The evolution path of 4G networks: FDD or TDD?

Chan, P.W.C.; Lo, Ernest S.; Wang, Rui; Au, Edward; Lau, V.K.N.; Cheng, R.S.; Mow, Wai Ho; Murch, R.D.; Letaief, Khaled B.

doi:10.1109/mcom.2006.273098

Cited by 135 publications

(73 citation statements)

References 6 publications

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“…From Shannon's capacity formula, it can be seen that the transmission energy per bit can be reduced exponentially by increasing its transmission time [11]. In dynamic Time-Division Duplex (TDD) systems the base station can adjust the time allocated to uplink and downlink traffic dynamically [12,13]. Traditionally, this feature has been used to compensate for the asymmetry in uplink and downlink traffic demand.…”

Section: Introductionmentioning

confidence: 99%

Mode selection for energy efficient D2D communications in dynamic TDD systems

Penda

Johansson

2015

2015 IEEE International Conference on Communications (ICC)

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Abstract-Network-assisted Device-to-Device (D2D) communication is a promising technology for improving the performance of proximity-based services. This paper demonstrates how D2D communication can be used to improve the energy-efficiency of cellular networks, leading to a greener system operation and a prolonged battery life of the mobile devices. Assuming a flexible TDD system, we develop optimal mode selection policies for minimizing the energy cost (either from the system or from the device perspective) while guaranteeing a certain rate requirement. The jointly optimal transmit power and time allocation, as well as the optimal mode selection, is found by solving a small convex optimization problem. Special attention is given to the geometrical interpretation of the obtained results. We show that when network energy is the primary concern, D2D mode is preferable in a large portion of the cell. When the device energy consumption is most important, on the other hand, the area where D2D mode is preferable shrinks and becomes close to circular. Finally, we investigate how network parameters affect the range where direct communication is preferred.Index Terms-Network-assisted Device-to-Device, Mode Selection, TDD-LTE, Energy Efficient Communications I. INTRODUCTION During the last decade, the number of mobile subscribers and their traffic demand has increased tremendously, resulting in a larger energy consumption for cellular networks. Furthermore, the battery lifetime of mobile devices has been reduced considerably. Network-assisted Device-to-Device (D2D) communication is a promising technology to improve energy efficiency in future wireless networks: when mobile users in proximity to each other need to exchange data at high rate (e.g. media sharing, gaming, and other proximity-based services [1,2]), direct communication can potentially offload the BS and improve throughput, delay and energy consumption [3,4].A natural question in the context of D2D communication is under which condition two users should communicate through a direct link rather than via the BS. We call this problem the mode selection problem. The optimal mode selection naturally depends on the performance measure that we would like to optimize. For example, the authors in [5] select the transmission mode to maximize user rate in both single-cell and multiple-cell scenarios, while satisfying SINR constraints on active cellular links. In [6] and [7], the authors focus on maximizing the power-efficiency of the network. A joint mode selection and resource allocation problem in a multicell scenario is presented in [8] and shown to be NP-Hard. In [9], the authors address the mode selection problem of

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Section: Introductionmentioning

confidence: 99%

Mode selection for energy efficient D2D communications in dynamic TDD systems

Penda

Johansson

2015

2015 IEEE International Conference on Communications (ICC)

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“…By contrast, TDD systems use a single channel that is alternately uplink and downlink. Implementation tradeoffs abound and there is a literature comparing these approaches and evaluating the tradeoffs (see [18] and [19], for example). From the point of view of fungibility, one key factor is that an FDD system requires spectrum that is paired because the uplink and the downlink operate at different frequencies.…”

Section: Technologicalmentioning

confidence: 99%

When is electromagnetic spectrum fungible?

Weiss

Krishnamurthy

Doyle

et al. 2012

2012 IEEE International Symposium on Dynamic Spectrum Access Networks

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Abstract-Fungibility is a common assumption for marketbased spectrum management. In this paper, we explore the dimensions of practical fungibility of frequency bands from the point of view of the spectrum buyer who intends to use it. The exploration shows that fungibility is a complex, multidimensional concept that cannot casually be assumed. We develop two ideas for quantifying fungibility -(i) of a fungibility space in which the "distance" between two slices of spectrum provides score of fungibility and (ii) a probabilistic score of fungibility.

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“…With the exponential growth of mobile Internet, the data traffic will increase by 1000 times beyond 2020. The existing 4G system cannot meet the increasing traffic demand of the future mobile communication, which put forward beam can be focused within a narrow range; hence, various kinds of interference can be substantially suppressed [4,[6][7][8][9][10].…”

Section: Introductionmentioning

confidence: 99%

Beam-domain hybrid time-switching and power-splitting SWIPT in full-duplex massive MIMO system

Shen

Wang

2018

J Wireless Com Network

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In this paper, we consider the beam-domain hybrid time-switching (TS) and power-splitting (PS) simultaneous wireless information and power transfer (SWIPT) protocol design in full-duplex (FD) massive multiple-input multiple-output (MIMO) system, where the FD base station (BS) simultaneously serves a set of downlink half-duplex (HD) users (cellular users) and a set of fixed uplink HD users (fixed sensor nodes) which are uniformly distributed in its coverage area. In order to reduce the computational complexity, we investigate the beam-domain representation of massive MIMO channels based on the basis expansion model, and then the beam-domain SWIPT protocol which lies in intelligently scheduling the users and sensors based on the beam-domain distributions of their associated channels to mitigate SI and enhance transmission efficiency is designed for full-duplex massive MIMO system. The whole beam-domain hybrid TS and PS SWIPT protocol is divided into two phases based on the ideal of TS. The first phase is used for cellular users uplink training and sensor nodes energy harvesting as well as downlink training, wherein the cellular users transmit uplink pilots for uplink channel estimation at the BS, while the BS simultaneously transmits energy signals to the sensor nodes. Based on the idea of PS, the sensor nodes utilize the received energy signals for energy harvesting and downlink channel estimation. In the second phase, the BS forms the transmit beamformers for information transmission to the users as well as the receive beamformers for the sensors transmit their data to the BS simultaneously. By optimizing the TS ratio and transmit powers at the BS in two phases, the system achievable sum rate performance is maximized. Simulation results show the superiority of the proposed protocol on spectral efficiency compared with the existing massive MIMO SWIPT protocol.

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The evolution path of 4G networks: FDD or TDD?

Cited by 135 publications

References 6 publications

Mode selection for energy efficient D2D communications in dynamic TDD systems

Mode selection for energy efficient D2D communications in dynamic TDD systems

When is electromagnetic spectrum fungible?

Beam-domain hybrid time-switching and power-splitting SWIPT in full-duplex massive MIMO system

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