Non-contiguous Carrier Aggregation Research Articles

The Evaluation of the Throughput Performance of an LTE-Advanced Urban Area Network with the Inter-Band Non-Contiguous Carrier Aggregation Method

Data obtained from the drive-test in the urban area (a case study of Siliwangi Stadium, Bandung) revealed that the low throughput occurred on the downlink, which was 3.56 Mbps. On the uplink, it was 20.7 Mbps. Additionally, based on the Operating Support System (OSS) data, the site had high resource block usage (80% of PRB usage). It revealed the high traffic volume in the area, which resulted in poor throughput values received by users. The area is one of the potential market areas in the city of Bandung, which is indicated by housing, military area command education and training regiment, schools, hotels, markets, and stadiums. Based on the Site Database (SDB), it was known that the site has not yet implemented the carrier aggregation method. This study evaluated throughput using the Inter-Band Non-Contiguous Carrier Aggregation method by comparing three scenarios: Non-CA, CA Non-Repeater, and CA Repeater. Based on the results of the non-CA simulation, the downlink throughput increased by 23,582 Mbps, and the uplink throughput by 20.098 Mbps. Meanwhile, in the non-repeater CA simulation, the downlink throughput increased by 44.56% to 34.091 Mbps, and the uplink throughput increased by 39.22% to 27.980 Mbps. Furthermore, the CA Repeater simulation increased downlink throughput by 63.70% to 38.603 Mbps and uplink throughput by 45.06% to 29.154 Mbps.

Performance Analysis of 5G Stand Alone Inter-band Carrier Aggregation

Today, high data rate is the prior requirement to support services and applications. It is definitely a challenge for the 5G New Radio (NR) in providing high data rates, in order to support use cases, especially enhanced Mobile Broadband (eMBB). The objective of this research is to design a 5G network which has greater data rates employing carrier aggregation techniques. Carrier Aggregation (CA) is a way which is able to improve data rates by aggregate component carriers, hence, it can make a wider bandwidth. There are three modes of CA scenario that can be used: intra-band contiguous CA, intra-band non-contiguous CA, and inter-band noncontiguous CA. In this research, the 5G network planning with carrier aggregation on inter-band employing bandwidth 40 MHz at frequency 2300 MHz and bandwidth 100 MHz at frequency 3500 MHz was simulated in Mentum Planet software. The simulation implemented at Marunda Center Industrial Area in Bekasi used downlink outdoor-to-indoor (O2I) with Line of Sight (LOS) scenario. The parameters analyzed in this research employed three main parameters: SS-RSRP, SS-SINR and data rate, which resulted CA SS-RSRP increased by 0.14%, SSSINR increased by 4.48%, and peak data rate increased up to 1412.26 Mbps from 312.872 Mbps

Wideband Linearization of a Carrier Aggregation Transmitter Using Analog Signal Injection and 2-D Digital Predistortion

We introduce a transmitter (TX) architecture and a linearization technique for concurrent transmission of two intraband noncontiguous carrier aggregation signals in the 5 GHz frequency band. The technique is based on low-power and narrowband analog signal injection to compensate for out-of-band (OOB) third-order intermodulation distortions (IMD3), together with 2-D digital predistortion to address error vector magnitude (EVM) degradation caused by in-band intermodulation and cross-modulation distortions. The hybrid analog-digital design enables wideband linearization over the entire third-order distortion bandwidth (BW) using practical sampling rate requirements from the digital-to-analog converter (DAC) and analog-to-digital converter (ADC). The system’s performance was evaluated using a class AB power amplifier implemented in the 180 nm CMOS technology and two VHT 802.11ac Wi-Fi signals with a 20 MHz modulation BW. The linearization technique achieves 7–12 dB cancellation of OOB IMD3 products along with 6–9 dB of in-band EVM correction at 8 dBm average output power over a BW of up to 1.2 GHz, with only 60 MHz BW requirement from the DACs and ADCs.

