Frequency domain equalization for single-carrier broadband wireless systems
TL;DR: This article surveys frequency domain equalization (FDE) applied to single-carrier (SC) modulation solutions and discusses similarities and differences of SC and OFDM systems and coexistence possibilities, and presents examples of SC-FDE performance capabilities.
Abstract: Broadband wireless access systems deployed in residential and business environments are likely to face hostile radio propagation environments, with multipath delay spread extending over tens or hundreds of bit intervals. Orthogonal frequency-division multiplex (OFDM) is a recognized multicarrier solution to combat the effects of such multipath conditions. This article surveys frequency domain equalization (FDE) applied to single-carrier (SC) modulation solutions. SC radio modems with frequency domain equalization have similar performance, efficiency, and low signal processing complexity advantages as OFDM, and in addition are less sensitive than OFDM to RF impairments such as power amplifier nonlinearities. We discuss similarities and differences of SC and OFDM systems and coexistence possibilities, and present examples of SC-FDE performance capabilities.
Citations
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03 May 2011
TL;DR: This paper considers a single-carrier MIMO and proposes a maximum likelihood block detection using recursive QR packet combing and M-algorithm called recursive QRM-MLBD, and shows it provides a better throughput performance than the conventional bit-level log likelihood ratio (LLR) packet combining.
Abstract: For achieving very high-speed and high quality packet transmission, the joint use of multi-input multi-output (MIMO) spatial multiplexing and hybrid automatic repeat request (HARQ) is very effective. The HARQ throughput depends on the packet combining scheme. In this paper, we consider a single-carrier (SC) MIMO and propose a maximum likelihood block detection using recursive QR packet combing and M-algorithm called recursive QRM-MLBD. We will show, by computer simulation, the recursive QR packet combing provides a better throughput performance than the conventional bit-level log likelihood ratio (LLR) packet combining. We also compare the achievable throughput performance of proposed recursive QRM-MLBD to that of the frequency-domain detection based on the minimum mean square error criterion (MMSED).
5 citations
Dissertation•
01 Jan 2008
TL;DR: This dissertation proposes an MIMO transmission scheme using STBC with adoptive subband adaptive array (SBAA) processing, where the received signal is converted into the frequency-domain and adaptive processing is done in each subband, and a novel construction of SBAA is introduced to process received signal based on STBC.
Abstract: Recently, many works have been accomplished on transmit diversity for a high-speed data transmission through the wireless channel. A Multiple Input Multiple Output (MIMO) system which employs multiple antennas at transmitter and receiver has been shown to be able to improve transmission data rate and capacity of the system. When the channel state information (CSI) is unknown at the transmitter, an multiple input single output (MISO) system combined with the transmit diversity of space time coding modulation known as space-time block coding (STBC) has taken a great attention. However, the performance of STBC is deteriorated under frequency selective fading due to inter symbol interference (ISI). An STBC employing tapped delay line adaptive array (STBC-TDLAA) is known as a solution for this problem since it utilizes the delayed signals to enhance the desired signal instead of excluding them as interferences. However, this method requires a large computational load compared to the conventional adaptive array system. In this dissertation, assuming the CSI is unknown at the transmitter, and at the receiver the CSI is exploited from pilot signal, we propose an MIMO transmission scheme using STBC with adoptive subband adaptive array (SBAA) processing, where the received signal is converted into the frequency-domain and adaptive processing is done in each subband. A novel construction of SBAA is introduced to process received signal based on STBC. In addition, to improve the performance of STBC-SBAA, single carrier cyclic prefix (CP) is also introduced. Simulation results demonstrate that the proposed scheme has a better performance compare to the conventional STBC, and has a better performance and less computational load compare to STBC-TDLAA. Furthermore, we extend the proposed method to uplink multi-user space-time block coding (STBC) code division multiple access (CDMA) over a frequency selective fading channel. The proposed scheme utilizes CDMA with STBC and a receive array antenna with SBAA processing at the receiver. The received signal is converted into the frequency domain before de-spreading and adaptive processing is performed in each subband for each user. In order to reduce the effect of ISI and multiple access interference (MAI), a novel SBAA construction is introduced to process STBC CDMA signals. To improve the performance of the proposed scheme, we evaluate STBC-SBAA using spreading codes cyclic prefix (CP). Simulation results demonstrate an improved performance of the proposed system for single and multiuser environments compared to the conventional techniques. Moreover, we also evaluate the STBC-SBAA for the multi-code multi-rate CDMA system. Finally, we present a modified spatio-temporal adaptive array for multiuser STBC (Modified STBC-STAA) transmission in frequency selective fading channel with the presence of co-channel interferences (CCIs). This method based on the transversal filter adaptive array performing the joint interference suppression and equalization to overcome the problem of one symbol delay, namely codes synchronization error. The Modified STBC-STAA can maximize the transmission efficiency by incorporating the receive signal component for both non-conjugated and the complex conjugated version of desired signal in the receive signal, which is not only dispersed in space, but also in the time. Furthermore, Modified STBC-STAA overcomes the multiuser timing errors by re-aligning the asynchronous multiuser signal to undergo the synchronous joint interference suppression and equalization. Simulation results show that both our proposed scheme has a better performance than the conventional STBC-STAA for frequency selective fading channel.
