Proportional-fair

This paper proposes a new QoS control method for the ad hoc Wireless LAN (W-LAN), which adjusts the Contention Window (CW) size dynamically based on the required and achieved bit rate. By the proposed method, a node with higher bit rates can have better chance to send the data in order to satisfy the Quality of Service (QoS) requirement. This paper also shows the effectiveness of the proposed method based on the results of computer simulations.

The fifth-generation wireless communication is expected to provide a huge amount of capacity to cater to the need of an increasing number of mobile consumers, which can be satisfied by device-to-device (D2D) communication. Reusing the cellular user's resources in an efficient manner helps to increase the spectrum efficiency of the network but it leads to severe interference. The important point in reusing cellular user resources is that D2D communication should not affect the cellular user's efficiency. After achieving this requirement, the focus is now turned toward the allocation of resources to D2D communication. This resource allocation strategy is to be designed in such a way that it will not affect communication among the cellular user (CU). This scheme improves various performance objectives. This paper aims at designing a proportional fair resource allocation algorithm based on the bipartite graph which maintains the quality of service (QoS) of CUs while providing D2D communication. This algorithm can be merged with any other scheme of resource allocation for improving QoS and adopting changing channels. In this scheme, a D2D pair can be allocated with one or more than one resource blocks. The MATLAB simulations analyze the performance of the proposed scheme.

A key feature of LTE system is that the packet scheduler can make use of the Channel Quality Information (CQI), which is periodically reported by user equipments either in an aggregate form for the whole downlink channel, or distinguished for each available subchannel. This mechanism allows for wide discretion in resource allocation, thus promoting the flourishing of several scheduling algorithms, with different purposes. It is therefore of great interest to compare the performance of such algorithms in different scenarios. We here carry out a thorough performance analysis of different scheduling algorithms for saturated UDP and TCP traffic sources, and considering both time-domain and frequency-domain versions of the schedulers and for both flat and frequency selective channels. The analysis makes it possible to appreciate the difference among the scheduling algorithms and to assess the performance gain, in terms of cell capacity, users' fairness, and packet service time, obtained by exploiting the richer, but heavier, information carried by subchannel CQI. An important part of this analysis is a throughput guarantee scheduler which we propose in this work. The analysis reveals that the proposed scheduler provides a good tradeoff between cell capacity and fairness both for TCP and UDP traffic sources.

A key feature of LTE system is that the packet scheduler can make use of the Channel Quality Information (CQI), which is periodically reported by user equipments either in an aggregate form for the whole downlink channel, or distinguished for each available subchannel. This mechanism allows for wide discretion in resource allocation, thus promoting the flourishing of several scheduling algorithms, with different purposes. It is therefore of great interest to compare the performance of such algorithms in different scenarios. We here carry out a thorough performance analysis of different scheduling algorithms for saturated UDP and TCP traffic sources, and considering both time-domain and frequency-domain versions of the schedulers and for both flat and frequency selective channels. The analysis makes it possible to appreciate the difference among the scheduling algorithms and to assess the performance gain, in terms of cell capacity, users' fairness, and packet service time, obtained by exploiting the richer, but heavier, information carried by subchannel CQI. An important part of this analysis is a throughput guarantee scheduler which we propose in this work. The analysis reveals that the proposed scheduler provides a good tradeoff between cell capacity and fairness both for TCP and UDP traffic sources.

Long Term Evolution (LTE) is well known as a cellular network that can support very high data rates in diverse traffic conditions. One way of achieving it is through packet scheduling which is the key scheme of Radio Resource Management (RRM) for LTE traffic processing that is functioning to allocate resources for both frequency and time dimensions. The main contribution of this paper is the design of a new scheduling scheme and its performance is compared with the Proportional Fair (PF) and Round Robin (RR) downlink schedulers for LTE by utilizing LTE Downlink System Level Simulator. The proposed new scheduling algorithm, namely the Modified-PF scheduler divides a single subframe into multiple time slots and allocates the resource block (RB) to the targeted User Equipment (UE) in all time slots for each subframe based on the instantaneous Channel Quality Indicator (CQI) feedback received from UEs. Simulation results show that the Modified-PF scheduler provides the best performance ...

