Wideband Code Division Multiple Access Research Articles

Numerical Modeling of Smartphones with WCDMA, LTE, and WLAN Bands for Epidemiological Studies

This paper presents the representative numerical modeling of smartphones with wideband code division multiple access (WCDMA), long-term evaluation (LTE), and wireless local area network (WLAN) bands for epidemiological studies. For this purpose, based on specific absorption rate (SAR) test reports for commercial smartphones released in South Korea from 2013 to 2019, we determined the smartphone size, frequency band categorization, antenna locations, and target 1-g peak-spatial SAR (psSAR) values for a specific anthropomorphic mannequin (SAM) phantom. Numerical results showed that the designed numerical smartphone models yielded good matching and radiation performance, and more importantly, their 1-g psSAR values were within ±16% of the target 1-g psSAR values.

Design of a Compact Dual-Band MIMO Antenna System with High-Diversity Gain Performance in Both Frequency Bands.

A compact four-element dual-band multiple-input and multiple-output (MIMO) antenna system is proposed to achieve high isolation and low channel capacity loss. The MIMO antenna was designed and optimized to cover the dual-frequency bands; the first frequency band is a wide band, and it covers the frequency range of 1550–2650 MHz, while the other frequency band covers the 3350–3650 MHz range. The measured wide-band impedance bandwidths of 1.1 GHz and 300 MHz were achieved in the lower and upper frequency bands, respectively. The proposed structure consists of four novel antenna elements, along with a plus-sign-shaped ground structure on an FR4 substrate. The overall electrical size of the whole dual-band MIMO antenna system is (W) × (L) × (H) for the lower frequency band. It achieved greater than 10 and 19 dB isolation in the lower and upper frequency bands, respectively. The antenna system accomplished an envelope correlation coefficient of in the lower frequency band, while it achieved in the higher frequency band. The computed channel capacity loss remained less than almost 0.4 bits/s/Hz in both frequency bands. Therefore, it achieved good performance in both frequency bands, with the additional advantage of a compact size. The proposed MIMO antenna is suitable for compact handheld devices and smartphones used for GSM (Global System for Mobiles), UMTS (Universal Mobile Telecommunications Service), WCDMA (Wideband Code Division Multiple Access), LTE (Long Term Evolution), 5G sub-6 GHz, PCS (Personal Communications Service), and WLAN (wireless local area network) applications.

A Tutorial on 3GPP Initial Cell Search: Exploring a Potential for Intelligence Based Cell Search

This tutorial guides the reader through the open literature on the aspect of Initial Cell Search (ICS) in both Code Division Multiple Access (CDMA) and Orthogonal Frequency Division Multiple Access (OFDMA) systems perspectives with a special focus on the DownLink (DL), where the ICS represents the very first operational stage of commercial mobile station modem’s always-on mobility. There is no comprehensive up-to-date tutorial of the ICSs encompassing 3G, 4G, and 5G systems. Hence, we review the ICS-related operations which have been proposed for Wideband CDMA (W-CDMA), Time Division-Synchronous CDMA (TD-SCDMA), Long Term Evolution Frequency Division Duplex (LTE-FDD), and Time Division LTE (TD-LTE) from the point of view of 3rd Generation Partnership Project (3GPP) standard and implementation. In the case of TD-SCDMA, there is no in-depth literature illustrating the details of ICS. Therefore, this tutorial aims to fill the related gap in the literature. As an evolution from the operational systems, we also shed light on the ICS being employed in New Radio (NR) system operating at sub-6 GHz and provide insight into interesting and challenging technical issues in millimeter-Wave spectrum bands, which is an ultimate foundation to be deployed in the full-scale NR system. Furthermore, we exemplify entire cell search operations over diverse spectrum bands and elucidate intelligent ways of designing multi-mode mobile station modem in a systematic manner. A taxonomy diagram also classifies three main targets constituting ICS procedures in 3G, 4G, and 5G systems. It is expected that this tutorial is beneficial not only for academic researchers but also for practical modem development engineers.

