Mari Ochiai

A Throughput Performance for a Point-to-Multipoint Gigabit WLAN System on 60 GHz Millimeter Wave

Increasing demand on the broadband wireless communication over Gigabits has focused renewed attention on 60 GHz millimeter wave. We developed a novel Point-to-Multipoint (P2MP) Gigabit WLAN System on 60 GHz millimeter wave. The proposed system employed wide angle beams antenna overcomes the usability of the conventional system, covers larger areas. Maximum transmission rate was designed to be 1.2 Gigabit/sec. Orthogonal frequency division multiplex (OFDM) using 1024 points FFT and convolutional code were implemented with PHY layer of the WLAN equipments. Superframe for multiple beams and frame aggregation for high throughput were designed for MAC layer. All control channels for downlink such as broadcast, frame control and access feedback were aggregated to reduce overhead in addition to aggregation of data frame. Evaluated throughput using proposed frame aggregation was confirmed to be more than 800 Mbit/sec with developed prototype in the case of aggregation size of 10 t1500byte.

On the Design of a Point-to-Multipoint Gigabit WLAN System on 60 GHz Millimeter Wave

Increasing demand on the broadband wireless communication over Gigabits has focused renewed attention on 60 GHz millimeter wave. We developed a novel Point-to-Multipoint (P2MP) Gigabit WLAN System on 60 GHz millimeter wave. The proposed system employed wide angle beams antenna overcomes the usability of the conventional system, covers larger areas. Maximum transmission rate was designed to be 1.2 Gigabit/sec. Orthogonal frequency division multiplex (OFDM) using 1024 points FFT, and convolutional code were implemented with PHY layer of the WLAN equipments. Superframe for multiple beams and frame aggregation for high throughput were designed for MAC layer. All control channels for downlink such as broadcast, frame control and access feedback were aggregated to reduce overhead in addition to aggregation of data frame. Maximum improvement of throughput due to control channel aggregation was evaluated to be 200 % compared with individual transmission. Evaluated throughput using proposed frame aggregation was confirmed to be more than 852 Mbit/sec in the case of aggregation size of 16 × 1500byte.

Non-coherent ToA estimation for UWB multipath channels using max-eigenvalue detection

Due to the fine delay resolution in ultra-wideband (UWB) wireless propagation channels, a large number of multipath components (MPC) can be resolved; and the first arriving MPC might not be the strongest one. This makes time-of-arrival (ToA) estimation, which essentially depends on determining the arrival time of the first MPC, highly challenging. In this paper, we consider non-coherent ToA estimation given a number of measurement trials, at moderate sampling rate and in the absence of knowledge of pulse shape. The proposed ToA estimation is based on detecting the presence of a signal in a moving time delay window, by using the largest eigenvalue of the sample covariance matrix of the signal in the window as the test statistic. We show that energy detection can be viewed as a special case of the eigenvalue detection. Max-eigenvalue detection (MED) generally has superior performance, due to the following reasons: 1) MED collects less noise, namely only the noise contained in the signal space, and 2) if multiple channel taps fall into the time window, the MED detector can collect energy from all of them. Simulation results confirm that MED outperforms the energy detection in IEEE 802.15.3a and 802.15.4a channels. Finally, the selection of the threshold of the MED is studied both by simulations and by random matrix theory.

Implementation of 324Mbit/sec WLAN equipment

We developed a high speed wireless LAN prototype in the 5 GHz band. The developed WLAN equipment had a data rate of 324 Mbit/sec using 6 PHY transmission channels of IEEE 802.11a. We presented the system of 324 Mbit/sec WLAN equipment focus on PHY layer using high grade FPGA devices. In this system, we proposed channels-interleave to improve characteristics of the equipment under multi-path environment. We confirmed that the effect of channels-interleave was about 2-4 dBm under a wireless condition of 324 Mbit/sec