Delay-based and QoS-aware packet scheduling for RT and NRT multimedia services in LTE downlink systems

EURASIP Journal on Wireless Communications and Networking, Jul 2018

Guaranteeing Quality of Service (QoS) for heterogeneous traffic is a major challenge in the Fourth Generation (4G) mobile networks. Therein, the absence of sophisticated resources allocation process at the base station jeopardizes QoS in terms of latency data transfer. It has been observed from the literature that low delay bounds might be ensured, however, at the expense of other QoS aspects; for example, throughput and data loss. Therefore, in this article, we propose an effective Delay–based and QoS–Aware Scheduling (DQAS) scheme with a low complexity overhead as an efficient solution for the resource allocation issue in LTE Medium Access Control (MAC) layer. The ultimate aim of DQAS is to minimize delay for Real-Time (RT) traffic while still offering a good level of QoS. Complying with QoS of different traffic types, we effectively analyze the queue buffer of each user flow by developing an algorithm called Efficient Delay Control (EDC) that weights each flow priority in terms of delay. Then, this weight is utilized as a principle for the scheduling decision on the attending flows. Furthermore, the Least Delay Increase (LDI) algorithm is developed to tune the scheduler behavior to maintain a balance between delay and system throughput. Simulation results considering different user mobility levels reveal that DQAS significantly guarantees a low end-to-end delay trend that is independent of increased RT load, and moreover, a reasonable throughput and data drop levels compared to other existing schedulers.

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Delay-based and QoS-aware packet scheduling for RT and NRT multimedia services in LTE downlink systems

Madi et al. EURASIP Journal on Wireless Communications and Networking Delay-based and QoS-aware packet scheduling for RT and NRT multimedia services in LTE downlink systems Nadim K. M. Madi 0 Zurina Mohd Hanapi 0 Mohamed Othman 0 1 Shamala K. Subramaniam 0 0 Department of Communication Technology and Networks, Universiti Putra Malaysia , 43400 UPM, Serdang, Selangor D.E. , Malaysia 1 Computational Science and Mathematical Physics Lab, Institute of Mathematical Science, Universiti Putra Malaysia , 43400 UPM, Serdang, Selangor D.E. , Malaysia Guaranteeing Quality of Service (QoS) for heterogeneous traffic is a major challenge in the Fourth Generation (4G) mobile networks. Therein, the absence of sophisticated resources allocation process at the base station jeopardizes QoS in terms of latency data transfer. It has been observed from the literature that low delay bounds might be ensured, however, at the expense of other QoS aspects; for example, throughput and data loss. Therefore, in this article, we propose an effective Delay-based and QoS-Aware Scheduling (DQAS) scheme with a low complexity overhead as an efficient solution for the resource allocation issue in LTE Medium Access Control (MAC) layer. The ultimate aim of DQAS is to minimize delay for Real-Time (RT) traffic while still offering a good level of QoS. Complying with QoS of different traffic types, we effectively analyze the queue buffer of each user flow by developing an algorithm called Efficient Delay Control (EDC) that weights each flow priority in terms of delay. Then, this weight is utilized as a principle for the scheduling decision on the attending flows. Furthermore, the Least Delay Increase (LDI) algorithm is developed to tune the scheduler behavior to maintain a balance between delay and system throughput. Simulation results considering different user mobility levels reveal that DQAS significantly guarantees a low end-to-end delay trend that is independent of increased RT load, and moreover, a reasonable throughput and data drop levels compared to other existing schedulers. 4G LTE networks; Downlink packet scheduling; Resource allocation; Delay; QoS awareness; QoS balancing 1 Introduction Long Term Evolution (LTE) is recently the most promising mobile technology which allows various multimedia applications to be transferred with a high network capacity and utility [ 1 ]. LTE employs Orthogonal Frequency– Division Multiple Access (OFDMA) as a radio access technology at the downlink channel; this grants more flexibility by contiguously utilizing portions of the spectrum to maximize the network performance. QoS provisioning has been defined as a major objective in 4G LTE radio access networks. Therein, MAC layer scheduling, which is a gist function in radio resource management (RRM) entity of LTE network architecture, presents an immanent challenging issue that seeks effective and realistic solutions to conform with the variety of data traffic evolution. In channel–aware scheduling [ 2–5 ], a trivial scheduling principle is based on the users’ reported channel information. This may return a reasonable data rate level. However, in scenarios of multi–traffic types, channel– aware scheduling concept by itself is not sufficient to guarantee a good network QoS performance, particularly on RT applications. According to [6], the maximum tolerated delay for RT applications is defined to be less than 0.1 s and 0.3 s for Voice-over-IP (VoIP) and video flows, respectively; otherwise, traffic QoS is deteriorated. Commonly, queue–related parameters are adopted beside channel rate to allow obtaining a delay–awareness trait. For example, buffer delay with a maximum bound has been adopted in many works (see for instance [ 7–9 ]) to assign delay–oriented scheduling weights to different flows. A straightforward QoS improvement might be realized, the performance, in this case, is compromised during high offered load though. The reason here is that these scheduling rules are designed based on a singledimension QoS consideration, hence this precludes the scheduler to tweak its behavior to adopt changes of the network load states [ 10 ]. In addition to that, minimum delay is observed to be guaranteed only over a single traffic type and at the expense of low QoS on other types. For example, in [ 11, 12 ], the algorithms are observed to reduce delay only on burst RT video, this indeed causes a high data loss ratio though. Basically, these schemes deliberately trigger a dropping procedure during the network load congestion states against certain flows in order to alleviate delay and improve throughput on other flows with good channel conditions. Such an excessive dropping event usually leads to a frequent data retransmissions which eventually deteriorates delay and QoS on delay–sensitive and small flows like VoIP. Motivated by the aforementioned scheduling issues, we remark that maximizing system throughput is not always the main goal, but rathe (...truncated)


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Nadim K. M. Madi, Zurina Mohd Hanapi, Mohamed Othman, Shamala K. Subramaniam. Delay-based and QoS-aware packet scheduling for RT and NRT multimedia services in LTE downlink systems, EURASIP Journal on Wireless Communications and Networking, 2018, pp. 180, Volume 2018, Issue 1, DOI: 10.1186/s13638-018-1185-3