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OFDM, DS-CDMA, And MC-CDMA Systems With Phase Noise And Frequency Offset Effects
White Papers We focus our work on DS-CDMA (IS95, UMTS, Cdma2000) and OFDM (IEEE802.11a, HiperlanII, DVB-T). The case of MC-CDMA is analysed. This paper analyses the effects of either a frequency offset or a phase noise process on the performances of different...
[August 1, 2004, 0:00]
Paired Carrier Multiple Access (PCMA) For Satellite Communications
White Papers PCMA is a novel method for frequency re-use with existing and planned satellites which allows two different earth stations to use the same frequency, time slots, and/or CDMA code at the same time. We describe how this technique can be applied with...
[November 22, 2007, 23:00]
Multiple Users Adaptive Modulation Schemes For MC-CDMA
White Papers Multi-carrier CDMA (MC-CDMA) unites CDMA and OFDM together and potentially offers the advantages of both technologies. Under a frequency-selective fading channel the subchannel frequency functions have different amplitude and phase.
[October 11, 2005, 0:00]
Comparison Of Multi-Cell Multi-Antenna CDMA And TDMA Systems
White Papers When comparing TDMA and CDMA in the uplink, there is a crossover in capacity. At low SNR CDMA is preferable, at high SNR TDMA performs better. The interference from another cell sharing the same frequency is calculated, and the total interference...
[July 20, 2004, 0:00]
Drowning In Wireless Spaghetti
News This is known as Code Division Multiple Access (CDMA), but it's also known as spread spectrum: a company called Qualcomm holds many patents for this as applied to mobile phones, but the technique's been in use since the 60s and is a key part of...
[November 1, 2005, 12:00]
Simulation Of A Dual-Mode EDGE /W-CDMA Receiver With Digital IF Down Conversion
White Papers This paper presents a simulation of a dual mode receiver with special emphasis on the digital IF (Intermediate Frequency) for W-CDMA (Wide band Code Division Multiple Access) and EDGE (Enhanced Data Rates for GSM Evolution) formats.
[July 25, 2004, 0:00]
Securing Wireless Technology
White Papers Wireless technology is a broad reaching term that can signify Wireless Local Area, (WLAN or Wi-Fi); Wireless Wide Area (WWAN), such as CDMA or GRPS; Radio Frequency IDentification (RFID); or personal area networking technologies such as Bluetooth.
[February 11, 2008, 23:00]
Improving The Performance Of Third Generation Wireless Communication Systems
White Papers The third generation (3G) mobile communication system uses a technique called code division multiple access (CDMA), in which multiple users use the same frequency and time domain. For more efficient use of resources, one wishes to allow more users...
[March 21, 2005, 23:00]
Sub-Band Loading For Pre-Equalized Uplink OFDM-CDMA Systems
White Papers In this paper a new pre-equalization technique is presented for uplink OFDM-CDMA systems. All users employ spreading both in frequency (on sub-bands of the available spectrum) and time; moreover, bit and power loading is used at the mobile...
[October 29, 2004, 0:00]
The Impact Of Fading On The Performance Of Large CDMA With Parallel Interference Cancellation
White Papers In this paper, the large-system performance of a multistage first-order linear Partial Parallel Interference Cancellation (PPIC) receiver for a synchronous Direct-Sequence Code Division Multiple Access (DS-CDMA) system over a frequency-flat fading...
[February 14, 2006, 23:00]
Low-Complexity Performance Optimization For MIMO CDMA Systems
White Papers A low-complexity approach is proposed for optimizing the performance of a multiple input multiple-output (MIMO) direct sequence code division multiple-access (DS-CDMA) system in the uplink for frequency selective fading channels.
[October 11, 2005, 0:00]
Parametric FPGA Early-Late DLL Implementation For A UMTS Receiver
White Papers CDMA makes possible simultaneous communications, spreading the user's information over a large frequency range by the means of orthogonal codes. Third generation communication schemes, mainly based on W-CDMA access technique, are replacing the...
[July 19, 2005, 0:00]
Tradeoff Between Source Coding And Spreading In A Multicarrier DS-CDMA System Operating Over Multipath Fading Channels With Narrow-Band Interference
White Papers For a fixed total bandwidth expansion factor, and for a fixed channel code rate, the authors' consider the problem of optimal bandwidth allocation between the source coder and the spread-spectrum unit for a multicarrier direct-sequence CDMA system...
[February 14, 2006, 23:00]
Power-Control-Based Band Allocation In Multiband CDMA
White Papers The method by which users are assigned to their respective frequency bands, termed 'band allocation', is an important part of assuring good performance in multiband CDMA systems. Multiband CDMA is useful for constructing DS-CDMA (CDMA) systems over...
[July 24, 2004, 0:00]
Sequences For OFDM And Multi-Code CDMA: Two Problems In Algebraic Coding Theory
White Papers This paper studies the peak-to-average power ratio (PAPR) problem for two different kinds of communications systems, Orthogonal Frequency Division Multiplexing (OFDM) and Multi-Code Code-Division Multiple Access (MC-CDMA).
[August 1, 2004, 0:00]
CDMA Matched Filter Implementation In Virtex Devices
White Papers CDMA is a technique used for wireless data transmission. CDMA base stations must be able to discriminate these different code sequences in order to distinguish one transmission from another. Every mobile handset and every wireless base station...
[July 25, 2004, 0:00]
Four User, 2.5 Gb/s, Spectrally Coded O-CDMA System Demonstration Using Low Power Nonlinear Processing
White Papers In O-CDMA, different users whose signals may be overlapped both in time and frequency share a common communications medium; multiple-access is achieved by assigning different, minimally interfering code sequences to different CDMA transmitters.
[July 25, 2004, 0:00]
Achieving High-Capacity Wireless By Merging Multicarrier CDMA Systems And Oscillating-Beam Smart Antenna Arrays
White Papers The MC-CDMA component supports high performance (in a probability-of-error sense) via frequency diversity and high network capacity via code division. This paper shows how to establish the network capacity (measured in terms of number of users) of...
[August 3, 2004, 0:00]
Data-Aided Channel Estimation For MC-CDMA Systems With Transmit Diversity In Wireless Channels
White Papers This paper will address the problem of data-aided channel estimation in an MC-CDMA system with multiple transmitting antennas. First, the paper takes into consideration a method proposed for OFDM with transmit diversity that relies on the frequency...
[July 29, 2004, 0:00]
Dynamic Resource Allocation For CDMA-TDD Indoor Wireless Systems
White Papers The Code Division Multiple Access - Time Division Duplex (CDMA-TDD) system is a promising solution to cope with the problem of traffic asymmetry. In this paper, the resource allocation in the CDMA-TDD is formulated as a Mixed Integer Programming...
[February 21, 2006, 23:00]
