In the multi-user p2p scenario, we consider multiple source-destination pairs that aim to com- municate via multiple FF relays. We assume that all nodes in the network have a single antenna only and we do not assume channel equalization at the destinations. The resulting system model is a special case of the system model for multi-user downlink communication. This multi-user p2p scenario can be seen as an extension of the works  and  on FF relaying, where only one source and one destination node have been assumed. From a somewhat different perspective, this contribution can be seen as a non-trivial extension of the p2p approach of  which considers the system model of 2.2.1 for K = M . Note that the problem formulation in  involves MUI (caused by multiple peers), but it does not include any ISI, as the channels are assumed to be frequency-flat. Here, two practically relevant beamforming problem formulations are developed. Our first formula- tion amounts to a problem of the form (2.15), as we aim to minimize the relay sum power subject to the destination QoS constraints. Our second problem is a max-min fairness problem of the form (2.16). The resulting problems are non-convex and, therefore, difficult to be solved exactly. We will use SDR to relax them to convex semi-definite programming (SDP) problems that can be solved efficiently using interior point methods.
Our model shows that the two-waycommunication between the public and the bank is com- plementary. When the bank fails to communicate its inflation target, financial markets fail to reveal information about the aggregate state of the economy to the bank. The literature on mon- etary policy under data uncertainty assumes that the degree of uncertainty facing the bank is exogenously given. 19 In this paper we show that the degree of uncertainty is endogenously de- termined by the communication problem. Improving communication from the bank can make the measurement problem less serious. This has important policy implications. If we take the measurement problem as exogenously given, a policy prescription may be not to respond ac- tively to those economic variables subject to measurement errors. For example, Orphanides and Williams (2005) argue that it is desirable for monetary policy not to respond actively to the unemployment gap because it can be subject to large measurement errors. Orphanides (2003b) argues that a version of nominal income targeting performs well under uncertainty because it is less sensitive to measurement errors. 20 On the other hand, our model implies that imper-
Communication in the marketing context can be seen as formal and informal exchanging and sharing of meaningful and timely information between buyers and sellers. It is also defined as the consumer’s perception of the extent to which a seller interacts with its regular customers in a warm and personal way (Naoui and Zalem, 2010). It is the ability of the service provider to provide timely and trustworthy information that will enable customers to flow with the providers. Such an interaction is reflected in the feelings of familiarity and friendship. As a relationship marketing underpinning, communication means keeping touch with valued customers, providing timely and trustworthy information on services and service changes and communicating proactively if a delivery problem occurs. It enables unsatisfied customers to know what the organization is doing to rectify the causes of dissatisfaction. It has been observed that when there is communication between providers and customers, a good relationship will result and customers will be more loyal (Ndubisi, 2007; Agu, 2017). Communication is the ability to provide timely and trust worthy information at all stages of the purchase decision process; during the pre-selling, selling, consuming and post-consuming stages. It involves providing information pro-actively if a delivery problem occurs. Open, sincere and frequent interactions describe effective communication. Bi-directional communication leads to a strong relationship, which in turn leads to increased loyalty.
More attention should be given to improve students' main tools required in the hospitality career (foreign languages, computer and internet practical courses). Starting extra courses on how to increase social awareness, dealing with surrounding environment, dealing with each other in a respectful way, the same way they will be dealing with customers in the future, which will help them gain the experience while being at the faculty, such lectures to give them better attitudes. Such lectures can be arranged to be given to students as extra lectures, without the need to have final examinations at, or to be given as courses arranged by the faculty's staff members to have better students with better attitudes. Finally, taking Alexandria as a Model City, as it has been, and its people are famous for their love of beauty and order, and they are a good example of being an idol city. The students of the hotel department can participate in such community activities that will increase awareness of the citizens of the city as well.
For these multimodal transportation networks to be implemented, public involvement is a key factor in the planning and decision-making process. This process should involve two-waycommunication between citizens and government, allowing public transportation agencies to notice, inform, and include the public while using the feedback to develop relationships within the community and build better transportation projects. Lack of public participation can lead to minimal community support, resistance from stakeholders and elected officials, and outcries from the public that could end up in costly project delays or even lawsuits ii .
