An Adaptive Allocation Scheme in Multiuser OFDM Systems with Time-Varying Channels

Pao, Wei-Chen; Chen, Yung‐Fang; Tsai, Meng-Gu

doi:10.1109/tw.2013.123013.121981

Cited by 20 publications

(8 citation statements)

References 19 publications

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“…It can also be noted that resource allocation/scheduling in the uplink of OFDM systems have been very well investigated, however, mainly from an SE [12], [13], EE [14], [15] and more recently, joint SE and EE maximization [16], [17] perspective, where the authors jointly maximized both the SE and EE in green heterogeneous networks. Margin adaptive resource allocation has been investigated in [18]- [20], where the authors minimized transmit powers in OFDM systems. However, these works do not consider the signaling powers of the transmitters nor the transmission duration, which are critical in evaluating EM emission.…”

Section: Introductionmentioning

confidence: 99%

Electromagnetic Emission-Aware Schedulers for the Uplink of OFDM Wireless Communication Systems

Sambo

Al-Imari

Héliot

et al. 2017

IEEE Trans. Veh. Technol.

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Abstract-The popularity and convergence of wireless communications have resulted in continuous network upgrades in order to support the increasing demand for bandwidth. However, given that wireless communication systems operate on radiofrequency waves, the health effects of electromagnetic emission from these systems are increasingly becoming a concern due to the ubiquity of mobile communication devices. In order to address these concerns, we propose two schemes (offline and online) for minimizing the EM emission of users in the uplink of OFDM systems, while maintaining an acceptable quality of service. We formulate our offline EM reduction scheme as a convex optimization problem and solve it through water-filling. This is based on the assumption that the long-term channel state information of all the users is known. Given that, in practice, long-term channel state information of all the users cannot always be available, we propose our online EM emission reduction scheme, which is based on minimizing the instantaneous transmit energy per bit of each user. Simulation results show that both our proposed schemes significantly minimize the EM emission when compared to the benchmark classic greedy spectral efficiency based scheme and an energy efficiency based scheme. Furthermore, our offline scheme proves to be very robust against channel prediction errors.

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Section: Introductionmentioning

confidence: 99%

Electromagnetic Emission-Aware Schedulers for the Uplink of OFDM Wireless Communication Systems

Sambo

Al-Imari

Héliot

et al. 2017

IEEE Trans. Veh. Technol.

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“…Multiple Rayleigh fading channels with unit average gain are shared by 8 users, and 4-QAM, 16 exhausting search algorithm, and the classical iterative waterfilling algorithm (WFA) [4]. Here, the channel error ratio (CER) is defined as the ratio between the variance of channel estimation error and noise variance.…”

Section: Simulation Resultsmentioning

confidence: 99%

“…An optimal downlink resource management scheme is proposed in [2] for OFDM wireless communication systems to maximize the system throughput under certain constraints such as the signal-to-noise ratio requirement, the fairness, and the total transmission power constraint. While, in [3] [4], the minimization problem of the overall transmit power is considered, and the adaptive multiuser subcarrier, data rate, and power allocation scheme is investigated for the downlink OFDMA systems. For the uplink OFDMA transmission, the maximization and minimization problems are addressed in [5] and [6], respectively, and the near optimal solutions are derived through the joint subcarrier and power allocation.…”

Section: Introductionmentioning

confidence: 99%

Radio resource management for the uplink OFDMA system with imperfect CSI

Liu

Wang

Zhang

et al. 2015

2015 IEEE Wireless Communications and Networking Conference (WCNC)

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This paper investigates the effect of imperfect channel state information (CSI) on the performance of radio resource management for the uplink OFDMA system. First, we prove that the imperfect CSI introduces a constellation-point dependent and error-floor symbol error rate (SER), which correspondingly yields the nonconvex and nondifferentiable throughput function in real communication systems. Then, in the uplink OFDMA system, a bisection algorithm and BA-based algorithm are proposed for single-user and multi-user cases, respectively, for the adaptive resource allocation to minimize the total transmit power.

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“…1 with four different paths. The design inputs are the channel and distance matrix [20]. The channel conditions are formed as a matrix form (by experimental study) for different modulation [11].…”

Section: Optimization Processmentioning

confidence: 99%

Optimizing Network Layer with Adaptive Modulation for Time Varying Channel

Navaneethan

Prabha²

2016

Wireless Pers Commun

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A finite group of nodes placed in the network layer for inter process communication has to guarantee specified performance measures like high throughput, low jitter, avoid contention, etc. At present, the data security is taken care by the upper layer i.e. Transport (TCP/IP) to some extent and the network layer has to simply deliver the packets in an optimal manner. The security now offered by the TCP/IP layer is in the form of retransmission for the corrupt packet(s). If the channel conditions are not good, then repeated retransmission requests, can lower the throughput, increase the jitter and render the network less useful. Hence, to ensure uniform SNR in each of the link, it is necessary to place critical design issues intrinsically in the individual nodes. This includes, for example, that, each node can autonomously detect the modulation and demodulate among a group set, and thereby support dynamic/adaptive modulation capability. This can enable the node to alter the modulation to maintain a uniform SNR and reduce the outage probability. Additionally, the communication strategy need to look for the shortest path, identify the channel support in that path and choose the best modulation based on shortest path algorithm. In this context, in this paper, each node is provided with the capability to perform (a) Autonomous Modulation (to maintain uniform SNR) (b) Switch to the corresponding demodulator and get the packet (reduces contention) and (c) route the packets to the next intended node through the shortest path (reduces jitter). This process is recursively done at every node as and when they receive the data. The metrics studied include the network layer metrics, wireless channel related metrics, modulation based aspects etc.

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An Adaptive Allocation Scheme in Multiuser OFDM Systems with Time-Varying Channels

Cited by 20 publications

References 19 publications

Electromagnetic Emission-Aware Schedulers for the Uplink of OFDM Wireless Communication Systems

Electromagnetic Emission-Aware Schedulers for the Uplink of OFDM Wireless Communication Systems

Radio resource management for the uplink OFDMA system with imperfect CSI

Optimizing Network Layer with Adaptive Modulation for Time Varying Channel

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