Daniel J. Marchok

First stage multicasting in a growable packet (ATM) switch

A three-stage packet switch architecture that uses a two stage, self-routing, memoryless, interconnection network to interconnect a third stage of smaller packet switches was proposed by K.Y. Eng. et al. (Proc. IEEE Globecom, p.1159-65, vol.2, 1989). Two new routing algorithms that facilitate the multicastings of packets with this architecture are proposed. The two routing algorithms, one of which duplicates packets at only the first stage and the other which duplicates packets at the first and third stages, require only minimal alterations to the switch. An analysis is made of the switchs multicast performance, finding an overbound on the packet loss probability. The analysis, which identifies three sources of packet loss, shows that good multicast performance is maintained with only a small increase in the architectures expansion provided that, on average, the load is not severely concentrated onto any particular input section as a result of multicasting.<<ETX>>

Blind synchronization techniques for telephony over HFC networks using M-QAM

This paper describes blind synchronization techniques for cable-telephony systems using M-ary quadrature amplitude modulation (M-QAM). The development of accurate, reliable and economically realizable synchronization algorithms is a challenging problem with significant impact on overall system design and performance. The method of loop timing is used for synchronizing multiple remote units with a single head-end. Each remote transceiver blindly recovers downstream timing and uses it to derive its upstream clock. The issue of overcoming frequency offsets incurred on the cable network is addressed. A novel two-stage search and acquisition procedure comprising of all-digital baseband synchronization algorithms is described.

Asynchronous communication and symbol synchronization in multipoint-to-point multicarrier systems

Discrete multitone (DMT) has been selected as the modulation technique for multipoint-to-point systems such as cable telephony and in home networks over conventional single-carrier techniques by several vendors, because it provides superior impulse noise immunity, frequency diversity, and spectral efficiency for many communication systems. This paper provides novel solutions for two key issues in such DMT and OFDM systems. First, a technique for in-band asynchronous communication, essential for adding new remote units, is presented. Second, a robust symbol synchronization technique, especially for aligning the transmissions of the remote units at the headend (the central site), is presented. Both techniques are highly efficient and cause negligible degradation in SNR.