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ABSTRACT: For high-speed packet access, hybrid automatic repeat request (HARQ) and multiple-input multiple-output (MIMO) multiplexing are indispensable techniques. As the multiple-access technique, single carrier (SC)-frequency-division multiple-access (FDMA) using transmit filtering is promising. The use of square root Nyquist transmit filter reduces peak-to-average power ratio (PAPR) of the transmit SC-FDMA signal and increases the frequency diversity gain. However, if the carrier-frequency separation among multiple-access users is kept the same as in the case of the transmit filter's roll-off factor α=0 (i.e., brick wall filter), the adjacent users' signal spectra overlap and the multi-user interference (MUI) is produced. In this paper, we propose an iterative minimum mean square error signal detection and interference cancellation (MMSED-IC) for turbo coded uplink SC FDMA MIMO using HARQ. In the proposed MMSED-IC, not only the inter-antenna interference (IAI) and residual inter-symbol interference (ISI) but also MUI are cancelled in an iterative fashion. We evaluate the HARQ throughput performances by computer simulation, and show that the use of roll-off factor α=1 achieves the highest throughput performance.
Communications (ICC), 2011 IEEE International Conference on; 07/2011
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ABSTRACT: QR decomposition with M-algorithm maximum likelihood detection (QRM-MLD) block signal detection can significantly improve the packet error rate (PER) performance of cyclic prefix-inserted single-carrier (CP-SC) multi-input multi-output (MIMO) spatial multiplexing when compared to the frequency-domain spatial filtering based on the minimum mean square error (MMSE) criterion. However, in order to achieve the sufficiently improved performance, the use of a fairly large number M of surviving paths in the M-algorithm is required because if smaller M is used, the probability of removing the correct path at early stages increases. In this paper, to reduce this probability, we proposed a training sequence-aided QRM-MLD block signal detection for SC MIMO spatial multiplexing. We show by computer simulation that training sequence-aided SC (TA-SC) MIMO spatial multiplexing using QRM-MLD block signal detection with M=16 can achieve the PER performance similar to CP-SC MIMO spatial multiplexing with M=1024 in the case of 16QAM and 4×4 MIMO spatial multiplexing.
Communications (ICC), 2011 IEEE International Conference on; 07/2011
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ABSTRACT: Network coding at the physical layer (PNC) can be used to improve the network capacity in a wireless channel. Broadband analog network coding (ANC) was introduced as a simpler implementation of PNC. The coherent detection and self-information removal in ANC require accurate channel state information (CSI). In this paper, we theoretically investigate an impact of the channel time-selectivity on the bit error rate (BER) performance of broadband ANC with practical channel estimation (CE) scheme using orthogonal frequency division multiplexing (OFDM). The achievable BER performance gains due to the first and second order polynomial time-domain channel interpolation are evaluated using derived close-form BER expressions.
Vehicular Technology Conference (VTC Spring), 2011 IEEE 73rd; 06/2011
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ABSTRACT: Uplink multi-user direct sequence-code division multi-access (DS-CDMA) suffers from strong multi-user interference (MUI) and self inter-chip interference (ICI) caused by severe frequency-selective fading. In this paper, we propose a joint Tx/iterative Rx frequency-domain equalization (FDE) based on minimum mean square error (MMSE) criterion and successive MUI cancellation (MUIC) for DS-CDMA uplink. In the proposed scheme, each user applies one-tap Tx FDE before transmitting signal. At the base station, joint one-tap Rx FDE and successive MUIC is iteratively performed. The FDE weights of users and base station are jointly optimized based on the MMSE criterion in order to reduce MUI and ICI while exploiting channel frequency-selectivity. Computer simulation results show that the proposed scheme provides much improved bit error rate (BER) performance than the conventional iterative Rx MMSE-FDE with successive MUIC.
Vehicular Technology Conference (VTC Spring), 2011 IEEE 73rd; 06/2011
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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).
