno logy o f spectr umhando ff and cooperative communicatio n in the multi-radio multi-channe l wire lessmes h network, ma in contr ib utio ns are as fo llows.1.To ma ximize the throughput of wire less network, this paper proposes a nove lspectrum ha ndoff scheduling proble m to solve the sched uling of link fo r spectrumhando ff with guarantee ing connectivity o f network, and proves that the proble m is anNP-hard proble m. To so lve the proble m, we propose a cross-layer optimizatio nalgor ithm by jo int cons ider ing the spectrum hando ff scheduling a nd QoS Re-routing.Spectrum hando ff exec utes in se vera l rounds in the algor ithm. To reduce the tota ldelay o f spectrum handoff a nd to guara ntee the ne twork connectivity, the a lgor ithmcomputes links sets whose spectrum needs to ha ndoff in ever y round based onweighted Minimum Spanning Tree. To satis fy the QoS require ment o f every flow, thealgor ithm co mputes a QoS routing for ever y flow in e ver y round. The s imulatio nresults demo nstrate that the proposed algor ithm can make full use of multi-radiomulti-cha nne l and obtain high thro ughp ut for multip le flo ws. 2.We for mulate a Jo int Routing, Cha nne l ass ignment and Re la y for Thro ughp utMaximizatio n prob le m.To so lve this proble m, we propose an optimized jo intalgor ithm to ma ximize the s yste m throughput. I n the a lgor ithm, we so lve theprob le m thro ugh three stages. The first sta ge is to find an optima l cooperative pathfor flows in network, whic h is based on proposed Conte ntio n Aware Channe lUtilizatio n metr ic. The two is based on firs t stage, and is to readjust channe lassignment, whic h is based on proposed Traffic-aware Channe l Adjustme nt Metr ic.The third sta ge is to readjust routing, re la y se lection loca lly for the cha ngedtopo logy. The s imulatio n results demo nstrate that the proposed a lgor ithm ca n get thega in of c hanne l d ivers ity and cooperative d ivers ity and obta in high thro ughp ut.