In big cities in Asia, a road pricing system is one of the effective solutions for traffic congestion. We have developed “Integrated Urban Road Pricing system” based on active DSRC communication proven in Japan. Our internal battery OBU (on-board unit) has contactless IC card interface able to accept the cards which circulate widely as a payment media in Asian countries. Wiring work is not needed for installation, and introduction of OBU is easy for users. By a trial in Malaysia for one year, our system has been operated in practical use without trouble as a road pricing system.
This paper presents a method for estimating the frequency of sampled sinusoidal signal. Firstly, the coarse estimate of frequency is obtained by discrete Fourier transform and then a reference signal is constructed with the estimated value. By conjugate multiplying the reference signal and the original signal, a new sinusoidal signal is obtained. Through superimposing the new signal sequence, the Signal-to-Noise ratio (SNR) is improved. When SNR»1, the additive noise can be considered as an equivalent phase noise. Based on the designed optimal superimposition, the frequency of the new signal can be obtained by Least-Square estimation. Theoretical analysis and simulation results show the performance of proposed method is closed to the Cramer-Rao bound with low complexity.
The decomposition of continuous phase modulation (CPM) signals into a set of PAM waveforms is a very effective approach to reduce the receiver complexity. Recently, CPM signals using rectangular frequency shaping (FS) pulses having the so-called separable phase (SP) property can be reformulated as a compactor connected with an equivalent CPFSK scheme, and was proved to have minimal number of PAM waveforms among the existing PAM approaches. In this letter, we propose a new class of phase separable CPM schemes, which is extended from our previous work. Here FS pulses are constructed by using two-steps overlapping phase separable rectangular pulses. We show that the number of PAM waveforms required to represent this new class of CPM signals can be reduced up to 75 percent compared with other PAM decomposition approaches.
We propose a simple transmission mode switching scheme for an access point of the last mile wireless network in a hybrid wireless optical access network. This scheme includes the criteria for switching WLAN transmission mode of an IPTV multicast session to take advantage of two transmission modes: unicast and multicast. In addition, the multicast PHY rate adaptation scheme is proposed to maintain the frame delivery failure rate of multicast frames within bounds. We implemented and evaluated the proposed scheme on a real hybrid optical network testbed and verified the feasibility of the scheme.
In this letter, the bistatic Multiple-Input Multiple-Output radar with non circular signal is considered, and a novel non circular Unitary ESPRIT-MUSIC algorithm for the joint direction of departure (DOD) and direction of arrival (DOA) is presented. Firstly, the properties of the non circular signals are utilized to extend the received data, which corresponds to double elements of MIMO virtual array. Then the complex valued data matrix can be converted into a real valued matrix by Unitary transformation, and the DODs and DOAs can be estimated by Unitary ESPRIT and Unitary Root-MUSIC, respectively. The proposed method can provide better angle estimation performance and handle more targets than Unitary ESPRIT-MUSIC. Some simulation results are used to show the performance of the proposed method.
This paper clarifies the Electromagnetic Interference (EMI) with medical devices from mobile phones that use high-speed radio access technologies including those in Release 8 specified by the 3rd Generation Partnership Project (3GPP) in a hospital environment. The Single Carrier Frequency Division Multiple Access (SC-FDMA) technique used in Release 8 has a higher Peak to Average Power Ratio (PAPR) than previous techniques such as Wideband Code Division Multiple Access (W-CDMA), and it may incur higher levels of EMI. The EMI is evaluated with respect to 32 medical devices that are typically used in hospitals. The evaluation results show that effect of increasing PAPR is not found significantly. The EMI strongly depends on the average transmission power of mobile phones. The maximum EMI distance is 80 and 8cm when the average transmission power is the nominal maximum (23 or 24dBm) and 10dBm, respectively.
The 1+1 protection provides instantaneous receiver-initiated recovery from any single link failure by using at least double network resources. This letter presents an Integer Quadratic Programming (IQP) model to determine an optimum set of routes that minimizes the required network resources for 1+1 protection using the network coding (NC) technique while maintaining the capability of instantaneous recovery. The cost obtained from our developed IQP model is compared with that of the conventional minimal-cost routing policy, where both approaches include the NC effect. Numerical results show that the IQP model achieves almost double resource saving effect in our examined networks.
Electric vehicles and hybrid vehicles have been popularized in recent years. In such a vehicle, an inverter circuit which converts a direct current to an alternating current is mounted. Due to the noise from the inverter, reception quality of AM radio is deteriorated. This paper proposes a novel noise cancellation system composed of a noise sensor and an adaptive filter which is controlled based on PI (Power Inversion) algorithm. Numerical results show that the inverter noises can be reduced by the proposed system.