Dynamic Polling MAC Scheme Considering Emergency Access in

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Dynamic Polling Media Access Control (DPMAC) ... cy events with different access priorities in WSNs. ... sensor node and is used to transmit poll and query.
Di GI TAL COMMUNI CATI ONS 

Dyna  mi c Pol l i ng MAC Sc  hem e 

Consi deri ng Em m er t  g nc ̄ genc , ,Ac  Access 。 i n  W S  Ns Ba  sed on Pri ori t  i es  Pei  Qi ngqi   ,Chen Chen ,Xi   e  W ei guang  ’ The  St at e Key Labor at or y of   I nt egr at ed Ser v i ces Net wor ks Ndi an Uni v er si t y,   ’ an  710071,P.R.Chi na  ,

I ns t i t u t e   of   Chi na   El ec t r o ni c   Sys t em  En gi ne er i ng   Cor por a t i on,Bei j i ng,P.R.Chi n a  

Abs t r a ct :I n  W l es s  Se nsor   Net wor ks( W SNs ) .pol -   and adi ust ed bandw i dt h ca n pr ovi de  t he par am e—   l i ng can obvi ousl y i mpr ove t he t hroughput  and de—  

cr ease average access  deNy by al l ocat i ng band.  

t er s  suc h as  qua ̄y of  ser vi ce  s uppo ̄ [ 2— 3] .   W  l ess Sensor  Net work s  f W SNs1  suppor t  bot h 

i ke CSM A | c  and guar-   wi dt h ef ici ent l y and r easona bl y.I n t hi s  Paper ,a  random access methods l

 m e t hods l i ke pol l i ng.CSM Af c  has   Dyna ic m  Pol l i ng Me di a Acc ess  Cont r ol( DPMAC)   anteed access scheme desi 2ned accor di ng t o W SNs’f eatur es i s 

a  good  perf or r m nce i n t he sDar se net work  envi ron-  

pr oposed.DPM AC i s a pri or it y based access  con—  

e nt m  but  a poor perf orr m nce when t he number  of 

tr ol   prot ocol  w i th t he char acteri st i cs  t hat  i ts  pol l i ng 

nodes  gr e at l y i n cr eases because of  a l arge num b er 

tabl e i s dynam i cal l y r ef r eshed dependi n g on whet h—   er  t he sensor  node i s act i ve and  that  t he  bandw i dt h 

of   cont ent i ons  e xi st ng  i among  node s[ 4] .Fo ̄unat e—   l y,t he  pol l i ng s cheme  can r easona bl y al oca t e  

s dynami i cal l y al l ocat ed accordi ng t o t he t rafi c 

bandw i dt h for  act i ve nodes  whi ch have t a fi r c to 

t ypes.The access  pr ior iti es are det enr ined by t he e—  

t ransmi t  and  avoi d cont enti ons.However,t he  t radi -  

mer gency l evel s of events  and t he sche dul er  pro—  

t  ̄nal   pol l i ng sc hem e  l i ke  Round— Robi n( RR)[ 5- 6]  

posed i n  OH/ "M AC  s pr i e empti ve based on t he dead—  

makes  channel  ut i l i zat i on decrease and access  de—  

l i ne of  t he event s.Si r m nt i on r esul ts  show t hat  DP.  

l ay i ncr ease when the num b er of acti ve nodes i s 

Ⅳ  C can ef i ci ent l y ut i l i ze  ba n dw i dt h a n d decr e ase 

r m ch sm a ler  t han t he t ot al   num b er  ofnodes i n  the 

aver age access  del ay a n d r esponse t i me f or emergen—  

net work.To overcon ̄ t hi s drawback, son] e r e—  

cy event s wi t h di fer ent  access pr ior iti es  i n W SNs.  

searchers  have proposed schemes to el i mi nat e t he 

Key wol ds:W SNs;pol l i ng;t hr oughput;M AC 

deNy a nd e ne r gy  consum e d nul  pol l s.I n Re f[ 7] ,   a n Embedded Round Robi n ( ERR)sc hedul er  was  

l I  I NTRO DUCTl o N 

proposed i n  r ml ti r nedi a W i r el ess  Local  Ar e a Net.  

As  a  popul ar  M edi a  Acc ess   Cont r ol (MAC)  

by di vi di n g stat i ons i nto dual  queues,i .e. ,the 

scheme,pol l i ng i s w i del y  used i n i nf rast u ct r ure net .  

“busy’   queue and t he “cl ear” queue Skr ml at i on 

wor ks. I n t he pol l i ng system,nodes  i n net work s  ac—  

e sul r ts  show  that  by r e duci n g t he pol l i ng over head 

cess t he medi um  to t ransmi t  or  r ecei ve data i n an 

generat ed by t he pol stati ons  w it h no data t o 

orderl y r mnner,so t hat  t her e  are no access  cont en-  

t ransm it , a l ar ge amount  of bandw i dth can be 

t i pns.W hat ’ s  i l 1) r e,by i mpl ement i ng an ef i ci ent  

saved a n d t hen be al l ocat ed to “busy” user s.  

and r easonabl e schedul i ng al gori t hm,ba n dw i dt h u.  

t her eby i ncr easi ng t he overal l   net wor k t hr oughput.  

ti l i mt i on i ncr ease and thr oughput  enhancement  can 

Al though 瞰

wor s ( k wLANs)t o i nc r ea se  t he  pol l i ng  ef ici e nc y 



has  the abi l i ty t o r e duce nul  pol l s.  

be  a chi eved[ 1] .Anot her   out st n di a ng  char act er i st i c1   i t i s onl y sui tabl e f or  net wor s  w k it h l i ght  or  moder-   of  t he pol l i ng syst em  i s that  bounded access del ay 

at e l oads.The Least —Recentl y— Used ERR rU   一  

2012. 4 

45 

哼园通{ 专   C h i n a   C O I T I W  ̄   n i c a t i o n s   Consi der ing t he charact er i st i cs of  W SNs.we pr o.  

E1   1  al go血 hm,whi ch i s an enhanced ver si on of 

ERR,was  pr ese nt ed  i n Ref .[ 8]t o  i r r or ove  t heⅡ 

pose t he syst em mode depi ct ed i n Fi gure 1.I n t he 

perf onm nce of t he networ k wi t h hi gh l oads  and 

pr oposed syst em  m o de,sensor  nodes di r ect l y ac—  

bur st y ar ri val s.The perf or rmnce eval uati on showed 

cess si n k and do not  need rel ay nodes.Upl i nk i s 

t hat  I R U—E耐   can out per f or m exhaust i ve r ound 

def ined as  a cor nm ni cati on l i nk f rom  the sensor 

robi n under   cond ̄i ons of  syrm' etr i c and asyr m  ̄t r i c 

node t o t he si n k node and i s used to t a nsl r rf it  t he 

t r af i cs.Even t he af or ementi oned  two I   based pr o—  

dat a col l ect ed by sensor  nodes.Downl i nk  s def i ined 

tocol s COUl d i mpr ove t he channel  ut i l i zat i on and de—  

as a conaI  ̄ni cati on l i nk fr om t he si nk node t o the 

cr ease t he access  del ay caused by nul l  pol l s,t hey 

sensor  node and i s used to t a nsmi r t  pol l  and query 

ar e bot h des ned f or  W LANs.I n W SNs,to our  

cor r r mnds.Sensor   nodes  i oi n or   l ea ve  t he  ne t wor k 

best  knowl edge,t her e  i s st i l l  no st udy about  over-  

mai ntai ned by t he si n k  node by sendi n g associ ati on 

coni ng t he nul l  pol l  pr obl em and consi deri ng t he 

r equest s or  di sassoci ati on request s def n ed i i n the 

t af r ic— - t ype- - adapti ve bandw i dt h alocati on st ategy  r



at  t he sar i l e ti me.I n order  t o addr ess  t hi s  pr obl em,  

cei ves an associ at i on request,i t  alocates a 16一 bi t 

Dl PM AC i s proposed.DPM AC di vi des  nodes  i n t he 

shoa addr ess  t o t he sensor  node and adds t he 

W SNs  i nt o act i ve nodes  whi ch gener at e t r af i cs.and  i dl e nodes  w h i ch do not  gener ate t af r i c.I t  al so dy—  

