International Journal of Ad Hoc and Ubiquitous Computing (6 papers in press)

Regular Issues

• Throughput Enhancement of RIS and STARRIS Using Adaptive Modulation and Coding for 6G Systems  
  by Nadhir Ben Halima, Sajid M. Sheikh 
  Abstract: In this article, the throughput of reconfigurable intelligent surfaces (RIS) is improved using adaptive modulation and coding (AMC). The best modulation and coding scheme (MCS) is selected at the transmitter using the instantaneous signal to noise ratio (SNR) measured at the receiver and sent back on the feedback channel. RIS is placed between the transmitter and the receiver so that the SNR is maximised at the receiver side as RIS reflections are combined coherently at the receiver and results in significant spatial diversity. All reflections on RIS have a zero phase at the receiver. We show that RIS using AMC offers a larger throughput than conventional RIS with fixed MCS for all SNR range. RIS with AMC offers 48, 42, 36, 30, 24, 18 dB gain for N = 256,128,64,32,16,8 reflectors. We obtained 10 dB gain when RIS uses AMC versus 256-QAM. We also improve the throughput of Simultaneously Transmitting And Reflecting RIS (STARRIS) using AMC. We obtained 13 dB gain when STARRIS uses AMC versus 256-QAM.
  Keywords: AMC; RIS; MCS; throughput enhancement; 6G.
  DOI: 10.1504/IJAHUC.2024.10064800
   
  
• Throughput Optimization of Intelligent Omni-Surfaces (IOS) with Hybrid Solar and RF Energy Harvesting  
  by Faisal Alanazi 
  Abstract: This contribution computes the throughput of intelligent omni-surfaces (IOS) when the source recovers power from the sun and radio frequency (RF) signals to be able to transmit data to two users Ut and Ur. Ut and Ur are located at the transmit and reflect spaces of IOS. We compute the harvested energy as well as its SINR. The harvesting process is optimised to maximise the throughput. We investigate the impact of harvesting time t and the number of reflectors of IOS denoted by N. IOS with N = 64 reflectors offers 48 dB versus N = 8. The results are valid for any size of the PV system. Hybrid solar and RF energy harvesting offers 32 dB gain and 3 dB gain versus RF and solar energy harvesting.
  Keywords: intelligent omni-surfaces; IOS; solar energy; RF energy harvesting; SINR; Rayleigh channels.
  DOI: 10.1504/IJAHUC.2024.10064827
   
  
• Deep Learning Based Detector for Downlink IM-NOMA Systems  
  by Issa Chihaoui, Mohamed Lassaad Ammari 
  Abstract: This work proposes a deep learning (DL) based detector for downlink index modulation non-orthogonal multiple access (IM-NOMA) systems, which we call DL-IM-NOMA. The proposed detector involves a multilayer fully connected deep neural network (DNN) block. The received signal is preprocessed using zero-forcing (ZF) and channel knowledge at the receiver before being fed into the DNN block. Architecture complexity and bit error rate (BER) performance of DL-IM-NOMA have been presented for several configurations, and compared to these of the suboptimal log-likelihood ratio (LLR) detector. Simulation results show that DL-IM-NOMA outperforms LLR detector for high signal-to-noise ratios (SNRs) with lower complexity. It has been shown that DL-IM-NOMA avoids BER floor occurred at strong users using LLR detector. In contrast, for low SNRs, DL-IM-NOMA causes an insignificant performance loss, especially for systems using large constellation size.
  Keywords: Deep learning; NOMA; subcarrier index modulation; OFDM.
  DOI: 10.1504/IJAHUC.2024.10064906
   
  
• CDMA Extension using STARRIS  
  by Sami Touati, Rachid Samouda, Musaed A. Alhussein 
  Abstract: In this paper, we extend the coverage of code division multiple access (CDMA) using simultaneously transmitting and reflecting reconfigurable intelligent surfaces (STARRIS). The signal is broadcasted from the source S to the relay R using a CDMA link. Then, relay node R decodes the symbols of two users Ut and Ur and transmits the signal to them using STARRIS. We show that STARRIS with N = 8, 16, 32, 64, 128 elements offers up to 26, 34, 42, 50 and 58 dB versus CDMA in both first and second hop. CDMA using STARRIS offers 8 dB versus CDMA using RIS.
  Keywords: code division multiple access; CDMA; rake receiver; STARRIS; reconfigurable intelligent surfaces; RIS; Rayleigh channels.
  DOI: 10.1504/IJAHUC.2024.10065511
   
  
• Horse Herd Optimised Elliptic Curve Cryptography for Secure Data Aggregation in WSN  
  by Maravarman M, Babu S, Pitchai R 
  Abstract: Data aggregation is a highly effective mechanism for improving the lifetime of wireless sensor networks. The prominent problem in data aggregation is security and communication overhead, which increases extra data transmission. The existing work faces problems of accuracy in data transmission, delay, and privacy. In this work, an efficient secure data aggregation with a clustering approach is performed. At first, the nodes in the sensor network are clustered using an adaptive fuzzy clustering approach. An optimal selection of cluster heads shrinks the energy consumption and maximises the network lifetime. Furthermore, enhanced lattice-based homomorphic encryption is applied to the encrypted data for aggregation. This hybrid horse herd optimised elliptic curve cryptography with an enhanced lattice-based homomorphic approach provides security improvement in data transmission. The simulation of the proposed hybrid horse herd optimised elliptic curve cryptography with an enhanced lattice-based homomorphic approach is implemented using a Python tool, and performance was evaluated using various metrics. While compared with existing schemes, the simulation outcomes indicate a considerably higher throughput of 5002bps and an average delay of 98.08 ms.
  Keywords: wireless sensor network; WSN; horse herd optimised elliptic curve cryptography; enhanced lattice-based homomorphic; optimal rule-based fuzzy approach; data aggregation.
  DOI: 10.1504/IJAHUC.2024.10065525
   
  
• Throughput and Delay Analysis of Intelligent Omni Surfaces (IOS) with Wind Energy Harvesting for 6G  
  by Eman Bouazizi, Majed Abdouli 
  Abstract: This contribution computes the throughput and the delay of intelligent omni surfaces (IOS) when the source recovers power from the wind to be able to broadcast data to two users Ut and Ur. Ut and Ur are located at the transmitted and reflected spaces of IOS. We derive the statistics of the recovered energy as well as that of the SINR. The harvesting time is chosen wisely to enhance the throughput. We investigate the effects of average wind speed and the number of reflectors of IOS denoted by N. IOS with N = 64 reflectors offers 43 dB enhancement versus N = 8. The results are valid for a Rayleigh channel.
  Keywords: wind energy harvesting; IOS; throughput optimization; Rayleigh channels.
  DOI: 10.1504/IJAHUC.2024.10065588