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 address the problem of fast point-to-point channel capacity estimation in the case where the receiver undergoes unknown interference from multiple sources, whereas the channel with the transmitter is perfectly known. For this particular context, we propose a fast estimator for the capacity estimation, and compare its performance with that of the traditional methods. More precisely,...
OFDM-based cognitive radio (CR) systems are shown to be an effective solution for increasing spectrum efficiency by activating the certain group of subcarriers (subbands) in locally available spectrum. However, each CR receiver should synchronize itself to appropriate carrier frequency and to identify currently activated subbands. Moreover, energy and bandwidth efficiency of CR systems can be improved...
In this paper we introduce a multiple access scheme in which frequency reuse is achieved using the difference in the signal amplitudes. For this amplitude division multiple access (ADMA) system, a locally optimal multiuser detector (LOMUD) is proposed to detect a weak binary phase shift keying (BPSK) signal in the presence of a similar modulated cochannel interference and additive white Gaussian noise...
In this paper, we propose an enhanced channel estimation method for multi-user multiple-input multiple output (MU-MIMO) based long term evolution (LTE)-Advanced system. In MU-MIMO based LTE-Advanced system, the orthogonality between co-scheduled layers is not perfectly guaranteed. In this case, significant performance degradation in channel estimation can occur due to the interference from transmit...
Femtocells are data access points installed by the subscribers to provide better indoor voice and data coverage and to increase system capacity. The integrated femtocell/macrocell networks offer an efficient way to increase access capacity by improving coverage and quality of service while on the other side the deployment cost for the service provider is kept in extremely low levels. One of the major...
Compared with the conventional AF-based single-relay cooperative networks, there is nearly double spectrum efficiency in the AF-based two-path relay cooperative networks. However, there are few channel estimation methods for that. In this paper, we propose this channel estimation scheme. Firstly, we find the necessary channel state information (CSI) based on the FIC (full interference cancelation)...
This article considers the two-way bidirectional relaying scenario, in which it is crucial to improve the transmission efficiency to make up for the extra hop in the communication. Single-antenna two-way relaying can be implemented through a Self-Interference (SI) cancellation scheme known as Bidirectional Amplification of Throughput (BAT). This paper analyzes the impact that an imperfect cancellation...
In this paper we investigate uplink carrier aggregation in the context of dense residential deployments of LTE-Advanced Femtocells. Previous work in the literature based on macro-cells suggested considering UE power limitations to infer which UEs should be allowed to employ multiple component carriers. However, due to the very small radius of femtocells, UEs are not expected to become power-limited...
This paper presents an adaptive interference control method to mitigate undesirable interference from femtocells to macrocell users in hierarchical cellular networks. Such mechanisms usually require over-the-air signalling for estimation of interference resulting significant bandwidth overhead. The proposed ‘Adaptive Interference Scaling’ (AIS) method uses geolocation information for femtocell power...
Prior work in implementing spectrum sharing scenarios for cognitive radio networks has relied on the unlikely assumption of full cross-channel knowledge made available to the cognitive transmitter (CT) and/or the target primary receiver (PR). However, estimation of this cross-channel knowledge is not only important from a practical stand-point, but also in limiting the real interference power felt...
TDD multiuser downlink MIMO channels with delayed channel state information at the transmitter (CSIT) are considered. Block diagonalization is applied at the base station (BS). In order to cope with the inter-user interference caused by the delayed CSIT, we develop a novel capacity estimation method at first and then propose robust delayed CSIT aware multimode selection schemes based on the estimation...
A discretized version of a continuous optimization problem is considered for the case where data is obtained from a set of dispersed sensor nodes and the overall metric is a sum of individual metrics computed at each sensor. An example of such a problem is maximum likelihood estimation based on statistically independent sensor observations. By ordering transmissions from the sensor nodes, a method...
In LTE system, in order to access the network, user equipment (UE) should detect the primary synchronization signal (PSS) and secondary synchronization signal (SSS) in downlink (DL) signal from the surrounding base stations (BS). This paper presents a novel initial cell search (ICS) scheme in TD-LTE system that contains two steps. In the first step, modified normalization based PSS detection is proposed...
To further increase the spectrum efficiency of cellular mobile communication systems, it is important to control co-channel interference among cells. To control co-channel interference and improve spectrum efficiency over the whole cell, we proposed QoS-guaranteed multi-cell coordinated transmit power control, which limits the communication of some users and fully guarantees the QoS for the remaining...
In scenarios with time-varying channels such as intelligent traffic systems or high speed trains, the orthogonality between subcarriers in orthogonal frequency division multiplexing (OFDM) is destroyed leading to inter-carrier interference (ICI). In the literature, ICI equalization algorithms have been proposed; however, they assume perfect channel knowledge at sample level. Unfortunately, existing...
The increasing popularity of the femtocell concept has revamped the interest in dynamic interference coordination techniques for dense and uncoordinated deployments of low- power home base stations. One of the proposed schemes for 4G OFDMA femtocells is known as Autonomous Component Carrier Selection (ACCS). ACCS capitalizes on the carrier aggregation framework of LTE-Advanced to curb inter-cell interference...
RFID has been gaining popularity due to its variety of applications, such as inventory control and localization. One important issue in RFID system is tag identification. In RFID systems, the tag randomly selects a slot to send a Random Number (RN16) packet to contend for identification. Collision happens when multiple tags select the same slot, which makes the RN packet undecodable and thus reduces...
This paper investigates the problem of single-tone jamming in orthogonal frequency division multiplexing (OFDM) systems. A frequency-domain estimation and elimination scheme for single-tone interference is proposed. The proposed scheme is independent of any pilot or vacant sub carrier. Simulation results demonstrate that the proposed method is superior to the typical time-domain prediction filter...
Time varying channel breaks the orthogonality between the subcarriers of Orthogonal Frequency Domain Multiplexing (OFDM). This introduces Intercarrier Interference (ICI). One of the ways to mitigate ICI is to first estimate the channel and then equalize it. In this paper we propose to estimate the channel using Discrete Proplate Spheroidal Sequences (DPS) using pilot carriers interleaved with data...
As an alternative to the OFDM transceiver, single carrier frequency domain equalization (SC FDE) based transceiver has received much attention because of its simple implementation and low peak to average power ratio (PAPR). In this paper, a minimum mean square error (MMSE) FDE for single carrier block transmission is presented to effectively equalize the channels with high frequency selectivity such...
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.