nar r i caly r ef res hes  t he pol l i ng tabl e by i nt r oduci ng 

ac t i ve   node s  a nd  de l et ng i i dl e  node   1 .D] PMAC c a n  al so al l ocat e r esour ces  accor di n g t o t he t r af i c t ypes  

n or i der t o adapt  t o di ferent  t a fi r c f lows  i n W SNs.   Fur t her more。w h en dynami c pol l i ng st i l l  cannot  meet   t he del ay r equi reme nt s especi al l y f o r emergency e—   vent s,a  pr eer r oti ve schedu ̄r  i s i nt roduced based on  t he deadl i ne of events.I n  sunm a ry.D 

AC cannot  

onl y f ul l V ut i l i ze t he syst em  ba n dwidt h but  al so han—   dl e t he net wor ks bur st  data a n d em e r genci es wel 1 .  

8 0  . 1 5. 4 s t andar d r l1 ] .W hen  t he  si nk  node   r e —  

node i nt o t he net wor k nodes  l i st  show n  i n Tabl e I I.   t al I so r e cor ds  t he t a 伍 c t r ype and stat us f acti ve or 

i dl e)i n t he ne 砬 pol l i ng r ound of   t he  s ens or  node.   W hen t he si nk node recei ves  a di sassoci at i on r e—   quest,i t r em o ves  t he node f r om t he net work node 

l i st.T h e sensor node has  t wo t r a珩 c  t ypes.nort ml   and rea1 . t i me t r af i c.whi ch have d  rent   bandw i dt h 

a nd ac cess  de l a y r equi r eme nt s『 1 2] .T he  s nk  i node   al l ocat es  bandw i dt h and assi gns  packet  l engt h f or   the t wo di 仃erent  ki nds  of  tr a 所cs.And because not   al  the  nodes  i n W SNs have data t o send dur i ng t he  same per i od,i n ot her  words,t her e ar e bot h act i ve  nodes  and i dl e nodes i n W SNs  at  a gi ven t i me.we 

1 I _SYSTEM M O DEL  Gener al l y.t he mai n pur pose Of W SNs i s to col l ect   di 仃er ent  ki nds  ofdat a such  as t er r  ̄er at ur e ori mage.   And t he I mi n t ra筒 c f low i n W SNs i s f rom  sensor  

nodes  t o si nk,suppose t hat  t he si nk al ways  has   r mi n suppl y and has  su衔 ci ent  memor y and compu-  

put  t he act i ve nodes i nto t he act i ve nodes l i st  

show n  i n Tabl e HI  and put  t he i dl e nodes  i nto t he i —   dl e nodes l i st  show n  i n Tabl e I V.I n  Tabl es I l l and  I V,t he channel  occupati on  ti me r ef er s t o t he number   of  packets  a sensor  node can send when poled.  

h i T s  di vi si on of  nodes  wi l l  enabl e t he si n k node t o  al l ocat e  bandw i dt h ef i ci entl y by si mpl y ref en- i ng t o 

t he sensor  nodes’t a 跖c t r ype.  

t at i on s pee d[ 1 0] .The   t ypi ca l   par a me t e r s  of   t he  si nk  node and sensor  node are shown i n Tabl e I.   Tabl e  I   Pr i mar y  par amet er s  ofsi nk  and  sensor   node 

i g. r 1  Syst em  mode 

46  2 0 1 2 . 4  

DI GI TAL COMMUNI CATI ONS 

I1 able 11  Net wor k nodes l i st  

pe n  j us t  bef or e t he l as t  pol l i ng f r a e  i m n t he  s upe r -   f r am e  so t hat   t hey can  be handl ed a t  the f ir st  f r am e   i n  t he nex t superf r ame 纬 er ea s  t he wor st  ca s e i s t ha t 

t he  e vent s   ha ppe nj us t   af te r   t he   begi nni ng  oft he   i f r s t   schedul ed f rame and have t o wai t  f or  al most  a whol e  super f r ame t o obt ai n t he oppor t uni t i es  t o access t he  Tabk Ⅲ   cf i ve nodes l i st  

cha n ne1 .The l at t er  case wi l l  undoubt edl y cause t he 

mi ssi ng of  t he deadl i ne of  emer gency  event s a n d  may  cause heavy l i f e and pr oper ty l osses.To i l l ust r ate  how  sever e t he r esul t s  of  mi ssi ng t he deadl i ne ar e,a  ir f e moni t ori ng syst em  car l  be a t ypi cal  e ̄r npl e.W e  11 abk Ⅳ Idl e nodes l i sr  

assun3 g t hat  t he f ire al er t shoul d be r eport ed wi t hi n 5  seconds,ot her wi se t he f ir e wi l l  be out  of cont r o1 .   Ther ef or e  5 seconds  af ter  t he occur ance of  t he event   i s  t he  deadl i ne.The deadl i ne  based em e r gency sched—   ul er   ca n  be e ̄ hi ned by Fi gur e  2.The event  sched—  

ul ed  bef or e  t he  de adl i ne  i s i l l us t r a t e d i n Fi gur e 2( a  

l l l _ DYNAM l c POLUNG MAC  SCHEM E 

whe e  r a n  eve nt   ha ppe ns   j us t   be f or e  t he   end  ofpol l i ng  so that  i t ca n  be  i nset  i nt o t he begi nni ng ofnex t  pol -  

3. 1  NetwOI k  i ni t l " al i zaf ion 

l i ng supe r f r a me.Whe ea r s  i n Fi gur e  2( b) ,t he e vent  

The t mi n task of net wor k i ni t i al i zati on i s  t hat  t he 

shoul d w a i t  f or al most  a whol e pol l i ng per iod t o be 

si nk node shoul d establ i sh t he networ k  node l i st  as  

schedul ed i n t he  nex t  super fam e ,t hus  l riSSi ng i ts f in—  

depi ct ed i n  Tabl e I 1.The net work  node l i st  cont ai ns  

shi i ng deadl i ne.I n  SUl m m y,we not  onl y pr opose a n 

al l  t he nodes’ i nf onm ti on wi t hi n t he si n k node’ s  

enha n ced pol l i ng schem e  f o r nor mal  events  but  al so 

cover age,so t hat  t he si nk can readi ly get  t he ent i r e 

pr ovi de the ha n d ̄ g m e cha ni sm f o r em e rgency e—  

net wor k' s  t opol ogV i nf o nm t i on.Fi rst,t he si n k node 

vent s  based on t hei r  deadl i nes.  

responds t o t he sensor node a s soci ati on r equest  

End  ofpol l i ng 

Fi rst  

and alocat es  a 16一 bi t  short  address t o the sensor  Acti ve  

node.Second,t he si n k node speci ies f  t he t r af i c 

印 

t ype of  t hi s node.I f  t i i s r eal  ti me t r af i c,t he si nk  node wil l  set  t he sensor  node’ s  packet  l engt h to be  1 00 byt es.Ift he t r af i c type i s norr ml ,t he si n k  node  wi l l  set  the packet  l engt h t o be 50 byt es.Thi r d,t he  si nk node shoul d r m ke cl ear whet her t he sensor  

( a)Ev ent   ha ppe ni n gjus t  

( b)Ev ent   ha ppe ni n gjus t  

be for e   end 

a ft e rbe gi nni ng 

i g2 Emer r gency events 

node wi l l   be acti ve or  not  i n  t he next  pol l i ng r ound.  