A Reconfigurable Spectrum-Compressing Receiver for Non-Contiguous Carrier Aggregation in CMOS SOI

This article demonstrates a signal processing technique for receiving non-contiguous RF channels by concurrently mixing several RF bands to adjacent IF channels. Consequently, channel selection does not require local oscillator tuning and the proposed receiver (RX) can switch channels in less than 25 ns. The RX chip operates over a frequency range of 100 MHz–1.4 GHz and demonstrates an out-of-band rejection of 49 dB and a measured RX sensitivity of −86 dBm, which is the lowest measured for $N$ -path-based RXs. The chip was fabricated in a 45-nm RF silicon-on-insulator (SOI) CMOS process and occupies an active area of 0.55 mm2 with the power consumption of 23.1 mW when operating at 1 GHz. The chip performance is verified with over-the-air measurement of two transmitted signals 80 MHz apart that are received simultaneously with a 10-MHz analog-to-digital converter (ADC) at an error vector magnitude (EVM) around −20 dB. The measured dynamic range for EVM less than −20 dB is better than 86 dB for a QPSK constellation.

Energy-Efficient Virtual Radio Access Networks for Multi-Operators Cooperative Cellular Networks

5G networks will be characterized by massive densification of base stations (BSs). To minimize the network power consumption due to the increased BS deployment, we leverage emerging paradigms to propose BS energy-saving strategies applicable to 5G networks. We explore the potentials of virtualized radio access and core networks to enable spectrum sharing among mobile network operators (MNOs) by harnessing inter-band non-contiguous carrier aggregation. We propose the sleep-mode with efficient beamformers and spectrum-sharing (SEBS) strategy, which minimizes BS power consumption of cooperative MNOs. The licensed bandwidth of each MNO is partitioned into private and shared bands to provision active BSs with sufficient spectrum resources for serving all UEs. Moreover, an optimization problem is formulated to obtain the optimal intra- and inter-RAN beamforming vectors for efficient BS transmission power and improved user signal reception. Numerical simulations show that the proposed strategies yield significant reductions of total power consumption as compared to other schemes. We present different bandwidth sharing ratio formulations to motivate the cooperation among MNOs by the spectrum-user support trading. We also show that the trading does not always yield a higher spectral efficiency in the cooperative cellular network.

A 1.5–1.9-GHz All-Digital Tri-Phasing Transmitter With an Integrated Multilevel Class-D Power Amplifier Achieving 100-MHz RF Bandwidth

We present a prototype RF transmitter with an integrated multilevel class-D power amplifier (PA), implemented in 28-nm CMOS. The transmitter utilizes tri-phasing modulation, which combines three constant-envelope phase-modulated signals with coarse amplitude modulation in the PA. This new architecture achieves the back-off efficiency of multilevel outphasing, without linearity-degrading discontinuities in the RF output waveform. Because all signal processing is performed in the time domain up to the PA, the entire system is implemented with digital circuits and structures, thus also enabling the use of synthesis and place-and-route CAD tools for the RF front end. The effectiveness of the digital tri-phasing concept is supported by extensive measurement results. Improved wideband performance is validated through the transmission of orthogonal frequency-division multiplexing (OFDM) bandwidths up to 100 MHz. Enhanced reconfigurability is demonstrated with non-contiguous carrier aggregation and digital carrier generation between 1.5 and 1.9 GHz without a frequency synthesizer. For a 20-MHz 256-QAM OFDM signal at 3.5% error vector magnitude (EVM), the transmitter achieves 22.6-dBm output power and 14.6% PA efficiency. Thanks to the high linearity enabled by tri-phasing, no digital predistortion is needed for the PA.

Multiband Linearization Technique for Broadband Signal With Multiple Closely Spaced Bands

Under the scenario of noncontiguous carrier aggregation with closely spaced multiple bands, the interband modulation products after power amplifying will overlap with the bands of interest. This leads to linearization performance degradation for the conventional three-band digital predistortion (DPD) method which only accounts for in-band intermodulation (IMD) and cross modulation. To resolve the spectral overlaps, a multiband linearization technique combining the direct power amplifier (PA) model extraction and the indirect DPD learning strategies is proposed. A multidimensional memory polynomial (MD-MP) model is first presented to jointly extract: 1) the in-band IMD; 2) the cross modulation; and 3) the interband modulation products from the observations for the multiple bands of interest to yield an improved frequency/time selective modeling. The extracted MD-MP models are then used in the indirect learning structure instead of the physically filtered observations to estimate the multiband DPD coefficients, given the fact that the observations spectrally overlap with each other which would result in interference for DPD coefficients estimation with direct filtering. Moreover, a novel MD cubic spline (MD-CS) basis is applied for the first time to the considered three-band scenario while the principal component analysis is used to alleviate any ill-conditioning problem during the model extraction. Improved PA modeling and DPD linearization performances are verified through experiments performed on three groups of wide-bandwidth noncontiguous aggregated signals covering a variety of application scenarios.

