Joint Uplink Research Articles

Uplink Decentralized Joint Bandwidth and Power Allocation for Energy-Efficient Operation in a Heterogeneous Wireless Medium

In this paper, energy efficient uplink communications are investigated for battery-constrained mobile terminals (MTs) with service quality requirements and multi-homing capabilities. A heterogeneous wireless medium is considered, where MTs communicate with base stations (BSs) and access points (APs) of different networks with overlapped coverage. Different from the existing works, we develop a quality of service (QoS)-based optimization framework for joint uplink bandwidth and power allocation to maximize energy efficiency for a set of MTs with multi-homing capabilities. The proposed framework is implemented in a decentralized architecture, through coordination among BSs/APs of different networks and MTs, which is a desirable feature when different networks are operated by different service providers. A suboptimal framework is presented with a reduced computational complexity as compared with the optimal framework. Simulation results demonstrate the improved performance of both the optimal and suboptimal frameworks over a state-of-the-art benchmark.

User association with jointly maximising downlink sum rate and minimising uplink sum power for heterogeneous cellular networks

In heterogeneous cellular networks (HCNs), the user association is a challenging topic since some different base stations coexist. Moreover, because of the asymmetric uplink and downlink in HCNs, a joint uplink and the downlink association algorithm should be designed to improve the system performance. For the practical implementation, the authors need to ensure that the algorithm is highly effective. Thus, they try to design an association strategy that jointly maximises downlink sum rate and minimises uplink sum power, and formulate it as a sum-utility maximisation problem. To solve this problem, they design a centralised association algorithm via a gradient descent method, and develop a distributed association algorithm via dual decomposition. Simulation results show that, compared with the signal strength-based association, range expansion association and the method proposed by Ye, their scheme has some significant advantages in the mass.

Joint allocation of uplink and downlink resources for interactive mobile cloud applications

AbstractCloud‐based mobile applications are interactive in nature. Due to the strong correlation between uplink request and downlink response, it is irrational to optimize the uplink and downlink resource allocation problem separately and independently. In this paper, the joint uplink and downlink resource allocation problem for interactive mobile cloud applications is considered. The data exchange characteristics between mobile terminal and cloud server is investigated and a novel traffic model including both uplink and downlink transmission queues is constructed. Based on the new traffic model, the resource allocation problem can be formulated as a constrained Markov Decision Process. The objective is to minimize the application response time, that is, the roundtrip delay of causally related packet group (PG) pairs, with a constraint on PG drop rate. The Q‐learning algorithm and Value Iteration Algorithm are employed to obtain a solution that converges to the optimal one. To combat the curse of dimensionality, a sub‐optimal solution is proposed to solve the problem with an acceptable complexity. Numerical results indicate that the reduced complexity solution can achieve a delay performance approximate to that of the optimal solution and outperform other allocation schemes. Copyright © 2014 John Wiley & Sons, Ltd.

Distributed Inter-Cell Interference Mitigation Via Joint Scheduling and Power Control Under Noise Rise Constraints

Consider the problem of joint uplink scheduling and power allocation. Being inherent in almost any wireless system, this resource allocation problem has received extensive attention. Yet, most common techniques either adopt classical power control, in which mobile stations are received with the same Signal-to-Interference-plus-Noise Ratio, or use centralized schemes, in which base stations coordinate their allocations. In this work, we suggest a novel scheduling approach in which each base station, besides allocating the time and frequency according to given constraints, also manages its uplink power budget such that the aggregate interference, "Noise Rise", caused by its subscribers at the neighboring cells is bounded. Our suggested scheme is distributed, requiring neither coordination nor message exchange between the base stations. We rigorously define the allocation problem under noise rise constraints. Inspired by the fact that under the noise-rise constraints, interference experienced by base stations is bounded and its variance is expected to be low, we suggested an approximation in which each base station assumes fixed interference. Under this approximation we formalize the joint scheduling and power control under the noise rise constraints as an optimization problem and characterize the optimal solution. For the special case of homogeneous deployment we give the optimal solution and derive an efficient iterative algorithm to achieve it. We then discuss a relaxed problem, where the noise rise is constrained separately for each sub-channel or resource unit. While sub-optimal, this view renders the scheduling and power allocation problems separate, yielding an even simpler and more efficient solution, while the essence of the scheme is kept. Via extensive simulations, we show that the suggested approach increases overall performance dramatically, with the same level of fairness and power consumption.