Communication complexity questions have been intensively studied in theoretical computer science (see the book of Kushilevitz and Nisan  for example). In both the classical and quantum cases, though, most attention has focused on two-waycommunication, meaning that Alice and Bob get to send messages back and forth. We believe that the study of one-way quantum communication presents two main advantages. First, many open problems about two-waycommunication look gruesomely difficult—for example, are the randomized and quantum communication complexities of every total Boolean function polynomially related? We might gain insight into these problems by tackling their one-way analogues first. And second, because of its greater simplicity, the one-way model more directly addresses our opening question: how much “useful stuff” can be packed into a quantum state? Thus, results on one-waycommunication fall into the quantum information theory tradition initiated by Holevo  and others, as much as the communication complexity tradition initiated by Yao .
In , a MIMO PNC scheme was proposed to extract the summation and the difference of the information of the two source nodes at the relay with linear MIMO detection scheme.  explored a two-step communication protocol with virtual MIMO and network coding. An adaptive network coding scheme for MIMO bidirectional relaying with precoding was proposed in  to improve the e2e throughput performance. An optimal transmit strategy for the multiple-input single-output bidirectional broadcast channel was proposed in . However, they all assume symmetric transmission scenarios where the two source nodes use the same modulation schemes, considering only BPSK or QPSK modulation, and the BER at the relay or the e2e BER at the two source nodes is inferior to that of the optimal maximum likelihood (ML) detection.
The lifetime of the network is an important perfor- mance indicator in energy-constrained wireless networks, such as WSNs, since sensors are usually equipped with limited energy supplies. Harvesting energy from the envi- ronment is a promising approach to prolong the lifetime of the energy-constrained wireless networks. The basic idea of simultaneous wireless information and power trans- fer (SWIPT) was first proposed in [15,16], and a general receiver architecture was then developed in . Then, the SWIPT was extended to various communication sce- narios such as the cellular system , the broadcasting system [19,20] with a single energy receiver and a sin- gle information receiver when they are separately located or co-located, the cooperative relay system [21-25], the two-wayrelaying system , and the interference chan- nel [27-29]. For broadcasting system,  investigated the R-E trade-off for a transmitter transferring energy and information to two separated/co-located information- decoding and energy harvesting receivers. And  optimized the beamforming designs of general broadcast- ing system where there are multiple separated/co-located information-decoding and energy harvesting receivers. For a DF cooperative network,  derives the outage probability of time switching relay receiver. In , the authors studied the outage probability and network capac- ity of end-to-end one-way relay system with a battery-free relay. For multiple source-destination pairs communica- tion system aided by a relay,  studied the relays’ strategies to distribute the harvested energy among the multiple users and their impact on the system perfor- mance. For multiple-input multiple-output relay channels,  proposed a low complexity dynamic antenna switch- ing between information decoding and energy harvesting
Recently, various data and voice services have been incor- porated over modern wireless communication networks, such as the Internet, video calling and gaming. These networks are required to provide both high speed and quality services to gain consumer satisfaction. The use of multiple-antenna nodes in communications is a known technology to increase capacity and improve reliability, especially when compared with single-antenna node net- works. This is known as multiple-input multiple-output (MIMO) technology. This is, however, infeasible in some applications due to the size, cost and environmental con- straints . The potential spatial diversity that arises from the presence of multiple distributed nodes in a network
In recent years, a seamless increase of various innova- tive multi-media services has kept pushing the limits of current wireless networks, urging for higher-speed com- munications [1, 2]. As the smart mobile devices popularize progressively, the demand for higher wireless transmis- sion rate will grow exponentially in the next decades and a 1000 times increase in the current system capacity is required by 2020 [3, 4]. However, the fourth generation mobile communication systems which can support a rate of 1Gbit/s hardly satisfy the demand of mobile commu- nication in the next 10 years . Therefore, the fifth generation (5G) cellular network is being considered . One of the key technologies for 5G systems, which has recently attracted huge attention and can greatly enhance the spectral efficiency [7–9], is device-to-device (D2D) communication.
