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In this paper, the effects of energy harvesting (EH) on an automatic repeat request based cooperative communication network comprised of a source, a relay, and two destination nodes, are investigated in Rayleigh fading channels. The energy of the decode-and-forward relay is provided by EH throughout the radio frequency signal from the source. In the proposed transmission protocol, the source transmits a data packet to the relay and two destination nodes by direct links. If the transmission is successful at both destination nodes, these nodes reply by an acknowledgement (ACK) signal to the source and the relay. Otherwise, there are two alternatives: If the relay has received this data packet successfully and replied by an ACK signal, then it cooperates and transmits the data packet for a second time to two destination nodes. If the relay has failed and replied by a non-acknowledgement signal, the source in this case retransmits this packet to the destination nodes by direct links. First, a broadcast channel is considered where the source transmits the same data packet to the relay and destination nodes. Second, the non-orthogonal multiple access technique is applied to the same network where different packets are sent to each destination node by means of superposition coding. In both cases, the system throughputs are obtained from the derived closed-form expressions for the outage probabilities based on the Markov chain model. All theoretical results are supported by computer simulation results. [ABSTRACT FROM AUTHOR]

Information-theoretic analysis of the communication systems performances is of practical and theoretical importance. In this paper, (i) Specifically, we generalize the Cover–Chiang work on point to point channel with two-sided state information to two-receiver less noisy broadcast channel (2R-LN-BC) with different side information non-causally known at the encoder as well as the decoders, and obtain the capacity region including the previous works as its special cases. Then, (ii) the obtained result is expanded to the continuous alphabet Gaussian version. In this Gaussian version, the side information available at the receivers are supposed to be correlated on the channel noises and the impact of these receivers cognition of the noises on the capacity region is analyzed. [ABSTRACT FROM AUTHOR]

In this paper, authors propose novel limited feedback scheduling algorithms for multiple-input multiple-output (MIMO) orthogonal frequency division multiplexing (OFDM) broadcast channels (BC). Users feed back the maximum signal-to-interference-plus-noise ratio (SINR) and the index of the corresponding transmit antenna to base station. Here, it is proposed that a given user transmits back the maximum SINRs corresponding to each transmit antenna. It is shown that by this process the overall throughput improves significantly with comparatively small increase in feedback overhead (FO). Further, FO increases linearly with number of sub-carriers used in MIMO–OFDM. Adjacent sub-carriers experience similar channel conditions. Hence, they are grouped into clusters to reduce FO. Moreover, we propose that feedback of each user should consist of sum of the logarithmic values of the maximum SINRs corresponding to each transmit antenna for all sub-carriers present in a given cluster. The logarithmic based algorithm below a specific cluster size attains system sum-rate comparable to scheduling algorithms without sub-carrier grouping but with a reduction in FO by a factor equal to cluster size. [ABSTRACT FROM AUTHOR]

Broadcasting is one of the basic ways to access XML data via mobile wireless networks. In these networks, XML data are disseminated over a wireless broadcast channel and mobile clients can connect to this channel via portable devices and receive the XML data they need. To date, various indexing methods have been proposed to broadcast the XML data over mobile wireless broadcast networks, each of which attempts to reduce the latency and energy consumption of mobile devices in processing the different types of XML queries. Most of the proposed indexing methods use only a single wireless broadcast channel for XML data dissemination. Due to the sequential data access over a wireless broadcast channel, the access time to retrieve the desired XML data over a broadcast channel is longer if the length of generated XML data stream is large. This paper proposes two new XML data placement schemes to disseminate the XML data over multiple wireless broadcast channels by partitioning the XML data stream into several partitions and placing them into multiple wireless broadcast channels. The goal of both of which is a further reduction of the access time during the process of XML querying over the broadcast channels. According to the experimental results, the proposed XML data placement schemes have achieved the goal of further reducing the access time, especially when the size of XML document to be disseminated is large. [ABSTRACT FROM AUTHOR]

