These deterministic guarantees can be provided by a network that reserves the required bandwidth and other resources. This reservation paradigm prompted the Internet Engineering Task Force (IETF) to propose the Intserv architecture and the RSVP signaling protocol. However, a major concern with this architecture is that the soft-state mechanism it uses to maintain consistency of reservation state may not be scalable to high-speed backbone networks. This can cause the refresh messages (apart from consuming memory, processing power, and bandwidth) to experience significant queuing delays and prevent correct functioning of the soft-state mechanism because of the large number of flows. For the refresh mechanism to function properly, the reservation state size must be either eliminated or drastically reduced. 

Mobile users worldwide are increasingly using wireless devices to access the internet, and thus, there is a greater need for reliable client-server communications over wireless links.  However, the current internet protocol for reliability, TCP, has demonstrated severe performance problems when operated over wireless links. TCP has multiple problems with its congestion control algorithms because TCP can only use packet loss to detect congestion in the network.  In addition, wireless links are inherently inferior and suffer from long periods of fading. TCP has no mechanism to differentiate these losses from congestion, so it treats all losses as congestive by reducing its transmission window. This effectively reduces the throughput of the connection by more than half.

Multicast communication generalizes the unicast (information sent from one point to another point) and broadcast (information sent from one point to all points) communication models in computer networks to multipoint dissemination of messages. A source only needs to send packets once to the network interface to then be transparently replicated on their transmission paths to the receivers. This method is necessary  for high-volume data transfer applications such as distributed software updates, newscasts, on-demand video, and telecollaboration systems. However, when the multicasting concept is adapted and deployed with IP multicast protocols in the internet, those systems cannot provide reliable or order-preserving delivery of packets to a multicast group. As a result, there is no guarantee that all of the packets sent from a source to a group of receiving hosts are disseminated without error or that the consistency and coherence of the data has been preserved, which calls for a more reliable multicast system. 

Brief description not available

Brief description not available

VSLI chips contain gates that are synchronized by clock signals. High performance depends on a high clock rate, but if the gates are unable to maintain the same frequency, the chip doesn’t perform well. Therefore, to increase performance, the clock signals need to retain multiple frequencies on the same device without using too much power.  The demand for high performance electronic systems has grown, leading to the use of Very Large Scale Integration (VLSI) chips. These chips have been developed to exhibit higher performance and density, and the current technological aspiration is to continue the advancement of these two aspects. These demands, however, require a great deal of power, which in turn creates more heat, leading to circuit failure.

Portable electronic devices require long battery lifetimes to meet the longer use times. This can only be obtained by utilizing low-power components, which have become quite critical in system-on-chips (SOCs) because interconnections found in scaled technologies is consuming an increasingly significant amount of power. Researchers have demonstrated that the major consumers of this power are global buses, clock distribution networks (CDNs), and synchronous signals in general. In addition to power, interconnect delay poses a major obstacle to high-frequency operation. Technology scaling reduces transistor and local interconnect delay while increasing global interconnect delay. Moreover, conventional CDN structures are becoming increasingly difficult for multi-GHz ICs because skew, jitter, and variability are often  proportional to large latencies. Prior to to and in early CMOS technologies, current-mode (CM) logic was the attractive high speed signaling scheme because they were used for long global wires or, more commonly, off chip signals. Standard logic signals, however, have remained in voltage mode (VM) to benefit from low static power of CMOS logic. Researchers at University of California, Santa Cruz, have proposed a scheme that utilizes the power and reliability of CM signaling, yet retain compatibility with low-power CMOS logic.  

The problem of estimating and tracking the frequency of a weak sinusoidal signal occurs in many areas of signal processing. There are a variety of approaches to estimate the frequency of a harmonic signal. The most common approach is to directly measure the time difference between zero crossings and the number of cycles per second. However, this approach is very sensitive to signal noise. Solutions to overcome this problem have been proposed, such as the Fourier transform technique, correlation, the least square error technique, recursive algorithms, chirp Z transform (CZT), adaptive notch filters, and Kalman filtering that estimates instantaneous frequency of the signal. The Kalman filter is a recursive stochastic technique that gives an optimal estimation of state variables of given linear dynamic system from noisy measures. Moreover, the filter must always deal with the inherent nonlinearity and with extreme noise levels. Coincidentally, the Kalman filter also gives a time-varying gain, which is not amendable to frequency domain analysis.