Efficient and Flexible Dynamic Reconfiguration for Multi Context Architectures

Dynamic reconfiguration is possible on both fine-grain and coarse-grain architectures. One of the used methodology used consists in the use of multi-context architectures. Unfortunately, the multiple contexts bring power and area overhead. This paper introduces the Dynamic Unifier and reConfigurable blocK (DUCK) concept, a new structure to perform efficiently dynamic reconfiguration on both custom designed fine-grain and coarse grain architectures. The DUCK allows to separate the configuration path and the configuration registers which facilitates simultaneous configuration and computing steps. The reconfiguration process is presented in detail, and synthesis results are given for different structures. Our solution is finally validated with the implementation of a WCDMA (Wideband Code Division Multiple Access) receiver on a multi-context embedded FPGA and on the dynamically reconfigurable processor DART. This implementation demonstrates the interest and the efficiency of the use of dynamic reconfiguration and the proposed flexible structure.

Design of compact patch antenna with enhanced gain and bandwidth for 5G mm‐wave applications

A super compact parasitic patch loaded patch antenna with enhanced gain and super wide band is proposed in this study for 5G millimetre-wave (mm-wave) applications. The proposed antenna has hybrid geometry and is constructed using circular and two rectangular driven patches with two semi-circular parasitic patches fed by stepped impedance microstrip line. The two rectangular stubs are incorporated on driven patch to improve the voltage standing wave ratio (VSWR) bandwidth. The two semi-circular parasitic patches are added on the fundamental radiator (driven/main patch) to further enhance the bandwidth to cover the entire Ka-band spectrum for 5G mm-wave requirements and covers 24–40 GHz frequency spectrum with VSWR ≤2. This designed radiator is feasible to be placed inside the multilayered housing systems or can be integrated along with the electronic components existing on the printed circuit board. Furthermore, a four-element modified corporate feed array configuration is constructed and their enhanced gain performances are compared with proposed radiator (single element). Both the prototypes are fabricated and experimentally validated for impedance and radiation characteristics and it is observed that, the simulated and measured responses are in good arrangement. The presented radiating element finds its applications in future 5G mm-wave, 5G base station controlling networks and 5G wideband code division multiple access.

Power-Amplifier Stabilization Through Out-of-Band Feedback

This letter presents a power-amplifier (PA)-stabilization technique based on the low-frequency out-of-band feedback. The proposed structure replaces a conventional stability network to ensure unconditional stability at the frequencies up to the radio-frequency (RF) operating band, with the in- and above-band frequencies stabilized through the matching network design. The approach offers an alternative to inserting the lossy components in the RF signal path, which can significantly degrade the realizable in-band gain of the amplifier. The 900-MHz proof-of-concept PA based on a 10-W gallium-nitride (GaN) device is characterized under the continuous-wave (CW) and Wideband Code Division Multiple Access signal (W-CDMA) excitations and realizes 25.6-dB small-signal gain and 73% power added efficiency (PAE) at P3dB.

Load‐modulation technique without using quarter‐wavelength transmission line

A proposed method for achieving active load-modulation technique without using a quarter-wavelength transmission line is discussed and evaluated. The theoretical analysis shows that the active load-modulation can be achieved without using a quarter-wavelength line, where the main amplifier sees a low impedance when the input signal level is low, and this impedance increases in proportion to the amount of current contributed from the peaking amplifier. The peaking amplifier sees an impedance decreasing from infinity to the normalized impedance. To validate the method, a circuit was designed, simulated and fabricated using two symmetrical gallium nitride (GaN) transistors (6 W) to achieve a peak power of 12 W and 6 dB output back-off efficiency. The design operates with 400 MHz bandwidth at 3.6 GHz and showed an average efficiency of 50% at 6 dB back-off and an efficiency of 75% at peak power. The designed circuit was tested with CW and modulated signals, the amplifier showed an Adjacent Channel Power Ratio (ACPR) of 31–35.5 dB when tested with a wideband code division multiple access signal of 6 dB peak-average-power ratio (PAPR) at 35.5 dBm average power. Additional 20 dB of linearity improvement was achieved after adding a lineariser.