3. 2 W or ki ng pr ocedur e 

I ft he sensor  node’ s st at us  i s act i ve i n the nex t pol -  

One pol l i ng r ound can be di vi ded i nt o t wo pa rt s,one 

l i ng r ound,t he si nk  wi l l  add  t hat  node i nt o t he act i ve 

bei ng wor ki ng per iod,a n d t he ot her  bei n g sl eepi n g 

node l i st  as shown i n Tl abl e Ⅲ :ot her wi se i t  wi l l  add 

per iod,as  show n  i n Fi gur e 3.I n  t he sl eepi ng per iod,  

t hat  node i nt o t he  i dl e  node l i st  as shown i n  Tl abl e  I V 

t he sensornodes  t ur n  of thei rmdi o t o save  t he  ener-  

I n emergency conm ̄ni cat i on systems,an event  

gY consumed i n i dl e l i steni ng.I n  t he wor ki ng per iod,  

it w h hi gh  pr ior it y  shoul d  be   ha ndl ed  i mmedi at el y  f or  

t he si nk  pol s the act l i ve nodes  t o get  t hei r dat a and 

ts i  st ict r  del ay l i mi t.Ther ef or e ,t he af or em e nti oned 

sends quer y to them.I t  al so pol l s t he i dl e nodes t o 

em ̄ne t hei r  st at us i n t he next  pol l i ng r o und.   sc hedul e   wi l l   pr obabl y  r r  ̄ ss  t he   e me r gency  event s  i f   det t happens i  i n  t he earl i er  par t  oft he  pol l i ng super f r ame.  

1 )Pol l act i ve   nodes  

The best  case of  emer gency event s  i s t hat  t hey hap—  

W e pol l  acti ve nodes  shown i n Tabl e HI  usi ng 

2012  4 

47 

/ { 『 西迤{ 专  

chi na  Com m uni cati ons 

r r  ̄di e d  l f Di s posabl e   Token  MAC  Pr ot oc ol( DTMP)   [1 3] ,as  shown i n Fi gur e  4.The  n ̄di icat f i on i n—   cl udes  three aspects  as  f ol l ows.  

Fi g3  An e xampl e  o fDPMA  C 

5  Ex ampl e  f si o nk  nodepol b i dl e  nodes   3、Pr eempt i ve schedul e f or em e rgency events   W hen emergency event s happen.t hey shoul d 

be queued by t he ti me s   equence of  thei r  deadl i nes  

i n an Fi rst  I n Fi r st  Out (FI F0、or der  and be as.   ig, r 4  Modi fed  di s posabl e  t oke n MA  Cpr ot ocol  

si gned  pr ior it i es  based  on t he posi ti on i n t he queue  so that  t hey can be repor t ed wi thi n  a preset  al er t  

Fi rst.t he si n k  node uses  d  rent  packet  l engt hs  and channel   occupati on t i mes,whi ch ar e  menti oned  i I 1  Tabl eⅢ .to adapt  to dm r ent  tr a街 cs  i n W sNs.   Second,we change t he dat a pr ocessi ng or der i n  DTMl P.I I 1洲

P.aft er  nodes  get  pol i ed.upl i nk  dat a 

s f i ir st  sent  and t hen downl i nk dat a i s recei ved,  

whi ch does not  mat ch t he character i sti c of  W SNs.   I n t he W SNs.dow n l ink dat a i s al ways  quer y or   cont rol  conaTand a n d upl i nk data i s al ways answer   or  r epor t.Thus t he quer y f rom   downl i nk shoul d be  deak wi t h f ir st.and t he upl i nk  n swer i a s  sent  j nm 一   di atel y.   Th砌 .a shor t contr ol  f rame l i ke Acknowl edgement  

( ACK)a n d No Pac ke t  i s pi ggy— ba c e d wi k t h da t a  tr ansr r i ssi ons  i n or dert o reduce syst em over head.   Fi n al l y.we def ine t hat i ft he si n k node consecu-   t i vel y r e cei ves two “No Packet”si gnal  f rom  one  sensor  node i n  t wo hi ni - edi atel y pol l i ng rounds,t he  si n k node removes t hat  node f rom  t he act i ve node 

l i st  and puts  i t  i nt o t he i dl e node l i st.  

2)Pol  i dl e  nodes   W e pol i dl e nodes show n  i n Tabl e I V  to det er-   r mae whet her   t hey  have data  to t r ansr rf i t  i n  t he  ne殖  pol l i ng r ound or not.I f t hey have,t he si nk node  e moves r  t hem f rom the i dl e nodes l i st  and t hen  puts  them   i nto the acti ve  nodes  l i st  and uses  m o di -  

led DTM P  f to  pol l   t hem i n  the next  r ound.The si nk  node uses  short  pol l  f r ame  to quer y  t he i dl e sensor 

nodes,and i dl e sensor  nodes  use shor t “Have Da-   ta’ ’or“No Data”response  to r espond.as  depi ct ed  n Fi i gur e 5.  

48  

2012. 4 

e伍  ct v e per i iod.The af o rem e nti oned FI F O queue i s 

nam e d pr i r m ry queue and created when t he fi rst   node i s pol ied.The queue si ze can be pr eset  based  on t he f requency of  emer gency event s occur rence.  

The earl i est  deadl i ne event  i s pl aced at  t he head of  the pr i n ̄r y  queue and t he l atest  one at  the end of  the queue.Fur t her mor e ,an auxi l i ar y  queue i s set   o r l f at er  occurance of event s when the pr imar y 

queue i s f u1 1  and i s al so ordered i n  the sai r l e l i lt n—   ner  n  t i he pri r mr y  queue.The aux i l i ar y  queue wi l l  

be pr ocessed af ter  t he pri r mr y  queue has been  popped.W hen t he auxi l i ar y  queue i s i n pr ogress,   t he newl y generated events  wi l l   be coHect ed by t he  pf ir mr y queue.That   s to say.t i he r ol e oft he  pr i rm —   y  and auxi r l i ary queue wi l l  be exchanged when ei -   t her  them has  been em p ti ed.The r easons of  thi s  e cha m n i sm  are:f irst,the m o st  i mpor tant  em e r gency 

events  wi l l   not  be i nf luenced  by t he newl y gener a—   ted event s i f  they ar e put  i n to t he auxi l i ar y queue;  

and second,i ft he deadl i nes oft he newl y gener a ted  events ar e al ways  ear l i erthan those al readY sched—   ul ed i n t he queue,the event s occur r i ng f ir st  but   i th a l w ater deadl i ne wi l l   be hungr y  or  even dead,  

otherwi se t hey m a y have never been schedul ed.   On t he ot her  hand,t he non— pr eempt i ve schedu-   l er  i s not  f it  f o r emer gency connm ni cat i ons.The  e ason why the non— r pr e em p t i ve m e chani sm f ai l s t o  handl e em e r gency events  i s descr ibed i n  Fi gure 6.   The events  shoul d wai t f o r  the ne对 super iar f ne t o 

be   ha n dl ed  base d  on  t hei r  a ssi gne d  pr ior it i es  so 

DI GI TAL COMMUNI CATI ONS 

t hat  r r  ̄st  of  t hem  mi ss  t hei r  deadl i nes  i n Fi gur e 6.   As  a r esul t,we desi gn t he emer gency schedul er   based on t he pr eempt i ve mode as  shown i n Fi gur e  7.W hen emer gency event s  happen,t hei r  occur-   rence r epor t ed by t he i nt er rupt er  i n devi ces  wi l l  be  br oadcast  i n net wor ks.The comi ng pol l i ng node 