Joint Uplink Resource Allocation Algorithm with Proportional-Fair in Heterogeneous Wireless Networks

In this paper, we exploit the uplink radio resource allocation considering proportional fairness among users in heterogeneous wireless networks. Meanwhile, multi-mode user terminals are assumed to have the capability of using multiple radio access technologies simultaneously. To this end, a joint optimization problem is formulated for power and bandwidth allocation for uplink transmission. Since the formulated primal problem is difficult to solve directly, we make continuous relaxation and obtain a near-optimal solution using Karush-Kuhn-Tucker conditions, and then propose a joint resource allocation algorithm. Simulation results show the proposed algorithm work, and the algorithm provides superior system throughput and much better fairness among users comparing to a heuristic algorithm

Utility-based uplink joint power and subcarrier allocation in SC-FDMA wireless networks

In this letter, the problem of optimal joint uplink power and subcarrier allocation in single-carrier frequency-division multiple access wireless networks with real-time services is addressed, via the introduction and adoption of a utility-based framework. A joint optimisation power and subcarrier allocation problem is formulated and the optimal power allocation is determined, while an iterative algorithm to realise the joint allocation is presented. Finally, numerical results are provided that demonstrate the effectiveness of the proposed approach in terms of power savings and user satisfaction.

Energy-efficient relay selection and optimal relay location in cooperative cellular networks with asymmetric traffic

Energy-efficient communication is an important requirement for mobile relay networks due to the limited battery power of user terminals. This paper considers energy-efficient relaying schemes through selection of mobile relays in cooperative cellular systems with asymmetric traffic. The total energy consumption per information bit of the battery-powered terminals, i.e., the mobile station (MS) and the relay, is derived in theory. In the joint uplink and downlink relay selection (JUDRS) scheme we proposed, the relay which minimizes the total energy consumption is selected. Additionally, the energy-efficient cooperation regions are investigated, and the optimal relay location is found for cooperative cellular systems with asymmetric traffic. The results reveal that the MS-relay and the relay-base station (BS) channels have different influence over relay selection decisions for optimal energy-efficiency. Information theoretic analysis of the diversity-multiplexing tradeoff (DMT) demonstrates that the proposed scheme achieves full spatial diversity in the quantity of cooperating terminals in this network. Finally, numerical results further confirm a significant energy efficiency gain of the proposed algorithm comparing to the previous best worse channel selection and best harmonic mean selection algorithms.

Joint Uplink and Downlink Performance Profiling of LTE Protocol Processing on a Mobile Platform

This article provides a detailed profiling of the layer 2 (L2) protocol processing for 3G successor Long Term Evolution (LTE). For this purpose, the most processing intensive part of the LTE L2 data plane is executed on top of a virtual ARM based mobile phone platform. The authors measure the execution times as well as the maximum data rates at different system setups. The profiling is done for uplink (UL) and downlink (DL) directions separately as well as in a joint UL and DL scenario. As a result, the authors identify time critical algorithms in the protocol stack and check to what extent state-of-the-art hardware platforms with a single-core processor and traditional hardware acceleration concepts are still applicable for protocol processing in LTE and beyond LTE mobile devices.

Joint uplink and downlink admission control to both streaming and elastic flows in CDMA/HSDPA systems

TCP-based data flows generate packets and ACKs in two directions, be it in the wireline or wireless networks. In the latter case, packets are typically found in the downlink whereas ACKs are in the uplink. These two links are asymmetric in the case of CDMA-based High Data Rate (HDR) and High-Speed Downlink Packet Access (HSDPA) systems, the uplink being much slower than the downlink and thus, in some cases, restrictive in terms of the achievable throughput of the TCP flow. The aim of this work is to evaluate the performance of such a setting, in the presence of both streaming and elastic traffic, under a dynamic scenario where users arrive at the system and leave it after completion of their service. We specifically quantify the impact of the uplink on the overall performance of TCP and study the model variations as functions of several parameters such as load, file size and radio conditions.

Performance Evaluation of an Enhanced Uplink 3.5G System for Mobile Healthcare Applications

The present paper studies the prospective and the performance of a forthcoming high-speed third generation (3.5G) networking technology, called enhanced uplink, for delivering mobile health (m-health) applications. The performance of 3.5G networks is a critical factor for successful development of m-health services perceived by end users. In this paper, we propose a methodology for performance assessment based on the joint uplink transmission of voice, real-time video, biological data (such as electrocardiogram, vital signals, and heart sounds), and healthcare records file transfer. Various scenarios were concerned in terms of real-time, nonreal-time, and emergency applications in random locations, where no other system but 3.5G is available. The accomplishment of quality of service (QoS) was explored through a step-by-step improvement of enhanced uplink system's parameters, attributing the network system for the best performance in the context of the desired m-health services.

Leveraging Downlink for Efficient Uplink Allocation in a Single-Hop Wireless Network

In this correspondence, we consider joint uplink and downlink rate allocations over a multiaccess/broadcast channel pair in a single-cell system. We assume a network of heterogeneous users, where the uplink utility of each user is held as private information and is unknown to the base station. The challenge is to design an optimal rate allocation scheme in the presence of such incomplete information when considering strategic users. Here, we provide an incentive-compatible mechanism that leverages downlink demand to ensure that users truthfully reveal their uplink utilities, enabling the socially optimal uplink rate allocation. In addition, we give numerical results on a kind of efficiency of downlink allocations for two specific uplink multiple-access channels (MACs): information theoretic additive white Gaussian noise (AWGN) , MAC, and code-division multiple-access (CDMA)-based uplink.