The Infona portal uses cookies, i.e. strings of text saved by a browser on the user's device. The portal can access those files and use them to remember the user's data, such as their chosen settings (screen view, interface language, etc.), or their login data. By using the Infona portal the user accepts automatic saving and using this information for portal operation purposes. More information on the subject can be found in the Privacy Policy and Terms of Service. By closing this window the user confirms that they have read the information on cookie usage, and they accept the privacy policy and the way cookies are used by the portal. You can change the cookie settings in your browser.
In this paper, we investigate the resource allocation for the video streaming service in the cognitive radio network (CRN) based on orthogonal frequency division multiple access (OFDMA). Considering the channel estimation error between secondary transmitters (STx) and primary receivers (PRx), we address the probabilistic interference constraint model. With imperfect CSI between STx and secondary receivers...
Non-orthogonal multiple access (NOMA) is a promising multiple access technique for future wireless communications as it results in high spectral efciency. In this paper, we study a NOMA based dual-hop X-relay system, where a decode-and- forward relay assists the communication between the sources and the destinations. We assume that the statistical channel state information is known to the network...
This work studies the secrecy outage performance of buffer-aided dual-hop multi-antenna relay systems without eavesdropper's channel state information (CSI). By modeling the dynamic buffer state transitions with the Markov chain, the secrecy outage probability at each state is investigated and the stationary distribution probabilities of all states are subsequently derived. Using the total probability...
The spectrum sensing methods have been incorporated in an essence to fulfill the sensing requirements associated with the detection of primary user in cognitive radio (CR) networks. Energy detection (ED) is the simplest and most commonly employed method to sense the licensed spectrum so that secondary user can make proficient use of it. The conventional energy detector has predefined value of sensing...
The use of massive multiple input multiple output (MIMO) systems can improve the performance of energy efficiency and increase the capacity limits due to the improvement of the spatial correlation. The effect of the exponential correlation model on the massive MIMO energy and spectral efficiencies is investigated using a base station (BS) with a large number of antennas and a single antenna user terminal...
In following paper, firstly we have considered a 2-hop relay network in which more than one relay is accessible. And then analysis of relay selection for the decode-and-forward cooperative protocol for minimizing the outage probability over a short-term power constraint is done. Investigation of effect of power control in selecting a relay from view of capacity is done. Here an assumption is made...
In this paper the impact of exponential correlation model on massive multiple input multiple output (MIMO) channel estimation is analyzed using a large number of antennas in the base station (BS) and a user terminal. We consider pilot-based channel estimation in the UL channel. The Linear minimum mean square error (LMMSE) estimator is used to investigate the effect of correlation factor on the average...
In this paper, we propose a relay selection method in an amplify-and-forward (AF) scenario considering complete outdated channel state information (CSI) of all links. Differing from the methods in the literatures considering only outdated CSI over the link from the relay to the destination, another type of outdated CSI, i.e., the outdated CSI over the link from the source to the relay, is also considered...
Atmospheric turbulence is a practical obstacle in deployment of free space optical (FSO) communications. Due to its ease of implementation, on-off keying (OOK) is a widely-adopted modulation technique for intensity modulation with direct detection (IM/DD) in optical communications. For optimal signal detection, the receiver needs to know the instantaneous channel fading coefficient to detect OOK symbols...
Massive MIMO brings both motivations and challenges to develop the 5th generation mobile wireless technology. The promising number of users and the high bitrate offered per unit area are challenged by uplink pilot contamination due to pilot reuse and a limited number of orthogonal pilot sequences. This paper proposes a solution to mitigate uplink pilot contamination in an indoor scenario where multi-cell...
In this paper, we study the outage probability of the amplify-and-forward (AF) cognitive relaying in spectrumsharing environments with outdated channel state information (CSI) over Rayleigh fading channels. A selection of the best relay in the secondary system with outdated channel information is considered. We derive a closed-form expression for the tight lower bound on the end-to-end outage probability...
In this paper, we study the degrees of freedom (DOF)for three-user multiple-input and multiple-output (MIMO) Y channel, where each user equipment (UE) sends two independent messages to the other two UEs while receiving two independent messages from them via a common relay node. We assume each UE is equipped with M antennas and is semi-blind in the sense that no channel state information at the transmitter...
Channel state information (CSI) is critical for the performance of multicell cooperative transmission. This paper compares two cooperative multicell precoding methods, namely, centralized precoding with global CSI and distributed precoding with local individual CSI. For both cases, the BSs have access to the data of all the users. The only difference is that in centralized precoding, the precoding...
This paper has proposed an adaptive antenna selection technique in multiple input multiple output (MIMO) system that optimizes the system energy efficiency to achieve maximum throughput. Though throughput increases with the dimension of MIMO system, the energy consumed per RF module is a major concern. The antenna selection technique exploits the channel state information (CSI) at transmitting end...
In this paper, we propose a scheme to design transmit beamforming considering the effect of channel estimation at the transmitter. Under the multi-cell downlink massive MIMO system, coordinated beamforming is obtained by applying uplink-downlink duality for transmit power minimization problem subject to signal-to-interference-plus-noise ratio (SINR) constraints. To handle much information exchange...
This paper addresses a practical aspect of coded on-off keying free-space optical communication systems: quantization of demodulator outputs in receiver. Receivers with and without knowledge of channel state information (CSI) are considered. Proposed quantization schemes for soft decision decoding with CSI are uniform with quantization intervals proportional to channel gains. The schemes are studied...
Adaptive Modulation and cooperative Diversity are considered as two of the most commonly deployed techniques for wireless communication, which aims to compensate the performance degradation and enhance the capacity as much as possible. In this survey, several studies and research works that were introduced in the literature will be investigated, aided by the followed methodology and main concepts...
The outage performance of decode-and-forward cognitive ratio opportunistic relay (DF CR-OR) systems is investigated over Rayleigh fading environments. We specially consider the case where the systems are impaired by the imperfect channel state information (CSI) between the secondary users and the primary user, and by the co-channel interference (CCI) at secondary relays and destination. We first obtain...
In a cognitive radio (CR) network, how to eliminate the interference between primary users and secondary users is a curial work. The emergence of interference alignment (IA) provides an effective way to solve this problem. However, in order to utilize the IA algorithm, the real-time and accurate channel state information (CSI) is required at both transmitters and receivers. But in practical IA system,...
In this work, we consider relay selection strategy in an amplify-and-forward cooperative cognitive ratio system in order to prolong lifetime of the energy-constrained relay network. The network lifetime considered in this work is based on the outage probability of the secondary cooperative system. Not only the channel condition of each relay, selection of best relay has to satisfy the interference...
Set the date range to filter the displayed results. You can set a starting date, ending date or both. You can enter the dates manually or choose them from the calendar.