The development of new wireless cellular network technologies is always in progress. As 3G has been considered the foundation of mobile broadband, the latest generation of cellular mobile communications, that is, 5G New Radio, is expected to realize the networked society, where everyone and everything are seamlessly connected everywhere and every time. To ensure the connectivity and provide the required services, the cellular network could first be simulated, and the performance evaluated. Simulations are made as a method to evaluate the performance of the connectivity and services. In addition, building new network simulators and efficient scheduler algorithms, could be crucial for dimensioning the networks to fulfill the new services/use cases demands. This thesis work includes two main parts. First, a network model that reflects modern cellular architectures and user services, are defined and implemented. Second, a system level simulator that uses different scheduler algorithms i...

The proposal of LTE in the standardization of cellular network systems has received considerable attention in the research domain, and most subscribers widely use it. Despite the enormous acceptance of the system, academia as an industry is usually disadvantaged in training students due to the cost implication in setting up a prototype. In bridging this gap, simulators are traditionally developed as a testbed to aid students appreciate how these systems work. Although there are several simulators available on the market, these simulators are quite expensive to acquire while others come with license restrictions. In this study, a classical LTE cellular system simulator is proposed as a testbed to aid the education of computer networks at college. The proposed simulator is an extension of the functionality of LTE-Sim frameworks. Usability testing of the proposed study reveals that the system is much easier to simulate the various scenarios in wireless communication.

In this paper, we present initial results on how the ns-3 LTE LENA stack is used to build a LTE testbed in an indoor lab network. We have extended the ns-3 MAC/PHY layer architecture to interface with a LabVIEW implementation of the LTE Physical layer and also extended ns-3 core modules to enable real-time performance. We present how this testbed can be used for prototyping a novel Software Defined Networking (SDN) scheme for interference management within dense heterogeneous deployments of cellular wireless networks. We provide an example case study for a Distributed Mobility Management (DMM) implementation using this testbed, where we demonstrate mobility of a emulated User Equipment device between LTE and WiFi networks. We plan to use this testbed for validation and demonstration of various SDN-based algorithms proposed within the framework of the EU FP7 CROWD (Connectivity management for eneRgy Optimised Wireless Dense networks) Project. We believe the proposed testbed is especially valuable for studying the cross-layer performance of cellular PHY/MAC algorithms in a realistic environment and shows how ns-3 can be used as a unified prototyping and simulation framework for wireless networks.

A key feature of LTE system is that the packet scheduler can make use of the Channel Quality Information (CQI), which is periodically reported by user equipments either in an aggregate form for the whole downlink channel, or distinguished for each available subchannel. This mechanism allows for wide discretion in resource allocation, thus promoting the flourishing of several scheduling algorithms, with different purposes. It is therefore of great interest to compare the performance of such algorithms in different scenarios. We here carry out a thorough performance analysis of different scheduling algorithms for saturated UDP and TCP traffic sources, and considering both time-domain and frequency-domain versions of the schedulers and for both flat and frequency selective channels. The analysis makes it possible to appreciate the difference among the scheduling algorithms and to assess the performance gain, in terms of cell capacity, users' fairness, and packet service time, obtained by exploiting the richer, but heavier, information carried by subchannel CQI. An important part of this analysis is a throughput guarantee scheduler which we propose in this work. The analysis reveals that the proposed scheduler provides a good tradeoff between cell capacity and fairness both for TCP and UDP traffic sources.

Long Term Evolution is standardized by the 3rd Generation Partnership Project to provide a high data rate up to 100 Mbps and 50 Mbps for downlink and uplink transmission respectively and can operate in different bandwidths ranging from 1.4MHz up to 20MHz. The incorporated scheduling mechanisms can significantly contribute to this goal. Scheduling mechanism is the process of allocated the resources (Time and Frequency) to users transmitting different flows in same time. In this paper, a novel scheduling algorithm is presented, modeled and compare to basic scheduler used in downlink LTE transmission, such as Round Robin, Max Rate and Proportional fair schedulers. Simulation results, presented in this paper, show that the newly proposed algorithm improves system capacity as compare with Proportional Fair scheduler with guaranty of 80% fairness between all users.

