Realization of Differentiated Quality of Service for Wideband Code Division Multiple Access Core Network

A novel algorithm for buffer management and packet scheduling is presented for providing loss and delay differentiation for traffic classes at a network router. The algorithm, called JoBS (Joint Buffer Management and Scheduling), provides delay and loss differentiation independently at each node, without assuming admission control or policing. The novel capabilities of the proposed algorithm are that (1) scheduling and buffer management decisions are performed in a single step, and (2) both relative and (whenever possible) absolute QoS requirements of classes are supported. Numerical simulation examples, including results for a heuristic approximation, are presented to illustrate the effectiveness of the approach and to compare the new algorithm to existing methods for loss and delay differentiation.

A set of optimisation algorithms are studied for high density wideband code division multiple access (WCDMA) mobile networks. The method to be introduced is a radio resource knapsack packing, as packet traffic is the main consideration. The method includes centralised packet scheduling (PS) and power control (PC) algorithms that will maximise a utility function defined by the operator. The goal of the proposed algorithms is to maximise either the throughput of the system (a cluster of cells) or the value of the correctly received packets.

General-purpose many-core network processors have been widely used in network packet processing due to its high programmability and parallel processing ability.The design of general-purpose many-core network processors involves a lot of key technologies, including packet scheduling, inter-core communication, co-processing, etc.The verification of these technologies is essential before applied to the system.However, there are some of limitations in the current software-based verification platform, such as low simulation speed and fidelity.A FPGA-based verification platform for general-purpose manycore network processors (VeriNP) is proposed in this paper.The VeriNP supports verification of network processor for at least 16 real RISC CPU cores, and the frequent of cores can run at 100MHz or higher.Based on the VeriNP platform, two packet scheduling algorithms are studied and verified.

We investigate the packet‐scheduling function within the access scheme of a unidirectional satellite system providing point‐to‐multipoint services to mobile users. The satellite system may be regarded as an overlay multicast/broadcast layer complementing the point‐to‐point third generation (3G) mobile terrestrial networks. The satellite access scheme features maximum commonalties with the frequency division duplex (FDD) air interface of the terrestrial universal mobile telecommunications system (T‐UMTS), also known as wideband code division multiple access (WCDMA), thus enabling close integration with the terrestrial 3G mobile networks and cost‐efficient handset implementations. We draw our attention on one of the radio resource management entities relevant to this interface: the packet scheduler. The lack of channel‐state information and the point‐to‐multipoint service offering differentiate the packet scheduler in the satellite radio interface from its counterpart in point‐to‐point terrestrial mobile networks. We formulate the scheduler tasks and describe adaptations of two well‐known scheduling disciplines, the multilevel priority queuing and weighted fair queuing schemes, as candidates for the time‐scheduling function. Simulation results confirm the significance of the transport format combination set (TFCS) with respect to both the resource utilization achieved by the scheduler and the performance obtained by the flows at packet‐level. The performance gap of the two schemes regarding the fairness provided to competing flows can be narrowed via appropriate selection of the TFCS, whereas the achieved delay and delay variation scores are ultimately dependent on the packet‐level dynamics of individual flows. Copyright © 2004 John Wiley & Sons, Ltd.

High speed downlink packet access (HSDPA) is a packet-based data service that supports downlink data rates of up to 14 Mbps in the WCDMA (wideband code division multiple access) system. In HSDPA, the packet scheduler is a key element for high-speed and efficient transmissions. In addition, hybrid automatic request (HARQ) plays a significant role in improving system performance. We propose an enhanced scheduling algorithm combined with HARQ to reduce transfer delay without the degradation of system throughput.

Network processors today consist of multiple parallel processors (micro engines) with support for multiple threads to exploit packet level parallelism inherent in network workloads. With such concurrency, packet ordering at the output of the network processor cannot be guaranteed. This paper studies the effect of concurrency in network processors on packet ordering. We use a validated Petri net model of a commercial network processor, Intel IXP 2400, to determine the extent of packet reordering for IPv4 forwarding application. Our study indicates that in addition to the parallel processing in the network processor, the allocation scheme for the transmit buffer also adversely impacts packet ordering. In particular, our results reveal that these packet reordering results in a packet retransmission rate of up to 61%. We explore different transmit buffer allocation schemes namely, contiguous, strided, local, and global which reduces the packet retransmission to 24%. We propose an alternative scheme, packet sort, which guarantees complete packet ordering while achieving a throughput of 2.5 Gbps. Further, packet sort outperforms the in-built packet ordering schemes in the IXP processor by up to 35%.