I f  not f ul l ( t r r pQ1 )/ / Det er r r me  t he  posi t i on of  cur r ent  pol -   l n g. i  

{   node i d = get —



node(i nt er r upt) ;/ / Cet  node i d f rom i nt e r -  

a pt r  r egi st e r  

t r r pQ1 一> nex t=node—i d;   / / Def ine  t er npomr y queue  t p Q  m 1  

wi l l  be pr eem p ted by t he em e r gency event  r epor-  

Lock;  

ti ng node when i t   recei ves  the  pol l i ng cont rol   f r ame 

Pr i or i t yMQ一>nex t =node—i d;/ / Ass ̄ni ng i ni t i al   pr ior i t i es  

i ssued by the net wor k si nk.Ther ef ore,t he enl er-  

I / Loc ki ng  cr i t i cal   ar e a f rom  concur r ent  r unni ng 

o ri f nt e r r upt  e vent s  i n pr i r mr y queue 

W hi l e( non empt y( Pr i or i t yMQ) )  

/ / W hen pr i -  



gency r epor ti ng nodes  wi l l  be pol l ed i nm' edi atel y 

mary queue l s  not empty,cont i nuous  preem p t n g  i

by t he  si nk i us t  a f t e r  f ini shi ng t he  c ur r ent  poled  node.Therefore,t he other wi se l ong del ay or  even 

{   Pr i or it yMQ一>nex t =mi n( dea dl i ne( t p Q、 m  / / Nodes   i n  pr im a r y  que ue  s sor i t ed  by  t hei r   dea dl i nes.  

deadl i ne mi ssi ng can be avoi ded by our  pr oposed 

node i d= r unO一>ne xt ;  

r unQ一>nex t= Pr i or i t yMQ一>nex t;   d;   u nQ一>nex r t 一>nex t =node i }  

pr eem p t i re schedul er.W hen t he pri n ̄r y and auxi l —   i ary queue are bot h empt y,t he dehyed nor n ̄l   nodes  wi l l   be pol l ed by t hei r  ti me sequence.  



Unl ock;  

// Unl ock cr iti cal  area 

}   el se   / N e / wl y ge nemt ed  event s  st or ed  i n a uxi l i ar y queue  

t p eQ2  m {   node i d = get nod e( nt i er r upt ) ;   —

_

t p Q2一>ne m t =node—i x d;   Lock;  

Fj g  Non- pr eempt i ve   schedul er  

d;   Pr i o ̄yAQ一>next=node i W hi l e( em p t y( Pr i or i t yMQ) &&( non—em pt y( Pr i or i t yAQ) )   —

{   Pr i or i t yAQ一>nex t=n " m( dea dl i ne( t p Q2、 m   node i d= r unQ一>nex t ;   unQ一>next= Pr r i o ̄yAQ一>nex t;   unQ一>nex r t一>nex t =node—i d;   }   —

Unl ock;  

i g. r 7  Pr eempt i ve  schedul er  

The ps   eudo code of  t he af or em e nti oned mecha-   ni sm  can be pr esent ed as  f olows.  

33 M ai nt enance of  DP] M  C  Of t en car ryi n g di fer e nt  t ypes  of tr af i c such as  vi deo,audi o,tem p er at ur e or  humi di ty et c. ,a sensor 

Whi le( t r ue) / /I nt er r upt  can be  t r i gge r ed by any  par t  of   t he  pmgmm, vi z   F amr ge ncyl SR0  {   f or( node—i d=1 ; node—i d<num( nodes) ; node—i d++)   {  

node al so has  di ferent  needs  f or  packets  si ze and 

avai l abl e bandwi dt h f or  gi ven m o m e nt s and events.   Our  pr oposed DPM A C can  pr ovi de t he m e chani sm 

it w h dyna ic m  adj us t e nt m  t o t he  needs  f or   pac ket s  

i f  have Dat a( node i d) {  

si ze and  bandwi dth so t hat   i t  can f it  f or   com p l exi n—  

mnQ[ node—i d]=1; / / RunQ  i s  queue  f or   act i ve  nodes}   el se{   i dl eQ[ node—i d]=1 ;/ / I dl eQ  i s  queue  or f   i dl e  nodes}  

tegmt ed appl i cat i on scenanos.  

}   Pol l ( runQ) ;   / / Pol l i ng act i ve   nodes  queue   Shor t Pol l ( i dl eQ) ;/ / Shor t   pol l i ng  i dl e   node s  que ue   }   En'  ̄r gencyl SRO / / nt I er r upt  se r vi ce  r out i ne 

The wor ki ng procedur e f o r dynam i c t uni n g i s  deputed i n detai l  as  fol l ows:  

1 )I f   t her e  e is f t s  a ny r e ques t  f or   t he  t uni ng of  packets  si ze or  bandwi dth needs,i t wi l l  be f orwar -   ded to t he si n k node through upl i nks.  

2012. 4 

49  

呻 迤怯  C h i n a   C o m m u n i c a t i o n s   2、The requests  wi l l  be admi t t ed or ref used ac—  

Tabl e V Si mul at i on par ameter s 

cor di ng t o the r esour ces  uti l i zati on stat us  i n curr ent   net work.  

3)I f   r equest s  ar e   per mi t t ed,si nk  node  wi l l   t r a ns—  

Parameters  

Val ues 

Ar ea ( m×m1  

1  50o× 1  50o 

Bo  SO 

it m  an ACK corespondi ng t o the pr evi ous  r e-  

Nodes nurr ber 

10 

Packets si  / Bvte  

1 27 

dopt  t he new  par a met er s i n t he next  pol l i ng t ur n .If 

Si mul at i on t i me/s 

30o 

r equest s ar e ref used,the si nk node al so sends  an 

Aba se   s upe rf r a n  ̄ du r a t i on(S ymbol s)  

96o 

ACK t o the appl i cant s t hat  wi l l  keep thei r ori gi nal  

Normalt af r i c 

100  packet s/s 

Real -t i me t ra伍 c 

150 packet s/ s 

Bandwi dt h/ M bps  

l  

quest s t hr ough downl i nk and t he recei vers  wi l l  a.  

paramet er s.  

