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.
Long Term Evolution (LTE) is a standard for wireless communication of high speed data for mobile phones and data terminals. LTE is capable of delivering large data rate on the order of several megabits per second, which is even larger than the current 3G systems. This is very challenging as the wireless networks are subjected to interference, multipath and poor propagation channel characteristics...
Code-hopping multiple access (CHMA) has been an emerging multiple access technology designed to increase the number of users in Code-division multiple access (CDMA) systems. It was designed to overcome the limitations in the number of code word's required for communication in existing systems. However, it may experience degradation due to symbol perforation occurring due to code collisions when the...
One of the outcomes in the last world radio communication conference 2007 (WRC-07) is assigning the 790-862 MHz band to the digital broadcasting (DB), and the new mobile system called International Mobile Telecommunication - Advanced (IMT-A) in co-primary basis in 2015. Until that year, the primary service (i.e., DB) should be protected from the new system (i.e., IMT-A). This paper investigates the...
Reducing interference induced by secondary users is one of the most challenging problems in spectrum sharing. In this paper, we derive the optimum transmission strategy that minimizes the average interference power created by cognitive radios at a given point of space i.e. the location of a primary receiver. Surprisingly, this is not given by the water-filling solution.
In this paper, we elaborated on a new interference alignment technique for downlink multi-user system in a MIMO-X channel with multiple antennas. We considered two transmitters, each equipped with M antennas, and L users, each equipped with K antennas. Here, we consider a MIMO-X scenario that some users are receiving transmissions from both transmitters. The proposed approach is focused on rank-1...
A network consisting of a point-to-point (P2P) link and a multiple access channel (MAC) sharing the same medium is considered. The resulting interference network, with three transmitters and two receivers is studied from degrees of freedom (DoF) perspective, with and without cognition. Several cognition variants are examined. Namely, the setup is studied with (1) no cognitive transmitters, (2) a cognitive...
Noise frequency modulation signal (noise FM signal) is the main form of noise jamming. The research on it is focused on its signal characteristics. However, the material about best parameters selection of the jamming with which the best cover effect can be gotten is rare. The noise FM signal and its output of the radio receiver are derived theoretically in the paper, and the range of signal parameters...
Numerous interrelated trade-offs are undertaken for any receiver or receive chain design, which must be jointly optimized for the intended operational environment. Some of the requirements resulting from this environment are: noise figure (NF), input 3rd order intercept point (IP3), input 1dB compression point (P1dB), dynamic range, input desensitization level, non-damage input power, out-of-band...
We study the definition of exclusion region through handshake control bursts. The RTS/CTS (request to send/clear to send) bursts that typically take part in the handshake between the radio transmitter and receiver are a perfect medium for sounding their surroundings. Therefore, they can be utilized for setting exclusion regions - geographical areas protecting the active receivers from interference...
A multiple packet receiver (MPR), which jointly performs timing acquisition of the incoming packets and decoding of the packet payloads, is analyzed. The payload decoding consists of iteratively performed parallel interference cancellation, followed by individual error control decoding. Timing acquisition is repeated at every stage of the interference cancellation in order to acquire packets that...
Non-coherent UWB receivers are often implemented using energy detection architectures which are very sensitive to noise in the channel and interference. Therefore, the receiver bandwidth plays an important role since the total noise and interference energy is proportional to this bandwidth. This work provides analytical expressions to find the optimal receiver bandwidth and quantifying the effect...
Wake-up radio technology is a means to improve energy efficiency in low-power wireless sensor networks. In such radios, low-power low-complexity designs are considered, often based on narrow-band transmission, simple modulation techniques, noncoherent detection and matched filter receivers. In order to improve the performance of wake-up radios in interference limited scenarios, while keeping the power...
This article addresses the signal distortion caused by receiver phase noise (PN) on OFDM waveforms in direct-conversion radio receivers. A closed-form solution for the observed signal-to-interference-plus-noise ratio (SINR) is derived, describing the level of intercarrier interference (ICI) stemming from PN. Compared to existing literature, the analysis is valid for arbitrary oscillator spectral shape,...
Cognitive radio (CR) technology provides great flexibility in spectrum utilization with orthogonal frequency-division multiplexing (OFDM) as its candidate transmission technique. In this paper, we propose a simple spectrum shaping scheme for OFDM-based CRs to enhance spectral compactness and ensure bandwidth efficiency. By mapping antipodal symbol pairs onto adjacent subcarriers at the edges of the...
This paper examines a type of linear beamforming for communications in interference networks. First, a receiver beamformer design is derived from a Maximum Likelihood (ML) framework with Automatic Gain Control (AGC) constraints. The studied beamformer keeps the complexity of the receiver low and it is able either to remove full coherent arrivals or to enhance them when required when different AGC...
In this paper we propose a power control policy over an imperfect fading channel within a cognitive spectrum sharing area. In particular, our proposed scheme maximizes the secondary user effective capacity subject to the average interference power and the secondary user transmit power constraints. We also investigate the minimization of average interference power at the Primary Receiver (PR) under...
We consider the 3-user Gaussian interference channel and provide an outer bound on its capacity region. Under some conditions, which we call the mixed strong-very strong interference conditions, this outer bound is achievable. These conditions correspond to the case where at each receiver, one transmitter is causing strong interference and the other is causing very strong interference. Therefore,...
In this paper a novel Space Time Diversity Generalized Decorrelating Discrete Time Rake (STD-GD-DTR) for Upstream DS-CDMA system is proposed. The chosen algorithm for estimating the correct data is Maximum likelihood. In this method, a robust receiver based on maximum likelihood estimation is represented in which, space time diversity technique has been combined with generalized decorrelating discrete-time...
Impulsiveness, or a high degree of peakedness, of interchannel interference in digital communication systems typically results from the non-smooth nature of any physically realizable modulation scheme designed to transmit a discrete (discontinuous) message. Even modulation schemes painstakingly designed to be `smooth' are not. The non-smoothness of the modulation can be caused by a variety of hardware...
We consider a reuse-1 cellular system and study the improvement in SINR possible for a fixed/nomadic receiver, from the use of an optimally oriented directional patch antenna or a Uniform Linear Array (ULA) with 2 or 4 antenna elements along with Minimum Mean Square Error (MMSE) combining. We perform the studies with a ray-tracing propagation model as well as an empirical statistical model that is...
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.