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One Dimensional (1D) Double Weight (DW) code families are one of the coding schemes reported for Spectral Amplitude Coding — Optical Code Division Multiple Access systems. Modified Double Weight code and Enhanced Double Weight code are two algorithms which increase the scope of DW code for even and odd weights respectively. By using above mentioned codes, two Dimensional (2D) codes are generated....
This paper addresses the problem of single-cell point-to-multipoint communications. We consider a base station that needs to transmit a common information to a group of users. We propose a layered Wyner-Ziv coding (WZC) scheme based on nested lattice quantization. In our scheme, we use the base layer generated by a standard coder as the decoders side information. Then, WZC is performed for quality...
The Gaussian fading channel is studied, in which the channel from the transmitter to the receiver is corrupted by a multiplicative fading coefficient H and an additive Gaussian random noise. It is assumed that the channel is experiencing block fading, and the transmitter does not know the channel state information (CSI). The receiver is assumed to have full knowledge of the CSI. If the channel state...
Fountain codes are used in many applications where the channels are time varying and it is difficult at the transmitter to predict the appropriate code rate. In this situation, fixedrate codes are not suitable. Despite the good performance of fountain codes, universally optimal codes do not exist in the finite-length regime. In this paper, we design new fountain codes that are robust to the communication...
Cyber crime is the biggest shortcoming in this fully connected internetworking world. Third party attacks, phishing by intruder like hackers are always active to leak official, personal or legislative information in the form of a message using this public networks. This is why we call for Steganography where the sneaky message has been hiding the data/information firmly. Steganography is one of the...
We consider a communication scenario in which the channel undergoes two different classes of attacks at the same time: a passive eavesdropper and an active jammer. This scenario is modeled by the concept of arbitrarily varying wiretap channels (AVWCs), in which the channel varies from one channel use to the other in an unknown and arbitrary manner. It has been shown that uncorrelated codes fail to...
Two polar coding schemes are proposed for the degraded broadcast channel under different reliability and secrecy requirements. In these settings, the transmitter wishes to send multiple messages to a set of legitimate receivers keeping them masked from a set of eavesdroppers, and individual channels are assumed to gradually degrade in such a way that each legitimate receiver has a better channel than...
This paper shows that the slope at each corner point of the capacity region of the general broadcast channel coincides with that of the randomized time division (hence the Marton) inner bound and the Nair-El Gamal (as well as the Körner-Marton) outer bound. We then show that the optimal superposition coding inner bound by Bandemer, El Gamal, and Kim can be simplified to the convex closure of the union...
The two-user multiple-input multiple-output (MIMO) Gaussian broadcast channel (BC) with common, private and confidential messages is considered. The transmitter sends a common message to both users, a confidential message to User 1 and a private (non-confidential) message to User 2. The secrecy-capacity region is characterized by showing that certain inner and outer bounds coincide and that the boundary...
Classically encoding a group of symbols to be transmitted over a communication channel through baseband modulation can be done in various ways-namely Pulse Amplitude Modulation (PAM), Pulse Width Modulation (PWM), Pulse position modulation (PPM) etc. What we will be proposing in this paper is another encoding technique- mapping a symbol to a wave shape and transmitting that along a baseband channel...
Dynamic Index coding as a generalization of the traditional index coding problem, deals with transmission of some dynamic data flows in the presence of side information. For a dynamic index coding system, the set of average flow rates for which the system can be stable is named Code-Constraint Capacity region. In this paper, we identify the code-constraint capacity region for a dynamic index coding...
Transferring confidential data is a real challenge and is the need of the hour. Steganography deals with concealing secret message in the image whereas cryptography is about altering the message into a distorted form, so that it is prevented from unauthorized access. Combining both the steganographic and cryptographic techniques will yield a secure and sophisticated system for exchanging the secret...
A source coding problem over a noiseless broadcast channel where the source is preinformed about the contents of the cache of all receivers, is an index coding problem. Furthermore, if each message is requested by one receiver, then we call this an index coding problem with a unicast message setting. This problem can be represented by a directed graph. In this paper, we first define a structure (we...
Error and erasure exponents for the asymmetric broadcast channel are analyzed. The focus of the error analysis is on the main receiver where, nominally, both messages are to be decoded. A two-step decoding algorithm is proposed and analyzed. This receiver first attempts to decode both messages, failing which, it attempts to decode only the message representing the coarser information, i.e., the cloud...
The question of under what condition some side information for index coding can be removed without affecting the capacity region is studied, which was originally posed by Tahmasbi, Shahrasbi, and Gohari. To answer this question, the notion of unicycle for the side information graph is introduced and it is shown that any edge that belongs to a unicycle is critical, namely, it cannot be removed without...
In this paper, we propose a new rateless code based on overlapped generations. This proposed scheme works very well especially in a broadcast scenario, where channels with different characteristics are involved in the system. In the proposed scheme, we allow the adjacent generations to overlap. Our main focus is on the design of rateless codes to make any receiver able to recover all the source file...
Access reservation based on slotted ALOHA is commonly used in wireless cellular access. In this paper we investigate its enhancement based on the use of physical-layer network coding and signature coding, whose main feature is enabling simultaneous resolution of up to K users contending for access, where K ≥ 1. We optimise the slot access probability such that the expected throughput is maximised...
Layered coding elegantly handles user bandwidth heterogeneity in video conferencing, however, it incurs rate and complexity overheads. An alternative is partitioning the receiver sets and using non-layered coding for each group. In this paper, we investigate how to maximize the received video quality for both systems under uplink and downlink capacity constraints, while limiting the number of hops...
Unlike traditional file transfer where only total delay matters, streaming applications impose delay constraints on each packet and require them to be in order. To achieve fast in-order packet decoding, we have to compromise on the throughput. We study this trade-off between throughput and in-order decoding delay, and in particular how it is affected by the frequency of block-wise feedback, whereby...
This paper introduces a new applicable Gaussian wiretap channel with side information. In this channel, the state of the channel to the wiretapper is separated from the main channel's one. It means that the legitimate receiver and the wiretapper are listening to the transmitted signal through the different channels with different channel states which may have some correlation to each other. The state...
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