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- Channel Estimation Techniques for OFDM Systems
- Channel estimation is an important and necessary function for modern wireless receivers. With even a limited knowledge of the wireless channel properties, a receiver can gain insight into the information that was sent by the transmitter. The goal of channel estimation is to measure the effects of the channel on...
- Tags: Technique, Channel Estimation, OFDM, Wi-Fi, Wireless
- White papers 2007-03-01
- Capacity of Complexity-Constrained Noise-Free CDMA
- An interference-limited noise-free CDMA downlink channel operating under a complexity constraint on the receiver is introduced. According to this paradigm, detected bits, obtained by performing hard decisions directly on the channel's matched filter output, must be the same as the transmitted binary inputs. This channel setting, allowing the use of...
- Tags: Channel, CDMA, IEEE, Cellular Phones, Consumer Electronics, Personal Technology
- White papers 2005-09-16
- On the Achievable Information Rates of CDMA Downlink With Trivial Receivers
- A noisy CDMA downlink channel operating under a strict complexity constraint on the receiver is introduced. According to this constraint, detected bits, obtained by performing hard decisions directly on the channel's matched filter output, must be the same as the transmitted binary inputs. This channel setting, allowing the use of...
- Tags: Channel, CDMA, Cellular Phones, Consumer Electronics, Personal Technology
- White papers 2005-09-16
- Bandwidth Efficient Channel Estimation Using Super-Imposed Pilots in OFDM Systems
- This paper proposes a channel estimation algorithm using super-imposed pilots for OFDM systems. The pilot symbols are added linearly to the modulated data symbol at a fraction of the total transmit power, making the method spectrally efficient. This paper presents a series of iterative and non-iterative receivers in which complexity...
- Tags: Bandwidth, Complexity, Performance, IEEE, OFDM, Performance Management, Wireless, Human Resources, Workforce Management
- White papers 2006-10-05
- A High-Speed Mobile OFDM Receiver LSI With an Iterative Noise-Reduction Filter to Enhance Channel Estimation
- This paper presents an OFDM receiver LSI with an iterative noise-reduction filter. Experimental results show that the LSI drastically improves the mobile reception performance, especially in high-speed environment. The die is fabricated with 0.18um CMOS process, including ADC, DAC and PLL. Orthogonal Frequency Division Multiplexing OFDM is one of the...
- Tags: Broadcasting, OFDM, Wireless
- White papers 2006-03-03
- Optimal Backpressure Routing for Wireless Networks With Multi-Receiver Diversity
- This paper considers the problem of optimal scheduling and routing in an ad-hoc wireless network with multiple traffic streams and time varying channel reliability. Each packet transmission can be overheard by a subset of receiver nodes, with a transmission success probability that may vary from receiver to receiver and may...
- Tags: University Of Southern California, Network, Wireless Network, Networking, Wireless
- White papers 2006-10-01
- Centralized Joint Signature Sequence and Receiver Filter Optimization for Downlink MC-CDMA With Frequency Selective Channel
- The focus of this paper is on constructing Joint Optimal Signature sequence and receiver Filter (JOS&F) to minimize the weighted total mean square error for the downlink MC-CDMA system under frequency selective channel response. An iterative process is presented to numerically search such JOS&F for given channel status in the...
- Tags: Frequency, Optimization, Sequence, Engineering
- White papers 2005-05-31
- Code-Aided Channel Tracking for OFDM
- This contribution deals with the problem of tracking a frequency-selective channel for OFDM systems, where the data is protected by a powerful error-correcting code. This paper presents an EM-based receiver, operating on a single OFDM symbol at a time, that iterates between channel estimation and data detection. The channel estimator...
- Tags: Channel, Channel Estimator, Estimator, OFDM, Wireless
- White papers
- Design of IRA Codes for Non-Coherent Detection With OFDM
- Irregular Repeat Accumulate IRA codes are a special class Of Low-Density Parity-Check LDPC codes which perform very close to capacity for memory-less channels with coherent detection. Further, they can be encoded and decoded in linear-time. This paper considers the design of a non-coherent Orthogonal Frequency-Division Multiplexing OFDM system for block...
- Tags: Texas A&M University, OFDM, Wireless
- White papers
- Modulation-Index Estimation in a Combined CPM/OFDM Receiver
- The Software Defined Radio SDR project combines two different types of standards, Bluetooth and HiperLAN/2 on one flexible platform. The implemented part consists of the radio front-end of a receiver, so from antenna RF signal till and including demodulation raw bits. For this purpose, a CMOS wide band analog front-end...
