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A novel distributed localization method for wireless sensor networks (WSN) is proposed in this paper. Linear frequency modulation (LFM) waves are emitted from two anchors simultaneously to create an interference field. Through the frequency measurement of local RSSI (Received Signal Strength Indication) signal, the TDoA (Time-Difference-of-Arrival) is estimated independently at each sensor to detect...
This paper focuses on spectrum handover in cognitive radio networks where secondary users (SUs) opportunistically use licensed channels as long as the aggregate interference at the primary users (PUs) does not exceed a certain threshold. We incorporate power control into the proposed spectrum handover scheme to reduce the number of spectrum handovers and enhance the spectral efficiency. In our work,...
In this paper, we investigate joint sensing and power allocation schemes for OFDM-based cognitive radio (CR) systems. A CR system employing cooperative sensing based on energy detection is considered. Each primary user (PU) band is assigned a subset of sensors and equal gain combining is used at the access point to detect the presence of PU in that particular band. For such a system, we propose algorithms...
Cognitive radio is a new communication paradigm that is able to observe, learn, optimize, and intelligently adapt to achieve optimal frequency band usage. Cognitive radio (CR)-based wireless mesh networks (WMNS) provide infrastructures for secondary users' transmission, and it is necessary to develop techniques with low interference to primary users in such networks. In this paper, we propose an interference-minimization...
This work presents a novel approach for the avoidance of cross-tier interference in two-tier networks comprised of Orthogonal Frequency Division Multiple Access (OFDMA) macrocells and femtocells. This new technique is based on the use of Intracell HandOvers (IHOs), and it makes possible that either a macrocell or a femtocell can reassign its sub-channel or power allocation upon the detection of cross-tier...
In this paper, we propose a novel end-to-end resource allocation approach for wireless mesh networks with quality-of-service (QoS) assurance. By introducing additional interference tolerability to each multimedia flow, our proposed approach is shown effective in fostering frequency reuse and increasing the number of multimedia flows supported in the system, outperforming its conventional resource...
The interference induced by UWB communication on systems operating in the frequency range between 0 and 10.6 GHz is the main reason why the essential role in these systems' design is played by the pulse shape selection. That's why an accurate shaping choice can lead to avoid severe performance reduction and to guard systems coexistence. To this end, FCC (and ETSI in the near future) gave strict indications...
The requirements of IMT-Advanced dictate innovations in radio resource management, including cross-layer optimization of radio resource allocation, inter-cell coordination, and interference mitigation strategies, dynamic and aggressive resource reuse, as well as state-of-the-art spatial signal processing. All of these technologies must be supported by an advanced radio access network capable of exploiting...
Realization of all-digital baseband receiver processing for multi-Gigabit communication requires analog-to-digital converters (ADCs) of sufficient rate and output resolution. A promising architecture for this purpose is the time-interleaved ADC (TI-ADC), in which several "sub-ADCs" are employed in parallel. However, the timing mismatch between the sub-ADCs, if left uncompensated, leads to...
We consider a simple ad-hoc cognitive scenario with two data up-links, one licensed to use the spectral resource (primary) and the other unlicensed (secondary or cognitive). It is assumed that the cognitive link accesses the channel only when the channel is sensed idle. An ON-OFF channel model is used for the primary link, where traffic statistical characteristics are taken into account. A closed-form...
Phase noise can severely impair transmission, especially in uplink space division multiple access (SDMA) scenarios. We derive a soft-decision-directed phase noise estimation and compensation algorithm in combination with iterative block decision feedback equalization (IBDFE) for uplink SDMA single carrier systems, such as those proposed in the 3GPP-LTE standard. The algorithm generalizes earlier algorithms...
The uplink transmission performance, e.g., bit error rate (BER) performance, of multi-carrier-code division multiple access (MC-CDMA) is limited by the multi-access interference (MAI). Recently, we proposed a FD-PR/MC-CDMA, which uses frequency domain phase rotation and symbol mapping onto equi-distantly spaced sub-carriers. In FD-PR/MC-CDMA, multiple users can be multiplexed without causing MAI as...
It is well known that symbol timing offsets larger than the cyclic prefix as well as carrier frequency offsets between transmitter and receiver stations destroy the orthogonality among OFDM subcarriers and induce additional interference. In conjunction with MIMO transmission on frequency selective fading channels where different users interfere with each other, these effects strongly degrades the...
This paper describes the design of several simple IR-UWB receivers that could be used for sensor networks. The research is looking for a simple design with low complexity and good performances. To achieve this, a priori information is needed: the statistical knowledge of the Multi User Interference (MUI). In many systems the Gaussian distribution is a common presumption but due to the impulsive nature...
In this paper, we propose a new interference alignment (IA) scheme designing jointly the linear transmitter and receiver for the MIMO interference channel system, using minimum total mean square error criterion, subject to individual transmit power constraints. We show that transmitter and receiver under such criterion could be realized through a joint iterative algorithm. The convergence of the proposed...
This paper considers the design of secondary wireless mesh networks which use leased frequency channels. In a given geographic region, the available channels are individually priced and leased exclusively through a primary spectrum owner. The usage of each channel is also subject to published interference constraints so that the primary user is not adversely affected. When the network is designed...
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