The 5G New Radio synchronization procedure is the first step that the user must complete to access the mobile network. It mainly consists of the detection of the primary and secondary synchronization signals (PSS and SSS, respectively) and the decoding of the physical broadcast channel (PBCH). Our goal is to provide a comprehensive study of the synchronization procedure and investigate different techniques and approaches, through the implementation of a 5G New Radio-compliant simulator. Of significant interest is the investigation of impairments such as the fading channel, the frequency offset, and the delay spread. The results are provided in terms of detection probability for the PSS and SSS detection, and in terms of block error rate for the PBCH. From the data collected, there is evidence that choosing M-sequences for the PSS leads to an appreciably robust solution against frequency offset. The structure of the Gold sequences for SSS generation can be exploited to reduce the detection complexity, and different approaches can be chosen to improve reliability against delay spread. Moreover, the polar coding for 5G PBCH outperforms the former 4G coding technique, but they are still sensible to frequency offset. Finally, the simulator functionalities are validated through real captures of 5G signals. [ABSTRACT FROM AUTHOR]

Two explicit schemes are designed to illustrate bidirectional controlled teleportation in a fair and practical manner. One is a symmetric scheme for single-qutrit states. The other is an asymmetric scheme for single- and two-qutrit states. Then, we extend three-dimensional system to high-dimensional system and come up with a universal scheme for arbitrary n 1 - and n 2 -qudit states by using a (2 n 1 + 2 n 2 + 1) -qudit entangled state as the quantum channel, where n 1 ≤ n 2 . The senders and the controller need to perform general Bell basis measurement and Z basis measurement, respectively. According to their measurement results, the receivers can reestablish the initial states simultaneously by performing single-qudit recovery operations which are derived by a general formula. It is worth mentioning that 2 n 1 + 1 dit classical communication cost is saved at the controller's broadcast channel with the aid of network coding. Moreover, we consider the effect of two-type high-dimensional decoherence noises: dit-flip noise and d-phase-flip noise. [ABSTRACT FROM AUTHOR]

In this work, we consider the transmissions of structured data such as text over a noisy channel and correlated texts over a broadcast channel. As the separate source-channel coding principle no longer holds in such scenarios, we propose a joint source-channel coding scheme which is based on deep learning architecture. In order to enhance the convergence speed, we adopt the bidirectional gated recurrent unit at the encoder. For the decoder, to improve the recovery quality, we propose the following two types of strategies: (1) After a unidirectional neural network based decoder is used, a generative adversarial network is applied to train the whole joint source-channel coding framework and pointwise mutual information is added to the objective function of beam search process; (2) Rather than using a unidirectional neural network-based decoder, we develop a bidirectional neural network based and bidirectional attention mechanism integrated decoder to utilize past and future information. Experiments under different types of channels show that our schemes are superior to the existing deep learning joint source-channel coding method and in the case of low bit budget, long sentence length and small channel signal to noise ratio, our models are significantly superior to those of separate source-channel coding. In addition, we extend the proposed unidirectional and bidirectional decoders to the broadcast channel. Additionally, to improve the performance of unidirectional decoding, we utilize not only the correlation between adjacent words in the same text but also the correlation between words in different languages with the same meaning in the beam search process. [ABSTRACT FROM AUTHOR]

We propose a W state-based protocol for anonymously transmitting quantum messages in a quantum network. Different from the existing protocols [A. Unnikrishnan, et al., Phys. Rev. Lett. 122, 240501 (2019)], the proposed protocol can be effectively implemented in the network only equipped with quantum channels and regular broadcast channels. Throughout the design procedure, we develop three sub-protocols using the W state, including the quantum collision detection protocol and the quantum notification protocol. Moreover, together with the conventional anonymous entanglement protocol, the whole anonymous communication protocol has been constructed. Finally, we examine the correctness and security of the proposed quantum anonymous communication protocol. [ABSTRACT FROM AUTHOR]