- Tags: Intel Pentium 4, Processors, Semiconductors, Hardware, Components
- White papers
- OFDM Power Loading Using Limited Feedback
- Orthogonal Frequency Division Multiplexing OFDM is a practical broadband signaling technique for use in multipath fading channels. The implementation of power loading, however, is dependent on the presence of complete forward link channel knowledge at the transmitter. In systems using Frequency Division Duplexing FDD, this assumption is unrealistic. This paper...
- Tags: Transmitter, OFDM, Wireless
- White papers 2005-09-01
- Efficient Detection of Zero-Padded OFDM Signals With Large Blocks
- This paper presents a frequency-domain receiver for ZP-OFDM schemes (Zero-Padded Orthogonal Frequency Division Multiplexing) where the duration of the channel impulse response is a significant fraction of the duration of the OFDM block. The proposed receiver has a relatively low complexity, allowing an FFT-based Fast Fourier Transform implementation. The proposed...
- Tags: Block, Receiver, OFDM, Wireless
- White papers 2006-10-10
- Asymptotic Analysis of the Conventional Decision Feedback Receiver in Flat Fading Channels
- Spectral efficiency presents the ultimate limit on the data rate per unit bandwidth of a certain communication system. For the DS-CDMA systems spectral efficiency has been derived for optimal and linear multiuser receivers in case of synchronous reception, fading and non-fading environment as well as single and multi-cell cellular networks....
- Tags: Channel, Efficiency, Analysis
- White papers
- Iterative Interference Cancellation and Channel Estimation for Mobile OFDM
- In mobile reception, the reliability of Orthogonal Frequency Division Multiplexing OFDM is limited because of the time-varying nature of the channel. This causes InterCarrier Interference ICI and increases inaccuracies in channel tracking. This paper models the ICI using derivatives of the channel amplitude. This allows the authors to design a...
- Tags: Mobile, IEEE, Advertising & Promotion, OFDM, Marketing, Wireless
- White papers 2005-01-01
- On the Capacity of Noncoherent Wideband MIMO-OFDM Systems
- In this paper the capacity behavior of full-band MIMO-OFDM systems in the absence of channel state information both at the transmitter and the receiver is studied. Based on capacity lower and upper bounds, the transmission rate penalty due to channel uncertainty as a function of the number of transmit antennas,...
- Tags: ETH Zurich, Workforce Management, Human Resources
- White papers 2005-06-23
- Generalized 8-PSK for Totally Blind Channel Estimation in OFDM
- Channel estimation in OFDM systems can conveniently be done by inserting a stream of pilot symbols at the transmitter and by using FIR interpolation filters at the receiver. Most blind channel estimation approaches are based on higher order statistics and converge slowly, making them unsuitable for mobile environments. Moreover, the...
- Tags: Channel Estimation, OFDM, Wireless
- White papers
- Pilot-Tone Based ZP-OFDM Demodulation for an Underwater Acoustic Channel
- Existing coherent underwater acoustic communication systems rely on single carrier transmission and adaptive decision feedback equalization to deal with time-varying and highly dispersive UnderWater Acoustic UWA channels. Equalization complexity prevents any substantial rate improvement with the existing single-carrier approach, as the channel frequency selectivity increases considerably when the symbol rate...
- Tags: Channel, Equalization Complexity, OFDM, Wireless
- White papers 2006-07-26
- Design of a Multiband OFDM System for Realistic UWB Channel Environments
- There are many differences between real-world behavior of narrow-band and UWB systems. All wireless systems must be able to deal with the challenges of operating over a multipath propagation channel, where objects in the environment can cause multiple reflections to arrive at the receiver RX. For narrow-band systems, these reflections...
- Tags: UWB, Channel, Bandwidth, Environment, IEEE, Ultrawideband (UWB), Wireless
- White papers 2004-09-01
- RAKE Receiver
- RAKE receiver is used in CDMA-based Code Division Multiple Access systems and can combine multipath components, which are time-delayed versions of the original signal transmission. Combining is done in order to improve the signal to noise ration at the receiver. RAKE receiver attempts to collect the time-shifted versions of the...
- Tags: W-CDMA, TeliaSonera, CDMA, Cellular Phones, Consumer Electronics, Personal Technology
- White papers 2004-12-07
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