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Next Generation Wireless Technologies
Published in K. R. Rao, Zoran S. Bojkovic, Bojan M. Bakmaz, Wireless Multimedia Communication Systems, 2017
K. R. Rao, Zoran S. Bojkovic, Bojan M. Bakmaz
In LTE-Advanced systems, the transmission bandwidth can be further extended up to 100 MHz, with the potential of achieving more than 1 Gb/s throughput for downlink and 500 Mb/s for uplink, through the support of a so-called carrier aggregation concept [62]. According to this solution, multiple component carriers are aggregated and jointly used for transmission to/from a single mobile terminal, as illustrated in Figure 1.7. In addition, it can be used to effectively support different component carrier types that may be deployed in heterogeneous environments. Carrier aggregation is attractive because it allows operators to deploy a system with extended bandwidth by aggregating several smaller component carriers while providing backward compatibility to legacy users.
Cellular Communications and Wireless Standards
Published in Mário Marques da Silva, Cable and Wireless Networks, 2018
4G aims to support the emergent multimedia and collaborative services, with the concept of any- where and anytime, facing the latest bandwidth demands. The LTE-A (standardized by 3GPP) consists of a 4G system. Based on LTE, the LTE-A presents an architecture using the all-over IP concept [Bhat et al. 2012]. The support for 100 Mbps in vehicular and 1 Gbps for nomadic access* and a latency lower than 5 ms is achieved with the following mechanisms: Carrier aggregation, composed of multiple bandwidth components (up to 20 MHz) in order to support transmission bandwidths of up to 100 MHz.Advanced antenna systems, increasing the number of downlink transmission layers to eight and uplink transmission layers to four. Moreover, LTE-A introduced the concept of multiuser MIMO, in addition to the single-user MIMO previously considered by the LTE.Multihop relay (adaptive relay, fixed relay stations, configurable cell sizes, hierarchical cell structures, etc.), in order to achieve a coverage improvement and/or an increased data rate.Advanced inter-cell interference cancellation (ICIC) schemes.Advanced BS cooperation, including macrodiversity.Multiresolution techniques (hierarchical constellations, MIMO systems, OFDMA multiple access technique, etc.).
3GPP LTE/LTE-Advanced Radio Access Technologies
Published in Jerry D. Gibson, Mobile Communications Handbook, 2017
The E-UTRA is designed to operate in the frequency bands defined in Table 24.2. The requirements were defined for 1.4, 3, 5, 10, 15, and 20 MHz bandwidth with a specific configuration in terms of number of resource blocks (see Table 24.2). Using carrier aggregation, a number of contiguous and/or noncontiguous frequency bands can be aggregated to create a virtually larger bandwidth.
Reconfigurable Microstrip Patch Antenna with Switchable Polarization
Published in IETE Journal of Research, 2020
Rajesh K. Singh, Ananjan Basu, Shiban K. Koul
Polarization diversity in an antenna system has received much attention in the current wireless communication systems. A microstrip patch antenna is attractive to get polarization switching because of light weight, low profile, and simple fabrication properties. The antenna with switchable polarization is capable to double the system capacity in communication systems by using frequency reuse concept. Circular polarization (CP) can be obtained by introducing some perturbation into the patch element. For obtaining CP, two orthogonal modes must be excited with equal amplitude and 90° phase shift between them. In [1,2,4] and [5], the two orthogonal modes were obtained by truncating two corners of the radiator which were placed diagonally. To get impedance matching in all three polarizations states (left-hand circular polarization (LHCP), linear polarization (LP), and right-hand circular polarization (RHCP)) is difficult because of the change in the antenna structure. In [3], polarization switching among LP or CP has been achieved by using two switches. Polarization switching between LHCP and RHCP has been obtained by truncating two corners of the patch [6]. In this paper, a novel reconfigurable microstrip patch antenna with polarization diversity is presented. To obtain the polarization switching among LHCP, LP, and RHCP, two corners of the patch are cut off and small parasitic patches are connected at truncated corners by using two PIN diodes. PIN diode switches are used to control the radiation from the patch element. One corner of the antenna is truncated to get CP, occurred a slight change in the physical dimension of the patch and hence the shift in the resonance frequencies is less among all three polarization states. The proposed antenna is having a simple structure; it can be easily translated to the other frequencies as per the requirement. The impedance matching in different polarization states is achieved in the circuit by optimizing the design parameters. In the current advanced technologies like LTE and 5G, there is a need for large bandwidth in the operating band. In carrier aggregation, a device can transmit or receive on various channels simultaneously for increased data rate. The used channels can exist within the same frequency band (intraband CA). The large bandwidths are required in the band to allow more channels. The impedance bandwidth (IMBW) and axial ratio bandwidth (ARBW) are enhanced by changing the shape of the truncated corners. The proposed antennas are designed in CST Microwave Studio [8], fabricated, and tested. The measured results are agreed with the simulated results in all three polarization states. The proposed reconfigurable antenna is also tested at high RF power. Since diode is a non-linear device; it plays a role at high RF power in the system. In this paper, the performance of the circuit is also tested by using high-power handling switches and increased the range of transmission.