5 citations
Cites background from "Frequency domain equalization for s..."
...Many works have been proposed to overcome STBC transmission in frequency selective fading channel [62, 72, 73, 80, 91, 92]....
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...In particular, Time-Reversal STBC (TR-STBC) [62] and singlecarrier Frequency Domain Equalization (FDE) [72, 73, 80, 91, 92] have received the most attention....
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12 Jan 2021
TL;DR: In this article, the realization and evaluation of multi input multi output (MIMO) wireless system and fiber based sigma delta Radio-over-Fiber (∑Δ-RoF)based optical link as a front haul using 5G NR multiband signals.
Abstract: This paper introduces the realization and evaluation of multi input multi output (MIMO) wireless system and fiber based sigma delta Radio-over-Fiber (∑Δ-RoF)based optical link as a front haul using fifth generation (5G) new radio (NR) multiband signals. The proposed 5G NR signals comprise of 3 GHz flexible waveforms and 23 GHz-400 MHz bandwidth. The ∑Δ-RoF has been demonstrated by using 2nd order Sigma-Delta Modulation (SDM) with 5 km of Standard Single Mode Fiber. The EVM performance for the system meets the 3GPP Release 16. Furthermore, EVM performance for received optical power is evaluated up to 400 MHz bandwidth. It can be concluded that ∑Δ-RoF-MIMO system suits the required range of the 5G C-RAN fronthaul networks and can be a propitious candidate for future mobile haul applications.
5 citations
TL;DR: This paper focuses on the equalization applied in massive MIMO schemes, more specifically in two new low complexity receivers based on an iterative block decision feedback equalizer (IB-DFE) that avoid matrix inversion operation by replacing in the equalizer the feedforward part by an equal gain combiner or a maximum ratio combiner module.
Abstract: Massive multiple-input and multiple-output (MIMO) schemes involving several tens or even hundreds of antenna elements are pointed as one of the key technologies for 5G systems. However the huge capacity gains attainable by these schemes, are only possible with receivers able to cope with the frequency selective fading that may affect the signals. These systems can be combined with single-carrier with frequency domain equalization (SC-FDE) schemes to improve the power efficiency in uplink due to the low envelope fluctuations. However, when more antennas are involved in the communication link, channel matrix size grows and the complexity involved in equalization process can be an obstacle to power consumption and low latency. In this paper we will focus on the equalization applied in massive MIMO schemes, more specifically in two new low complexity receivers based on an iterative block decision feedback equalizer (IB-DFE) that avoid matrix inversion operation by replacing in the equalizer the feedforward part by an equal gain combiner (EGC) or a maximum ratio combiner (MRC) module.
5 citations
TL;DR: It is shown that, by extending the fast Fourier transform (FFT) block size, overlap FDE can achieve almost the same BER performance as SWCE with much less computational complexity than SWCE.
Abstract: Recently, overlap frequency-domain equalization (FDE) based on minimum mean square error (MMSE) criterion which requires no guard interval (GI) insertion was proposed for signal transmission using multi-code direct sequence code division multiple access (DS-CDMA) in a frequency-selective fading channel. Another promising equalization technique is time-domain sliding-window chip equalization (SWCE). In this paper, the bit error rate (BER) performances achievable with overlap FDE and SWCE are compared. It is shown that, by extending the fast Fourier transform (FFT) block size, overlap FDE can achieve almost the same BER performance as SWCE with much less computational complexity than SWCE.
