Amnart Boonkajay

Performance evaluation of Low-PAPR transmit filter for single-carrier transmission

Single-carrier transmission is a promising transmission technique due to its low peak-to-average power ratio (PAPR) property compared to multicarrier transmission, and using frequency-domain equalization (FDE) at the receiving side also mitigate the adverse effect of channel frequency-selectivity. An introduction of transmit filter can improve the system performance in terms of either PAPR or error probability. In this paper, we focus on the transmit filter aiming to reduce PAPR by employing the minimization of variance of instantaneous transmit power. Filter roll-off factor is also considered in order to provide excess-bandwidth transmission. With a combination of an FDE and spectrum combining at the receiver, excess-bandwidth transmission inherits additional frequency diversity gain, and therefore improves error probability. Performance evaluation of the proposed filtering algorithm is done by computer simulation, while the PAPR and bit-error rate (BER) performance of proposed algorithm are compared with conventional square-root Nyquist filter.

Selective mapping for broadband single-carrier transmission using joint Tx/Rx MMSE-FDE

Joint transmit/receive frequency-domain equalization based on minimum mean-square error criterion (joint Tx/Rx MMSE-FDE) is a promising frequency-domain-based technique suppressing inter-symbol interference (ISI) in broadband single-carrier (SC) transmission. However, it changes the frequency-domain spectrum shape and hence increases the peak-to-average power ratio (PAPR) of transmit signal. In this paper, we introduce the selective mapping (SLM), which is typically used in orthogonal frequency division multiplexing (OFDM), to reduce PAPR of SC transmission using joint Tx/Rx MMSE-FDE. The SLM is applied to the frequency-domain SC signal after applying the transmit FDE (Tx-FDE) and prior to inverse fast Fourier transform (IFFT). It is shown, by computer simulation, that the SLM can reduce PAPR without significant effect on bit-error rate (BER). Performance of SLM is also evaluated in various phase-rotation sequence types, in both deterministic and random points of views, and number of candidates. Computational complexity of the proposed transmission scheme employing SLM algorithm is also discussed.

Frequency-domain single-carrier spread spectrum with joint FDE and spectrum combining

In this paper, a DFT-based frequency-domain spread spectrum (FDSS) technique for SC transmission is introduced. The transmitted data is initially transformed to frequency-domain signal by using DFT. Frequency-domain spreading can achieve large frequency diversity gain through joint frequency-domain equalization (FDE) and spectrum combining. Performance of the proposed FDSS is evaluated by computer simulation in aspects of bit-error rate (BER), peak-to-average power ratio (PAPR), and average throughput, and then compared to the conventional TDSS scheme with spreading sequence.

Selected mapping technique for reducing PAPR of single-carrier signals

Single-carrier transmission with frequency-domain equalization SC-FDE is widely known as a promising transmission technique providing low error probability with low peak-to-average power ratio PAPR of transmit signal. However, the low-PAPR property of SC-FDE cannot be maintained if multi-level data modulation is introduced. The low-PAPR property of SC-FDE can be maintained by applying transmit filtering with roll-off factor at the expense of spectrum efficiency. In this paper, we propose two types of selected mapping SLM to reduce the PAPR of SC-FDE transmit signal. The first SLM technique is conducted in the frequency domain, where the phase rotation is applied to subcarriers similar to the SLM technique for orthogonal frequency division multiplexing transmission. The second SLM technique is conducted in the time domain, where the phase rotation is applied directly to data-modulated symbol sequence. Computer simulation confirms that both SLM techniques are able to reduce the PAPR of SC-FDE signal without significant degradation of bit-error rate performance and spectrum efficiency. Copyright

A blind selected mapping technique for low-PAPR single-carrier signal transmission

Single-carrier (SC) signals have a low peak-to-average power ratio (PAPR) property. However, the PAPR becomes higher as the modulation level increases. We have recently proposed a frequency-domain selected mapping (FD-SLM) which can effectively reduce PAPR of SC signal with high modulation level, but standard SLM technique requires the transmission of side-information to the receiver side. In this paper, a new FD-SLM with minimum mean-square error (MMSE) based blind signal detection is proposed, where there is no change on SLM algorithm at the transmitter and no necessity of side-information transmission. Simulation results show that the proposed blind FD-SLM technique reduces the PAPR of SC signals without significant degradation of bit-error rate (BER) performance.

