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Multiple antennas in conjunction with Multiple Input Multiple Output (MIMO) systems offer significant increases in capacity without increasing transmit power or spectrum and are becoming an integral part of all modern wireless communication systems. For example multiple antenna technology is already used in wireless communication systems such as in IEEE 802.11n, WiMAX and LTE. This paper reviews some...
The design of antennas for compact multiple-input multiple-output (MIMO) terminals is a challenging feat, due to the space constraint and the physical structure of the terminal. The space constraint forces the antennas to be closely spaced, which degrades MIMO performance due to high signal correlation and low antenna efficiency. Moreover, the terminals are equipped with ground planes which further...
In this paper, we investigate material perturbation as a means to introduce frequency reconfigurability into microstrip patch antennas (MPAs) and Multiple-Input Multiple-Output dielectric resonator antennas (MIMO DRAs). A detailed analysis via eigenvalue perturbation has been carried out to determine the optimal material perturbation placement for maximum frequency agility. The results obtained agree...
In this paper, a multiple-input-multiple-output (MIMO) for dual frequency band is proposed. Each antenna consists of two folded planar inverted F structure with slits and split ring resonator (SRR) cells on a ground plane. It is designed on a FR-4 substrate (relative permittivity = 4.4, height = 0.8 mm) using micro-strip technology. The size of the ground plane and each chip type planar inverted F...
This paper proposes an adaptive impedance control for MIMO (Multiple Input Multiple Output) antennas and evaluates its basic performance in a realistic environment of usage of the compact mobile device through a computer simulation modeled with a 3D antenna radiation pattern including the human body effect and MIMO propagation channel. The control method searches for a combination of variable capacitors...
In this paper, the design concept of the antenna for the portable devices is first discussed and then typical characteristics of FLA and a change of compact balanced antennas for portable devices are presented. Lastly, an L-shaped folded monopole antenna, which is considered to be a compact balanced antenna for portable devices, is newly proposed for multiple-input multiple-output (MIMO) system and...
This paper presents recent status and some technological issues for the development of human phantoms used for antenna designs from the above-mentioned two perspectives. Furthermore, as a new trend of phantom applications towards future wireless radios, MIMO over-the-air testing (MIMO-OTA) using a phantom and an arm waving dynamic phantom for the assessment of body area network (BAN) systems are briefly...
In this paper we analyze the performance of advanced OFDM packet scheduling techniques based on 3GPP UTRAN Long Term Evolution (LTE) framework for high velocity scenarios. Based on our previous investigations in system performance analysis, we demonstrate that packet scheduler being part of the whole radio resource management (RRM) process has a major impact on it. On the other hand high user velocities...
Emerging cooperative MIMO communication is a promising technology in improving communication quality for wireless sensor networks. However, the security problems inherent to cooperative communications also arise. In this paper we investigate the situation where some of the cooperative nodes are compromised and try to corrupt the communications by sending garbled signals. To combat the compromised...
Multiple-Input Multiple-Output (MIMO) communications have shown great promise in providing high spectral efficiency for wireless ad hoc networks. In this paper we study the problem of joint routing, scheduling, power control and bit rate selection in MIMO-based ad hoc network with the goal of maximizing the system throughput that satisfies a given end-to-end traffic demand. We formulate this cross-layer...
In this paper, we consider a slow-fading nt ×nr multiple-input multiple-output (MIMO) channel subjected to block fading. Reliability (in terms of achieved diversity order) and rate (in number of symbols transmitted per channel use) are of interest in such channels. We propose a new precoding scheme which achieves both full diversity (nt ×nrth order diversity) as well as full rate (nt symbols per channel...
A number of peak-to-average power ratio (PAPR) reduction techniques have been proposed for multiple-input multiple-output (MIMO) orthogonal frequency division multiplexing (OFDM) systems; however, most of them involve very high computational complexity and are not applicable to MIMO-OFDM systems with space frequency block coding (SFBC). In this paper, we propose a low-complexity PAPR reduction scheme...
A multi-cell hybrid channel state information (CSI) feedback scheme was proposed, which has an ideal nested hierarchical structure to support not only the advanced multi-cell MIMO precoding, but also the traditional single-cell single-user and multi-user precoding transmissions. A quantization scheme for the multi-cell hybrid CSI feedback was provided, using codebook based vector-quantization for...
In this paper, we propose a codebook construction method for multiple-input multiple-output (MIMO) beamforming systems operating under the per-antenna power constraint (PAPC). Under the PAPC which limits the individual power of each transmit antenna, it is known that only phase steering information is required to form the optimal beamforming vector at the transmitter. For systems with non-reciprocal...
A systematic scheme is proposed to facilitate arbitrary virtual channel (VC)-to-user mappings in space dimension, through multiple-input multiple-output physical layer multicasting. It is a divide-and-conquer strategy, which breaks down the VC-to-user mapping to manageable orthogonal sub-mappings, each represented in terms of a multicast antenna group (MAG). A generalized form of block diagonalization...
We consider a wireless communication scenario with K source-destination pairs communicating through several half-duplex amplify-and-forward relays. We design the relay beamforming matrices by minimizing the total power transmitted from all the relays subject to quality of service constraints on the received signal to interference-plus-noise ratio at each destination node. We propose a novel method...
Hierarchical femtocell architectures have become popular recently because of their potential to provide increased coverage and capacity in cellular systems. However, introduction of femtocells might reduce the overlay macrocell system performance due to increased interference caused to macrocel-lular users. With MIMO precoding, the Least Interference (LI) technique can be employed at the femtocellular...
This paper presents results from a novel OFDMA multi-cell mobile broadband system level simulator. The tool is used to statistically characterize uplink and downlink inter-cell interference. Without suitable interference management, multi-billion dollar networks can collapse under the strain of heavy traffic loads. Fully loaded interference studies cannot be performed on the network until it has been...
In this paper, we consider the adaptive power allocation in the MIMO cognitive network with limited feedback. It is well known that, with the view of guaranteeing the link quality of primary receiver (PRx), the transmit power of second transmitter (STx) is strictly constrained, resulting in that it is difficult to provides QoS guarantee to second receiver (SRx) in the fading channel. This paper focuses...
Uplink collaborative multiple-input-multiple-output (MIMO) processing among multiple base stations (BSs), also known as uplink multi-BS MIMO, is an effective way to solve the inter-cell interference in cellular systems. However, the significantly increased overhead on the backhaul network due to inter-BS information exchange has seriously restricted its application in practical systems with limited...
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