Multi-Carrier Systems & Solutions (MC-SS), 2011 8th International Workshop on; 06/2011
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Wireless Communications and Mobile Computing 12/2010; 10(12):1537 - 1547. · 0.88 Impact Factor
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ABSTRACT: Broadcast nature of the wireless channel enables wireless communications to make use of network coding at the physical layer (PNC) to improve the network capacity. Recently, narrowband and later broadband wireless analog network coding (ANC) were introduced as a simpler implementation of PNC. The coherent detection and self-information removal in ANC require accurate channel state information (CSI). In this paper, we present the bit error rate (BER) performance analysis with imperfect CSI for broadband ANC using orthogonal frequency division multiplexing (OFDM). The effect of time-selectivity is also studied to investigate its effect on the BER performance. It is shown that the fading tracking is an important problem for self-information removal.
Communication Systems (ICCS), 2010 IEEE International Conference on; 12/2010
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ABSTRACT: Cooperative networking schemes provide spatial diversity gain (named cooperative diversity gain) using the antennas of spatially distributed users. Consistent research has been focusing on cooperative networks using orthogonal frequency division multiplexing (OFDM) and single carrier with frequency domain-equalization (SC-FDE). Coherent detection and frequency-domain equalization (FDE) require accurate channel estimation. In this paper, we present a performance comparison of cooperative OFDM relay network and cooperative SC-FDE relay network with pilot-assisted channel estimation. We consider a joint diversity combining and FDE in order to obtain a larger frequency diversity gain. When channel coding is used, cooperative OFDM relay network performs similarly to cooperative SC-FDE relay network in a frequency-selective fading channel.
Communication Systems (ICCS), 2010 IEEE International Conference on; 12/2010
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ABSTRACT: In the single-carrier (SC) transmission, minimum mean square error frequency-domain equalization (MMSE-FDE) can achieve a good bit error rate (BER) performance in a frequency-selective fading channel. The conventional FDE requires the insertion of cyclic prefix (CP) to make the received signal block to be a circular convolution of the transmit signal and the channel. Overlap FDE requires no CP insertion. However, its BER performance improvement is limited by the residual inter-block interference (IBI). In this paper, we present the theoretical analysis of the BER performance achievable with overlap FDE by taking into account the residual IBI after overlap FDE. Then, by using the Gaussian approximation of the residual IBI as well as the residual inter-symbol interference (ISI), we derive the conditional BER for the given set of the channel gains. The average BER performance is numerically evaluated.
Communication Systems (ICCS), 2010 IEEE International Conference on; 12/2010
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ABSTRACT: Frequency-domain filtered single carrier (SC)-FDMA signal has properties of reduced peak-to-average power ratio (PAPR) and increased frequency diversity gain. However, if the carrier-frequency separation is kept the same as in the case of the transmit filter roll-off factor α=0, the adjacent users' signal spectra overlap and the multi-user interference (MUI) is produced. In our previous work, we proposed an iterative joint single-user minimum mean square error frequency-domain equalization/successive MUI cancellation (called iterative joint MMSE-FDE/SMUIC), which performs iteratively a series of MMSE-FDE, spectrum combining, and SMUIC, for frequency-domain filtered SC-FDMA uplink. However, the residual ISI and MUI limit the BER performance improvement. In this paper, we replace the single-user MMSEFDE by an MMSE spatial filtering (MMSE-SF) and propose an iterative joint multi-user MMSE-SF/SMUIC (called iterative joint MMSE-SF/SMUIC). The achievable bit error rate (BER) and throughput performances are evaluated by computer simulation.
Communication Systems (ICCS), 2010 IEEE International Conference on; 12/2010
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ABSTRACT: Multi-user multi-input multi-output (multi-user MIMO) can increase the number of users simultaneously accessing the same base station (BS) without increasing the signal bandwidth. MIMO signal detection which can provide better bit error rate (BER) performance than linear detection with less computational complexity is indispensable in order to enhance the uplink cellular capacity of multi-user MIMO. Maximum likelihood detection (MLD) employing QR decomposition and M algorithm (QRM-MLD) is one of its candidates. It can reduce the complexity of MLD drastically and obtain BER performance close to MLD. QRM-MLD has been widely studied for MIMO spatial multiplexing using orthogonal frequency division multiplexing (OFDM). Recently, it has been reported that QRM-MLD can be applied to the signal detection of single-carrier (SC) transmission in a frequency selective fading channel. In this paper, we introduce the frequency-domain QRM-MLD block signal detection to the SC multi-user MIMO uplink of a cellular system and evaluate the uplink capacity. We show that QRM-MLD can obtain larger uplink cellular capacity compared to the minimum mean square error detection (MMSED) at the cost of the increased computational complexity, but with much less than MLD.