Long Term Evolution (LTE) Carrier Aggregation (CA) was introduced by the Release-10 3GPP specifications. CA allows aggregation of up to 5 cells for a terminal; both downlink (DL) CA and uplink (UL) CA are supported by the 3GPP specifications. However, the first commercial deployments focus on the aggregation of two cells in the downlink. The benefits of LTE CA are increased terminal peak data rates, aggregation of fragmented spectrum and fast load balancing. In this paper, we analyze different strategies of DL scheduling for LTE CA including centralized, independent and distributed schedulers, we provide the corresponding simulation results considering UE data rate limitations and different traffic models. Also, we compare the performance of a single LTE carrier with LTE CA using the same total bandwidth.

In this paper, we consider the operational impact that VoLTE will have on the performance of mobile broadband data in the real world from a throughput perspective when the two service types are mixed on the same channel. We begin by proposing an M/G/1 priority queueing model with non-preemptive scheduling to analyze scheduler latencies that can be expected when there are services with different levels of priority in service on the same channel. We then discuss the direct impact that latency has on packet data convergence protocol layer throughputs, and simulate scheduler scenarios in a longterm evolution environment. Scheduler algorithms are highly proprietary and vary greatly from one vendor to another; however, there are some laws and constraints of both space and time that cannot be avoided. In this paper, we quantify these limitations using modeling and simulations. Finally, we provide solutions from a hardware configuration and capacity planning perspective to help to overcome these hidden limitations that are typically difficult to measure and quantify, and complex to understand.

In order to provide an increased capacity, throughput and QoS guarantee for terrestrial users in emergency scenarios, a low-medium-altitude aerial platform based time-division-duplex long term evolution (TD-LTE) system referred to as Aerial LTE, is presented in this paper. Additionally a power-efficient radio resource allocation mechanism is proposed for both the Aerial LTE downlink and uplink, which is modeled as a cooperative game. Our simulation results demonstrate that the proposed algorithm imposes an attractive tradeoff between the achievable throughput and the power consumption while ensuring fairness among users.

Managing radio resources in Long Term Evolution (LTE) networks is considered as one of the essential design factors for enhancing the overall system performance. Common approaches are introduced to either achieve fairness between network users or attain maximum spectral efficiency. However, these approaches do not consider optimizing energy consumption. Therefore, in this paper, a novel resource allocation algorithm based on the Dragonfly metaheuristic technique is proposed to allocate bandwidth to users. The new algorithm is called Dragonfly-based Joint Delay/Energy (DJDE) and considers the Quality of Services (QoS) requirements of the users while achieving a high level of energy efficiency. The proposed solution utilizes the Dragonfly algorithm to optimize the integration process of different scheduling policies. To evaluate the proposed algorithm, an extensive set of experiments are conducted to compare the proposed solution to the state-of-the-art techniques. Also, to assess the energy efficiency of the proposed method, another set of experiments are simulated to compare it with various algorithms that optimize energy consumption. The obtained results prove that the DJDE algorithm can satisfy the QoS requirements of the users while improving the overall system performance.

Long Term Evolution is standardized by the 3rd Generation Partnership Project to provide a high data rate up to 100 Mbps and 50 Mbps for downlink and uplink transmission respectively and can operate in different bandwidths ranging from 1.4MHz up to 20MHz. The incorporated scheduling mechanisms can significantly contribute to this goal. Scheduling mechanism is the process of allocated the resources (Time and Frequency) to users transmitting different flows in same time. In this paper, a novel scheduling algorithm is presented, modeled and compare to basic scheduler used in downlink LTE transmission, such as Round Robin, Max Rate and Proportional fair schedulers. Simulation results, presented in this paper, show that the newly proposed algorithm improves system capacity as compare with Proportional Fair scheduler with guaranty of 80% fairness between all users.

We have proposed a high-speed fluid-flow rate allocation scheme. We show that this method is well suited for ephemeral web-like traffic which is proliferating as network speed is increasing. We look at the flow level properties and packet level algorithm. We further discuss the equilibrium properties and show that this algorithm can achieve proportional fairness. The simulation results for both permanent and short-lived flows are promising.