5 citations
Additional excerpts
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References
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Book•
01 Jan 1986
TL;DR: In this paper, the authors propose a recursive least square adaptive filter (RLF) based on the Kalman filter, which is used as the unifying base for RLS Filters.
Abstract: Background and Overview. 1. Stochastic Processes and Models. 2. Wiener Filters. 3. Linear Prediction. 4. Method of Steepest Descent. 5. Least-Mean-Square Adaptive Filters. 6. Normalized Least-Mean-Square Adaptive Filters. 7. Transform-Domain and Sub-Band Adaptive Filters. 8. Method of Least Squares. 9. Recursive Least-Square Adaptive Filters. 10. Kalman Filters as the Unifying Bases for RLS Filters. 11. Square-Root Adaptive Filters. 12. Order-Recursive Adaptive Filters. 13. Finite-Precision Effects. 14. Tracking of Time-Varying Systems. 15. Adaptive Filters Using Infinite-Duration Impulse Response Structures. 16. Blind Deconvolution. 17. Back-Propagation Learning. Epilogue. Appendix A. Complex Variables. Appendix B. Differentiation with Respect to a Vector. Appendix C. Method of Lagrange Multipliers. Appendix D. Estimation Theory. Appendix E. Eigenanalysis. Appendix F. Rotations and Reflections. Appendix G. Complex Wishart Distribution. Glossary. Abbreviations. Principal Symbols. Bibliography. Index.
16,062 citations
"Frequency domain equalization for s..." refers methods in this paper
...Adaptation can be done with LMS (least mean square), RLS, or least squares minimization (LS) techniques, analogous to adaptation of time domain equalizers [Hay96], [Cla98]....
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...Overlap-save or overlap-add signal processing techniques could also be used to avoid the extra overhead of the cyclic prefix [Fer85], [Hay96]....
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TL;DR: The analysis and simulation of a technique for combating the effects of multipath propagation and cochannel interference on a narrow-band digital mobile channel using the discrete Fourier transform to orthogonally frequency multiplex many narrow subchannels, each signaling at a very low rate, into one high-rate channel is discussed.
Abstract: This paper discusses the analysis and simulation of a technique for combating the effects of multipath propagation and cochannel interference on a narrow-band digital mobile channel. This system uses the discrete Fourier transform to orthogonally frequency multiplex many narrow subchannels, each signaling at a very low rate, into one high-rate channel. When this technique is used with pilot-based correction, the effects of flat Rayleigh fading can be reduced significantly. An improvement in signal-to-interference ratio of 6 dB can be obtained over the bursty Rayleigh channel. In addition, with each subchannel signaling at a low rate, this technique can provide added protection against delay spread. To enhance the behavior of the technique in a heavily frequency-selective environment, interpolated pilots are used. A frequency offset reference scheme is employed for the pilots to improve protection against cochannel interference.
2,627 citations
"Frequency domain equalization for s..." refers background in this paper
...OFDM transmits multiple modulated subcarriers in parallel [ 1 ]....
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...Several variations of orthogonal frequency-division multiplexing (OFDM) have been proposed as effective anti-multipath techniques, primarily because of the favorable trade-off they offer between performance in severe multipath and signal processing complexity [ 1 ]....
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TL;DR: In this contribution the transmission of M-PSK and M-QAM modulated orthogonal frequency division multiplexed (OFDM) signals over an additive white Gaussian noise (AWGN) channel is considered and the degradation of the bit error rate is evaluated.
Abstract: In this contribution the transmission of M-PSK and M-QAM modulated orthogonal frequency division multiplexed (OFDM) signals over an additive white Gaussian noise (AWGN) channel is considered. The degradation of the bit error rate (BER), caused by the presence of carrier frequency offset and carrier phase noise is analytically evaluated. It is shown that for a given BER degradation, the values of the frequency offset and the linewidth of the carrier generator that are allowed for OFDM are orders of magnitude smaller than for single carrier systems carrying the same bit rate. >
1,816 citations
TL;DR: This correspondence describes the construction of complex codes of the form exp i \alpha_k whose discrete circular autocorrelations are zero for all nonzero lags.
Abstract: This correspondence describes the construction of complex codes of the form exp i \alpha_k whose discrete circular autocorrelations are zero for all nonzero lags. There is no restriction on code lengths.
1,624 citations