A Blind Polyphase Time-Domain Selected Mapping for Filtered Single-Carrier Signal Transmission

Single-carrier (SC) signal has a low peak-to-average power ratio (PAPR) property. However, the PAPR of SC signal increases if transmit filtering and/or high-level modulation are applied. We have recently proposed a time-domain selected mapping (TD-SLM) which effectively reduces the PAPR of filtered SC signals by applying the binary phase rotation before transmit filtering, but the necessity of side-information decreases the spectrum efficiency (SE). In this paper, a blind TD-SLM which does not require side-information is proposed. Unlike the frequency-domain SLM (FD-SLM) and the original TD-SLM with side-information, polyphase rotations are used. Performance evaluation of the proposed blind TD-SLM is done by computer simulation assuming turbo-coded filtered SC block signal transmission in aspects of PAPR and bit-error rate (BER) to show that no significant BER performance degradation is occurred.

Spectrum Efficient Single-Sideband Single-Carrier with Frequency-Domain Equalization

In this paper, a novel spectrum efficient single-sideband single-carrier (SC) with frequency-domain equalization (SSB-FDE) using amplitude shift keying (ASK) modulation (ASK SSB-FDE) is proposed. Similar to the conventional SC transmission with FDE (SC-FDE), the ASK modulated symbol block to be transmitted is transformed by discrete Fourier transform (DFT) into frequency-domain signal. Then, inverse DFT (IDFT) is applied to the upper (or lower) sideband spectrum to obtain the time-domain SSB signal block. The cyclic prefix (CP) inserted SSB signal block is transmitted over a frequency-selective fading channel. At a receiver, the minimum mean square error (MMSE) based FDE is applied. ASK SSB-FDE has lower peak-to-average power ratio (PAPR) and better throughput performance than QAM SC-FDE when the throughput is plotted as a function of peak transmit SNR. This is confirmed by computer simulation assuming a frequency-selective Rayleigh fading channel.

Low-PAPR joint transmit/received SC-FDE transmission using time-domain selected mapping

Transmit filtering, transmit equalization, precoding, or power allocation increases the peak-to-average power ratio (PAPR) of transmit single-carrier (SC) signal due to change in frequency-domain spectrum. Recently, we proposed a frequency-domain based selected mapping (FD-SLM) for suppressing the increased PAPR introduced by the transmit frequency-domain equalization (Tx-FDE). However, FD-SLM provides minor contribution when computational complexity is considered. In this paper, we are motivated by the fact that a “bad” arrangement of modulated symbols in a transmission block leads to high peak power, and propose a time-domain phase rotation called time-domain SLM (TD-SLM). PAPR and BER performances when using the proposed TD-SLM are evaluated by computer simulation and are compared to conventional joint Tx/Rx SC-FDE and joint Tx/Rx SC-FDE with FD-SLM.

Distributed MIMO network for 5G enhanced mobile broadband

One of important applications in 5G mobile communications is the enhanced mobile broadband (eMBB). A promising approach for achieving 5G eMBB under the limited radio bandwidth and energy is an introduction of a small-cell structured network. An advanced utilization of multi-input multi-output (MIMO) transmission is also another possible approach. First, the conceptual structure of distributed MIMO network is introduced. A number of distributed antennas (DAs) are deployed over a macro-cell area and they are connected to a macro-cell base station (MBS) via optical mobile fronthaul. Then, we present the recent advances in distributed MIMO cooperative transmission, i.e., space-time block coded transmit diversity (STBC-TD) for improving the link capacity of a macro-cell edge area, minimum mean square error multiuser multiplexing combined with singular value decomposition (MMSE-SVD) for increasing the sum capacity, and blind selective mapping (SLM) for reducing the transmit signal peak-to-average power ratio (PAPR).

Cooperative Distributed Antenna Transmissions

Distributed antenna small-cell network is a promising 5G network. In this paper, a comprehensive report of recent advance in the cooperative distributed antenna transmission (CDAT) is provided. Single-user space-time block coded transmit diversity (STBC-TD) and multi-user minimum mean square error filtering combined with singular value decomposition (MMSE-SVD) are presented. Also presented is blind selected mapping (blind SLM) which can suppress the peak-to-average signal power ratio (PAPR) and requires no side information transmission. The effectiveness of CDAT in the presence of co-channel interference (CCI) from adjacent macro- cells is confirmed by computer simulation.