ChJster  nun' ber 

I V.PERFORMANCE EVALUATI ON  4. 1 Si mul at ion assumpti on  I n t hi s  sect i on.we eval uate t hr oughput  and aver-   age acces   s del ay perf orr m nce of  t he propos   ed DP—   M A C scheme.To make a  perf orl m nce compari son.  

we i nt roduce t hr ee pol l —based pr otocol s  for r esul ts  evahat i on. One  i s  t he  tr adi t i onal   RR  pol l i ng  schem e  and another i s  t he modi ied IR U一 f  Ⅱt R  str at egy whi ch has been coded f o r W SNs  bas   ed 

on  t he   RR  modul e   of   NS229  pl a t f or m『 1 3] .Besi des,   because our  DPM AC i s m o di f ed based on DTM P.  

we  t ake   DTMP  as   t he   t hi r d  c om p ar ison  obj ec t.The   i mpl ementat i on of  IR U一日RR shoul d al so i nt r oduce 

a   new  queue   o del m   L R U O i n  NS2- 29  t o st or e  t he  l atest  used pol l ed st at i ons  or  nodes,wher e t he i m-   pl ement ed queue m o del  i s used t o st or e nodes  ac—  

Cor r  ̄ runi cat i on r ange/ m 

10o 

1 )Thr oughput叼i s  de ine f d i n F _ q.( 1 ) ,whe e  r P  de—   not es  t he amount  ofdat a r ecei ved by t he si nk node  6l 0m  sensor  nodes  and i ts  uni t  i s bi t.T denot es  t he  r ecei ved t i me i n seconds.a n d C  denot es  t he capaci t y  ofchannel  i n bps.  

叼 = P/  C 

( 1 )  

2)Ave r a ge   acce ss   del ay  T  i s  def ined  n  i Eq.( 2)   whe r e Ef  , 1  denot es  t he  1 T  ̄an val ue  of  t he / t h  node’ s  access  del ay.and N  denotes  the tot a1   Rum-   ber  i n  W SNs.  

T   =∑E ( T   ) / Ⅳ 

( 2 )  

f= 1  

3) Bandwi dt h  Ut i l i z at i on 

s def i ne i d i n  Zq.( 3) ,  

where A  B denot es  the used bandwi dt h by al l oca—   ted sl ot s and C denotes  t he channel   bandw i dt h.   B U = A  B 

( 3 )  

cordi n g to t hek deadl i nes i n our  DPM AC.Furt her -   L  

more,a l ot  of  ti mer s are used t o to guar a nt ee t he  sat sf i icati o n of t he del ay  r equi rement   and t he  good—servi ce  out put  i n 删

一 ERR,whi ch j ust   needs  

a sl i ght  m o di icat f o n on our DPM A C pr i ot oco1 .At   ast,t l o show  the great  perf or r m nce i mprovem e nt  i n  our  di scussed scenar io,we al so conduct   a com p ar i-  

42 Si mul at ion Iesul t  and a n al ysi s 

F ̄ur e 8 s hows  t he  t hr oughput  of  t he I  U一 日  schenl e,DPMA C  scheme  rM P schem e ,RR schem e   n d CsI a vI A/CA schem e  wi t h  the i r l cr e ase oft he nurn-   ber  ofact i ve  nodes  i n t he  nonm l   t r afi c l oad.Uht i l   t he  nur r ber of acti ve nodes i s 3.the CSⅣI A/CA schem e  

son bet ween DPM A C and tr adi t i onal  cont ent i on—  

has  t he best  per f or r m nce.However.when the nur r ber 

based pr ot ocol  CSM A / CA .The CSM A/CA per-  

of act i ve nodes  i s gr eater t han 4.t he ( I 、  A/ CA 

or f r m nce eval uat o n uses i  t he M AC—CSM A m o dul e 

schem e  has  ver y  poor  pefonm nce.The r ea s on i s t hat  

i mpl ement ed i n N S229 as t he si r ml at on t i oo1 .  

t her e i s t oo I I 珊 v cont ent i ons a s  t he  number  ofacti ve 

The poi n ts  on si r r  ̄l ati on r esul t s cur ves  ar e t he 

nodes  i n cr ea s es.The  I U—E R  pr ot ocol  show s  bet t er 

aver a ge of  t he val ues  obtai n ed f rom l00 t i mes  of 

per f onm nce on t he t hr oughput  u n der  nonral  t raf i c 

M onte Carl o tests.The used si r r ul at i on par am e ter s 

l 0ad.Ⅵ, } l en t he nur r ber  of act i ve nodes i s gr eat er 

ar e  l i st ed i n  Tabl e V and t he i mport ant  eval uati on 

t ha n  3.删

vaf iabl es  ar e l i sted as f ol l ows.  

e ng di m fer ent  schem e s.However,a f al l i ng appear s 

50  2 0 1 2   4  

一胍

near l y ha s  t he best  perf onm nce a-  

DI GI TAL COMMUNI CATI ONS 

when  t he   numbe r   of   a c t i ve   nodes  i s  gr e a t er   t ha n 7   by 

m ey can dynan ̄cal l y alocate the channe1  occupa—  



一ERR The l eason of  thi s phenomenon i s t hat  t he 

ti on ti me f or  the sensor  nodes  to adapt  t o t hei r  t r af -  

U J 一日 R  have speci al  mechani sm  t o ha n dl e peri odi cal  

ic t t ypes.DTf v IP and RR bot h exper ience sever e 

n d passi a on ar ival r  t r aff ics  when t he 1 oad i s r el ati vel y 

per for mance degr adat i on under r e al — ti me l oad be-  

l i ght  a n d i t  al so di vi des  nodes  i nto 2 queues  “busy’ ’  

cause  t hei r  bandwi dt h  alocat i on  st rat egy  i s 

n d “cl a ear” queues.t o avoi d  nul l   pol l s.However,when 

n dependent i   oft he t raff ic  t ype and packet s l engt h de—  

t he t r af i c l o ad cont i nues  t o i n cr ea s e.  

t el rmaat i on st r ategy.T h e C 



begi ns 

t o ex p er i ence per f omance degr adat i on due  to i ts l ower 

/CA ha s  cor npambl e 

t hr oughput  per f or mance f or  e al r — t i me a n d norr ml   t r af -  

pri or i t y set t n g on “cl i ear” nodes.w h i ch ntl kes i t de-  

ics.I t t i s f or   t he  r ea son  t ha t CSMA/ CA i s de s ̄ne d  ge ne mt e  t o a s kwl e RR s c hedul er  j us t  on “busy”   f or content i on. . or ient ed a n d equal  probabl e- - access   node.The Dl PⅥAC scher r e  ha s  a st abl e and good  per -  

ser vi ces  w h i ch are not  sensi twe to t he t r af i c t ypes.  

f or r r ance a s t he l oad i n cr ea s es.I t  i s d u e t o t he use of  2- queue st r at egyegy  ai ning  at   el i r r ma ti ng t he  nul l   pol l s.  