Network Infrastructure and Digital Content, 2010 2nd IEEE International Conference on; 10/2010
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ABSTRACT: In this paper, we propose a spectrum division & adaptive subcarrier allocation for cooperative amplify-and-forward (AF) relay using single carrier-frequency division multiple access (SC-FDMA). To obtain increased frequency diversity gain, the transmit SC signal spectrum is divided into sub-blocks, to each of which a different set of subcarriers (resource block) is adaptively allocated based on the each user's channel condition. The adaptive subcarrier allocation has a tradeoff between the channel capacity and the peak-to-average power ratio (PAPR). We evaluate the outage channel capacity of SC-FDMA using cooperative AF relay and discuss such a tradeoff relationship. Simulation results show that the SC-FDMA using the proposed spectrum division & the adaptive subcarrier allocation can achieve the similar capacity to the orthogonal frequency division multiple access (OFDMA) while keeping lower PAPR property.
Network Infrastructure and Digital Content, 2010 2nd IEEE International Conference on; 10/2010
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ABSTRACT: Multicode direct-sequence code division multiple access (DS-CDMA) can flexibly support multimedia services with various data rates simply by changing the code multiplexing order. The use of simple one-tap frequency-domain equalisation (FDE) at a receiver is known to improve the bit error rate (BER) performance of multicode DS-CDMA in a severe frequency-selective fading environment. However, the BER performance improvement is limited due to the presence of the residual inter-chip interference (ICI). The authors propose a joint transmit/receive minimum mean square error (MMSE) FDE, which carries out one-tap transmit FDE and one-tap receive FDE jointly based on the MMSE criterion. The authors theoretically derive a suboptimal set of transmit and receive FDE weights and investigate the BER performance improvement by computer simulation in a freqeuncy-selective Rayleigh fading channel. The proposed scheme improves the received signal-to-interference plus noise ratio after despreading, and consequently, the BER performance can be significantly improved compared to the conventioal receive MMSE-FDE by (a) making the variations in the equivalent channel gain shallower to reduce the residual ICI for large code multiplexing order U and (b) allocating the transmit power to the frequencies having good condition to improve the received signal-to-noise ratio for a small U . This is conformed by the computer simualtion.
IET Communications 10/2010; · 0.83 Impact Factor
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ABSTRACT: Recently, we proposed a joint iterative transmit/receive (Tx/Rx) minimum mean square error (MMSE) frequency-domain equalization (FDE) & inter-symbol interference (ISI) cancellation (ISIC) for single-carrier (SC) block transmissions. In this paper, we extend the previously proposed joint iterative Tx/Rx MMSE-FDE & ISIC to the SC hybrid automatic repeat request (HARQ) packet access to exploit the retransmission of the same packet for improving the throughput. We optimize the set of Tx/Rx MMSE-FDE weights by taking into account the packet retransmission/combining as well as ISIC. We show by computer simulation that the proposed scheme significantly improves the packet error rate (PER) and throughput performances in a severe frequency-selective fading channel.
Vehicular Technology Conference Fall (VTC 2010-Fall), 2010 IEEE 72nd; 10/2010
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ABSTRACT: The peak-to-average power ratio (PAPR) of Nyquist filtered broadband single carrier (SC)-FDMA signals can be reduced by increasing the filter roll-off factor α. Furthermore, an additional frequency diversity gain can be obtained by making use of the excess bandwidth introduced by the transmit filtering. However, if the carrier-frequency separation is kept the same as in the case of α=0, the adjacent users' signal spectra overlap with the desired users' spectrum and the multiuser interference (MUI) is produced. In this paper, in order to improve the transmission performance of uplink SC-FDMA using frequency-domain filtering, we propose two type of frequency-domain iterative MUI cancellation scheme which can achieve the frequency diversity gain through MMSE-FDE&spectrum combining. The achievable bit error rate (BER) and throughput performances are evaluated by computer simulation.