to the duplex mode of resource nodes and RSs, the FD relaying network can be divided into four kinds. The first one is a relay system consisting of one FD RS and two HD source nodes. This kind of system has been exten- sively studied in the last decade [28–31]. For example, two hybrid relaying schemes opportunistically switching between FD and HD relaying modes are proposed in  to maximize the instantaneous spectral efficiency, and in  to minimize the outage probability, respectively. The second kind is a relay system consisting of a FD RS and two FD source nodes. This kind of system is first stud- ied in , where achievable rate regions are derived for different relaying schemes, including DF, compress-and- forward (CF), and AF relaying schemes. In , a relaying system with two FD source nodes and multiple FD RSs is studied, and a relay selection method is proposed for AF relaying scheme to achieve the maximum signal-to- interference-plus-noise ratio (SINR). The third kind is the relay network consisting of one FD RS, HD source nodes, and FD source nodes, which has been insufficiently stud- ied so far. In , a system consisting of a FD RS and two HD source nodes is studied, and the advantages and dis- advantages are analyzed in terms of sum-rate and resource wastage. In , a hybrid-scheduling algorithm is pro- posed for the third kind of system based on a three-step relaying scheme. The fourth kind of FD relay network is a relay system consisting of one HD RS and two source nodes, in which at least one source node works in FD mode. This kind of system can be widely used in cooper- ative communication scenarios. For example, in Internet of things (IoT) networks and vehicular communication networks , the devices or terminals can establish an ad hoc network, and each of them can play a role as a RS to assist another devices or terminals to communicate with a base station (BS) or an access point. To the best of the authors’ knowledge, this kind of system has not been studied yet.
Relaying is viewed as an energy saving technique because it can reduce the transmit power by breaking one long range transmission into several short range transmissions . In fact, relaying has been extensively studied from another viewpoint, i.e., it is able to extend the coverage, enhance the reliability as well as the capa- city of wireless systems . One-way relay transmission (OWRT) can reduce the one-hop communication dis- tance and provide spatial diversity, but its SE will also reduce to 1/2 of that of direct transmission (DT) when practical half-duplex relay is applied . Fortunately, two-way relay transmission (TWRT) can recover the SE loss when properly designed [8-10]. However, it is not well-understood whether these relay strategies are energy efficient, when various energy costs in addition to transmit power are considered.
The signals transmitted by all three nodes in the system in  are QAM-type linear modulations. While linear modulation has many desirable features, it imposes a relatively stringent requirement on amplifier linearity. This is especially true in the case of DSF, where the transmitted signal constellation at the relay is essentially the superposition of two constituent QAM constellations. In contrast, constant envelope modulation enables the use of inexpensive nonlinear (Class C) power amplifiers. These modulations are widely used in public safety (police, ambulance) and private mobile communication systems (taxi, dispatch, courier fleets), even though they are, in general, not as bandwidth efficient as QAM mod- ulations. The use of constant envelope modulations in
Over this three-day span, IEEE ICC 2012 will also punctuate its high-level schedule with the keynotes of noted experts like Eros Spadotto, Executive Vice President, Technology Strategy at TELUS; Matt Bross, CTO & Vice Chairman at Huawei; and Mar- cus Weldon, CTO at Alcatel-Lucent. Other renown scientists and industry professionals expected to speak at the event are Lucy Hood, Executive Director at Communication Technology Manage- ment (CTM); Lauren States, Vice President, Cloud Computing at IBM; Ian Akyildiz, Professor at Georgia Tech; Victor Bahl, Direc- tor, MCRC at Microsoft; Vincent Poor, Professor at Princeton University; Raj Jain, Professor at Washington University, St-Louis; and P. R. Kumar, Professor at Texas A&M University.
With a tremendous growth of wireless multimedia services and the number of customers, it has been an enormous pressure on available frequency bands and spectrum allocation policies. However, most of frequency bands are under-utilization according to the report of Federal Communication Commission (FCC). To get around this troublesome, cognitive radio (CR) technique has been proposed to allow the unlicensed user can utilize the licensed spectrum band . The principal idea of CR networks is that the secondary users (SUs) is able to use the spectrum bands of primary users (PUs) provided that the quality of service (QoS) of licensed networks is not compromised. Several CR schemes have been introduced in the literature to implement the CR network. In particular, for interweave paradigm, the unlicensed users is not allowed to occupy the spectrum bands if PU activities are detected. As such, the transmission of CR network strictly relies on the primary system. On the other hand, the underlay spectrum-sharing paradigm allows SUs to transmit its information simultaneously with PUs as
3 SYSTEM MODEL AND PROBLEM FORMULATION
The two-way relay network between point to point connection is recently getting attention from researchers due to the advantages of technology, and it also can consider as crucial key to opening some other technology such as cognitive radio and future connection for an internet of thing. In cooperative communication related to relay station, there are different transmission scheme that can be implemented based on the transmission purpose. There are three main replaying protocols: AF, DF, and CF. In this thesis, we used AF scheme transmission for our own simulation, which is a relay station, after received signal from a transmitter, amplified the signal included noise and interference then forwarded the processed signal to the destination. The proposed research model is two-wayrelayingmethods with a half-duplex connection. The most typical form two-way relay network, which is two signal antenna transceivers with an amount of number single antenna RSs are used in a simulation model in this paper. We also consider the covariance matrix of channel state information (CSI) of interference known. We optimize the network performance based on the TS architecture in the two-way replaying network. In this case, the ratio between the EH phase and the IT phase has a significant impact on network performance. We find the optimal ratio in order to maximize the sum rate two-way replying network.
