Performance analysis for IRS‐aided communication systems with composite fading/shadowing direct link and discrete phase shifts

Waqar, Omer

doi:10.1002/ett.4320

Cited by 11 publications

(14 citation statements)

References 38 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…71 IRS helps to mitigate the effect of wireless channel fading which in turn makes the network energy efficient and improves the signal strength. In a study, 72 it was demonstrated that an IRS-assisted communication system outperforms other baseline systems even with a small number of discrete phase shifts. IRS is capable of solving the problem of AirComp systems suffering a lot from challenging signal propagation conditions.…”

Section: Aircompmentioning

confidence: 99%

Federated learning and next generation wireless communications: A survey on bidirectional relationship

Shome

Waqar

Khan

2022

Trans Emerging Tel Tech

Self Cite

View full text Add to dashboard Cite

In order to meet the extremely heterogeneous requirements of the next generation wireless communication networks, research community is increasingly dependent on using machine‐learning solutions for real‐time decision‐making and radio resource management. Traditional machine learning employs fully centralized architecture in which the entire training data is collected at one node for example, cloud server, that significantly increases the communication overheads and also raises severe privacy concerns. Toward this end, a distributed machine‐learning paradigm termed as federated learning (FL) has been proposed recently. In FL, each participating edge device trains its local model by using its own training data. Then, via the wireless channels the weights or parameters of the locally trained models are sent to the central parameter server (PS), that aggregates them and updates the global model. On one hand, FL plays an important role for optimizing the resources of wireless communication networks, on the other hand, wireless communications is crucial for FL. Thus, a “bidirectional” relationship exists between FL and wireless communications. Although FL is an emerging concept, many publications have already been published in the domain of FL and its applications for next generation wireless networks. Nevertheless, we noticed that none of the works have highlighted the bidirectional relationship between FL and wireless communications. Therefore, the purpose of this survey article is to bridge this gap in literature by providing a timely and comprehensive discussion on the interdependency between FL and wireless communications.

show abstract

Section: Aircompmentioning

confidence: 99%

Federated learning and next generation wireless communications: A survey on bidirectional relationship

Shome

Waqar

Khan

2022

Trans Emerging Tel Tech

Self Cite

View full text Add to dashboard Cite

show abstract

“…2) RIS with Direct link: The work on performance analysis of RIS with direct link that is considered in [27]- [30], [33]- [35] is based on approximating the end-to-end SNR using various approximation methods such as the CLT. As shown in Table I, the channel model in [27]- [30], [34], [35] is considered as Nakagami-m, Rician and Rayleigh fading.…”

Section: A Related Workmentioning

confidence: 99%

“…As shown in Table I, the channel model in [27]- [30], [34], [35] is considered as Nakagami-m, Rician and Rayleigh fading. Waqar [33] considers the Rician and K-fading models. It is worth mentioning that the aforementioned fading models do not accurately capture the composite fading and shadowing that is usually experienced in practical channel models.…”

Section: A Related Workmentioning

confidence: 99%

On the Performance of RIS-Assisted Communications with Direct Link over κ-µ Fading

Al-Dweik¹,

Al-Rimawi²

2022

Preprint

View full text Add to dashboard Cite

Reconfigurable intelligent surfaces (RISs) is a new technology that can be used to create a virtual line-of-sight (LOS) link when the direct link is blocked. The signal-to-noise ratio (SNR) can be significantly improved by optimizing the reflecting elements’ phases to make the reflected signals add coherently at the receiver. Nevertheless, the RIS cannot control the phase of the direct link if it exists. In such scenarios, the RIS phase can still be controlled such that the direct and reflected signals add coherently, however, the gain obtained by using the RIS might be hindered. Therefore, this paper considers the performance analysis of such scenarios where a novel analytical framework is developed to evaluate the SNR, outage probability and bit error rate (BER). To capture a broad range of fading conditions, the channels are modeled as independent but not identically distributed generalized κ-µ shadowed fading channels. The Laguerre expansion is used to derive the probability density function (PDF) and cumulative distribution function (CDF) of the instantaneous channel fading, which are used to derive the PDF and CDF of the instantaneous SNR. The paper also considers deriving the asymptotic PDF, CDF, moment generating function (MGF) of the SNR, as well as the outage probability and BER. The derived expressions are used to evaluate the system performance in various fading environments such as Rayleigh, One-Sided Gaussian, Nakagami-m , Rician, and Rician-shadowed distributions since they are special cases of the κ-µ shadowed distribution. The obtained analytical results corroborated by Monte Carlo simulation show that a strong direct link can generally eliminate the gain obtained using the RIS. Therefore, the overhead required for the RIS operation becomes a burden on the network and may cause severe throughput degradation. In such scenarios, the RIS involvement should dynamically controlled to avoid unnecessary complexity and throughput reduction.