We investigate the optimal selection of minimum contention window values to achieve proportional fairness in a multirate IEEE 802.11e test-bed. Unlike other approaches, the proposed model accounts for the contention-based nature of 802.11's MAC layer operation and considers the case where stations can have different weights corresponding to different throughput classes. Our test-bed evaluation considers both the long-term throughput achieved by wireless stations and the short-term fairness. When all stations have the same transmission rate, optimality is achieved when a station's throughput is proportional to its weight factor, and the optimal minimum contention windows also maximize the aggregate throughput. When stations have different transmission rates, the optimal minimum contention window for high rate stations is smaller than for low rate stations. Furthermore, we compare proportional fairness with time-based fairness, which can be achieved by adjusting packet sizes so that low and high rate stations have equal successful transmission times, or by adjusting the transmission opportunity (TXOP) limit so that high rate stations transmit multiple back-to-back packets and thus occupy the channel for the same time as low rate stations that transmit a single packet. The test-bed experiments show that when stations have different transmission rates and the same weight, proportional fairness achieves higher performance than the time-based fairness approaches, in terms of both aggregate utility and throughput.

In LTE, resource scheduling algorithm is one of the key parameters that determine the overall system and UE performances in terms of throughput and fairness respectively. Multiple scheduling techniques are available that emphasizes on optimizing any one of the key system performance parameters. Among them the most potential algorithms are proportional fair (PF) and round robin (RR). PF optimizes UE throughput with a fairly high fairness index whereas RR provides the best fairness among the UEs but with a comparatively lower throughput. Moreover the scheduler performance is affected by the UE mobility and UE density. This can significantly degrade the overall system efficiency. In this paper we have analyzed and compared several LTE downlink performance parameters between PF and RR in heterogeneous network (HetNet) to determine which scheduling scheme is convenient for users with high mobility.

Distributed Opportunistic Scheduling (DOS) techniques have been recently proposed to improve the throughput performance of wireless networks. With DOS, each station contends for the channel with a certain access probability. If a contention is successful, the station measures the channel conditions and transmits in case the channel quality is above a certain threshold. Otherwise, the station does not use the transmission opportunity, allowing all stations to recontend. A key challenge with DOS is to design a distributed algorithm that optimally adjusts the access probability and the threshold of each station. To address this challenge, in this paper we first compute the configuration of these two parameters that jointly optimizes throughput performance in terms of proportional fairness. Then, we propose an adaptive algorithm based on control theory that converges to the desired point of operation. Finally, we conduct a control theoretic analysis of the algorithm to find a setting for its parameters that provides a good tradeoff between stability and speed of convergence. Simulation results validate the design of the proposed algorithm and confirm its advantages over previous proposals.

The performance evaluation of wireless networks is severely complicated by the specific features of radio communication, such as highly variable channel conditions, interference issues, and possible hand-offs among base stations. The latter elements have no natural counterparts in wireline scenarios, and create a need for novel performance models that account for the impact of these characteristics on the service rates of users.

—The heterogeneous cellular network (HCN) is a promising approach to the deployment of 5G cellular networks. This paper comprehensively studies physical layer security in a multi-tier HCN where base stations (BSs), authorized users and eavesdroppers are all randomly located. We first propose an access threshold based secrecy mobile association policy that associates each user with the BS providing the maximum truncated average received signal power beyond a threshold. Under the proposed policy, we investigate the connection probability and secrecy probability of a randomly located user, and provide tractable expressions for the two metrics. Asymptotic analysis reveals that setting a larger access threshold increases the connection probability while decreases the secrecy probability. We further evaluate the network-wide secrecy throughput and the minimum secrecy throughput per user with both connection and secrecy probability constraints. We show that introducing a properly chosen access threshold significantly enhances the secrecy throughput performance of a HCN.

OFDM is an attractive technique to implement multiuser diversity for the downlink. This paper deals with the problem of combining the increased cell throughput of multiuser diversity schemes with a fair distribution of resources among the users. A proportional fair scheduler for opportunistic OFDM is proposed. Its key features are that it can accomodate several quality-of-service (QoS) classes, that it has a tunable fairness level, and that it can be integrated with an opportunistic beamformer to increase system fairness. Simulation results show that the cell throughput of the opportustic scheme approaches that of a more complex smart antenna scheme for many users. For a densely populated system, the proposed scheme shows a graceful QoS degradation, possibly leading to a high average user satisfaction. The fairness parameter effectively tunes the scheduler between high cell throughput and high fairness.

