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Next generation packet radio networks will have far greater processing capabilities than current radio systems. We propose and evaluate decoding techniques that make use of such capabilities to increase the probability of successful decoding. We propose a metric derived from statistics collected during demodulation in a binary CDMA receiver. We investigate several methods to apply the proposed metric...
In this paper, the performance of Cognitive Radio (CR) CDMA networks is analyzed. More precisely, we develop a simulation testbed for analyzing the performance of a CR user with and without spectrum sensing in a three cell scenario. Three different schemes for spectrum sensing are studied. CR users belong to a Cognitive Radio Network (CRN) which is coexisting with a Primary Radio Network (PRN). Both...
Commercial HSDPA measurements are used in order to derive an approach for the location based orthogonality factor. It is found that the orthogonality factor is correlated with the difference between the free space path loss and the measured path loss. A path loss difference close to 0 dB indicates line of sight and the maximal orthogonality factor is reached. With increasing path loss difference the...
In this paper, a two-level frequency-hopping code-division multiple-access (FH-CDMA) scheme, which is flexible in the selection of modulation codes and FH patterns, is studied. This two-level FH-CDMA scheme can be modified by the partition of the modulation codes in order to support more subscribers without increasing the number of FH patterns. The performance and spectral efficiency (SE) analyses...
This paper proposes a game-theoretic approach to the problem of resource allocation for a CDMA wireless communication network, focusing on code synchronization. To capture the tradeoff between obtaining good synchronization performance and saving as much energy as possible, we propose a noncooperative game in which each pair transmitter-receiver in the network seeks to maximize the ratio of the probability...
Higher Order Modulation (HOM, 64-QAM) and Multiple Input Multiple Output (MIMO) transmissions are two key features introduced in the Release 7 (HSPA+) WCDMA systems to improve downlink performance. This paper focuses on the performance analysis of 64-QAM and MIMO in the WCDMA system. We describe the equalizer design for supporting these features as well as the simulation results demonstrating the...
This paper proposes a feed-forward neural network predictor to adaptively estimate and suppress the narrowband interference (NBI) in the Direct Sequence-Code Division Multiple Access (DS-CDMA) signal. The iterative code-aided estimation is used to further improve the system performance. Simulation results reveal that the proposed algorithm outperforms conventional linear prediction filtering and recurrent...
In this paper, we explore the potential of developing an interweave cognitive radio (CR) system based on a hierarchical wide-band two-dimensional spread multi-carrier directed-sequenced code division multiple access (MC-DS-CDMA). First, a small CR cell is embedded in a large primary cell such that the spatial separation gives a chance to share the spreading code resources with the primary system....
3rd Generation Partnership Project (3GPP) responsible of the standardization of 3G systems selected dual stream Transmit Antenna Array (D-TxAA) as the Multiple Input - Multiple Output (MIMO) scheme for High Speed Downlink Packet Access (HSDPA) in 3GPP specification Release 7. MIMO doubles the theoretical peak data rate of HSDPA from 14.4 Mbps to 28.8 Mbps. However, successful reception of dual stream...
Complementary sequences are well studied in the communication field for their good correlation properties. Besides being used as spreading sequences, they can also be used for channel estimation, synchronization, reduction of peak-to-average power ratio of symbols, preamble design, sequence design, Target detection and so on. A recursive construction of complementary sequences based on orthogonal...
Multicarrier code division multiple access (MC-CDMA) is a promising technique for high data rate and high capacity (large number of users) transmission. However, rapidly time varying channels degrade the performance due to loosing the orthogonality among the subcarriers as well as code patterns. Channel estimation is very important to design adaptive system for improvement in all round performance...
In this paper we study the uplink-downlink duality for Gaussian vector channels with colored noise, and we derive the duality transformations (downlink-to-uplink and vice versa) that imply transmit co-variance matrices for which user rates in uplink and downlink are identical. These transformations are then applied for transmitter adaptation in Code Division Multiple Access (CDMA) systems to obtain...
Coexistence of multiple wireless body area networks (WBAN) is a very challenging problem because each piconet can have a large number of sensors and their movement is unpredictable. Moreover, suitable global coordination schemes do not exist as there is no natural choice of coordinator between piconets. Adaptive schemes that work well with low-occupancy channels, such as listen before transmit, are...
Interleave-division multiple-access (IDMA) has recently been proposed as a multiuser scheme that uses low complexity turbo-like iterative receivers and can outperform coded CDMA. Power allocation has been shown as an effective means for improving the performance of iterative receivers, and can be readily applied to multiuser systems including IDMA and CDMA. Power allocation allows the decoder to operate...
In this paper, a new technique for dynamic spectrum management of a Wideband Code Division Multiple Access (WCDMA)/Digital Video Broadcasting (DVB) heterogeneous system is introduced. The solution is obtained using coloring theory, and significantly reduces the complexity of spectrum management.
In this paper, performance analysis of multi-tone (MT-CDMA) transmission system is carried out in a mobile radio environment. The analysis is conceded out to find the carrier to Multi-Access Interference (MAI) with a Rake receiver. The expression of Bit Error Rate (BER) is found with respect to number of users and signal to noise and interference (SNIR). Also, BER performance results are evaluated...
This paper provides a performance comparison of two macrocellular topologies from the point of view of RF-repeater deployment. The numerical, system level, performance estimation was done in the downlink direction using high speed downlink packet access technology. In addition to a detailed repeater model, a distance dependent orthogonality model for wideband CDMA codes was included in the performance...
TD-SCDMA, as one of the 3G mobile system, is commercially operated in China successfully. TD-LTE, as the evolution of TD-SCDMA, will be operated in the future. However, these two systems may coexist in one area. The inter-system interference may degrade the performance of both. In this paper, we analyze the coexistence interference by minimum coupling loss (MCL) method. The isolation requirements...
We propose a quantization scheme based on a Kd (K dimensional)-tree algorithm for signature sequence in a reverse-link direct sequence (DS)-code division multiple access (CDMA). With a few feedback bits, a receiver quantizes the optimal signature that minimizes interference for a desired user, and relays it to the user via an error-free feedback channel. A user performance depends on the quantization...
Existing Wireless Local Area Networks (WLAN) networks solutions based on IEEE 802.11 have be known to perform badly in the presence of noise and interference. These networks therefore have problems with the scalability of crowded networks, with the result being highly variable delays rendering them unsuitable to delay sensitive applications such as voice and video. Here, interference causes significant...
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