An FPGA-Oriented Baseband Modulator Architecture for 4G/5G Communication Scenarios

The next evolution in cellular communications will not only improve upon the performance of previous generations, but also represent an unparalleled expansion in the number of services and use cases. One of the foundations for this evolution is the design of highly flexible, versatile, and resource-/power-efficient hardware components. This paper proposes and evaluates an FPGA-oriented baseband processing architecture suitable for communication scenarios such as non-contiguous carrier aggregation, centralized Cloud Radio Access Network (C-RAN) processing, and 4G/5G waveform coexistence. Our system is upgradeable, resource-efficient, cost-effective, and provides support for three 5G waveform candidates. Exploring Dynamic Partial Reconfiguration (DPR), the proposed architecture expands the design space exploration beyond the available hardware resources on the Zynq xc7z020 through hardware virtualization. Additionally, Dynamic Frequency Scaling (DFS) allows for run-time adjustment of processing throughput and reduces power consumption up to 88%. The resource overhead for DPR and DFS is residual, and the reconfiguration latency is two orders of magnitude below the control plane latency requirements proposed for 5G communications.

Investigations of Component Carrier Selection Algorithms in Long Term Evolution-Advanced

<p>Given that the demand for real-time multimedia contents that require significantly high data rate are getting of high popularity, a new mobile cellular technology known as Long term Evolution-Advanced (LTE-A) was standardized. The LTE-A is envisaged to support high peak data rate by aggregating more than one Component Carriers (CCs) of the same or different frequency bandwidths. Since the inter-band non-contiguous carrier aggregation is likely to be used due to the current frequency allocation, this paper provides a performance study of a number of CC selection algorithms for use in the inter-band non-contiguous downlink LTE-A. It should be noted that CC selection is of paramount importance in the LTE-A operating in backward compatible mode as the LTE-A contains a mixture of the legacy Long Term Evolution (LTE) users that support packets (re)transmission on a single CC and the LTE-A users that utilize more than one CCs for packets (re)transmission. Simulation results demonstrated the efficacy of the Channel-Throughput Aware (CTA) algorithm for maximizing the system capacity without compromising the required Quality of Service of real-time video users.</p>

Near‐band digital predistortion for wideband power amplifiers with mmWave non‐contiguous carrier aggregation

A near-band digital predistortion technique is proposed to linearise a wideband power amplifier (PA) with millimetre wave (mmWave) non-contiguous carrier aggregation (CA). The proposed method employs low-bandwidth linearisation architecture to only focus on the in-band compensation and part of the out-of-band (OOB) distortion suppression, which largely alleviate the bandwidth limitation for baseband operation. Experiments have been carried out on an mmWave PA with the centre frequency of 41 GHz. Good measurement results can be achieved when the PA is excited by a very wideband modulated signal with 1001 CA configuration and the total bandwidth of 640 MHz.

Modeling and Joint Mitigation of TX and RX Nonlinearity-Induced Receiver Desensitization

In this paper, we provide detailed modeling of the spurious intermodulation distortion products appearing in the own receiver (RX) operating band as a result of coexisting transmitter (TX) and RX nonlinearities with noncontiguous carrier aggregation transmissions. Furthermore, an efficient digital front-end signal processing technique is proposed, which can flexibly mitigate the resulting RX in-band self-interference caused either by individual or simultaneously coexisting TX and RX nonlinearities. The technique is based on accurately estimating the effective leakage channel that models the nonlinearities of the TX and RX chains and the duplexer filters characteristics. In the parameter estimation stage, an observation RX chain is adopted for separately estimating the TX passband leakage response, which facilitates efficient joint estimation and regeneration of the TX- and RX-induced self-interference. In the online digital cancellation, the actual transmit data are used in conjunction with the estimated channel responses to generate a replica of the overall nonlinear self-interference, which is subsequently suppressed by subtracting it from the actual observation. In general, the proposed technique can efficiently estimate and suppress the self-interference at arbitrary spurious sub-bands located at the RX band. The performance evaluations with comprehensive numerical simulations and practical RF measurements indicate highly accurate and efficient operation, with up to 28 dB of measured self-interference suppression.