Study of Uplink Interference in UMTS Network: ASIACELL Company, Iraq

Universal Mobile Telecommunications System (UMTS), is the third generation (3G) of mobile communication which is based on the wideband code division multiple access (W-CDMA) radio access to provide bandwidth and spectral efficiency. Interference in 3G system is significantly lower compared to the preceded generations. However, it does not mean 3G is free from the issues associated with interferences, such as low signal quality and call drop. The interference level in UMTS can be measured by using the well-known parameter Received Total Wideband Power (RTWP). This parameter is affected by many factors such as number of the users connected to the system, combining second generation (2G) and 3G frequencies within the same geographical area, geographical causes (difference of Altitude), and hardware impairment. In this paper we intensively study how these factors affect the uplink interference level (i.e. RTWP value) in 3G system used by a particular telecommunications company, Asiacell company, Iraq. The obtained data shows that call drop is the most serious issue raised due to high value of RTWP in 3G system. We demonstrate that system enhancement, in terms of lower RTWP level, are obtained by adding second carrier to the sites, separating 2G band from 3G band using special filter, and optimizing the hardware components.

Multistage Multirate Transfer Function Automated Synthesis Using Hybrid Sampling Strategy-Based Differential Evolution

Modern digital systems require one or more frequency shaping modules that realize certain transfer functions, usually in the form of digital filters. Breaking up the design into multiple stages results in reducing the implementation area and power consumption. However, there is no well-defined automation methodology to design an optimum multistage multirate filter. This article proposes a new design flow automation tool using a hybrid sampling strategy-based differential evolution (HSS-DE). The user specifies the inputs and outputs of the system, including the input spectrum, the sample rate change, the magnitude and phase responses, and the required signal-to-noise ratio. The tool uses this information to generate a solution indicating the number of stages and the filters' specifications for each stage such that the generated architecture satisfies the user requirements. We compared the proposed tool to subsystems designed by experts in the ASIC industry. Several case studies are presented to demonstrate the proposed tool's efficiency in different design problems. The case studies include decimation filters for sigma-delta (ΣΔ) analog-to-digital converters (ADCs) and interpolation filters for wideband transmitters such as wideband code division multiple access (WCDMA). The case studies' results indicate that the proposed design automation flow reduces the design time remarkably, in addition to reducing the implementation in all cases.

RPAS COMMUNICATION CHANNELS BASED ON WCDMA 3GPP STANDARD

First built models of Remotely Piloted Air System (RPAS) communication channels based on Wideband Code Division Multiple Access (WCDMA) 3GPP Standard were designed. Base Station (BS) transmission within the Radio Line of Sight (RLoS) and through the satellite using Beyond Radio Line of Sight (BRLoS) was considered. The dependencies of the Bit Error Rate (BER) on the signal-noise ratio for different RPAS velocities and WCDMA сhannel models were obtained. The dependences of the BER on the signal-noise ratio for different levels of satellite transponder nonlinearity were studied. The dependence of the BER on the BS antenna diameter in case of the transponder nonlinearity was analysed. The dependencies for satellite channel characteristics, first obtained taking into account the motion of the RPAS, make it possible to predict the behavior of the communication system in critical conditions.

A high-efficiency Doherty Power Amplifier for wireless base stations

ABSTRACT This paper presents a new high-efficiency two-way Doherty Power Amplifier (DPA) with a modified output matching structure for Wideband Code Division Multiple Access (W-CDMA) low-to-medium power base station applications. A blended design is proposed using the symmetrical topology of equal rated power amplifying devices with unequal output impedances for the carrier and peaking amplifier to achieve enhanced efficiency and desired linearity in 1900 MHz band. The proposed output circuit modifications encompass the usage of parasitic capacitor compensation technique for the carrier amplifier, optimum offset line along with the Doherty combiner to achieve high efficiency over 6 to 10 dB extended range of back-off operation. The measured results of the DPA demonstrate a Power Added Efficiency (PAE) of more than 49.9% at +34 dBm W-CDMA signal power, which is between 8 and 8.5 dB back-off from the peak power level of 42.2 dBm. The DPA has a large signal power gain of 13 dB at 1960 MHz. Further, the PAE is 39.5% and linearised Adjacent Channel Power Ratio (ACPR) is −46.2 dBc, both at 10 dB back-off from peak power. In these back-off power levels, this implementation provides significant efficiency improvement using symmetrical devices and with excellent linearity.

