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Capacity is one of the significant factors in determining the performance of any cellular system. However, the capacity is limited by the interference. In cellular systems, the major source of interference is the Co-Channel Interference(CCI). In this paper, an analytical method is proposed to evaluate the erlang capacity of 3G WCDMA systems under CCI and the performance analysis with the use of adaptive...
CDMA-based technologies deserve assiduous analysis and evaluation. We study the performance, at call-level, of a CDMA cell with interference cancellation capabilities, while assuming that the cell accommodates different service-classes of batched Poisson arriving calls. The partial batch blocking discipline is applied for Call Admission Control (CAC). To guarantee certain Quality of Service (QoS)...
Strict quality of service requirements of industrial applications, challenged by harsh environments and huge interference especially in multi-vendor sites, demand incorporation of cognition in industrial wireless sensor networks (IWSNs). In this paper, a distributed protocol of light complexity for congestion regulation in cognitive IWSNs is proposed to improve the channel utilization while ensuring...
Future growth in Internet-of-Things applications will lead to an operating environment with many independent networks operating in the same location. Co-existence and internetwork interference in IEEE 802.15.4 networks is particularly interesting because of the popularity of the radio and limited number of “good” channels, making it likely that there will be nearby networks operating on the same channel...
Dense carrier sensing wireless networks are important scenarios to enable ubiquitous mobile Internet access. In this work, we study user experience from the end-to-end performance of dense p-persistent CSMA networks that suffers from operation interference among many non-coordinated APs. Results show that in dense networks, the effective coverage of APs shrinks and most STAs don't receive satisfactory...
Due to the high expected increase in mobile data traffic and the scarcity of licensed spectrum for cellular networks, 3GPP has started preliminary work for standardizing LTE operation in the 5 GHz unlicensed band (LTE-U). However, LTE-U would interfere with other legacy technologies operating in the unlicensed band, the most important being contention-based Wi-Fi, which would be blocked by conventional...
Rapid increases in mobile data demand and inherently limited RF spectrum motivate the use of dynamic spectrum sharing between different radio technologies such as WiFi and LTE, most notably in small cell (HetNet) scenarios. This paper provides a analytical framework for interference characterization of WiFi and LTE for dense deployment scenarios with spatially overlapping coverage. The first model...
In this paper a new binary sequence family with 2n + 1 cyclically distinct sequences each having length 2n − 1 is presented for an even integer n. The correlation distribution of the family is fully determined. The family has six-valued correlation distribution and its maximum correlation magnitude equals equation.
The bit error rate (BER) performance of CDMA system will rapidly deteriorate under the co-channel interferences. To solve the problem, we give a polyphase complete complementary sequence-based direct-sequence code-division multiple access (CC-DS-CDMA) for additive white Gaussian noise (AWGN) channel in this paper. Sets of sequences with complete complementary principle are known because of their ability...
Wideband Code Division Multiple Access (WCDMA) is an air interface standard specially designed for third generation (3G) mobile networks to provide low data rate voice services to high data rate multimedia services. But different types of multipath fading, multi-access and co-channel interferences put a limit on overall system performance. The mechanism of power control provides a best alternative...
The recently proposed LCL-PTV structures for narrowband interference suppression in DS/SS systems are examined and compared in terms of output SIR. New LCL-PTV prediction/subtraction filters are proposed, which are shown to provide the same SIR performances of the LCL-PTV whitening structures, with the additional advantage of being amenable to blind adaptive implementation. Simulation results are...
In this paper, new polyphase sequences and a sequence generation method are suggested. The correlation properties of the sequences are investigated. These sequences have good correlation properties. Since the suggested generation method consists only of integer sums and modular techniques, sequence generation is also easy. The performance of the sequences is investigated for QS-CDMA systems in frequency...
Code Division Multiple Access or CDMA has its roots in WWII era spread spectrum technology. In this technology, multiple users can transmit the data simultaneously in a channel using the same frequency band and each user is assigned a distinguished code for transmission. CDMA uses spread-spectrum technology to minimize the problems relating to interference in the channel. Different types of codes...
This paper deals with the general problem of the design/choice of spreading sequences for asynchronous DS-CDMA communication systems, employing a linear multiuser detection front-end. After a brief problem formulation, we propose a new near-optimal spreading sequences design, based on piece wise linear chaotic Markovian sequences (PLM sequences). The performance evaluation of this spreading sequences...
To date, random access protocols like Carrier Sense Multiple Access (CSMA) have been the preferred means of sharing the radio channel in SpeckNets and other ad hoc wireless sensor networks. This paper considers Code Division Multiple Access (CDMA) as an alternative multiple access method, and evaluates the introduction of exclusion zones around each node as a low cost means of managing the Near Far...
Using chaotic sequences for spreading is a new approach for optimising the BER (Bit Error Rate) performances in the DS-CDMA (Direct Sequence - Code Division Multiple Access) systems. This paper presents the use of a very well known family of PWAM (Piece-Wise Affine Markov) maps, namely (n, t) - tailed shifts maps, and their optimum quantized versions. This optimisation involves the variance minimisation...
This paper deals with narrowband interference suppression in direct-sequence code-division multiple-access (CDMA) systems. In order to take advantage of the cyclostationary nature of the interfering signal, we propose here to adopt a linear conjugate-linear (LCL) polyperiodically time-varying (PTV) filter in the suppression stage, whose adaptive implementation is based on the RLS algorithm. Unlike...
Linearly constrained optimization techniques based on the minimization of the output energy have been proposed for the design of single rate DS-CDMA detectors. The goal of this paper is to apply this approach to dual rate systems where low rate users have symbol periods which are multiples of those of high rate users. It is observed that a high rate (HR) user experiences the same frequency selective...
This paper deals with the reduction of both self interference (SI) due to multipath, and multiuser interference (MUI) due to multiple access for synchronous DS-CDMA communications over frequency-selective fading channels. We are concerned with the down-link where the base station transmits all the users information synchronously and any mobile receiver must perform a reliable demodulation. In this...
Code division multiple access (CDMA) is the multiple access scheme retained for the third generation wireless communication systems, that must support high data rate transmissions, and operate over jammed Rayleigh fading channels. In the current work, we propose and analyze multi-antenna spatio-temporal adaptive receiving structures of detection at the base station, able to cope with degradations...
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