Multi-antenna Solutions Research Articles

Dynamic Spectrum Management for 5G

The articles in this special section focus on dynamic spectrum management for fifth generation (5G) communications which is expected to continue strong growth in the near future. In the last decade global mobile data traffic has approximately doubled each year, growth that is projected to continue unabated, due mainly to the introduction of new services and features specified by standards bodies. Thus, the wireless industry is asked to fulfill an increase in mobile data demand by a factor of 1000, which is one of the most challenging requirements that the 5G system design has to address. There are various opportunities to enhance the network capacity, for example, by exploiting advanced receiver techniques, novel cooperative multipoint transmissions schemes, innovative multi-antenna solutions, and finally, an effective and broad deployment of heterogeneous networks. Unfortunately, these foreseen technical innovations on small cells and macrocells seem insufficient to reach the 1000 target. One of the key enablers that can allow supporting the required data traffic is to exploit additional bands, and to guarantee access to as much licensed and unlicensed spectrum as possible. Therefore, the wireless research community has to focus much more on enhanced, more effective, and also completely new spectrum management techniques.

Low-Cost Dual-Loop-Antenna System for Dual-WLAN-Band Access Points

A low-cost, printed three-antenna system suitable to be embedded inside a wireless access point (AP) for multiple-input multiple-output (MIMO) applications in the 2.4 and 5 GHz WLAN bands is presented. The antenna system comprises three circular dual-loop antennas occupying a moderate area and printed on the same layer of a circular antenna substrate. Each dual-loop antenna further includes a large outer loop and a small inner loop, both operating at one-wavelength resonant mode and sharing common antenna feeding and grounding. The antennas are set in a sequential, rotating arrangement on the substrate with an equal inclination angle of 120° to form a symmetrical multiantenna structure. The antenna substrate is further stacked above the system circuit board of an AP by a small distance. In this case the design can fully integrate the circuit board of the AP as an efficient reflector for loops into an internal multiantenna solution. The results showed that well port isolation were obtained together with high-gain and dual-polarized radiation characteristics over the 2.4 and 5 GHz bands. Details of a design prototype are described and discussed in this paper.

Printed, integrable, dipole-slot diversity-antenna system for compact, 5 GHz WLAN access point

A printed, diversity-antenna system embedded inside a compact, 5 GHz wireless local area network (WLAN) access point (AP) and integrated with the system printed circuit board (PCB) thereof is proposed. The antenna system comprises two closely packed antennas: one dipole and one open slot, which form into a hybrid of dipole and slot antennas. The antennas occupy a small size of 12.5 × 27 mm2 and are etched on an inexpensive FR4 antenna substrate, which is situated above the AP system PCB by an air separation of distance 6.4 mm. In this case, the design makes use of the ground plane of the system PCB as an efficient reflector for both antennas and integrates the system PCB into an internal multiantenna solution for wireless AP applications. The dipole and the slot antennas were also positioned in such a way that the radiation with polarization diversity can be realized. The results showed that good input matching with a reflection coefficient of −14 dB over the 5 GHz bands was obtained. High-gain and directional radiation patterns were also observed. © 2011 Wiley Periodicals, Inc. Microwave Opt Technol Lett 53:1087–1094, 2011; View this article online at wileyonlinelibrary.com. DOI 10.1002/mop.25911

LTE Advanced The 4G Mobile Broadband Technology

By the design and optimization of upcoming radio access techniques and a further evolution of the existing system, the Third Generation Partnership Project (3GPP) had laid down the foundations of the future Long Term Evolution (LTE) advanced standards-the 3GPP candidate for 4G. This paper offers an overview of the research work carried out to meet the requirements of 4G. The various technology components like wideband transmission and spectrum sharing, multiantenna solutions, coordinated multiple transmission/reception (CoMP) and relaying, introduced to meet the requirements for LTE Advanced systems, have been discussed.

Printed, multi-loop-antenna system integrated into a concurrent, dual-WLAN-band access point

A printed, planar multi-loop-antenna system having high-gain, quasi-dual-polarized radiation properties for concurrent, dual-band WLAN operation in the 2.4 and 5.2 GHz bands is presented. The multi-antenna design comprises four printed loop antennas arranged to be of a orthogonal configuration, printed on the same-layer of a 1.6-mm thick FR4 substrate, and one system PCB serving as an efficient reflector for the loops. The four antennas are set within the boundary of the PCB of the typical size for compact, outdoor access-point (AP) applications and stacked there above by a small distance. In this study, the design integrates the system PCB of an AP into an internal multi-antenna solution for compact outdoor APs. The results show that good input matching with 10-dB return loss over the 2.4 and 5.2 GHz bands can be attained. Directional radiation patterns with comparable Eθ and Eφ fields were also obtained. © 2010 Wiley Periodicals, Inc. Microwave Opt Technol Lett 53:317–322, 2011; View this article online at wileyonlinelibrary.com. DOI 10.1002/mop.25736

The Evolution of LTE towards IMT-Advanced

This paper provides a high-level overview of some technology components currently considered for the evolution of LTE, referred to as LTE-Advanced. First, a brief overview of LTE and some of its technologies are given and then the IMT-Advanced requirements are discussed. One of the targets with the evolution of LTE is to reach or seven surpass these requirements. The technology components considered for LTE-Advanced include extended spectrum flexibility to support up to 100MHz bandwidth, enhanced multi-antenna solutions with up to eight layer transmission in the downlink and up to four layer transmission in the uplink, coordinated multi-point transmission/reception, and the use of advanced repeaters/relaying.

Technical solutions for the 3G long-term evolution

Work has started in the 3GPP to define a long-term evolution for 3G, sometimes referred to as super-3G, which will stretch the performance of 3G technology, thereby meeting user expectations in a 10-year perspective and beyond. The fundamental targets of this evolution - to further reduce user and operator costs and to improve service provisioning - will be met through improved coverage and system capacity as well as increased data rates and reduced latency. This article presents promising technologies to fulfil these targets, including OFDM, multi-antenna solutions, evolved QoS and link layer concepts, and an evolved architecture. Furthermore, the results of a performance evaluation are presented, indicating that the requirements can indeed be reached using the proposed technologies.

Optimization of PIFA-IFA combination in handset antenna designs

As commercial needs have expanded the functions of the wireless cellular handsets, multiantenna development in one handset has become more and more common. This paper addresses a multiantenna solution for the wireless handset application. A planar inverted "F" antenna (PIFA) was designed as the main antenna of the handset to cover the 800 MHz band (824 MHz-894 MHz) and the 1900 MHz band (1850 MHz-1990 MHz). A side-mounted inverted "F" antenna (IFA) was designed as the 1575.42 MHz global positioning system (GPS) antenna. The location of the feed/ground pins of both antennas affected not only the total antenna efficiency, but also the polarization of the GPS IFA. The length of the GPS IFA affected the isolation between the two antennas and the specific absorption rate (SAR) of the PIFA at the 1900 MHz band. A three-dimensional efficiency measurement of the prototypes in both free space and against-head position will be presented. Measurement of SAR and its distribution will also be presented to demonstrate the impact of the IFA on the near field of the PIFA.