Unified multiple access structure based on FBMC modulation for multi‐RAT coexistence in heterogeneous wireless networks

With the evolution of the fifth generation (5G) and beyond heterogeneous wireless networks, telecommunications operators and researchers are driven to develop advanced transmission technologies that enable the coexistence of multiple radio access technologies (multi-RATs). By employing the efficient implementation of filter-bank multi-carrier (FBMC) transceiver and the scalable matrix transformation (SMT) module, in this study, a unified multiple access architecture termed as FBMC-SMT is proposed, which is capable of flexibly integrating with both 3G and 4G transmission schemes and improving the system performance. As a special case of FBMC-SMT, the performance evaluation of FBMC-CDMA is conducted by extensive simulation. It is verified that FBMC-CDMA with 16 subbands allocated outperforms the traditional single carrier wideband code division multiple access when the number of code channels assigned is larger than 5. Moreover, the signal-to-interference-plus-noise ratio analysis of FBMC-SMT is also given and matches the simulation results very well. Hence, the proposed FBMC-SMT can serve as a unified architecture to flexibly integrate multi-RATs, thus to meet variable application requirements in 5G and beyond heterogeneous wireless networks.

Interference reduction using particle swarm optimisation in MIMO-WCDMA multicellular networks

In this paper, particle swarm optimisation (PSO) algorithm based interference reduction is proposed in multiple input multiple output (MIMO) using wide-band code division multiple access (WCDMA). During transmission MIMO network may get interfered by some interference such as co channel interference and adjacent channel interference. To reduce these interferences many algorithms have been proposed in previous research. Further improve the performance of the MIMO-WCDMA network and reduce the bit error rate (BER) an optimised algorithm is proposed. Simulation results of this paper show that bit error rate (BER) is reduced and also throughput of the network also improved.

Interference reduction using particle swarm optimisation in MIMO-WCDMA multicellular networks

In this paper, particle swarm optimisation (PSO) algorithm based interference reduction is proposed in multiple input multiple output (MIMO) using wide-band code division multiple access (WCDMA). D...

A 20.5 dBm Outphasing Class-F PA with Chireix Architecture at 3.5 GHz for RF Transmitter Front-end

An outphasing class-F power amplifier (PA) with Chireix architecture is presented in Global Foundry (GF) 0.13µm Complementary Metal Oxide Semiconductor (CMOS) technology. The proposed circuit is composed of two branch class-F PA and Chireix power combiner with a floating load. The designed outphasing amplifier can provide 20.5 dBm output power from 1.8 V power supply at 3.5 GHz with 52.9 % power added efficiency (PAE). Wideband Code Division Multiple Access (W-CDMA) signal is implemented as input signal to simulate ACPR and the adjacent channel leakage ratios (ACLRs) at ±5 MHz are -20.5 dBc/-20.7dBc. After DPD (Digital Pre-Distortion) ACLRs can achieve -44.5 dBc/-44.7dBc at ±5 MHz. Furthermore, the chip area including testing pads is 1.98*1.62 mm2.

The peak windowing for PAPR reduction in software defined radio base stations

The utilization of the techniques for Peak to Average Power Ratio (PAPR) reduction makes the wireless infrastructure conform to rigorous telecommunication standard specifications (error vector magnitude (EVM), bit error rate (BER), transmit spectrum mask (TSM)). In modern modulation schemes reduction of PAPR is important requirement for distortion free and energy-efficient operation of power amplifiers (PA). In this paper novel implementation of Peak Windowing method for PAPR reduction in Software Defined Radio (SDR) Base Stations (BS) is presented. The measurement results in terms of EVM and ACPR are given for 5 MHz, 10 MHz, 15 MHz, 20 MHz Long-Term Evolution (LTE) and Wideband Code Division Multiple Access (WCDMA) modulations. In case of 10MHz LTE signal, we achieved PAPR = 8 dB, EVM = 2.0%, ACPR -52dBc at modulated PA output, antenna point.