An Interference-Resilient Wideband Mixer-First Receiver With LO Leakage Suppression and I/Q Correlated Orthogonal Calibration

A mixer-first receiver design in 28-nm CMOS is discussed. An embedded 5-bit mixer digital-to-analog converter provides wideband tuneability to enhance device matching and, hence, suppress the multiple local oscillator (LO) harmonics as well as to improve the overall image rejection (IR) performance. Two-stage baseband amplifiers support a 50-MHz baseband bandwidth, which covers the entire channel for long-term evolution non-contiguous carrier aggregation. The proposed design effectively reduce multiple LO harmonics down to below -62 dBm. The system achieves 2.6-dB noise figure, > 15-dBm out-of-band third-order input intercept point, and an IR ratio > 66 dB with 60-mW power, including five on-chip low dropout regulators.

Carrier Aggregation Technique to Improve Capacity in LTE-Advanced Network

Carrier aggregation (CA) is a major feature in LTE-advanced technology that allows network provider to use more than one carrier simultaneously to increase capacity. CA uses two or more individual component carriers (CCs) of the same (intra-band) and different (inter-band) frequency bands. In this paper, we evaluate CA techniques with the test parameter using BLER and throughput inside the tested area of LTE network. The tested area is designed to represent most common environment in which LTE will be deployed. We use 30 MHz frequency bandwidth in the simulation to evaluate intra-band and inter-band CA technique performance. Two CCs is allocated for primary serving cell (PCell) and secondary serving cell (SCell). Simulation result shows for the downlink, BLER tend to increase, as the frequency configuration is increase. However, for the uplink BLER is zero. We found that for CA configuration with wider PCell bandwidth resulting better throughput. In CA intra-band, the throughput of non-contiguous CA is better than CA contiguous. Then in the inter-band CA, CC combination with a lower frequency produces higher throughput.

A Filter-Bank Transceiver Architecture for Massive Non-Contiguous Carrier Aggregation

Current application of carrier aggregation (CA), a key enabling technology for wideband communications over fragmented spectrum, is limited to only a small number of component carriers (CCs). However, wireless broadband connectivity of future networks requires the exploitation of multiple, contiguous, and non-contiguous CCs (NC-CCs). By considering a large number of aggregated NC-CCs, the concept of massive non-contiguous CA (NC-CA) is realized, which offers the highest flexibility in spectrum aggregation. In order to fully exploit the system-level benefits of massive NC-CA, transceivers capable of efficiently accommodating parallel transmissions over all of the available NC-CCs are required. This is a challenging task in which current NC-CA transceiver architectures, including the straightforward parallel chains implementation, fail to accomplish, as they suffer from scalability and efficiency issues. Focusing on the digital baseband processing part of the transceiver, this paper proposes an efficient filter-bank transceiver architecture able to accommodate a large number of NC-CCs with a small complexity increase compared with the ideal case of the transceiver operating on a single CC with the same aggregate bandwidth. Specification of this new architecture is cast as a filter design problem with minimal assumptions on transmitted waveform format, channel statistics, and decoding scheme, allowing for universally applicable designs. Both heuristic and optimal design methodologies are provided, the latter obtained using the notion of capacity mean square error as an appropriate performance/design metric. The performance of the proposed architecture is evaluated analytically, and a case study where it is applied for OFDM transmissions is provided.

Digital Compensation for Transmitter Leakage in Non-Contiguous Carrier Aggregation Applications With FPGA Implementation

In this paper, a generalized dual-basis envelope-dependent sideband (GDES) distortion model structure is proposed to compensate the distortion induced by transmitter leakage in concurrent multi-band transceivers with non-contiguous carrier aggregation. This model has a generalized structure that is constructed via first generating a nonlinear basis function that maps the inputs to the target frequency band where the distortion is to be cancelled, and then multiplying with a second basis function that generates envelope-dependent nonlinearities. By combining these two bases, the model keeps in a relatively compact form that can be flexibly implemented in digital circuits such as field programmable gate array (FPGA). Experimental results demonstrated that excellent suppression performance can be achieved with very low implementation complexity by employing the proposed model.

Multispectrum Signal Transmitters: Advances in Broadband High-Efficiency Power Amplifiers for Carrier Aggregated Signals