Vehicular Technology Conference Fall (VTC 2010-Fall), 2010 IEEE 72nd; 10/2010
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ABSTRACT: The frequency-domain filtered single-carrier (SC) signal transmission can achieve improved bit error rate (BER) performance due to additional frequency diversity gain while keeping a lower peak-to-average power ratio (PAPR) property than orthogonal frequency division multiplexing (OFDM). In this pa-per, we extend our recently proposed frequency-domain block signal detection (FDBD) with MLD employing QR decomposition and M-algorithm (QRM-MLD) to the frequency-domain filtered SC block transmissions. QR decomposition is applied to a concatenation of the transmit filter, propagation channel, and discrete Fourier transform (DFT). We evaluate BER and throughput performances by computer simulation. From performance evaluation, we discuss how the filter roll-off factor affects the achievable BER and throughput performances and show that as the filter roll-off factor increases, the required number of surviving symbol-candidates in the M-algorithm can be reduced.
Vehicular Technology Conference Fall (VTC 2010-Fall), 2010 IEEE 72nd; 10/2010
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ABSTRACT: In cellular systems, multi-user multi-input multi-output (MIMO) multiplexing can increase the number of simultaneous users per cell; however co-channel interference (CCI) from other cells limits the number of users/cell (defined as the cellular capacity). The well-known zero-forcing detection (ZFD) and minimum mean square error detection (MMSED) are computationally efficient detection methods, but their diversity order decreases as the number of users increases. The multi-user signal detection method which has the full diversity order and less complexity is required in order to enhance the cellular capacity. In this paper, we introduce the lattice reduction (LR) aided ZFD and MMSED to the uplink multi-user MIMO using orthogonal frequency division multiplexing (OFDM) and investigate the uplink cellular capacity. LR using Lenstra-Lenstra-Lovasz (LLL) algorithm is a promising technique to improve the performance of ZFD and MMSED. We show that LR aided ZFD and MMSED can obtain larger uplink capacity than conventional ZFD and MMSED at the cost of relatively low increase of computational complexity.
Vehicular Technology Conference Fall (VTC 2010-Fall), 2010 IEEE 72nd; 10/2010
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ABSTRACT: In this paper, a 2-dimensional water-filling (2D-WF) based transmit weight that maximizes the channel capacity is theoretically derived for the downlink transmit diversity of single-carrier distributed antenna network (SC DAN) in a frequency-selective channel. The 2D-WF transmit weight allocates the transmit power in both transmit antenna dimension and frequency dimension: power allocation across frequencies based on WF theory and across transmit antennas based on maximal ratio transmission (MRT). The cumulative distribution function (CDF) of the achievable channel capacity by 2D-WF transmit diversity is evaluated by the Monte-Carlo numerical computation method. Channel capacities achievable with 2D-WF, MRT, and 1D WF transmit weight are compared. It is shown that the 2D-WF transmit weight provides the highest channel capacity among three transmit weights.
Vehicular Technology Conference (VTC 2010-Spring), 2010 IEEE 71st; 06/2010
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ABSTRACT: Frequency-domain equalization (FDE) based on minimum mean square error (MMSE) criterion is a promising equalization technique for the broadband single-carrier (SC) transmission. However, the presence of timing offset produces the inter-symbol interference (ISI) and degrades the bit error rate (BER) performance. As the roll-off factor of the transmit filter increases, the performance degradation gets larger. In this paper, we propose joint MMSE-FDE & spectrum combining which can achieve the frequency diversity gain while suppressing the negative impact of timing offset for the SC transmission.
Vehicular Technology Conference (VTC 2010-Spring), 2010 IEEE 71st; 06/2010
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ABSTRACT: In this letter, we present the performance of broadband bi-directional transmission with analog network coding (ANC) in a frequency-selective fading channel. To cope with the channel frequency-selectivity we introduce the use of frequency domain equalization (FDE) with broadband ANC based on orthogonal frequency division multiplexing (OFDM) and single carrier (SC) radio access. We evaluate, by theory and computer simulation, the achievable bit error rate (BER) and ergodic capacity of bi-directional ANC scheme based on OFDM and SCFDE radio access in a frequency-selective fading channel. Our results show that SC-FDE achieves a better BER performance, but on the other hand, a lower ergodic capacity in comparison with OFDM in a frequency-selective fading channel. Through both analysis and computer simulation, our findings show that a drawback of ANC scheme is its lack of diversity combining at the destination, which causes a slightly lower ergodic capacity in comparison with cooperative relaying irrespective of radio access scheme.
IEEE Transactions on Wireless Communications 06/2010; · 2.59 Impact Factor
