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Uplink Contention Based SCMA for 5G Radio Access  [PDF]
Kelvin Au,Liqing Zhang,Hosein Nikopour,Eric Yi,Alireza Bayesteh,Usa Vilaipornsawai,Jianglei Ma,Peiying Zhu
Mathematics , 2014,
Abstract: Fifth generation (5G) wireless networks are expected to support very diverse applications and terminals. Massive connectivity with a large number of devices is an important requirement for 5G networks. Current LTE system is not able to efficiently support massive connectivity, especially on the uplink (UL). Among the issues arise due to massive connectivity is the cost of signaling overhead and latency. In this paper, an uplink contention-based sparse code multiple access (SCMA) design is proposed as a solution. First, the system design aspects of the proposed multiple-access scheme are described. The SCMA parameters can be adjusted to provide different levels of overloading, thus suitable to meet the diverse traffic connectivity requirements. In addition, the system-level evaluations of a small packet application scenario are provided for contention-based UL SCMA. SCMA is compared to OFDMA in terms of connectivity and drop rate under a tight latency requirement. The simulation results demonstrate that contention-based SCMA can provide around 2.8 times gain over contention-based OFDMA in terms of supported active users. The uplink contention-based SCMA scheme can be a promising technology for 5G wireless networks for data transmission with low signaling overhead, low delay, and support of massive connectivity.
Approximate sorting of packet-scheduling in high-speed networks
Approximate Sorting of Packet-Scheduling in High-Speed Networks

Wang Youcheng,Yu Shengsheng,Zha Hui,Zhou Jingli,

计算机科学技术学报 , 2001,
Abstract: Fairness, latency and computational complexity are three important factors in evaluating the performance of a scheduling algorithm. Fairness must be satisfied so that service can be distributed according to the reserved rate. Only when latency is irrelevant to the number of connections, is it possible to minimize the end-to-end delay through controlling the reserved rate. Among existing scheduling algorithms, Round Robin is the least complex. However, conventional Round Robin is unable to ensure fairness, and the improved round robin algorithms like Deficit Round Robin, Weighted Round Robin and Virtual Round Robin are unable to ensure that their latencies are irrelevant to the number of connections although they gua- rantee fairness. Potential Round Robin developed for analysis of fairness and latency reduction is thus proposed. It is based on the introduction of a new concept, Round Potential Function. The function splits service time into a number of service round periods to guarantee fairness regardless of the serving process used in the period. In the analysis of latency, service round periods are re-split into multiple scanning cycles for further service distribution with approximate sorting between scanning cycles. As a result, latency is no longer relevant to the number of connections while the low complexity of round robin is kept.
Performance Analysis of Scheduling Algorithms For VoIP Services in IEEE 02.16 Systems  [PDF]
M.A. Mohamed,F.W. Zaki,A.M. Elfeki
International Journal of Computer Science Issues , 2012,
Abstract: VoIP applications are being widely used in today's networks challenging their capabilities to provide a good quality of experience level to the users. In particular, There are several scheduling algorithms for Voice over IP (VoIP) services in IEEE 802.16 systems, such as unsolicited grant service (UGS), real-time polling service (rtPS), using Grant-Me bit of the generic MAC header. However, these algorithms have some problems of a waste of uplink resources, additional access delay, and MAC overhead for supporting VoIP services with variable data rates and silence suppression. To solve these problems, we propose a novel uplink-scheduling algorithm (Extended-rtPS) for the VoIP services in IEEE 802.16 systems through the performance analysis and simulation results of resource utilization, total throughput, and packet transmission delay, we show that our proposed algorithm can solve the problems of the conventional algorithms, and has the best performance among these algorithms.
A Joint Uplink/Downlink Opportunistic Scheduling Scheme for Infrastructure WLANs  [PDF]
Nischal S,Vinod Sharma
Computer Science , 2013,
Abstract: We propose a combined uplink/downlink opportunistic scheduling algorithm for infrastructure WLANs. In the presence of both uplink and downlink flows, an infrastructure WLAN suffers from the uplink/downlink unfairness problem which severely decreases the throughput of the access point (AP). We resolve the unfairness by maintaining a separate queue and a backoff timer for each associated mobile station (STA) at the AP. We also increase the system throughput by making the backoff time a function of the channel gains. This reduces the collision probability also. We theoretically analyze the performance of the system under symmetric statistics for all users and validate the analysis by extensive simulations. Simulation results show increase in system throughput by over 40% compared to the 802.11 MAC.
Uplink Scheduling Algorithms for QoS Support in Broadband Wireless Access Networks  [cached]
Mikael Gidlund,Gang Wang
Journal of Communications , 2009, DOI: 10.4304/jcm.4.2.133-142
Abstract: In order to support different types of multimedia applications, the IEEE 802.16 standard defines different service classes with their associated Quality of Service (QoS) parameters. The scheduling algorithm is the crucial point in QoS provisioning over such broadband wireless access (BWA) network and it is important that the scheduling algorithm have a multi-dimensional objective of satisfying QoS requirements of the users, maximizing system utilization and ensuring fairness among users. In this article we present two different scheduling algorithms for the uplink (UL) connection. One is a combination of legacy scheduling algorithms earliest deadline first (EDF) and weighted fair queuing (WFQ). The other proposed algorithm is a cross-layer algorithm that pledges fairness among admitted connections and it also supports all service classes. The proposed scheduling algorithms are compared to several other scheduling algorithms for UL traffic under different mixes of traffic and for various characteristics of the IEEE 802.16 MAC layer such as UL burst preamble, frame length and bandwidth request mechanisms. Simulation results indicate that legacy scheduling algorithms are not suitable for the multi-class traffic in IEEE 802.16 since they do not explicitly incorporate the QoS parameters for the given standard.
Universal Packet Scheduling  [PDF]
Radhika Mittal,Rachit Agarwal,Sylvia Ratnasamy,Scott Shenker
Computer Science , 2015,
Abstract: In this paper we address a seemingly simple question: Is there a universal packet scheduling algorithm? More precisely, we analyze (both theoretically and empirically) whether there is a single packet scheduling algorithm that, at a network-wide level, can match the results of any given scheduling algorithm. We find that in general the answer is "no". However, we show theoretically that the classical Least Slack Time First (LSTF) scheduling algorithm comes closest to being universal and demonstrate empirically that LSTF can closely, though not perfectly, replay a wide range of scheduling algorithms in realistic network settings. We then evaluate whether LSTF can be used {\em in practice} to meet various network-wide objectives by looking at three popular performance metrics (mean FCT, tail packet delays, and fairness); we find that LSTF performs comparable to the state-of-the-art for each of them.
iRGRR/PM: A New Packet Scheduling Scheme for High-Speed Crossbars