The growing demand for broadband mobile access drives the deployment of sophisticated and increasingly spectrum-efficient modulation techniques and access technologies resulting in communication signals with highly varying envelopes and increasing peakto-average power ratios (PAPRs). These communication signals call for advanced transmitter architectures and design techniques. This is particularly the case for the constituent radio frequency (RF) power amplifiers (PAs), which are required to amplify communication signals efficiently while maintaining signal quality and minimizing out-of-band emissions in adjacent channels. The Doherty [1] technique has been successfully applied to develop highly efficient solid-state PAs for wireless communication applications. Benefiting from recent advancements in laterally diffused metal oxide semiconductors (LDMOSs), and taking advantage of the advent of gallium nitride (GaN) technology, Doherty PA (DPA) demonstrators with average drain efficiencies approaching 50% were reported in [2]-[4]. Unfortunately, the underlying narrow bandwidth of these demonstrators currently restricts their use to infrastructure supporting third-generation (3G) wireless networks. Communication signals required by the 3G Partnership Project (3GPP) specifications for long-term evolution (LTE) will have to utilize carrier aggregation to meet the need for transmission bandwidth. Carrier aggregation refers to the use of more than one spectrum portion to deploy multiple component carriers to yield aggregated channels of wider transmission bandwidth (up to 100 MHz). Figure 1 illustrates the three carrier aggregation scenarios that are envisaged: 1) intraband contiguous carrier aggregation (contiguous component carriers aggregated in the same operating band), 2) intraband noncontiguous carrier aggregation (noncontiguous carriers aggregated in the same operating band), and 3) interband carrier aggregation (carrier aggregation of component carriers in different operating bands that may be contiguous or noncontiguous within each band).

Measurement and Analytical Study of the Correlation Properties of Subchannel Fading for Noncontiguous Carrier Aggregation

The new multichannel/multicarrier technologies can potentially support much higher data rates in mobile multiple- access environments, such as carrier aggregation (CA) defined in the fourth-generation Long-Term Evolution Advanced enhance- ment. The correlation properties of noncontiguous subchannels are critical for the performance of CA, including cell coverage, frequency diversity, and channel state estimation. This paper has studied the correlation of the large-scale fading (LSF) and small-scale fading (SSF) of arbitrarily separated subchannels by realistic channel measurement and analytical modeling. We first obtain the subchannel correlation from the ultrawideband (UWB) channel measurement. This new approach avoids probing multiple subchannels simultaneously with channel sounders, which would be prohibitively complicated. The cross correlation of two distinct subchannels and the autocorrelation of a single subchannel are evaluated. Second, a new propagation model for the Nakagami-m fading in a multipath environment is proposed. The frequency- domain level crossing rate (FD-LCR) is defined and derived based on the propagation model. Then, a Markov chain for the frequency fading of the wideband channel is established, which can generate the correlated gain/power of subchannels in a wide bandwidth. Therefore, this model can be used as a fast simulator of CA over correlated subchannels. Finally, the cross correlation coefficients (CCCs) between two Nakagami-m fading subchannels obtained from the measurement and the proposed Markov model are compared with the analytical results in the literature. This paper provides important insights into the fading correlation of the multicarrier channels and can be applied to the design and simulation of indoor/outdoor multicarrier communications. Index Terms—Carrier aggregation (CA), channel measurement, channel modeling, CLEAN, fading, ultrawideband (UWB).

Optimal Tone Space Selection Scheme for OFDMA-VTS in Carrier Aggregation

In this paper, we propose an optimal tone space selection scheme for orthogonal frequency division multiple access with variable tone spaces (OFDMA-VTS) in carrier aggregation based on user-specific channels. We begin by analyzing inter-symbol interference (ISI) and inter-carrier interference (ICI) in non-contiguous carrier aggregation, which differ according to the delay and Doppler spreads associated with each user, as well as the tone space that each user utilizes. Based on that, we propose an optimal tone space selection scheme as a way to minimize both ISI and ICI. We also derive an upper bound on OFDMA-VTS capacity when it is applied to the proposed scheme. Furthermore, we investigate the effect of inter-user interference (IUI) in contiguous carrier aggregation and show that the proposed scheme can be applied to OFDMA-VTS in contiguous carrier aggregation as a suboptimal solution. Numerical results demonstrate that the proposed scheme maximizes OFDMA-VTS capacity by minimizing the total ISI and ICI interference, thereby enhancing the system capacity over what is possible with conventional OFDMA.

Dependence of power amplifier backoff on resource allocation for non‐contiguous carrier aggregation

The dependence of power amplifier (PA) backoff on resource allocation for non-contiguous carrier aggregation is investigated. To be specific, assuming two non-contiguous carriers, the power spectral density (PSD) of the third-order intermodulation distortion (IM3) is approximated as a function of power allocation and PSD allocation. Based on the closed-form expression, it is proven that the PSD of IM3 is maximised when the resource allocation is inversely proportional to the PSD allocation. The PA simulations verify that such resource allocation also maximises the PA backoff.