Population size estimation of chirp and grunt generating fish and mammals using cross-correlation based technique with three acoustic sensors

Passive acoustic monitoring has the potential to be a useful tool for population estimation of sound-producing fish and mammals(mostly whales).Previous work on population estimates of callers employed a simple cross-correlation technique with recordings from two acoustic sensors,and the current work extends the technique to two configurations of a 3-acoustic sensors array using two different sounds,i.e.,chirps which is commonly generated by damselfish(Dascyllus aruanus),humpback whales(Megaptera novaeangliae),dugongs(Dugong dugon)etc.,species,and grunts which is commonly generated by Japanese gurnard(Chelidonichthys kumu),Grey gurnard(Eutrigla gurnardus),gulf toadfish(O.beta),etc.,species.We compared simulated results from this technique with values determined by theoretical approach.We have found that an increasing number of cross-correlation function(CCF)provide better results using this technique.However,the technique has some limitations including negligence of multipath interference,assuming the delays to be integer.

Bandwidth Allocation and Control Message Scheduling Algorithms for Improving the QoSs of High Priority Traffic in PON

The passive optical network(PON)is the most promising candidate for supporting multiple service classes,i.e.,high priority(HP)traffic and best-effort(BE)traffic,in the next-generation broadband access networks.Providing an efficient dynamic bandwidth allocation(DBA)algorithm is the most important issue for supporting multiple service classes of traffic simultaneously.This paper presents a new DBA algorithm,which is the modified version of the hybrid slot-size/rate(HSSR)scheme,and is called the modified HSSR(MHSSR)algorithm.We have also modified the control message scheduling algorithm to fit it to the proposed scheme.In the proposed MHSSR scheme,each cycle time,i.e.,the length of a time cycle,is equally divided into two parts.In the 1st part of the cycle time,the bandwidth is dynamically allocated to the HP traffic of all the optical network units(ONUs).In contrast,in the 2nd part of the cycle time,the bandwidth is dynamically allocated to the BE traffic of one or multiple ONUs.Furthermore,to ensure guaranteed service for the HP traffic,the 1st part of the cycle time is extended while the 2nd part of the cycle time is compressed if the demand of the HP traffic is very high.However,the 1st part of the cycle time will never be compressed,even at the lightly loaded condition of the HP traffic.The modified control message-scheduling algorithm effectively coordinates the timing sequence between the two parts of the cycle time and ensures the synchronization between two Gate messages to each ONU.We have evaluated the performance of the proposed schemes through numerical simulations in terms of endto-end packet delay,bandwidth wastage,remaining bytes per time cycle,jitter,and throughput for different offered loads.From the comparative analysis,it can be seen that the proposed scheme provides better performance than the existing HSSR and delay variation-guaranteed schemes.