We consider scheduling and resource allocation in long-term evolution (LTE) networks across voice over LTE (VoLTE) and best-effort data users. The difference between these two is that VoLTE users get scheduling priority to receive their required quality of service. As we show, strict priority causes data services to suffer. We propose new scheduling and resource allocation algorithms to maximize the sum- or proportional fair (PF) throughout amongst data users while meeting VoLTE demands. Essentially, we use VoLTE as an example application with both a guaranteed bit-rate and strict application-specific requirements. We first formulate and solve the frame-level optimization problem for throughput maximization; however, this leads to an integer problem coupled across the LTE transmission time intervals (TTIs). We then propose a TTI-level problem to decouple scheduling across TTIs. Finally, we propose a heuristic, with extremely low complexity. The formulations illustrate the detail required to realize resource allocation in an implemented standard. Numerical results show that the performance of the TTI-level scheme is very close to that of the frame-level upper bound. Similarly, the heuristic scheme works well compared to TTI-level optimization and a baseline scheduling algorithm. Finally, we show that our PF optimization retains the high fairness index characterizing PF-scheduling.
@cite_4: Despite the fact that Long Term Evolution (LTE) supports high-speed data transmission and supports different packet sizes by using Adaptive Modulation and Coding (AMC), LTE is not yet optimized for low bit rate voice communication, especially in case of using LTE in Professional Mobile Radio (PMR) context. In LTE, one pair of Physical Resource Blocks (PRBs) is the smallest User Assignment Unit. However, the smallest LTE packet size is still too large in case that low bit rate voice communication is transmitted in high Modulation and Coding Scheme (MCS). This reduces the voice capacity over LTE in PMR context. Therefore, we propose a new Multi-users Multiplexing Radio Voice Transmission method for enhancing voice capacity over LTE in PMR context. In this method, voice packets from different users are multiplexed into one LTE packet in the downlink transmission. In this paper, we propose a new scheduling method that can be used to transmit the multiplexed packets to corresponding users. This paper gives also a novel algorithm for classifying and grouping voice packets of mobile users having different MCS values. In case of low and medium number of users, the results show that the average voice capacity gain of the proposed method can rise up to 89.6 . In case of high number of users, the proposed method can improve the voice capacity by factor of 6.5.
@cite_22: In this paper, we propose a scheduling algorithm called MTSA that considers both real time and non-real time traffic Through extensive simulations, we evaluate the performance of MTSA and compare it with existing scheduling algorithms. We show that MTSA increases the percentage of real time packets served, decreases the percentage of real time packets rejected, and provides high total throughput while offering acceptable delay.
@cite_36: Nowadays, Voice of LTE (VoLTE) is used to support voice communications in LTE network. As one of the key techniques for VoLTE, semi-persistent scheduling (SPS) is important to improve the capacity of VoLTE users. However with SPS, the resource and modulation and coding scheme (MCS) are usually decided by the initial scheduling and keep unchanged during the active state. Considering the continuously changing channel, it is hard to ensure the performance of the voice packet. In order to solve this problem, a resource allocation algorithm is proposed based on the prediction of channel quality change. Furthermore, the data rate of Adaptive multi Rate(AMR) codec is adaptively adjusted in the resource allocation algorithm to reduce VoLTE's impact on other data services. Simulation results prove that the proposed algorithm can reduce the retransmission of VoLTE users and improve the throughput performance of other traffic businesses.
@cite_32: Long-term evolution (LTE) is becoming the first choice of mobile network operators (MNOs) when constructing a wireless network infrastructure because of its high data rate, high throughput, and low latency. These significant advancements are necessary for satisfying the delivery of a wide-range of mobile applications and managed network resources. However, deploying a new LTE network or a transition from current legacy cellular networks to LTE can take several years to roll out. In the meantime, working in a heterogeneous wireless communication network looks inevitable. This paper investigates Voice over LTE (VoLTE) Quality of Service (QoS) under a heterogeneous wireless communication scenario. The contributions of this paper are twofold. First, a novel downlink (DL) semi-persistent scheduling scheme is proposed to reduce VoLTE end-to-end delay and increase system capacity. Second, an extensive network simulation model has been designed and implemented to evaluate the proposed scheme. The performance of the proposed scheme is compared with the performance of two relevant and well-known DL packet scheduling methods. The simulation results confirm that the proposed scheme is able to reduce VoLTE end-to-end delay and achieve a better system capacity than current methods, and maintain the desired VoLTE QoS.