Cooperative communication is used as an effective measure against fading in wireless communication systems. In a classical one-way cooperative system, the relay needs as many orthogonal channels as the number of terminal it assists, yielding a poor spectral efficiency. Efficiency is improved in two-wayrelaying systems, where a relay simultaneously assists two terminals using only one timeslot. In the current contribution, a two-way quantize-and-forward (QF) protocol is presented. Because of the coarse quantization, the proposed protocol has a low complexity at the relay and can be used with half-duplex devices, making it very suitable for low-complexity applications like sensor networks. Additionally, channel parameter estimation is discussed. By estimating all channel parameters at the destination terminals, relay complexity is kept low. Using Monte Carlo simulations, it is shown that the proposed QF protocol achieves a good frame error rate (FER) performance as compared to two-way amplify-and-forward (AF) and one-wayrelaying systems. It is further shown that, using the proposed estimation algorithm, the FER degradation arising from the channel parameter estimation is negligible when compared to an (unrealistic) system in which all parameters are assumed to be known.
division protocol. In the proposed scheme, there are twocommunication phases, the MAC-phase and the BC-phase. In the MAC-phase, the two partner nodes transmit messages of both applications to the intermediate node where hybrid computations are performed. In the BC-phase, the intermediate node broadcasts the computed data to the partner nodes where the required application functions are determined. In both protocols, we give optimization problems which maximize the sum rate.In the superposition coding protocol, we show that 12 different decoding order combinations at the partner nodes are possible since SIC cannot be performed at one of the partner nodes. The sum rate is maximized with re- spect to the power portion for each superimposed message, and the constraints guarantee the successful transmission of the messages from the partner nodes. In the time division protocol, the optimization is performed with respect to the time portion allocated to the message that is broadcast from the intermediate node to the partner nodes. Simulation results shows that the decoding order combination is crucial to the performance of the superposition coding protocol. Under the given system settings, we show that the superposition coding protocol with certain decoding order combination outperforms the time division protocol.
However, all of the schemes discussed above are mainly designed to handle multiple-access interference and they do not work well when one or more channels from the terminal nodes to the relay node are in deep fade. Exploiting diversity is an efficient way to reduce the influence of deep fading. In frequency-selective fading channels, multi-path diversity is an important source of diversity gain. On the other hand, OFDM is widely used in systems with frequency- selective fading channels because it is effective to combat inter-symbol interference (ISI) caused by the frequency-selective fading. In point-to-point communication systems using OFDM, schemes exploiting multi-path diversity gain have been well investigated [10, 15, 57]. Among these schemes, precoding-based schemes are easy to implement and able to achieve higher spectral efficiency compared to other schemes. The objective of this paper is to design a precoding-based scheme to efficiently exploit the multi-path diversity in TWRC systems using the two-slot protocol and OFDM. The design can also obtain cooperative diversity gain which is effective to alleviate the impact of the multiple-access interference on the detection performance.
ABSTRACT: Data recovery refers to accessing logically or physically damaged data or over written data without the use any functioning backup. The advanced data recovery has two different methods where the first method - Part replacement which deals with the recovery from physically and/or logically damaged data. The second method of data recovery is the Magnetic recovery which deals with the recovery of the over written data. In this paper we are discussing about the methods and challenges for replacing, or refreshing firmware and system area information and for some part of the drive electronics. The magnetic recovery uses the Magnetic Force Microscopy for recovery of over written data. The backbone of the magnetic recovery is the interesting fact that the magnetic memory always remembers whatever is written on it till it is forced for a degauss under strong magnetic field. As far as the cyber forensics is considered the recovery of data after physical damage and over writing is of great importance. In this paper we discussed the limitations of current techniques and some probable future directions of data recovery. It is predicted that the data recovery is more important in near future.