Optical monitoring system for scalable all-optical networks

4:30pm - 4:45pm WEE3 Op ical Moni o ing Sys em o Scalable All-Op ical Ne wo ks lase wi h he local ca ie s and low pass il e ing he esul ing signal, pulses occu in he ime domain when coincidence is held be ween he he e od ned eauencies. Abdelha id Am ani, Jesus Roldan, Membe , IEEE, and Gab iel Junyen n/l/ EZXl In oduc ion : High a ic and high capaci y communica ions a e belie ed o become cos -e ec i e wi h he use o all-op ical ne wo ks based on OFDM (Op ical F equency Di ision Mul iplexing). In such ne wo ks, new s a egies o OA&M (Ope a ion, Adminis a ion and Main enance) unc ions need o be de eloped so as o sui he in oduc ion o a new op ical laye whe e in wa eleng h ou ing is exploi ed and aul s a e de ec ed in a anspa en manne [ 11. In his pape , we p opose a scheme o moni o op ical channels in he op ical laye o suppo ing OA&M unc ions o a anspa en and scalable pho onic ne wo k. powe de ec ed in a non-occupied channel. In his way, a SNR (signal o noise a io) es ima ion is p o ided all- Fig( 1) : Func ional block diag am o a local moni o ing sys em. The e o e, he shape o he de ec ed pulse indica es channel p esence o loss, hus can in o m abou a link o ansmi e aul . Mo eo e , channel powe deg ada ion could also be poin ed ou by compa ing he de ec ed op ical powe in he moni o ed spec um o a noise loo de e mined b he Expe imen al esul : In his sec ion, we aim a demons a ing expe imen ally he easibili y o he p oposed OMS in a local node. Fo he o he s nodes, i will be he same excep o he moni o ed wa eleng h ange which will be chosen o i ano he pa o he spec um u ilized by he op ical ne wo k. The ansmi e and equency scanning lase s a e unable DFB lase s om GEC-Ma coni. The equency scanning ange is adjus ed o 12,5 GHz because o moni o ing only one local ansmi e , al hough i could be enla ged i needed. The pe iod o sweep he equency scanning ange is se a 150 ms. Da a acquisi ion and channel supe ision a e implemen ed wi h a PC ca d and a windows en i onmen so wa e. Fig (2) shows he expe imen al esul o he Iocal moni o ed spec um o a pseudo andom FSK 0.4 - 0.35 L (D 0.3 Q 6 0.25 4- ._ - 0.2 0 25 50 75 100 125 ime (ms) Fig(2) : Local moni o ed spec um o a channel modula ed a 155 Mb/s wi h 223-1 bi s eam. wide de ia ion modula ed channel a 155 Mb/s wi h 223-1 bi s eam. P ope ope a ion o his OMS was also e i ied expe imen ally o 622 Mb/s and 2.5 Gb/s SONET/SDH ansmission eloci ies. 0-7803-3895-2/97/$10.00 01997 IEEE 270 The p esen OMS exploi s spec um pa i ioning by dis ibu ing moni o ing unc ion among he local nodes. The e o e, he o al moni o ed spec um could be enla ged as he numbe o nodes is ele a ed allowing scalabili y and modula i y o he OMS. Ano he ad an age o a dis ibu ed moni o ing sys em is i s as e esponse ime in compa ison o a cen alized moni o ing sys em. LOCAL OMS OF NO CHANNEL NODE DETECTED Link aul de ec ion : A wa eleng h channel ca ying a ic be ween wo nodes, i no moni o ed in he local OMS o he node des ina ion in o ms ha he link joining he wo nodes is ailed. Le us see how link aul can be au oma ically de ec ed by he p esen me hod in he case o an op ical ing ne wo k. The ing a chi ec u e is a ac i e o i s ailu e es o a ion capabili y and o using a minimized numbe o links. Fig (3) shows a sel healing bi-di ec ional OFDM op ical ing ne wo k wi h i s wa eleng h ma ix o a ull mesh a ic pa e n. Among se e al possibili ies, a link by link aul de ec ion can be accomplished as shown in Fig(4). No e ha only wo local op ical moni o ing sys ems (o nodes 1 and 3 in he example) a e su icien o in o m abou he heal h o all links in he ne wo k, when hey moni o some spec ied channels ecei ed in hei co esponding nodes (a link aul is assumed o be a simul aneous aul in he wo ibe s o ming he link). This me hod can be gene alized o an a bi a y opology ne wo k by co esponding o each link a pa icula wa eleng h (used also o a ic ansmission) and a pa icula local OMS. Ano he ad an age o he p esen scheme is i s abili y o o m pa o a equency con ol and measu emen sys em which is impo an o educing cos s o ne wo k OA&M sys em: Indeed, by he e odyning sepa a ely he sweeping lase (in Fig(1)) wi h a e e ence equency, he spec al posi ions o he moni o ed ca ie s can be compa ed wi h he e e ence equency, hus can be accu a ely measu ed and locked o p ecise o -se alues om he e e ence equency [2][3]. ALARM: LINK FAILED T ansmi ing node numbe Recei ing node numbe .. - - -) ** .- --> Fig (3) : A sel healing bi-di ec ional OFDM ing ne wo k wi h i s wa eleng h ma ix o ull mesh connec ion. OMS means op ical moni o ing sys em and OXC is an op ical c ossconnec . Fig(4) : link by link ailu e de ec ion i-j means he link joining nodes i and j. Conclusion : We ha e p oposed an op ical moni o ing sys em (OMS) o scalable all-op ical ne wo ks and expe imen ally demons a e i s easibili y in a local node. We ha e also desc ibed i s applica ion in a sel healing op ical ing ne wo k. The p oposed OMS p esen s in e es ing ad an ages like scalabili y and modula i y, unlimi ed o al moni o ed spec um ange, sui abili y o dense equency spaced channels, and link o ansmi e aul de ec ion. Re e ences: [l] Y. Tada e al. OA&M F amewo k o Mul iwa eleng h Pho onic T anspo Ne wo ks. IEEE Jou nal on Selec ed A eas in Coinmunica ions, pp. 914-921, Vo1.14, No.5, June 1996. [2] A. Am ani e al. Mul i equency Absolu e S abiliza ion o Pho onic Communica ion Ne wo ks. P oceedings o IEEE In e na ional Con e ence on Conununica ion Sys ems, pp 949-95 1, Singapo e, No embe 1996. [3] A. Am ani e al. Accu a e F equency Measu emen o Pho onic Ne wo k Managemen . P oceedings o he In e na ional Con e ence o Fibe Op ics & Pho onics. Vol 1, pp 552-555. Mad as, India, Decembe 1996. . 27 1