Yoshinori Nishiguchi

A design of single carrier based PHY for IEEE 802.15.3c standard

This paper proposes an air interface for ultra high-speed millimeter wave (60 GHz) systems which have been under standardization process at IEEE 802.15.3c: the proposed channel plan permits ease of portable device implementation employing the major crystal oscillator used in CDMA cellar phones. The proposed transmission modes offer much greater scalability, covering from several tens Mbps to over 4 Gbps. The proposed preamble employs Golay codes, providing sufficient robustness against wireless environment being subject to the characteristics of millimeter wave with reduced hardware complexity. Common mode is a novel technique to communicate with single carrier (SC) and OFDM camps with multi rates up to around 1.5 Gbps. This technique gives the proposed systems easy expandability from SC to OFDM or other SCs and vice versa.

Golay sequence aided channel estimation for millimeter-wave WPAN systems

In order to design a simple and highly accurate channel estimator for wireless personal area network systems, this paper proposes Golay sequence aided channel estimation. To evaluate the performance of proposed channel estimation, bit error rate performance of single-carrier transmission with frequency-domain equalization has been analyzed by computer simulation. When 8PSK modulation and Reed-Solomon coding RS(255, 239) as forward error correction are used, the proposed Golay sequence aided channel estimation works very well in millimeter-wave and non line-of-sight fading environments with a 1.8 dB degradation of Eb/N0 at 10-6 of bit error rate against the ideal channel estimation, which is practically acceptable. Moreover, comparing with Chu sequence aided channel estimation, the proposed Golay sequence aided channel estimation improves 0.4 dB of Eb/N0 at the bit error rate while achieving much less hardware than Chu sequence aided one, which is very important for mobile terminal applications.

Adjacent channel interference resistance of a multi-Gbps millimeter-wave WPAN system

This paper investigates the adjacent channel interference (ACI) resistance of a multi-Gbps single carrier wireless personal area network (WPAN) operating in the 60 GHz millimeter-wave band. The significance of performance degradation due to ACI is investigated corresponding to varying factors such as types of modulation and radio frequency (RF) hardware impairments. The level of modulation scheme is found to change the system resistance against ACI considerably. RF hardware impairments such as power amplifier (PA) non-linearity and phase-locked loop (PLL) phase noise are also major factors affecting ACI generation. The tolerable ACI for WPAN system design is defined as the ACI that causes 0.5 dB degradation in required signal to noise ratio (SNR) at bit error rate (BER)=10-6. It is found that for a system employing pi/2 binary phase shift keying (BPSK) with PA output backoff (OBO)=3 dB, ACI=13.5 dB causes 0.5 dB BER degradation. For systems employing quadrature phase shift keying (QPSK) modulation, the tolerable ACI with PA OBO=3 dB and 5 dB are observed at 9 dB and 15 dB, respectively. For modulation schemes with higher levels such as the 16-quadrature amplitude modulation (QAM) system with PA OBO=3 dB and 5 dB, the tolerable ACI of 1 dB and 5 dB are observed. Next, the maximum ACI resistance is defined as the tolerable ACI by the system before the BER performance degrades and saturates towards 0.5. The performance of pi/2-BPSK system with PA OBO=3 dB has maximum resistance against ACI up to 25 dB before the BER saturates towards 0.5. Similar performance can be observed in QPSK system, but with PA OBO increased to 5 dB. Systems with 16-QAM are found to saturate to BER=0.5 beyond ACI=10 dB. Additionally, the presence of PLL phase noise is found to severely compromise the system performance particularly those with higher modulation levels. ACI as low as 0 dB is found to cause error floor to 16-QAM systems.

Operation Range Estimation of Reed-Solomon Coded SC-FDE System in 60-GHz WPANs

60-GHz band is a popular choice of industry for next generation wireless personal area networks, which will enable data rates in the order of Gbps. Single-carrier frequency domain equalization (SC-FDE) systems are proposed to obtain such high data rates in low-power and low-cost consumer products. In this paper, we are suggesting to use simple zero- forcing equalization to reduce the complexity requirement. We test system performance through simulations and find associated range of the WPAN. Our simulations take into account non-line- of-sight (NLOS) multipath channel model, channel estimation errors and RF impairments of phase noise and power amplifier distortion, to obtain realistic results. Our results show zero- forcing equalization can be employed in applications robust to delay such as file transfer between PCs and peripherals up to 4 meters. This result encourages the usage of 60-GHz band in low-power devices such as cellular phones and cameras. For applications which are sensitive to delay such as video streaming, more complex MMSE equalizer is required.

Performance of Trellis-Coded-Modulation for a Multi-Gigabit Millimeter-Wave WPAN System in the Presence of Hardware Impairments

This paper proposes the employment of trelliscoded-modulation (TCM) to improve error performance and/or to increase system throughput in a multi-gigabit physical layer (PHY) design for millimeter-wave 60 GHz wireless personal area network (WPAN) systems. Hardware impairments such as the 60 GHz power amplifier (PA) non-linear distortion and the 60 GHz phase-locked loop (PLL) phase noise (PN) are considered in the system design. It is found that for residential environment, in the AWGN and line-of-sight (LOS) multipath channels, TCM with hard decision Viterbi decoding is able to offer coding gain of approximately 1.5 dB, and in the non-line-of-sight (NLOS) multipath channel, approximately 1.2 dB, compared with quadrature phase shift keying (QPSK). By considering non-linear distortion in the PA, bit error rate (BER) degradation of 0.8 dB is observed in LOS channel. As for NLOS channel, the same non-linear distortion causes error floor at BER=10 5. It is also observed that a maximum of 2-times improvement of the PHY throughput can be achieved by TCM in the NLOS environment. Additional gain of 0.8 dB can be obtained in NLOS channels by employing longer decoder traceback length (TBL) of 20 instead of 10.

A Feasible Frequency Domain Pre-Equalization Proposal Based on Cross Layer Design in 60GHz WPANs

The paper presents a feasible frequency domain pre-equalization (pre-FDE) proposal in order to reduce the number of frequency domain equalizer (FDE) in a piconet. The pre- equalization scheme based on the cross-layer design on both physical layer and MAC layer is proposed and investigated in millimeter-wave 60-GHz wireless personal area networks (WPANs). The physical structure is designed so that the mobile terminal is simplified without increasing circuit complexity in PNC. Based on the carefully designed physical structure, the MAC layer protocol is also proposed following IEEE 802.15.3c standard to successfully obtain the down-link channel from uplink. Both theoretical analysis and simulation results show that only one FDE is required in PNC instead of one FDE for each of devices and the pre-FDE scheme can furthermore achieve 2.5dB gain comparing to the SC-MMSE-FDE.