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.
We define a multiaccess communication scheme that effectively eliminates interference and resolves collisions in many-to-one and many-to-many communication scenarios. Each transmitter is uniquely identified by a coding vector. Using these vectors, all signals issued from a specific transmitter will be aligned along a unique dimension at all receivers hearing this transmission. This dimension is characteristic...
This paper presents an analysis on the performance of decode- and-forward cooperation transmissions in Rician fading channels. The users send the signals using multiband DS-CDMA transmission; the particular complete complementary code sets are used as spreading sets and to provide orthogonality and signal separation. These codes sets have an impulsive autocorrelation sum among each set and orthogonality...
In this paper, we introduce a Downsample Upsample Shift Add (DUSA) method that faithfully implements the Time Compression Overlap-Add (TC-OLA) technique while overcoming some of the existing TC-OLA implementation shortcomings. The mathematical framework of DUSA relies on three operators: downsample, upsample, shift and add operators, and is shown to yield the same results as TC-OLA. Moreover, at some...
Modern wireless communication networks need to support a variety of data intensive applications in various medium/channel scenarios. It requires high network throughput as well as robustness against Multiuser Interference (MUI), multipath fading and other channel effects. This is achieved by using the hybrid Direct Sequence Time Hopped CDMA (DS-TH CDMA) systems. In this paper, a novel usage of State-Space...
Code division multiple access (CDMA) is a widelyused multiple-access scheme in conventional communication systems. In this paper, we consider code division multiple access in molecular communication: since molecular communication has a non-negativity constraint, we consider a nonnegative variant of CDMA that was developed for optical communication. Our results include an information transmission scheme,...
Indoor-outdoor (IO) detection provides very useful hints for a mobile device to perform context-aware services. To that end, GPS presents a viable solution by relating a device's IO status with its positioning performance, which depends on the device's exposure to the open sky. This approach, however, is prohibitively expensive in terms of energy consumption and response time. Recent work has thus...
In this paper, the serial interference cancellation (SIC) is discussed from 3G, 4G typical application technologies (DS-CDMA, MIMO-OFDM) and non-orthogonal multiple access (NOMA) which is 5G candidate technology. We also simulate the SIC algorithm in the related technologies. The results show that SIC technology is concerned by domestic or foreign scholars and the research of SIC technology is more...
Wireless connectivity offers industrial automation the flexibility, mobility and reconfigurability it requires to cope with the new challenges of industry 4.0. Communication in industrial applications like factory automation (e. g. closed-loop control) imposes ambitious demands on wireless communication systems as these applications require very low latencies at ultra-high reliabilities. Additionally,...
The number of small wireless devices is rapidly increasing, making the radio channel efficiency in limited geographic areas (individual rooms or buildings) an important metric for MAC protocols. Many of these emerging devices have use-cases that are difficult to satisfy with current hardware solutions and channel access methods; for instance device mobility, small energy reserves, and requirements...
The clock bias in different sectors of a cellular base transceiver station (BTS) cell is studied. A dynamical model relating the clock biases in different BTS sectors is identified and validated experimentally. A theoretical estimation error lower bound due to the discrepancy between sector clock biases is derived and demonstrated against Monte Carlo simulation runs. Experimental results of an unmanned...
In this paper, the comparison of several optimization methods for solving the optimal multiuser detection problem exactly or approximately are discussed. The purpose of using these algorithms is to provide complexity constraint alternatives to solving this nondeterministic polynomial-time (NP)-hard problem. An approximate solution is found firefly based optimization which is used to provide an exact...
In this paper, we propose a novel architecture for IDMA system with low latency and high throughput for the uplink multi-user wireless system. The throughput of the proposed IDMA system can be improved to about double compared to the conventional IDMA system while the hardware complexity remains unchanged. To achieve this, the proposed system utilizes the interleaver/de-interleaver-less architecture...
The research is devoted to the reduction of multiple access interference (MAI) in chaos-based asynchronous direct sequence code division multiple access (DS-CDMA) communication systems by use of spreading sequences which are selected from a large set of generated chaotic sequences. For the generation of binary chaotic spreading sequences different 1-dimensional maps are examined. As selection criteria...
In this paper, we present a multi-user resource allocation framework using fragmented-spectrum synchronous OFDM-CDMA modulation over a frequency-selective fading channel. In particular, given pre-existing communications in the spectrum where the system is operating, a channel sensing and estimation method is used to obtain information of subcarrier availability. Given this information, some real-valued...
The deployment of high densities of node due to the advancement in Wireless Sensor Network (WSN) technology had created the concern regarding the lifetime and error presented in the network. From the previous studies, Hybrid ARQ (HARQ) error control techniques can combat errors and indirectly, can reduce the energy consumption of sensor nodes. Based on the latest previous work, the HARQ algorithm...
Code-Division Multiple-Access (CDMA) [1] is widely used in both civil and military applications. It does take advantages from the system characteristics. For example, higher data rate and user capacity, better multipath resolution [2] and resistance to jamming, low probability of interception, accurate timing and ranging, and more importantly, stronger ability to suppress interference and jamming...
Orthogonal frequency division multiplexing (OFDM) is not only a simple scheme used as a digital multicarrier modulation method, but it is one of the most popular and effective technologies used in nowadays communication systems. In this work we present a brief summary of the history of OFDM, a description of the key features of this technology is delivered, and with it we argue why OFDM has been the...
Wireless communication with multicarrier modulation is very attractive for present and future communication network due to immunity to delay spread and fading. However, such systems are receptive to carrier frequency offset (CFO) due to Doppler effect in a mobile communication system. Analysis is carried out for a wireless communication system with multi carrier (MC) direct sequence (DS) code division...
This paper organizes the performance of twodimensional (2-D) Modified Double Weight (MDW) code for Optical Code Division Multiple Access (OCDMA) system by employing Avalanche Photodiodes (APD) as a gain. To accomplish the perfection system capacity, their cardinality, bit error rates (BER) and noise interferences are analyzed. With 2-D MDW with APD able to recovered the cardinality at least 61%, which...
Massive machine type communication (mMTC) will become the key factor of the future industrial automation area. Also, with the rapid development of Internet of Things (IoT) technologies, more and more researchers in industries and universities have engaged in exploring the problems in mMTC. Currently, one attractive problem is how to cope the requirement of massive connections. One powerful candidate...
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.