Leaky coaxial cable (LCX) is applied broadly for many application scenarios because it can be utilized as antenna for user localization, wireless power transfer (WPT) and wireless coverage. Usually, one LCX can be used as one antenna, and therefore more cables are required for the configuration of an multiple-input and multiple-output (MIMO) system. This paper will provide a simple design that a 4-by-4 MIMO channel can be realized with one composite cable. Therefore the proposal can release the space limitation for MIMO deployment. The results show that, over 5~GHz frequency band, even though the distance between two V-type LCXs is 2 cm, the proposed 4-by-4 LCX-MIMO can have good channel condition which ensures the proposed composite cable can be made as a finer one. In addition, using user's position information (PI), we propose a simple power allocation scheme for the proposed LCX-MIMO system. Compared with the allocation method of equal power, the proposed method using PI can largely improve its capacity with the same level of computational complexity and without requirement of the feedback of channel status information (CSI).

In automotive infotainment systems, vehicles using the applications are serviced via continuous infrastructure-to-vehicle (I2V) communications. Additionally, the I2V communications can be combined with vehicle-to-vehicle (V2V) connectivity owing to the small area covered by road side units (RSUs). However, tens of vehicles have to compete for limited bandwidth when they request service simultaneously in the covered area. In this paper, we propose a joint scheduling and power control scheme for I2V and V2V links in the RSU' coverage range. Mapping the I2V and V2V links to tuple-links, we formulate a mixed-integer nonlinear programming (MINLP) problem where frequency scheduler and power controller for those tuple-links are jointly designed. Then, we employ the delayed column generation technique and the transmission pattern definition to decompose the MINLP problem into a transmission pattern scheduling problem, as well as a power control problem. Therein, the transmission pattern scheduling problem is solved by linear programming while a greedy power control algorithm is developed. Simulation results with practical parameter settings show that our proposed scheme outperforms several conventional schemes in terms of service disruption and achieved throughput while maintaining throughput fairness among the requesting vehicles. In particular, a high channel number, a small power level number, and a large buffer size at the requesting vehicles are shown to be helpful for our proposed scheme.

Electronically steerable parasitic array radiator (ESPAR) antenna is a novel low-cost technique to gain comparable diversity order to that of using multiple antennas while maintaining one radio frequency (RF) front-end, low power consumption, and simple wiring at the mobile receiver. It has huge potential to realize high energy efficiency for multiple and massive antennas systems. The main drawback of the ESPAR based OFDM system is that the channel estimation (CE) usually should be realized in time-domain with a huge computational complexity (CC) because the received signal to each parasitic element is overlapped each other both in frequency and time domain. This article will propose three ways to reduce the complexity of CE for the ESPAR-OFDM system. The parallel multi-column compressive sensing (CS) algorithm was first introduced to detect all locations of channel impulse response simultaneously using one small segment of sensing matrix. Furthermore, by exploiting the symmetrical properties of Digital Fourier transform (DFT), the size of matrix to decrease the CC of matrix operation. Finally, by selecting a small set of row vectors of sensing matrix at the receiver side, the CC involved in CS algorithm can be reduced. From the analysis and simulated results, the proposed method can obtain more than 90% CC reduction for CE of ESPAR-OFDM receiver can be confirmed.

This paper proposes an adaptive RF (radio frequency) front-end based handheld DTTB (Digital Terrestrial Television Broadcasting) receiver, which is capable of reducing average power consumption. Although OFDM (orthogonal frequency division multiplex), which is exploited as a physical layer transmission scheme of Japanese DTTB standard, ISDB-T (Integrated Services Digital Broadcasting for Terrestrial), requires the low NF (noise figure) and wide dynamic range LNA (low noise amplifier) at the first stage of RF (radio frequency) front-end circuit, it requires higher power consumption to design LNA with lower NF and wider dynamic range characteristics. On the other hand, the power consumption for handheld DTTB receiver is strictly limited due to its battery size. In order to reduce the power consumption, the proposed adaptive RF front-end uses two LNAs having different NF and power consumption characteristics. One of the LNAs gives lower NF but higher power consumption than the other one. In order to minimize the power consumption while maintaining the performance, the RF front-end chooses either one of the LNAs depending on the instantaneous BER (bit error rate) estimated from the modulation error ratio (MER), multipath delay spread, and maximum Doppler shift as well as the transmission mode and modulation format. Computer simulation result shows that the proposed adaptive RFfront-end is capable of reducing the power consumption in a multi-path fading environment.