@cite_6: Long Term Evolution (LTE) is the new generation wireless networks that support all IP transmission for multimedia services. One of the major challenges in LTE network is to provide the packet scheduling scheme that can supports the Quality-of-Service (QoS) requirements of multimedia services. In this paper, a Quality-of-Service (QoS) aware packet scheduler for Real Time (RT) downlink communication in LTE is proposed. A Resource Block (RB) preserver scheduling algorithm that has two layers is developed. The upper layer exploits the LTE frame features of aggregating multiple numbers of sub-frames. The lower layer adopts the concept of Proportional Fair (PF) algorithm to schedule the Non Real Time (NRT) flows. While for the real time flows, the Exponential Earliest Deadline (EXP ED) algorithm is utilized. Our simulation results show the proposed Resource Block Preserver (RBP) algorithm outperforms both the Exponential Proportional Fair (EXP PF) and Maximum-Largest Weighted Delay First (M-LWDF) scheduling algorithms in terms of lower Packet Loss Ratio (PLR) among users in the downlink 3GPP LTE system supports VoIP services.
@cite_24: With the design of data communications in mind, 3GPP Long Term Evolution (LTE) mobile network is now considered as the most promising technology for Internet of EveryThings (IoE). The IoE incorporates four pillars: people, process, data, and things. The pillars interact in a way that establishes three main connections in the IoE environment: people communicate with people (P2P), machines communicate with people (M2P), and machines communicate with machines (M2M). In order to accommodate the increased demand for P2P connections called Human-to-Human (H2H) data services, LTE packet scheduling (PS) algorithm aims to optimize system's performance and users quality of service (QoS) requirements by following specific policies. PS algorithm is responsible for the allocation of shared radio resources among mobile user equipment (UE). In this paper we focus on how LTE will handle the H2H connections and we propose a new packet scheduling algorithm for LTE Downlink called Decoupled-level with QoS-Aware (DLQA). Our proposed scheduling algorithm makes decisions based on two decoupled levels and QoS needs. Finally, we show, through simulation results that our proposed algorithm optimizes well system's performance and user's QoS requirements compared to competing well-known scheduling algorithms.
@cite_19: The Long Term Evolution (LTE) is a high data rates and fully All-IP network. Scheduling and resource allocation are very important tasks in LTE network. So that, the optimization of the real-time services transmission is very essential. However, there are many challenges when deploying the live multimedia services such as VoIP, Video, etc. This paper proposes a new scheduling scheme which based on the Wideband (WB) E-model, Channeland QoS-Aware (known as WE-MQS scheduler) for voice traffic in LTE downlink direction. The voice traffic flow is very sensitive to network impairments such as delay, packet loss, jitter, etc. The proposed scheduling scheme is based on the extension of the WB E-model and the consideration of Maximum Queue Size (MQS) as a factor for the metric. Since this scheduling scheme considers Mean Opinion Score (MOS) values, thus, it gets higher user perception. The simulation results show that the proposed scheme has the performance which not only satisfies QoS requirements of voice services but also outperforms well-known schedulers such as Frame Level Scheduler (FLS), Modified Largest Weighted Delay First (MLWDF) and Exponential Proportional Fair (EXP PF) schedulers in terms of delay for all the number of user (NU) and Packet Loss Rate (PLR) when the NU is more than 47. For the cell throughput, Fairness Index (FI), and Spectral Efficiency, the proposed scheduler is always in the middle of the remaining schedulers. The performance evaluation is compared in terms of Delay, PLR, Throughput, FI, and FI for FLS, M-LWDF, EXP PF schedulers and the proposed one.
Specifically for VoLTE, @cite_36 proposes a resource allocation algorithm based on the prediction of channel quality change for VoLTE users. Also, in @cite_32 a semi-persistent packet scheduling algorithm is proposed for VoLTE (GBR) users over heterogenous networks of fourth generation LTE and third-generation universal mobile telecommunications service (3G UMTS). A new channel- and QoS-aware scheduling algorithm (WE-MQS) is proposed in @cite_19 for downlink scheduling of VoLTE users which considers user perception. To reduce the waste of resources when scheduling a low-rate VoLTE user on a strong channel, a scheduling algorithm is proposed in @cite_24 in which voice packets for different users are multiplexed within one LTE packet in the downlink. Compared to these works we consider both GBR and non-GBR users in LTE networks. Also, the authors of @cite_6 proposed a Resource Block Preserver scheduling algorithm for both real time and non-real time flows. It includes two layers, the upper layer is designed to satisfy the QoS of real time flows based on sub-frame aggregation, while the lower layer allocates the resource blocks to users depending on flow types. @cite_22 and @cite_4 new scheduling algorithms are developed which can manage mixed traffic including both real time and non-real time traffic.