Three Decades of 3GPP Target Cell Search through 3G, 4G, and 5G

This survey provides the reader with the open literature on the detailed operational scenarios of Target Cell Search (TCS) in both 3G and 4G systems, with a particular emphasis on the DownLink (DL). There is no completely latest survey of the TCS scenarios. Therefore, we examine the TCS-involved solutions which have been chosen for Wideband-Code Division Multiple Access (W-CDMA), Time Division-Synchronous Code Division Multiple Access (TD-SCDMA), Long-Term Evolution Frequency Division Duplex (LTE-FDD), and Time-Division Long-Term Evolution (TD-LTE). Especially for TD-SCDMA, there is no concrete literature demystifying the details of TCS scenario. Accordingly, this survey aims for repairing the associated crack in the literature. Moreover, as a recent evolution from the operational systems, we also focus on the TCS scenario which can be exploited in New Radio (NR) systems operating at both sub-6 GHz and millimeter-Wave (mmW) spectrum bands. A taxonomy diagram is also provided to classify relevant target cell search scenarios in 3G, 4G, and 5G as well as followed by those in inter-Radio Access Technologies (RATs). In a nutshell, our endeavors definitize the first comprehensive survey on the TCS progress tailored to the evolution of commercial mobile communication systems over three decades. It is worth mentioning that this survey is also informative for engineers and researchers to design practical mobile station modem.

Outage Throughput Capacity of Hybrid Wireless Networks Over Fading Channels

How much information can be transported, i.e., the transmission rate, is a subject of great interest in hybrid wireless networks. The main focus of this paper is the effect of channel fading in hybrid wireless network, in which a wired network of base stations is deployed to support long-range communications between wireless nodes. Two types of transmission mode in hybrid wireless network, i.e., intra-cell mode and infrastructure mode, are considered. To effectively overcome fading impairment, optimal multiple access technique is applied, allowing opportunistic sources to transmit concurrently with the scheduled source. Those different sources, much like in wideband CDMA system, share the entire bandwidth. A successive interference cancellation (SIC) strategy is then introduced at receiver side to limit the intra-cell interference and achieve the maximum capacity. Meanwhile, frequency reuse scheme is employed to minimize the inter-cell interference. Since the outage capacity over different fading channels will exhibit different asymptotic behaviors, in this paper we examine the Rayleigh, Rician and Nakagami-m models, which are the most commonly used fading models. Close-form solutions for outage throughput capacity at high signal-to-noise-plus-interference ratio (SNIR) are derived. It is showed that, with opportunistic sources, the intra-cell mode effectively combats fading as wireless nodes increases; however, the infrastructure mode is bottlenecked by the downlink transmission since base station is the only transmitter in the cell during the downlink phase. The theoretical bounds obtained and proofs are instrumental to the future network modeling and design.

Total Isotropic Sensitivity Measurement in Switched Beam Antenna Systems

Smart antenna systems (SAS) play an important role in wireless communication systems, especially in rapidly developing fifth-generation (5G) systems. In normal device under test (DUT) applications with SAS, the antenna’s state may change in different external environments in order to obtain higher antenna gains and better connection with the base station, resulting in high uncertainties for over-the-air (OTA) tests using conventional methods. Before evaluating the transceiver performance, additional application programs are necessary to control the DUT, which increases the inconvenience for engineers and makes it impossible to reflect the real usage scenario. This article proposes a new convenient method for total isotropic sensitivity (TIS) measurement of each antenna group in SAS with multiple groups of antennas. This method monitors the status of the antenna systems, and the TIS is calculated from the received signal strength indicator (RSSI). The proposed method is suitable for Global System for Mobile Communications (GSM), wide band code division multiple access (WCDMA), long term evolution (LTE), and other wireless communication systems with RSSI report.

Analysis of Handover Planning in Wideband Code Division Multiple Access (W–CDMA)

Analysis of Handover Planning in Wideband Code Division Multiple Access (W–CDMA)