It is shown that a Partitioned Optical Passive Stars (POPS) network with g groups and d processors per group can route any permutation among the n = dg processors in one slot when d = 1 and 2⌈d/g⌉ slots when d > 1. The number of slots used is optimal in the worst case, and is at most the double of the optimum for all permutations π such that π(i) = i, for all i.

With the explosive growth of the Internet and ever-increasing users’ demand for various broadband applications, such as Internet telephony, high-definition television (HDTV), interactive games, and video on demand, subscriber access networks, which cover the “last mile” area, and serve numerous residential and small business users, have become a bandwidth bottleneck in providing broadband servi...

0140-3664/$ see front matter 2010 Elsevier B.V. A doi:10.1016/j.comcom.2010.01.018 * Corresponding author. Tel.: +65 67904512; fax: + E-mail addresses: [email protected] (Y. Yi Poo). Ethernet passive optical networks (EPONs) are being designed to deliver different quality of service (QoS) to carry heterogeneous traffic of end users. For this purpose, hierarchical scheduling is needed for up...

In order to reduce the cost for delivering future broadband services, network operators are inclined to simplify the network architectures by integrating the metro and access networks into a single system. Hence, extended reach passive optical networks (ER-PONs) have been proposed. ER-PON usually has four new features: high data rate in both upstream and downstream signals (>1 Gb/s); reach exte...

All-to-all broadcast scheduling problems are considered in WDM optical passive star networks where k wavelengths are available in the network. It is assumed that each node has exactly one tunable transmitter and one xed tuned receiver. All transmitters can tune to k di erent wavelengths, and have the same tuning delay to tune from one wavelength to another. In this paper, we take to be a nonneg...

Passive optical access networks are susceptible to intended attacks and unintended failures. This paper discusses intrusion by user-side signalinjection resulting in reduced network accessibility and it proposes possible countermeasures. The central function is that an intruding signal can be switched off when it is present.