show abstract

“…Reconfigurable intelligent surface (RIS) has emerged as a promising research topic for sixth‐generation (6G) wireless communications 1‐4 . RIS changes the behavior of the wireless propagation environment and helps to obtain high‐quality signals at the receiver.…”

Section: Introductionmentioning

confidence: 99%

“…Reconfigurable intelligent surface (RIS) has emerged as a promising research topic for sixth-generation (6G) wireless communications. [1][2][3][4] RIS changes the behavior of the wireless propagation environment and helps to obtain high-quality signals at the receiver. An RIS is fabricated by meta-surfaces and it consists of a planar structure to have the ability to reflect with low-cost passive elements.…”

Section: Introductionmentioning

confidence: 99%

Reconfigurable intelligent surface assisted downlink INOMA system

Kumar

Sharma

Thottappan

et al. 2022

Trans Emerging Tel Tech

View full text Add to dashboard Cite

Nonorthogonal multiple access (NOMA) and reconfigurable intelligent surface (RIS) methods are explored to enhance spectral and energy efficiency of a wireless network. In this article, we have proposed a downlink RIS-assisted index modulation NOMA for next-generation wireless systems, and it is referred to as R-INOMA. In the proposed R-INOMA system, a base station transmits information through RIS to three users, the first user is assigned in the spatial domain and the remaining two users are multiplexed using power domain NOMA. We provide an analytical analysis of bit error probability (BEP) for the proposed R-INOMA system. Impact of number of surfaces, transmit antennas, modulation order, diversity order, and imperfect channel estimation is analyzed for the R-INOMA. Simulation results show that the proposed R-INOMA achieved better BEP and sum-rate over existing NOMA techniques. In the R-INOMA, doubling of the reflecting surfaces provides a 4 dB gain for a fixed error probability, and the sum-rate improves as the number of transmitting antennas and reflecting surfaces increases. INTRODUCTIONReconfigurable intelligent surface (RIS) has emerged as a promising research topic for sixth-generation (6G) wireless communications. [1][2][3][4] RIS changes the behavior of the wireless propagation environment and helps to obtain high-quality signals at the receiver. An RIS is fabricated by meta-surfaces and it consists of a planar structure to have the ability to reflect with low-cost passive elements. 2,5,6 RIS smartly tunes the phase of the incident signals according to the channel environment, and the reflected signals can be constructively added to enhance signal-to-noise (SNR) toward receivers. 1,7 RIS creates a virtual line-of-sight (LOS) propagation path between transmitter and receivers. Therefore, RIS improves the network coverage, spectral, and energy efficiency. [8][9][10] On the other hand, index modulation (IM) and nonorthogonal multiple access (NOMA) are a promising technology for fifth-generation (5G) and beyond wireless networks to enhance spectrum efficiency and support massive connectivity. 11-16 IM-based spatial modulation (SM) transmits information using antenna indices along with modulation symbols of M-ary phase shift keying or M-ary quadrature amplitude modulation (QAM), therefore it increases the data transmission rate. Moreover, SM transmits information in a single activated antenna in multiple-inputs and multiple-output (MIMO) system by using a single radio frequency (RF) chain. 17,18 Further, a combination of IM and NOMA (IM-NOMA) can serve simultaneously more users at the same time/frequency without the effect of inter-user interference (IUI) [19][20][21] and it consists of superposition coding (SC) at the base station (BS) and successive interference cancelation (SIC) at the receivers. 22

show abstract

Performance analysis for IRS‐aided communication systems with composite fading/shadowing direct link and discrete phase shifts

Cited by 11 publications

References 38 publications

Federated learning and next generation wireless communications: A survey on bidirectional relationship

Federated learning and next generation wireless communications: A survey on bidirectional relationship

On the Performance of RIS-Assisted Communications with Direct Link over κ-µ Fading

Reconfigurable intelligent surface assisted downlink INOMA system

Contact Info

Product

Resources

About