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Ultra-multi-level PAM-SSB-DFTs-OFDM (Single Side Band DFT spreading Orthogonal Frequency Division Multiplexing) was proposed as one of the attractive approaches to achieve higher spectrum efficiency since it has advantages of lower PAPR (Peak to Average Power Ratio) than OFDM and robustness against reference carrier phase error. However, BER performance degradation caused by reference amplitude error...
A flexible filter-bank is one of the key components to efficiently utilize non-contiguous unused spectrum on a secondary basis. As bandwidth of transmitted signals can vary according to vacant spectrum available for secondary use, it is necessary to reduce adjacent channel interference (ACI) as much as possible for efficient and flexible spectrum utilization. This paper proposes a novel overlap FFT...
Ultra multi-level modulation such as 1024/4096QAM can achieve higher spectrum efficiency of 10/12 bit/s/Hz than 8 bit/s/Hz achieved by 256QAM in current WLAN/LTE standards, however BER (Bit Error Rate) performance is significantly degraded due to very small reference phase error for coherent detection. This paper proposes ultra-multi-amplitude-level BPSK (Binary Phase Shift Keying) based SSB-DFTs-OFDM...
Spectrum occupancy rate (SOR) is an important parameter for spectrum utilization efficiency in terms of frequency and time. We have proposed a novel spectrum occupancy rate (SOR) measurement method based on least square error (LSE) estimation of Gaussian noise CDF (Cumulative Probability Distribution Function) to improve SOR measurement accuracy in low SNR conditions, and its validity has been confirmed...
In this paper, we design LM-MIMO system using high-order m-PSK modulation and evaluate performance of the system. As simulation results, we can confirm that LM-MIMO system with high-order m-PSK modulation has a similar performance to conventional MIMO system with a number of RF chains.
As link quality in 60GHz WLAN is significantly affected by moving human body shadowing, it is required to introduce shadowing countermeasures such as diversity and fast session transfer. For performance evaluation of these techniques in various environments, we need a deterministic shadowing model for ray-tracing simulations rather than a traditional empirical shadowing model based on experimental...
In previous work, we proposed a frequency cooperative automatic repeat request (FC-ARQ) scheme for multi-band WLAN using 60GHz and 2.4GHz, and evaluated the performance of the FC-ARQ scheme with the perfect received SNR estimation in terms of download time. In this paper, we present further performance evaluation; throughput performance under severe shadowing in 60GHz and download time in the presence...
This paper describes performance evaluation results of SSB (Single Side Band) transmission of DFTs-OFDM (Discrete Fourier Transform Spreading Orthogonal Frequency Division Multiplexing) using multi-level BPSK (Binary Phase Shift Keying) through nonlinear HPA (High Power Amplifier). SSB-DFTs-OFDM is generated by eliminating USB (Upper Side Band) or LSB (Lower Side Band) spectrum in frequency domain...
OFDM (Orthogonal Frequency Division Multiplexing) has been widely accepted in various wireless systems such as cellular systems and wireless LAN because of its robustness to frequency selective fading. However it has a drawback of large PAPR (Peak to Average Power Ratio) since it is a multi-carrier transmission scheme. In order to apply DFTs-OFDM (DFT spreading OFDM) for low PAPR, DC offset error...
Satellite and terrestrial integrated mobile communication systems (STICS) is proposed to construct economical and highly-reliable communication networks. One of the promising approaches to share the frequency spectrum in STICS is dynamic spectrum assignment, which dynamically divides the spectrum into two parts according to the traffic demand of terrestrial service and satellite service. As smaller...
Dynamic channel assignment is a promising solution for flexible and efficient spectrum utilization in a satellite/terrestrial integrated mobile communication system (STICS), that uses multi-beam satellite and share the frequency spectrum allocated to mobile satellite services with terrestrial mobile services. This paper proposes a location based centralized dynamic channel assignment with channel...
60GHz has been attracting significant attentions for ultra-broadband WLAN applications because 9GHz wide spectrum is available for unlicensed use on a world-wide basis. However, 60GHz has some drawbacks such as significant shadowing loss caused by a moving human body and large free space loss. To develop anti-shadowing techniques in 60GHz, it is required to characterize features of shadowing loss...
This paper proposes energy efficient RSSI(Received Signal Strength Indicator) based 60GHz WLAN(Wireless LAN) discovery for multi-band WLAN, which uses both 2.4/5GHz band and 60GHz band in order to achieve higher spectrum efficiency and power-saving of multi-band WLAN device. The proposed scheme detects 60GHz WLAN coverage by using RSSI of 2.4/5GHz WLAN signals where space and time diversity is employed...
This paper describes feasibility of RSSI (Received Signal Strength Indicator) based access network detection for multi-band WLAN (Wireless LAN) using 2.4/5GHz and 60GHz aiming at power-saving of multi-band WLAN device and higher spectrum efficiency. The proposed scheme detects 60GHz coverage by using 2.4/5GHz WLAN signals without using 60GHz WLAN signals for on/off control of 60GHz part of multi-band...
Satellite and terrestrial integrated mobile communication systems (STICS) is proposed to secure communications services anytime and anywhere. In the case of natural disasters or special event, it is required for satellite systems to allocate the frequency resources to a specific area as much as possible. Dynamic channel assignment is one of the attractive solutions to achieve the flexible and efficient...
A cyclostationarity based feature detection by calculating autocorrelation function for OFDM signal with cyclic prefix is proposed as a spectrum sensing scheme for dynamic spectrum access. However, this approach cannot be applied to single carrier modulation signals without cyclic prefix. This paper proposes a novel spectrum sensing scheme for single carrier modulation signals using clock timing extraction...
Cognitive radio based wireless systems using TV white space have been attracting a lot of attentions. In the cognitive radio systems using TV white space, it is desirable to secure a control channel to exchange the information on the availability of white space and the frequency resource such as the frequency channel and the bandwidth. In addition, it is necessary to secure minimum frequency resource...
An orthogonal polarization based MIMO transmission scheme is proposed to achieve over 10Gbps transmission for advanced 60GHz WLAN. As the proposed MIMO transmission scheme uses V(Vertical)/H(Horizontal) polarization directional antennas, stable 2X2 MIMO transmission is enabled even in LOS (line-of-sight) environment. A ray-tracing method is employed for computer simulation to evaluate channel capacity...
A periodogram scheme, a multi-taper scheme, and a filter-bank scheme are proposed for spectrum sensing for dynamic spectrum access. The filter-bank scheme is advantageous in hardware implementation since the hardware required for communications can be reused for spectrum sensing. However, it is difficult for the conventional filter-bank scheme to change the detection bandwidth, filter type and frequency...
In order to realize very high throughput wireless local area network (WLAN) systems, which demand multi Gbps capacities/bitrates, the IEEE802.11.TGad (Next generation WLAN standard at 60GHz band) is in the standardization process. To evaluate and select the proposed physical layer modulation and coding schemes in the standardization process, channel models for each specified usage model are required...
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