LEF • MH: Yesaa Heidi ■••6".. ar. • Coverage Zang.. • N MID NIP ..•••• NFP
Hinh 4.16. Clic chiin lupv chuyin tiep goi
Mac da tinh don gian, djnh tuyin theo vj tri cult node cto the killing tim duqc tuyen hay djnh tuyen kh8ng hi8u qua. 1-11nh 4.17 minh hos nulmg hqp nay. Node Si din chuyen gdi dit liOu cho D. Theo do, node S 1 phai chqn node lan can din nhat den dich la buac ke tiip. Tuy nhien S2 vi S3 deu nim each xa dich hon Si.
Hinh 4.17. Gicii thudt djnh hryin khong hieu qua
Trong m8i tnrtmg mpg WSNs, cac cam Bien throng duqc nhimg vito cac vung kh6 hoc Ichtong the tiep can duqc, su c8 1#p c6 the xay ra. De pha 0 the c45 lip, m8 hinh duqc goi la right-hand rule duqc dua ra. Met g6i xuAt phat til node N i muton truyen den node Ni, xung quanh c6 nhieu node lin c#n thi tuyin duce chin ke tiep la tuyen du tien theo quy tic nguqc chieu kim dOng h6 tinh tir du6ng thing not MM.
Tuy nhien gian de nay g#p phai truong hqp khi tuyen cit ngang dutotig thing nAi nguOn va dich. MOt giai thu#t goi la face traversal nhim tranh cac dung cit ngang.
Neu tuyen duqc chip theo quy tic right-hand giao vai du6ng thing nAi MN ; thl tuyen
duqc chin se la tuyen ke flip theo chieu nguqc kim dog hO.
Minh hoa cho qua trinh cai thien chit luong djnh tuyen khi ap citing quy tic right-hand va face traversal. Gia stl node S i cin chuyen dt lieu den dich la node S. Tuyen du tien (1) tir S I den S2. Ke tiep theo quy tic right-hand chin tuyin (2) den S3. Tuy nhien, tuyin nay giao vol duong thing nei nguen va dich. Neu yin girt' nguyen thi se lam gam hieu qua ciia vies djnh tuyen. VI the tuyen nay can duqc thay the bing tuyen (4) la tuyen ke dip sau tuyin (2) theo chi& nguqc chieu kim ding hO. Qua trinh djnh toyer' dip Am cho den khi tim duqc dutmg den dich.
Si
Dinh tuyen theo vi tri ph6 hop cho mong WSNs vi yeu ciu it thong tin cho dieu khien va Wong tic coc be gitta cac node. Tuy nhien, cac lien ket bit dei xirng va cac dutmg giao nhau lam tang de phirc tap cua giao thirc.
4.4. Kit luln
Dac tinh cua WSN va tinh chit moi truOng la cho viec dinh tuyen trti nen rit kh6 khan. Nhieu giao thirc dinh tuyen duqc dua ra nhu nhOng giei phap kha thi cho vin de
dinh tuyen. VI su phut Win cac img (long mkt WSNs, so citi tier ve mat phin cimg va ding nghe chi tao pin se mO throng cho so phut Wen cac giao thirc dinh tuyin hieu qua km.