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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TL;DR: The complexity analysis and simulation results show that the FD approach is effective for high data-rate transmission and in the presence of many data flows, whereas RAKE is more suitable in low-data-rate systems transmitting few data flows.
Abstract: In this paper, we compare the performance of two different communication techniques for impulse radio ultra- wide-band (UWB) systems, which resort to impulsive modulations. These techniques can be applied in a short-range scenario where a central node synchronously communicates with several peripheral nodes. The first one is based on the pulse repetition according to the spreading factor value, whereas the second one relies on the cyclic prefix insertion and the detection in the frequency domain (FD). Since both techniques cause a throughput loss, they have to be compared both in terms of the performance and the maximum data rate that is afforded. An indoor scenario is considered, in which either low- or high-data-rate flows are synchronously transmitted by a central node in the presence of variable system loads. Lastly, alternative detection strategies are also taken into account, which are based on the partial knowledge of the channel parameters. The complexity analysis and simulation results show that the FD approach is effective for high data-rate transmission and in the presence of many data flows, whereas RAKE is more suitable in low-data-rate systems transmitting few data flows.
1 citations
Cites background or methods from "Frequency domain equalization for s..."
...[20], has been applied to single-user [21] and multiuser [22] direct sequence (DS) UWB, and to single-user [23] and multiuser [24], [25] IR-UWB....
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...Recently, FD equalization, which has been previously proposed and studied for a single-carrier single-user environment [20], has been considered for short-range IR communications [23], [24]....
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28 Sep 2005
TL;DR: A novel system based on layered space-time architecture and block spreading method is proposed in this paper, in order to enhance the system performance.
Abstract: In this paper, we propose a single-carrier block spread CDMA for multiple transmit and receive antennas. The spreading process is what differentiate the proposed scheme from conventional CDMA systems. Traditionally, symbol spread- ing and despreading lead to chip-wise processing. Here, block spreading and despreading lead to symbol-wise processing which reduces the receiver complexity considerably. A novel system based on layered space-time architecture and block spreading method is proposed in this paper, in order to enhance the system performance. The proposed system is studied extensively under different channel conditions and is compared against conventional single-carrier and multicarrier systems.
1 citations
Cites methods from "Frequency domain equalization for s..."
...In this context, single-carrier (SC) with frequency-domain equalization (FDE) was proposed in [3][4] with performance comparable to OFDM-based system....
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Journal Article•
TL;DR: It is confirmed that the SC-FDE contract will not be extended to include SSB.
Abstract: あらまし 従来のアナログ波形伝送では信号の帯域幅が狭いため,周波数非選択性フェージングチャネルにより 受信信号電力が長時間低下して伝送品質が劣化してしまう場合がある.そこで筆者らは最近,その伝送品質を向上 できる,周波数領域等化を用いるアナログシングルキャリア伝送(アナログ SC-FDE)を提案した.アナログ SC-FDE では送信機においてアナログ信号をサンプリングした後,離散フーリエ変換(DFT),スペクトル整形,周波数マッ ピング,逆 DFT(IDFT),サイクリックプレフィックス(CP)の挿入を行って信号を送信する.受信側では FDE を適用 することにより伝送特性が大幅に改善できることを示した.ところで,アナログ波形伝送の場合は信号スペクトル の半分を伝送するだけでも信号を復調できる(単側波帯(SSB)伝送).本稿では,アナログ SC-FDE を用いる SSB 伝送 を提案し,正規化平均二乗誤差(NMSE)特性を計算機シミュレーションにより求め,従来の SSB 伝送より NMSE 特 性を大幅に改善できることを示す. キーワード アナログ波形伝送,周波数領域等化,シングルキャリア伝送,単側波帯波形伝送
1 citations
Additional excerpts
...そこで,筆者らが注目しているのはシン グルキャリア周波数領域等化 (SC-FDE)である [3]-[5]....
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TL;DR: The results show that the MMSE receiver achieves a remarkable performance, especially in the case of highly loaded high data-rate systems, and the proposed approach is well suited for high-throughput applications in indoor wireless environments where multipath propagation tends to increase the effects of the interference.
Abstract: We study the performance of an innovative communication scheme for ultra-wideband systems which are based on impulse radio in two different short-range communication scenarios: the proposed system relies on both the introduction of the cyclic prefix at the transmitter and the use of a frequency domain detector at the receiver. Two different detection strategies based either on the zero forcing (ZF) or on the minimum mean square error (MMSE) criteria have been investigated and compared with the classical RAKE, considering two scenarios where a base station transmits with a different data rate to several mobile terminals in an indoor environment characterized by severe multipath propagation. The results show that the MMSE receiver achieves a remarkable performance, especially in the case of highly loaded high data-rate systems. Hence, the proposed approach is well suited for high-throughput applications in indoor wireless environments where multipath propagation tends to increase the effects of the interference.
1 citations
Cites background or methods from "Frequency domain equalization for s..."
...In order to perform FDE [8], each block is extended by means of a cyclic prefix (CP) of length K , that is, the last K samples of the block are repeated at the beginning of the block....
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...Frequency domain equalization (FDE) [8], proposed and studied for a single-carrier single-user environment, is simply the frequency domain analog of conventional equalizer....
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...Channel equalization in the frequency domain [8] is a possible solution to the IPI which is caused by the autocorrelation functions of the time-hopping sequences....
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...Channel impairments due to severe multipath propagation can be effectively faced by the FDE approach which proves to be computationally simpler than the corresponding time domain processing....
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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