The Transmission Control Protocol.

An increasing number of high performance internetworking protocol routers, LAN and asynchronous transfer mode (ATM) switches use a switched backplane based on a crossbar switch. Most often, these systems use input queues to hold packets waiting to traverse the switching fabric. It is well known that if simple first in first out (FIFO) input queues are used to hold packets then, even under benign conditions, head-of-line (HOL) blocking limits the achievable bandwidth to approximately 58.6% of the maximum. HOL blocking can be overcome by the use of virtual output queueing, which is described in this paper. A scheduling algorithm is used to configure the crossbar switch, deciding the order in which packets will be served. Previous results have shown that with a suitable scheduling algorithm, 100% throughput can be achieved. In this paper, we present a scheduling algorithm called iSLIP. An iterative, round-robin algorithm, iSLIP can achieve 100% throughput for uniform traffic, yet is simple to implement in hardware. Iterative and noniterative versions of the algorithms are presented, along with modified versions for prioritized traffic. Simulation results are presented to indicate the performance of iSLIP under benign and bursty traffic conditions. Prototype and commercial implementations of iSLIP exist in systems with aggregate bandwidths ranging from 50 to 500 Gb/s. When the traffic is nonuniform, iSLIP quickly adapts to a fair scheduling policy that is guaranteed never to starve an input queue. Finally, we describe the implementation complexity of iSLIP. Based on a two-dimensional (2-D) array of priority encoders, single-chip schedulers have been built supporting up to 32 ports, and making approximately 100 million scheduling decisions per second.

/pdf/the-islip-scheduling-algorithm-for-input-queued-switches-38q8iabi27.pdf

The iSLIP scheduling algorithm for input-queued switches

A system of distributing video and/or audio information employs digital signal processing to achieve high rates of data compression. The compressed and encoded audio and/or video information is sent over standard telephone, cable or satellite broadcast channels to a receiver specified by a subscriber of the service, preferably in less than real time, for later playback and optional recording on standard audio and/or video tape.

Audio and video transmission and receiving system

Providing various wireless connectivities for vehicles enables the communication between vehicles and their internal and external environments. Such a connected vehicle solution is expected to be the next frontier for automotive revolution and the key to the evolution to next generation intelligent transportation systems (ITSs). Moreover, connected vehicles are also the building blocks of emerging Internet of Vehicles (IoV). Extensive research activities and numerous industrial initiatives have paved the way for the coming era of connected vehicles. In this paper, we focus on wireless technologies and potential challenges to provide vehicle-to-x connectivity. In particular, we discuss the challenges and review the state-of-the-art wireless solutions for vehicle-to-sensor, vehicle-to-vehicle, vehicle-to-Internet, and vehicle-to-road infrastructure connectivities. We also identify future research issues for building connected vehicles.

http://bbcr.uwaterloo.ca/~xshen/paper/2015/cvsac.pdf

Connected Vehicles: Solutions and Challenges

We use the measured round trip delays of small UDP probe packets sent at regular time intervals to analyze the end-to-end packet delay and loss behavior in the Internet. By varying the interval between probe packets, it is possible to study the structure of the Internet load over different time scales. In this paper, the time scales of interest range from a few milliseconds to a few minutes. Our observations agree with results obtained by others using simulation and experimental approaches. For example, our estimates of Internet workload are consistent with the hypothesis of a mix of bulk traffic with larger packet size, and interactive traffic with smaller packet size. We observe compression (or clustering) of the probe packets, rapid fluctuations of queueing delays over small intervals, etc. Our results also show interesting and less expected behavior. For example, we find that the losses of probe packets are essentially random unless the probe traffic uses a large fraction of the available bandwidth. We discuss the implications of these results on the design of control mechanisms for the Internet.

/pdf/end-to-end-packet-delay-and-loss-behavior-in-the-internet-mgzpeb25au.pdf

End-to-end packet delay and loss behavior in the internet

The nonblocking packet switch under consideration has N inputs and N outputs and operates L times as fast as the input and output trunks. The effect of speedup (L) on packet loss probability and average transmission delay in the case of an arbitrary number L, such that 1<or=L<or=N, in two types of nonblocking packet switches is analyzed. One has buffers only at outputs. The maximum throughput is obtained on the assumption of an infinite number of buffers in the latter type, that is, 0.8845 and 0.9755 when L=2 and L=3, respectively. Some simulation results are also provided in the case in which a finite number of buffers are given at each input.<<ETX>>

Effect of speedup in nonblocking packet switch

The nonblocking packet switch under consideration has N inputs and N outputs and operates L times as fast as the input and output trunks. The effect of speedup (L) on packet loss probability and average transmission delay in the case of an arbitrary number L, such that 1 >

http://ieeexplore.ieee.org/iel5/799/1834/00049731.pdf

The performance of an asynchronous transfer mode (ATM) network subject to admission control and traffic smoothing is analyzed. Basically, an ATM switch is modeled as a discrete-time single-server queuing system in which a new call joins existing calls. Cell arrivals from a new call are assumed to follow a general distribution. It is also assumed that aggregated arrivals of cells from existing calls form batch arrivals with a general batch size distribution and a geometric distribution of the interarrival times between batches. Both finite- and infinite-buffer cases are considered. An exact analysis yields the waiting time distribution and cell loss probability for a new call and for existing calls. Numerical examples are given to show how the network performance depends on the statistics of a new call (burstiness, time that a call stays in an active or inactive state, etc.) and to demonstrate the effectiveness of admission control and traffic smoothing. >

/pdf/analysis-of-a-discrete-time-single-server-queue-with-bursty-3er7p02ajh.pdf

Analysis of a discrete-time single-server queue with bursty inputs for traffic control in ATM networks

Wireless LANs have been widely deployed, and multiple access points (APs) will be much more likely to be available there for STAs, which can roam from one AP to another by some rule. We here focus on an efficient and fair way to use the wireless access resources provided by multiple APs. In particular, our major concern is to develop a decentralized way to enable each of STAs to select an appropriate one of available APs independently. A straightforward way is to select an AP with strongest signal, which will be, however, shown to need further improvement. Hence, we propose decentralized AP selection strategies to achieve an efficient and fair share of wireless access resources, and evaluate them by simulations. Through our results, the proposed strategies can attain an excellent throughput performance by use of the number of active STAs sharing each AP even if STAs employ the strategies only when entering the wireless LAN. In addition, if STAs roam from one AP to another in response to changing situation, the total throughput and fairness can be further improved very much. keyword

Decentralized Access Point Selection Architecture for Wireless LANs

The major ATM switch architectures and their improvement techniques are categorized and discussed, focusing on performance issues. The performance measures of interest are the maximum throughput, the delay time, and the cell loss probability. The major assumptions and notations used are summarized. A survey is presented of nonblocking switches and their improvement techniques. The performances of a variety of nonblocking switches are compared. >

/pdf/survey-of-switching-techniques-in-high-speed-networks-and-vkcdnr3s1e.pdf

Yuji Oie

Papers

Effect of speedup in nonblocking packet switch

Effect of speedup in nonblocking packet switch

Analysis of a discrete-time single-server queue with bursty inputs for traffic control in ATM networks

Decentralized Access Point Selection Architecture for Wireless LANs

Survey of switching techniques in high-speed networks and their performance