Adaptive modulation over nonlinear time-varying channels

Alasady, H.; Ibnkahla, Mohamed

doi:10.1109/icecs.2005.4633522

Cited by 3 publications

(3 citation statements)

References 7 publications

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“…PERSPECTIVE PHY layer reconfiguration includes SDR, transceiver reconfiguration, adaptive antennas and beamforming, adaptive modulation and coding (AMC), etc. [5], [6], [16]. Most publications in this field target device-level reconfiguration that often does not take into consideration the network aspect (even when wireless devices are part of a wider network).…”

Section: Phy Layer Reconfiguration: a Networkmentioning

confidence: 99%

Reconfigurable Wireless Networks

et al. 2015

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Abstract-Driven by the advent of sophisticated and ubiquitous applications, and the ever-growing need for information, wireless networks are without a doubt steadily evolving into profoundly more complex and dynamic systems. The user demands are progressively rampant, while application requirements continue to expand in both range and diversity. Future wireless networks, therefore, must be equipped with the ability to handle numerous, albeit challenging requirements. Network reconfiguration, considered as a prominent network paradigm, is envisioned to play a key role in leveraging future network performance and considerably advancing current user experiences. This paper presents a comprehensive overview of reconfigurable wireless networks and an in-depth analysis of reconfiguration at all layers of the protocol stack. Such networks characteristically possess the ability to reconfigure and adapt their hardware and software components and architectures, thus enabling flexible delivery of broad services, as well as sustaining robust operation under highly dynamic conditions. The paper offers a unifying framework for research in reconfigurable wireless networks. This should provide the reader with a holistic view of concepts, methods, and strategies in reconfigurable wireless networks. Focus is given to reconfigurable systems in relatively new and emerging research areas such as cognitive radio networks, cross-layer reconfiguration and software-defined networks. In addition, modern networks have to be intelligent and capable of self-organization. Thus, this paper discusses the concept of network intelligence as a means to enable reconfiguration in highly complex and dynamic networks. Key processes in network intelligence, such as reasoning, learning, and contextawareness are presented to illustrate how these methods can take reconfiguration to a new level. Finally, the paper is supported with several examples and case studies showing the tremendous impact of reconfiguration on wireless networks.

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Section: Phy Layer Reconfiguration: a Networkmentioning

confidence: 99%

Reconfigurable Wireless Networks

et al. 2015

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“…For single-user communication systems, link adaptation techniques based on adaptive modulation and coding (AMC) and power control are well analyzed and utilized to improve the QoS performance over wireless channels with time-varying fading [11,12]. Moreover, for multiuser systems adaptive transmission is integrated with opportunistic scheduling in, for example, [6,[13][14][15][16], to increase spectral efficiency at the physical layer.…”

Section: Introductionmentioning

confidence: 99%

Effective capacity optimization for multiuser diversity systems with adaptive transmission

Harsini

Lahouti

2012

Trans. Emerging Tel. Tech.

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The effective capacity (EC) for a wireless system expresses the maximum arrival source rate that the system can reliably transmit over the wireless channel while fulfilling a probabilistic delay constraint. This paper presents an EC optimization for a multiuser diversity system exploiting proportional opportunistic scheduling at the medium access control layer in conjunction with adaptive modulation and coding (AMC) at the physical layer. We consider the downlink of a time‐slotted multiuser system with two different types of channel state information (CSI) at the transmitter, that is, (i) full CSI, whereby each user feeds back its normalized signal‐to‐noise ratio to the transmitter and (ii) quantized CSI, where each user feeds back the AMC mode for transmission. For each case, we first derive the EC function of the queue service process for the individual users at the medium access control layer. We then design the AMC scheme with power control aiming at maximizing the said function subject to a target packet‐error rate constraint. Both independent and identically distributed and time‐correlated fading channels are considered. The results illustrate the superior performance of the proposed schemes, when compared with the previous systems such as opportunistic scheduling with single‐rate transmission and round‐robin scheduling with AMC. Copyright © 2012 John Wiley & Sons, Ltd.

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“…Typical quasi-linear amplifiers are only linear for signals with small amplitude, which means that we either have high back-off (and, consequently, small amplification efficiency) or we need to work in the nonlinear region with significant signal distortion. Although this is especially serious for multicarrier schemes [5,6], it is also important for single-carrier modulations [7,8]. Whenever we need very high power amplifiers with low complexity we have to employ grossly nonlinear power amplifiers.…”

Section: Introductionmentioning

confidence: 99%

Analytical computation of the correlation of spreading sequences for nonlinear OQPSK‐type modulations

Afonso¹,

Cercas²,

Dinis³

et al. 2012

Trans. Emerging Tel. Tech.

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In this paper we study the behavior and correlation properties of some spreading sequences when applied to a system using nonlinear offset quadrature phase‐shift keying‐type modulations. These signals, which include as special cases continuous‐phase modulation schemes, can be designed to have very low envelope fluctuations or even a constant envelope, making them compatible with a very low‐cost and power‐efficient grossly nonlinear amplification. We use an analytical method to derive the correlation of those signals. The resulting expressions are then applied to maximum‐length sequences, Kasami, and Tomlinson, Cercas, Hughes sequences. It is shown that Tomlinson, Cercas, Hughes sequences have better correlation properties than other spreading sequences. Copyright © 2012 John Wiley & Sons, Ltd.

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Adaptive modulation over nonlinear time-varying channels

Cited by 3 publications

References 7 publications

Reconfigurable Wireless Networks

Reconfigurable Wireless Networks

Effective capacity optimization for multiuser diversity systems with adaptive transmission

Analytical computation of the correlation of spreading sequences for nonlinear OQPSK‐type modulations

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