Furt her r mr e,i ts  shor t pol f rar m ca n  efecti vel y capt ur e 

t he   bur st   t r af ic s   hi w ch i us t   a r r i ve   a f t e r   t he   l a st   pol l   o n  “i le” nodes.] d f l 1 i s st r at egy c an not  onl y a s si gn hi gher   pr i or it y t o “busy”nodes  but  al so c onsi der  t he f ai mess   “bu s y’ ’a n d “i dl e” no de s .T h er ef or e .DPM AC  has  bet t r per e f orr mnce t ha n  I _ RU-Ⅱ  when t he t r : l 伍c  1 oad i s heavy.The DTMP schem e  has  m e di um  per f or m-   ance a r m ng t h e  5 scher ms  becau s e ofi t s ext r a  nul l   Dol l s.   Hov ̄ve r,i t  st i l l  s hows pr ef er abl e per f onmnce cor r par ed 

wi t h R1 L  h e r T eason i s t h at  DTM P r m di ies f  t he pol l - e- r  

q ue st - pol l - da t a   c ycl e  i n RR  wi t h  j us t  a  p o l- da t a  c ycl e,  

- 9  Thr oughput  i n r eal - t One  t r a f ic  f oa l d 

t her eby el i r r i nati ng  t he need  t o pol  al l   no de s.   Fi gur e  1 0 show s  t he LRU- ERR schem e ,DPM AC  scheme,DTM P schem e ,  RR scheme  a n d CSⅣ【 A/ CA 

schem e  w it h t he i n cr ea s e of t he nur r be r of act i ve  nodes  i n  t he norr ml  t r af i c l oad.Unt i l  t he nur r ber  of  t he act i ve nodes  becomes  3,t he aver a ge access  del ay  of  G ⅥA/CA  becomes  sr ml l  because  of  t he smal l -si ze   system  over head.However,t he aver age access del ay  of CSM A/CA i s dmn ̄ti cal l y i ncr e ased when t he 

number of acti ve nodes  get s gr eater t han 4,t he  phenom e non i s because oft he l ar ge num b er   ofcol -   1 i si ons.The U   一日 R  st r at egy  ha s  t he  best  perf or m-  

nt a e e s pec i al l y whe n t r af ic  l oad i s r el at i vel y hea y. v   ig. r 8  Thr ough put  i n norma l   t r a f ic f  l oad  Fi gur e  9  shows t he t hr oughput  perf or r mnce coi n-  

par i sons  bet ween dl ferent i  prot ocol s under  r eal — ti me  tm伍 cs.I t  i s not abl e t ha t U  — ERR and DPI  AC  have compar abl e perf or mance i n t hi s scenar io.The  e ason i r s t hat  t hese t wo schemes  bot h have t he a.   bi l i t y t o adapt  t he t af r i c t ype i n thei r desi gns,i . e. ,  

The tea s on i s t ha t 删

一I  R ca n  wel l  consi del "t he 

f ai m ess  bet ween “busy” and “cl ea r ” nodes bv j I 1 t ro—   duci n g a n  ext a m r e cha ni sm  t o r ecor d t he l at est  used  sta ti ons/ nodes,t her e by r e sul t n g i i n  a l owest  aver age  access  del ay.The Dl PI  AC schem e  al so ha s  a st abl e  and good perf or r mnce on aver age access  del ay due  t o i t s  2- queue schem e .Fur t her r r or e .t he r e duced pop 

l i ng st eps a nd pi ggyback m e cha ni sms  descr ibed i n 

2012. 4 

51  

呻西逼镊 

Chi na  Com m uni cat i ons 

Sect i on 3. 2 al so cont n' but e to t hi s good per f or ma nce.  

The per f or r m nce compari son ar r  ̄ng t he LRU—  

DTMP and RR al ways show poor per f or r mnce when 

ERR scheme,DPM AC scheme,DTM P schem e .I  

t her e are nul l  pol l s,i . e,w h en t he nur r ber of acti ve 

scheme and CSM A/CA schem e  consi deri ng the e—  

nodes i s smal l er   t han  the nur r ber  oft ot al   poled  nodes.  

mer gency events  shown i n  Fi gure 12.W e count  

t he number  of  mi ssed events  f or each protocol  as   t he per f or r m nce eval uat i on par am e ter.For  ever y  acti ve node,t he pr obabi l i t Y f or  the occur ancc of  e—   e r m gency event s i s 

whi ch i s  expressed as  f ol -  

l ows.  

( 4)  

P :  ×  N 

wher e N i s t he num b er  of  acti ve nodes and Tr  de—   notes  the degree of  emergency event s burst.Tr i s  set  t o 3 i n  al our  si r ml ati ons corr espondi n g t o a  e di m um degree burst. For  an acti ve node not  

pol l ed,i f em e r gency event s ar e gener ated on i t,  

t hen the t i mes  of  occurance shoul d fal l  i n (t  BI—  ng. 1 0  Aver age  acce ss de  i n  nor mal   f 呦  l oad  The r esul t ant  aver age access del ay perf or r mnce i n  e al r —t i me  t af r i c l oad i s si mi l ar  t o  t hat  i n  nonm l   t r af ics, f   eⅪ: ept  t he sever e per f or mance degmda ti on f or RR 

scher i l e,as  shown i n  Fi gur e  11.I n r eal - ti me tr af i c  l 0ad.r r l or e nul l   pol l s a n d t he f ir ed bandwi dt h al l oca-   ti on st r ategy used i n RR f ur t her  l ll t ke i t  waste t he  pr eci ous access oppor tuni t i es.T h e LRU- ERR  and  DP—   M AC both consi der  t he access  oppor tuni t y t o di fer -   ent  t yoes oft r af i c,t hus  r e sul ti ng i n a compar abl e r e—   sui t.However,w it h t he r educed pol l i ng st eps,pi ggY—   back  n d t a he abi l i t y t o adapt  t he t r af i c t ypes.DP-   M AC  shows  a sl i ght l y bet t er  perf or r mnce t han LRU—   ERR  especi aHy when t he t r af i c l oad i s heavy.  

f 1 .where t  denotes  t he cur rent  t i me and BI  s t i he 

l e ngt h of   a  s upe r fam e  e xpr ess ed  n  i Eq.( 5) .   I = A base superf rame durati on x  2 

f 51  

I n  Eq.( 5) ,a BaseSupe r f r a e Dumt m i on i ndi ca t e s   t he r mai r r  ̄m  l engt h of  a superf rame and BO i s the 

Beacon Order by whi ch t he beacon per iod wi l l  be  determi ned at  l ast.The acti ve dumti on l engt h of 

t he   beacon i s def ine d  by  SD  as  Eq.( 6)e pr x e sses.   SD = A base  sup er f r ame  dur at i on x  2  

f 6)  

wher e SO i s the Super f ram e  O r der and has t he f o1 -  

l owi ng  r el at i on  it w h  BO  as  Eq.f 7)descr ibes  when  beacon model  i s enabl ed:   0 ≤ SO ≤ BO ≤ 1  

( 7)  

Each param e ter i n Eqs  ( 5— 7)has  be en l i st ed i n 

Tabl e V  and al l   deadl i nes  of  em e rgency event s ar e  set  t。 f +

B  I

× 3  n  au our i  si Ⅻ l at i 0ns  

As  Fi gure 12 shows,LRU— ERR,DPM AC and  CSM A/CA al l  have bet ter per for r m nce on t he ca—  

bmt y of  e spondi r ng t o em e rgency event s t han t he  t wo si r r ol e  pol l — based schem e s,i . e. ,DTM P  and RR.   The count  of  mi ssed events  for  DTM P and RR  pol —   l i ng i n Fi gure 12 i mpl ies  t hat  t hey are not  f it  for e-   mergency cor m mni cat i on syst em i n  nat ure.The 

reason i s t ha t  t he  pol l i ng schedu ̄r  has al ways  pre—   det er mi ned t he nodes  l i st  to be poled and cannot   respond t o  t he  new events   genemt ed  i n  t he 

Fi g. 1l  Aver a ge  a cc ess  d e  i n r eal - t i me  t r a f fw l oad 

52 

201 2. 4 

proces  s  of pol l i ng especi aly f or em e r gency ones.  