Low latency and efficient packet scheduling for streaming applications

Hint-based cache design for reducing miss penalty in HBS packet classification algorithm

One of the challenges in Delay Tolerant Wireless Sensor Networks (DT-WSN), is to handle situations where the available buffer space is insufficient- the buffer management problem. Although several buffer management algorithms have been proposed for DT-WSNs, to the best of our knowledge, there is no comprehensive study on the effects different factors have on their performance, and which evaluates the relative performance of these algorithms in different contexts. This paper evaluates in a fixed-factor factorial experiment the performance in terms of latency and Quality of Information (QoI) of four representative buffer management algorithms for DT-WSNs; two traditional, FiFO and Random, and two QoI-based algorithms- one proposed by Humber and Ngai and the SmartGap algorithm. The evaluation suggests that the buffer management algorithm in combination with employed routing protocol and the sensor node buffer sizes have a significant impact on latency, while the obtained QoI rather depends on the characteristics of the transported data and the routing protocol, provided a single-copy routing protocol is used. Moreover, the evaluation suggests that QoI-based buffer management algorithms do offer improved QoI, with an 31% improvement in MAE for SmartGap compared to FIFO. However, they do so at the expense of higher latency, with SmartGap giving a 60% higher latency than FIFO on average.

Current network processors (NPs) increasingly deal with packets with heterogeneous processing times. As a consequence, packets that require many processing cycles can significantly delay low-latency traffic, because the common approach in today's NPs is to employ run-to-completion processing. These difficulties have led to the emergence of the Multipass NP architecture, where after a processing cycle ends, all processed packets are recycled into the buffer and re-compete for processing resources. In this work we provide a model that captures many of the characteristics of this architecture, and consider several scheduling and buffer management algorithms that are specially designed to optimize the performance of multipass network processors. In particular, we provide analytical guarantees for the throughput performance of our algorithms. We further conduct a comprehensive simulation study that validates our results.

Chapter 14 - Scheduling packets

LTE-Advanced offers significantly higher data rates than the legacy system. The carrier aggregation (CA) technology allows scalable expansion of effective bandwidth provided to user equipment (UE) through simultaneous utilization of radio resources across multi-component carriers. In this paper we propose a new packet scheduling (PS) criterion algorithm that satisfies the fairness among the different kinds of UEs by designing a weighting factor to proportional fair (PF) packet scheduling (PS) algorithms, while enhancing their throughput performance. The proposed PS algorithm is implemented and validated in a PS module for LTE/LTE-Advanced via system level simulations. Results show that PS-enhanced algorithm achieve higher throughput for both LTE and LTE-Advanced UEs.

The I/O performance of applications in multiple-disk systems can be improved by overlapping disk accesses. This requires the use of appropriate prefetching and buffer management algorithms that ensure the most useful blocks are accessed and retained in the buffer. In this paper, we answer several fundamental questions on prefetching and buffer management for distributed-buffer parallel I/O systems. First, we derive and prove the optimality of an algorithm, P-min, that minimizes the number of parallel I/Os. Second, we analyze P-con, an algorithm that always matches its replacement decisions with those of the well-known demand-paged MIN algorithm. We show that P-con can become fully sequential in the worst case. Third, we investigate the behavior of on-line algorithms for multiple-disk prefetching and buffer management. We define and analyze P-Iru, a parallel version of the traditional LRU buffer management algorithm. Unexpectedly, we find that the competitive ratio of P-Iru is independent of the number of disks. Finally, we present the practical performance of these algorithms on randomly generated reference strings. These results confirm the conclusions derived from the analysis on worst case inputs.

Long Term Evolution (LTE) network deploys Orthogonal Frequency Division Multiple Access (OFDMA) technology for downlink multi-carrier transmission. To meet the Quality of Service (QoS) requirements for LTE networks, packet scheduling has been employed. Packet scheduling determines when and how the user’s packets are transmitted to the receiver. Therefore effective design of packet scheduling algorithm is an important discussion. The aims of packet scheduling are maximizing system throughput, guaranteeing fairness among users, andminimizing either or both PacketLoss Ratio (PLR)and packet delay. Inthis paper, the performance of two packet scheduling algorithms namely Log Maximum-Largest Weighted Delay First (LOG-MLWDF) and Max Delay Unit (MDU), developed for OFDM(Orthogonal Frequency Division Multiplexing)networks, has been investigated in LTE downlink networks, and acomparison of those algorithmswith a well-known scheduling algorithm namely Maximum-Largest Weighted Delay First(MLWDF) has been studied.The performance evaluation was in terms of system throughput, PLR and fairness index. This study was performed forboth real time (voice and video streaming)and non-real time (best effort)perspectives. Results show that for streaming flows,LOG-MLWDF shows best PLR performance among the considered scheduling schemes, and for best effort flows, it outperforms theother two algorithms in terms of packet delay and throughput.

Packet scheduling constitutes the core problem in efficient fair allocation of bandwidth to competing flows. To date, numerous algorithms for packet scheduling have been suggested and tested. However, only a few of them are currently deployed. One of the key reasons for rarity of applied packet scheduling methods lies in the complexity of their implementation. This paper describes a family of randomized algorithms for packet scheduling. These algorithms are simple to implement and require small amounts of computation time. Specifically we present an O(1) probabilistic weighted fair queuing algorithm that emits packets from flows with an improved delay jitter. Experimental results of the proposed randomized algorithms suggest that the randomized approach is a viable alternative to the currently deployed deterministic fair queuing algorithms.