—A multi-level soft frequency reuse (ML-SFR) scheme and a resource allocation methodology are proposed for wireless communication systems in this letter. In the proposed ML-SFR scheme, there are 2N power density limit levels, achieving better interference pattern and further improving the cell edge and overall data rate, compared to the traditional 2-level SFR scheme. The detailed design of an 8-level SFR scheme is demonstrated. Numeral results show that the cell edge spectrum efficiency is increased to 5 times of that of reuse 1 and the overall spectrum efficiency is improved by 31%. ML-SFR can be utilized in the current 4G system and would be a candidate key technology for future 5G systems. Index Terms—Multi-level soft frequency reuse, inter cell interference coordination, interference pattern, LTE, 5G.

The Long Term Evolution Advanced (LTE-Advanced) transmission bandwidth can be expanded by Carrier Aggregation (CA), where CA technology expands effective bandwidth supported to User Equipment (UE) by utilizing of radio resources across multiple carriers. Recently, many studies have been conducted on the radio resource allocation with CA. However, most of these studies are based on Proportional Fair (PF) packet scheduling algorithms. Indeed, these algorithms are not adequate to meet the requirements for supporting mixture real-time applications; they ignored channel condition; and finally, they are unable to support real-time application with delay constraint. Therefore, this paper proposes novel Packet Scheduling (PS) condition algorithm that attractively enhances the average system throughput by designing a weighting factor to modified largest weighted delay first PS algorithm. The novel algorithm is implemented in a PS module for LTE-Advanced via system level simulations. The results demonstrate that the effectiveness of enhanced Modified Largest Weighted Delay First (M-LWDF) algorithm in improving throughput.

LA are essential techniques in improving the LTE performance, giving e.g. both cell throughput and coverage gain of around 40 % over a distributed multiplexing scheme. However, there is a tradeoff with signaling overhead related to the CQI feedback and overall LA and PS performance, which is rather overlooked in the literature. We analyze four different CQI reporting schemes with respect to system spectral efficiency and conclude that the Best-M average and Threshold based CQI reporting schemes seem to be the most promising in terms of the compromise between system performance and signaling overhead.

In this paper, we propose a distributed adaptive interference coordination algorithm for a practical orthogonal frequency division multiple access (OFDMA)-based mobile cellular systems. The designed algorithm can achieve an efficient frequency reuse for any user distribution and traffic load. Since no a priori frequency planning is required, the minimal coordination between base stations is also achieved. Moreover, the proposed algorithm can adapt to different network interference conditions and is power-saving in some degree. We also develop a way to decompose a multi-cell optimization problem into distributed single-cell optimization problems, which greatly reduces the computational complexity.

Multi-User MIMO (MU-MIMO) is a useful technique to enhance uplink capacity in LTE because the base stations employ multiple receive antennas whereas the user equipments transmit with only a single antenna. In this paper we investigate several UE pairing schemes that maximize the total system utility while adhering to the LTE Release-8 constraint of allocating identical contiguous resource blocks (RBs) to the paired UEs. We design pairing decisions using either the wideband or sub-band channel cross-correlation values of the UEs. These mechanisms offer varying trade-offs between performance and complexity. We show that with appropriate modifications, these schemes work well even for finite queue traffic.

The planning of Physical Cell Identities (PCI) has a strong impact on the performance of Long Term Evolution cellular networks. Although several PCI planning schemes have been proposed in the literature, no study has quantified the performance gains obtained by these schemes. In this paper, a comprehensive performance analysis is carried out to quantify the impact of PCI planning on user quality of service and network capacity in the downlink of LTE. First, an analytical model for the influence of PCI planning on reference signal collisions is developed. Based on this model, different PCI planning schemes are tested on a dynamic system-level simulator implementing a macrocellular scenario. During the analysis, both Voice-over-IP and full buffer services over time-synchronized and non-time synchronized networks are considered. Results show that call blocking and dropping for real-time services and user throughput for non-real time services can be significantly improved by a proper PCI plan. 2 3 4 5 7 8 9 10

Abstract Self-organizing networks (SON) is currently seen as a key lever to improve network performance and simplify its management. This paper considers α-fair schedulers in an Orthogonal Frequency-Division Multiple Access (OFDMA) network. The convergence of the α-fair scheduler is analyzed. Closed-form formulas are given for certain cases to calculate the scheduling gain, as well as a Monte-Carlo method, for a MIMO channel.