DI GI TAL COMMUNI CATI ONS 

I n a f ew cases,t he pol l i ng can guar antee t hat  t he 

RR  n d CSM A/ a CA pr ot ocol s.Fr om   Fi gure 1 3.、   f ind 

repor t  of emergency events  f ini shes  bef or e dead—  

t hat  t he ba n dw i dth  ut i l i  ̄t on  i of  Dl PI v IAC  s st i i l l   hi gher 

l i ne,because t he happeni n g moments  of t hose e—  

t ha n  t he  ot her   f our  prot ocol s  w it h  di fer ent   t r afi c  l oa d s.  

vent s  a r e  j us t   bef or e   t he   end  of   t he   cur r ent  s upe ̄ 

h e  T rea s on i s t hat  

f r am e . DTM P i nt roduces  the  i nter acti ve  quer y 

by i nt r oduci ng t he er mr gency event s  ha n dl i ng r r echa-  

str at egy bet ween cont r ol  and pol l ed nodes  whi ch 

ni sm   Cor r oar ed  to DPM AC,C  A/ CA has a l i t t l e舢  

coul d caDt ul e some em e r genci es to a cer tai n ext ent.  

i n ba n dw i dt h  uti l i z at i on due  to i t s  wast e  ofti t e  i l n  col l i -  

The bet ter  per f or r m nce of  the CSM A / CA protocol  

si ons r esol ut i on.U  一E R al so shows a  sl i ghtperf or n ̄ 

s at i tr i buted t o t he fact  t hat  i t  i s f ai r  f or  any event s 

n te degener a at i on cor r oa red w it h t hat  of  DPI v I AC  but  

wi th di   r ent  access  pri or i ti cs  and pr ovi des equa1  

ha s a cor r oambl e BU  wi t h CSM A, CA.T h e l ea s on i s 

channel   access pr obabi l i ti es t o al l   nodes.Ther ef or e,  

t hat  I刚 一E R al so en ̄l oys t he efecti ve ba n dw i dt h 

em e rgency events  can al s  o obtai n equal  channel  

assi gnment  st r ategy ba s ed on t he deadl i nes  of  bur sts  

access  probabi l i t Y  based on t he number  of  t ot a1  ac—  

n d i a nt r oduces“busy”a n d “cl ear’ ’queues  t o save  t he 

ti ve nodes and r mi nt ai n a l ower  mi ssed deadl i ne 

pmci ous  ava ̄bl e ba n dw i dt h.Al t hough  RR  s desi i gne d 

than t he pol l i ng schem e  at  t he sacr i ice of  f access 

t O  ly ut i l i ze alocated sl ots.i t  pr esent s  t he l owest  

probabi l i t y of ot her  real  or  non—r eal  t r am cs.DP—  

ba n dw i dt h  ut i l i  ̄t i on among  t he  ive pr f ot ocol s.The  r ea-  

, I AC  l l y ut i l i ze s t he i dl e sl ots  

M A C can adapti vel y handl e the events  gener at n g  i

sons her e i ncl ude:f ir st.RR cannot  accur at el y f ol e ca st  

nodes  based on t hei r categor ies.i … e  act i ve,i dl e or 

t he sl ot s t o be alocat ed:second.due t o nodal  power  

emergent.I n case oft he occur ance  ofem e rgency e.  

ai f l ur e,n- ovi ng away f rom conlr tmi cati on r ange a n d 

vent s,i t  i nr ̄ di atel y preempts  t he next  sl ot  f o r 

cl ock synchr oni zat i on l oss  et c,i t  has a gr eat   pmb ̄ i l i t y 

handl i ng aft er  the cur r ent  sl ot.W hen no el rergen.  

t o waste t he alocat ed sl ot s;t hi r d,i ts appl i cati on see—  

cy event s occur,t he af or em e nt i oned dynami c pol -  

nar i os f ocus  r m ̄ at y on 

l i ng scheme wi l l  take ef f ect.A ccor di ngl y,DPM AC 

say,t he aHocat i on scher m wi l l  not  change f or a l ong 

can bot h guar ant ee l ower mi ssed deadl i nes  a n d keep 

peri od once i t  ha s  been det emm ed.I n vi ew of  t he a-  

t he ba n dwi dt h ut i l i z at i on f ai r f or  t he nodes.The U   .  

bove r ea s ons.RR  i nevi t abl y ha s  t he l owest  ba n dw i dt h 

sbt s al l ocat i on.t ha t i s to 

i l i  ̄t i on  a mo ng  t he  ve i f   pr ot oc ol s.S i ni l a r   t o  RL  r_   ERR  s c he me  ha s  a so l  i nt r oduce d adj us t a bl e  del a y. de —   ut pendent  pol l i ng m e cha ni sm whi ch ca n  capt ur e t he e-  

Ⅳ【 P al so pr esent s poor   per f or r mnce but  ha s  a l i t t l e i m-  

r r er genci cs ba s ed on t hei r ea rf i ̄ deadl i nes.  

pmver rent  t o RR due t o i ts  i nt er acti ve quer y n- echa-  

ni sm  whi ch coul d save some  ba n dwi dt h a n d do not   pol al l  nodes.  

| 2  Ti me s o fmi ssed  e mer genc y eve nt s  

Rga 3  a, 川口 讲 D o fbandwi dt h  ut i l i z at i on 

Fi gur e 1 3  shove s  t he  compari son ofba n dw i dt h  uti l i za-   ti on  per f or r mnce among  t he  I _ RU-ERR,DPM AC,DTM P,  

2012. 4 

53 

/ j F 西逼怯  C h i n a   C o m m u n i c a t i o n s   t or mt i on  and  Remot e  C o nt r ol ,200 9,70f 6) :997— 1 01 8.  

[ 7]RANASI N  { E  ANDREW L,HAYES D,et   a1 .Schedul i ng  111 e DPM AC schenq e desi gned f or  W SNs  Ve ls pr a o—   posed i n t hi s paper.The pr oposed scher r e i ncr eased  t he  t hroughput  and decr eases  t he  aver age access  del ay 

by  avoi di ng col l i si on i n heavy  t r af i c l oad  n d  a by f o cu—  

Di sci pl i nes  f o rM ul ti r nedi a W LAN s:Embedded  Round  Rob.  

n  i and W i r el ess  Dual  Queue『 C] l l  Pr oceedi ngs of   t heⅡ E  I nt e ma t i onal  C o nf er ence on Conrm ni cat ons. J i ul y 11— 1 4.   2001,Hel si nki ,Fi nl and.I皿

[ 8]ANDl RFⅣ L RANAS  

Press  2001.4:1243—1248

. 

{ F R Opt i nis i ng t he  Pol l i ng Se—  

si ng  j us t   on  t he   a ct i ve   nodes   whi ch  ha ve   da t a  t o  t i a ns .  

que nce  i n Embedde d  Round  Robi nⅥ, I   ANsf C1 / /Pr oce edi ngs  

nit.The pr oposed scheme can al so ad a pt  t o di fer ent  

of  t he Ⅱ 1 且E I nt em a t i onal  Conf er e nc e on W i r l e sskANs  and 

t ype s   of   t af r ic  l oa d  by  dyna r r i ca l l y a d j us t ng c i ha nne l   occupat i on  ti me,w h i ch r m de i t  have a good per for m-   ance  bot h i n  t he ca s es of  nor r ml  t r afi c bad a n d r eal —   t i me t rafi c bad.  

