A More General Version of the Costa Theorem
Mohammad
Molavi Kakhki
Ferdowsi University of Mashhad
author
Ghosheh
Abed Hodtani
Ferdowsi University of Mashhad
author
Nima
S. Anzabi-Nezhad
Ferdowsi University of Mashhad
author
text
article
2016
eng
In accordance with the Costa theorem, the interference which is independent of the channel input and known non-causally at the transmitter, does not affect the capacity of the Gaussian channel. In some applications, the known interference depends on the input and hence has some information. In this paper, we study the channel with input dependent interference and prove a capacity theorem that not only subsumes the Costa theorem but also explains interestingly interpretable impact of correlation between side information and channel input on the capacity.
Journal of Communication Engineering
Shahed University
2322-4088
2
v.
4
no.
2016
332
350
https://jce.shahed.ac.ir/article_308_e98d26e8e636777d1dfc3f21ad05a83c.pdf
An Adaptive LEACH-based Clustering Algorithm for Wireless Sensor Networks
H.
Bakhshi
author
M.
Bajelan
author
text
article
2016
eng
LEACH is the most popular clastering algorithm in Wireless Sensor Networks (WSNs). However, it has two main drawbacks, including random selection of cluster heads, and direct communication of cluster heads with the sink. This paper aims to introduce a new centralized cluster-based routing protocol named LEACH-AEC (LEACH with Adaptive Energy Consumption), which guarantees to generate balanced clusters over the network. In LEACH-AEC, more information from the current state of nodes (including the residual energy of nodes, the distance from sink, and the distances between cluster heads) are considered to select the optimal cluster heads. Also, the multi-hop routing extension via A-Star algorithm is utilized in LEACH-AEC to cope with routing in large topological WSN areas. In contrast to the previous cluster-based protocols, the main advantage of LEACH-AEC is to prolong the network lifetime, based on the application specifications. Simulation results show that the proposed routing protocol plays an effective role in reducing energy consumption, provides a balanced consumption of energy and increases the lifetime of the network.
Journal of Communication Engineering
Shahed University
2322-4088
2
v.
4
no.
2016
351
365
https://jce.shahed.ac.ir/article_310_0addc7b327181b7edd5e0d5c99913223.pdf
A Suitable Coding Scheme for Broadband Power-line Communication
Mohammad Reza
Zahabi
author
Hamid
Meghdadi
author
Roya
Khanzade
author
text
article
2016
eng
This paper introduces three coding strategies for using the Luby Transform (LT) code in a relay aided power-line communication scheme. In the first method, the relay decodes the received packets and re-encodes them for transmission towards the destination. In the second method, the relay only forwardes a random linear combination of its received packets towards the destination, while in the third method the relay tries to maintain the robust soliton distribution by favoring the first degree packets. Simulation results demonstrate that the use of LT codes in a network can significantly improve the system performance and reduce the overhead both in presence and in absence of impulsive noise. Also it is investigated that the first method outperforms the two ones but it has a higher complexity at the relay node.
Journal of Communication Engineering
Shahed University
2322-4088
2
v.
4
no.
2016
366
378
https://jce.shahed.ac.ir/article_312_cef0ddfb0737b41f3f28cdc68bccfd6a.pdf
Superconducting Microstrip-Fed Antenna Coupled to a Microwave Kinetic Inductance Detector
Seyed Mohammad Hassan
Javadzadeh
Faculty of Engineering, Shahed University
author
text
article
2016
eng
A proper antenna to couple to a microstrip Microwave Kinetic Inductance Detector (MKID) is designed and simulated. A twin-slot microstrip-fed inline antenna is designed for frequency band of 600-720~GHz integrated with an elliptical lens and coupled to the MKID. A systematic design procedure for design of such antenna with microstrip inline feeding is presented. Whole structure of lens and twin slot is simulated by full-wave electromagnetic numerical software. A locally changing technique is also used to have good matching between antenna and feed line. Results show good radiation pattern with directivity near 30dB and side lobe levels better than -10.5 dB in both H-plane and E-plan and also antenna efficiency is better than 93% and total coupling efficiency is better than 84% in whole frequency band. This antenna is recently used in a superconducting on-chip sub-millimeter wave filterbank spectrometer.
Journal of Communication Engineering
Shahed University
2322-4088
2
v.
4
no.
2016
379
389
https://jce.shahed.ac.ir/article_309_6b4cda0d6c0d6f64a98bd0fecab2cc1f.pdf
On the Practical Aspects of Joint Passive Phase Conjugation and Equalization Underwater Communication Systems
Azizollah
Jamshidi
Shiraz University
author
text
article
2016
eng
Underwater acoustic communication systems suffer from the channel impairments which results in time spreading of the transmitted signal. In underwater environment, multiple replicas of the transmitted signal are received at the receiver through different paths, which causes significant Inter-Symbol Interference (ISI). Decision Feedback Equalizers (DFE) was utilized to overcome this type of interference in digital communications so many years ago. However, because of the complexity of adaptive equalizers, Passive Phase Conjugation (PPC) was widely exploited in underwater communications in the recent years. Because of the poor performance of the PPC method, adaptive equalizers are jointed to improve the PPC performance. In this paper, experimental results conducted in Shiraz Electronic Industrys pool have been reported. Three different approaches are compared in terms of Symbol Error Rate (SER) versus the number of used channels at the pool: 1) the PPC method 2) DFE equalizer for only a single channel 3) the PPC method combined with the adaptive DFE. The experimental results showed that the third approach outperforms the others while a simpler receiver can be obtained.
Journal of Communication Engineering
Shahed University
2322-4088
2
v.
4
no.
2016
390
403
https://jce.shahed.ac.ir/article_311_8600e2b9c158425794ffbaedcde6d0f9.pdf
Asymptotic Close to Optimal Resource Allocation in Centralized Multi-band Wireless Networks
M.
Mirzaee
Shahed University
author
S.
Akhlaghi
author
G.
Aghaei
author
text
article
2013
eng
This paper concerns sub-channel allocation in multi-user wireless networks with a view to increasing the network throughput. It is assumed there are some sub-channels to be equally divided among active links, such that the total sum rate increases, where it is assumed each link is subject to a maximum transmit power constraint. This problem is found to be a non-convex optimization problem and is hard to deal with for large number of sub channels and/or users. However, relying on some approximation methods, it is demonstrated that the proposed sub-optimal problem has roots in combinatorial optimization, termed as Assignment problem which can be tackled through the so called Hungarian method. Simulation results demonstrate that the proposed method outperforms existing works addressed in the literature.
Journal of Communication Engineering
Shahed University
2322-4088
2
v.
4
no.
2013
404
409
https://jce.shahed.ac.ir/article_351_d41d8cd98f00b204e9800998ecf8427e.pdf