Peng Lai-xian,Lu Xin,Tian Chang,

电子与信息学报 , 2007,
Abstract: iRGRR(iterative Request-Grant-based Round-Robin) is a scheduling algorithm for input-queued crossbars, which has many good features, such as simple, scalability and fine performance. This paper proposes a new packet scheduling scheme based on iRGRR, called iRGRR/PM (iRGRR with Packet Mode), for high-speed crossbars. iRGRR/PM algorithm is appropriate to schedule IP packet, and can be used in routers with high-speed and large capacity. Compared to iRGRR, iRGRR/PM not only simplifies the design of packet output reassembly module, but also improves the bandwidth utilization of crossbar. The relation of packet delay between two algorithms is briefly analyzed, and simulation studies is done in detail. The results show that iRGRR/PM achieves higher throughput under the same circumstances, especially, reaches 100% throughput under nonuniform traffics. In addition, iRGRR/PM provides better performance of delay for larger packets.
Improved scheduling algorithm for real-time uplink services in IEEE802.16e

DONG Guo-jun,DAI Ju-feng,

计算机应用 , 2007,
Abstract: In IEEE802.16e, Scheduling services represent the data handling mechanisms supported by the MAC scheduler for data transport on a connection. Each connection is associated with a single scheduling service. A scheduling service is determined by a set of QoS parameters that quantify its behaviors. Taking three types of scheduling services into consideration, UGS (Unsolicited Granted Scheduling), rtPS (real-time Polling Scheduling) and ertPS (extended real-time Polling Scheduling), this paper proposed a real-time uplink scheduling service algorithm irtPS (improved real-time Polling Scheduling). The proposed algorithm maximized the usage of uplink access resource and guaranteed data rate and delay requirement. Mathematical modeling and analysis results show that the throughput performance of the proposed algorithm is better than the algorithms in IEEE802.16e on the precondition of guaranteed delay performance.
Dynamic Packet Scheduling in Wireless Networks  [PDF]
Thomas Kesselheim
Computer Science , 2012,
Abstract: We consider protocols that serve communication requests arising over time in a wireless network that is subject to interference. Unlike previous approaches, we take the geometry of the network and power control into account, both allowing to increase the network's performance significantly. We introduce a stochastic and an adversarial model to bound the packet injection. Although taken as the primary motivation, this approach is not only suitable for models based on the signal-to-interference-plus-noise ratio (SINR). It also covers virtually all other common interference models, for example the multiple-access channel, the radio-network model, the protocol model, and distance-2 matching. Packet-routing networks allowing each edge or each node to transmit or receive one packet at a time can be modeled as well. Starting from algorithms for the respective scheduling problem with static transmission requests, we build distributed stable protocols. This is more involved than in previous, similar approaches because the algorithms we consider do not necessarily scale linearly when scaling the input instance. We can guarantee a throughput that is as large as the one of the original static algorithm. In particular, for SINR models the competitive ratios of the protocol in comparison to optimal ones in the respective model are between constant and O(log^2 m) for a network of size m.
CAC and Packet Scheduling Using Token Bucket for IEEE 802.16 Networks  [cached]
Tzu-Chieh Tsai,Chi-Hong Jiang,Chuang-Yin Wang
Journal of Communications , 2006, DOI: 10.4304/jcm.1.2.30-37
Abstract: The IEEE 802.16 standard was designed for Wireless Metropolitan Area Network (WMAN). The coverage of this new technology is expanded up to 50 km. IEEE 802.16 also has inherent QoS mechanism while the transmission rate can be up to 70Mbps. However, the main part of 802.16 – packet scheduling, was not defined and left as an open issue. In this paper, we present an uplink packet scheduling with call admission control (CAC) mechanism that is token bucket based. Also, a mathematical model of characterizing traffic flows is proposed. Simulations are carried out to validate our CAC algorithms and models. These results show that the delay requirements of rtPS flows are promised and the delay and loss can be predicted precisely by using our mathematical models.
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