Hom e   Net wor k s, 20 01,Si nga por e.嘧

Pr es s, 20 01:1 77 — 1 86 . 

[ 9]PⅡ Qi ngqi ,LI  Hongni ng,PANG Li aoj un,et  a1 .Dynami c  Cl ust er   Ke y M ana gem e nt  Sc heme  on W i r el ess  Se nsor   Net —  

wor k s『 J 1 .Chi na  C o nml uni cat i on,201 0,7( 1) :73— 79.  

at ’ s  mDr e.i t  ca n  al so handl e  t he e—  

【 101   HA NES  R  AⅢ 、   M1  A.I ndoor   Radi o Envi r onm e nt   Consi d—  

r ner gency event s  gener at ed dur i ng t he pr ocess  of  pol -  

e r a t oas i  i n Sel e ct i ng a  M e di a Ac cess  Cont r ol  Pr ot ocol  f or  

l i ng a n d i nw ove t he er mr gency r espondi ng capabi l i t y 

Wi de ba n d Radi o Dat a  Conrmni c at ons『 i cy/Pr oce edi ngs  of   t he ⅡEE I nt em a t ona i l  Conf er e nce  on Cona m ni ca ti ons:M a y 

of  D_ PI v IACq西逼怯 

23— 26 ,1 9 93 ,Ge ne va,Swi t ze r l and.砸 庄 Pr ess,1 99 3,2: 990 _ 9 94.  

『 11 ]FALL  K,VARADHAN  K.The  nsM anual ,20 07.  

[ 12]SHEN  Yul ong,MA J   F,PⅡ Qi ngqi ,et   a1 .Anal ysi s  on t he  Resi ience f  of   Key P re- di st ibut f i on i n Sensor  Net wor ks『 J1 .   Thi s  wor k  was  suppor t e d by  t he  Nat onal i   Nat ur al  Sc i ence  Foun—  

Chi n a  o r C r r m ni ca t i ons,20 07,4f 3) :1 673— 5 447.  

旦 

da t on of  i Chi na  unde r(h nt s  No6l1 7  6 8.6l 00 B 3 00:t he  Ke y  Pr o—  

[ 1 3 ]sHI   Yul o ng,xu Qi j i a n,阳 Qi ngqi ,e t   a 1 .Ant — ol C on y 

gr am 0fNSFC — Oaa ngdong Uni on Foundat i on unde r  Gr ant  No.  

Based Rout i ng Al gor i t hm  n W i i r el ess  Sensor   Ne t wor s『 k J 1 .  

U08 3 500 l 4:t he  Nat onal i  Gr and  Fundan- ent al   Resea r ch  97 3 Pr ogr am  of   01 i na  unde r  C ra nt  No.A0o1 2O 0 9o7 :t he  Fundame nt a l  Res ear ch 

Chi na  Col r  ̄ r uni cat i on,201 0,7( 51 :1 20— 1 28.   『 1 4]G【J M M AIIA A,Ⅱ 悃

J.W i r el ess  M edi u m  Ac cess  C o nt r ol  

Funds  f or  t he  Ce nt r al  Uni ve r si t i es  unde r  Cra nt  No. K5 晒1 1 01 0OO 3  

Prot ocol s  .砸 EE  Cor m uni ca ti ons Surveys & Tutori al s,2I DOo。  

and  Pr ogr a m f or   Ne w  Cent ur y  E ̄ e l l e nt   Tal ent s  i n Uni ver s i t y  un—  

3I 2、 :2— 1 5.  

der   Ct ant  No. Naer — l 1—0回 1.  

Bi ogr aphi es 

PeiQi ngqL  r ece i ved  hi s  B. E. ,M . E.and Ph. D.de—   [ 1 ]HSI EH J ngr i ong,U卫 Ts emhuei ,KUO Yawwen.Ene r gy— Ef h_  

gr ees  i n  C o r r put er   Sci e nce   and  Cr ypt ogr a phy 

ci ent   M ul t i - Pol l i ng Scheme   or f   W l ess  LANs   r J] .— I FF — E  Tr ans —  

rom   f Xi di a n Uni ve r si t y,Chi na i n 1 998,2005  and 

ac t i ons  on  Wi r el ess  Conrm ni ca t ons. i 20 ∞ ,8 ( 31 :1 53 2— 1 541 .  

20 08,r e spec t i vel y.He  s now  i an  associ at e  pr of es —  

『 21   U 

an,M AO  Shi we n,PANW AR  S,et   a1 .On  t he   Per for m-  

sor   and m e mber  of   t he  St at e Key Labor at or y  of 

ance  of   Di st nbut ed Pol l i ng Ser vi ce— based M edi um   A ccess  

nt I egr at e d Ser vi ces  N e t wor s ,al k s o a pr of essi onal  m e mber  of 

Cont r ol  

ACM  and  J apan I EI CE,and a  seni or   e m m b er   of  Chi nes e I nst i -  

.I 皿

Tr ansac t i on on W   l es s  Conrr  ̄ni cat i on,  

2【 x】 8.7( 1   1、 :4635- 4645.  

t ut e  of  El ec t r oni cs  and C h i na C o mput er  Feder at o n.Hi i s  r e—  

[ 3]YANG  Zhi j un,ZHAO  Dongf eng.Qos  Suppor t  Pol l i ng Sche me   f or   M ul ti medi a  Tr af ic  n  i Wi r el ess   L  MAC  Pr ot ocol  l J1 .Ts—  

sear ch i nt er es t s  f ocus  on di gi t al  cont ent s  pr ot ec t i on and wi r e—   l ess  net wor s  and  k secur it y.  

i nghua  Sci ence  and Te chnol ogy, 200 8,1 3( 6) :7 54- 7 58.  

I 41  C 

A  P,KUMAR,P.The Capa ci t y  of   Wi r el es s  Net wor ks[ J ] .  

I FFF  Tr ans act i ons  on  I nf or ma t i on  The or y.   —



.4 6t 2) : 38 8- 4 04.  

1   HUR  Y_RYO0  J,HUH J.A Pol l i ng— Based Channel  Access   Cont r o1   M echani sm   t o P r obng a Li f et i me  Of 皿

802. 1 5. 4  

Cher t Cher t.r ecei ve d hi s Ph. D .degr ee  f r om t he  Tel econm ̄ u ni ca—   t on  i Depa r t me nt  OfXi di an Uni ve si r t y.Chi na i n 2008.He i s a n 

associ a t e  pr of ess or   n  i Na t onal i   Key Lab.of   I nt egr at e d Ser vi ce  Net wor ks  of   Xi di an Uni ver si t y now.H  r ese ar ch i nt e r est s  i n—  

LR— WPAN  Wi t h a Mai n— Power ed PAN Coor di nat or『c] / /  

cl ude vehi cl e Ad  Hoc  net wor s ,wi k r el ess  sensor   net w or s  and  k

r ocee P di ngs  of  t he 1 0t h I nt em at i onal  C o nf er ence on A d—  

near   s pace  t el econmam i ca t i ons.  

va nced C o nmam i cat on Tec i hnol ogy:Febr u ar y 1 7- 2O.20o8.   Gangwon—Do.Ⅱ正E Pr ess.2008:1951—1955.  

[ 6]RYKOV  V  On Ana ̄si s ofPe iodi r c  Pol l i ng Sys t er ns[ J] _Au一  

2012  4