LEO SATCOM and 3G/4G/5G Terrestrial Mobile Systems Architecture User Terminal

The following architectural diagram illustrates user terminal which can support both LEO SATCOM as well 3G/4G/5G Terrestrial mobile communication systems.

Observe that it relies on existing RFIC transceiver as well as MODEM SoC by ADI and Qualcomm, respectively.  Obviously, the multiple antennas and antenna array as well as diplexer can be designed to support the user terminal.  It worth mentioning that X55 SoC has beamforming and beam steering capabilities as well as primary and diversity channels with sensitive Eb/N0 which can also support higher QAM modulation with Adaptive Coding Modulation, ACM, feature set.

This architecture can be implemented and integrated into an actual product in about 1 year time frame.

Augment ORTENGA in your analysis, architect and systems definitions for LEO SATCOM and Terrestrial Mobile Communications Systems.

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Posted on February 11, 2020 

Antenna Array Factor over Ground Plane

5G NR, gNB, LEO SATCOMradar, and WiGig rely on beamforming, therefore Active Electronically Scanned Antenna Array, AESA.  Typically AESA has ground plane, consequently image theory must be utilized to arrive at proper radiation pattern of AESA for simulation and therefore in actual applications.  This particularly becomes important and critical for implementing Beamforming, Beam steering, and SLL management algorithms.

The appropriate simulations enable the architect, system design, and managements to validate assumptions made for feasibility of design.  ORTENGA provides simulation tools to validate your design and goes beyond what appropriate Phase Array Tool Box or SystemVue provide, independently. 

Augment ORTENGA into your architect and system design teams to validate design before its implementations.

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Posted on February 9, 2020 

Power Amplifier Efficiency Misconception, Under Utilization

Many companies strive to design more efficient Power Amplifier, PA.  In doing that, these companies utilize new technology and engineering resources over design and development cycle of project to achieve more efficient standalone Power Amplifier.

What is missing in overall goal is, analysis and addressing overall wireless systems operating power efficiency.  Power Amplifier efficiency does not necessarily translate percent for percent to less power consumption by the transmitter, if there are other culprits in the transmitter architecture which prevent achieving more efficient transmitter.

The above figure illustrates a typical wireless transmitter.  Power Amplifier efficiency is one of the figure of merits.  Except Power Added Efficiency, PAE, is defined at maximum power rating of the PA, which is rarely the actual operating point of the overall wireless system. 

Particularly, many SATCOM UT operates 3-5 dB below rating of PA.  The power added efficiency drastically reduced at couple of dB back off point of PA P1dB.  Therefore, all the hard work put in the PA design goes under-utilized. 

The following table illustrates under utilized power in Watts due to PA back off in order to meet EVM and distortion metrics.

You will be better off designing an architecture which does not suffer during the actual dynamic operation of the transmitter and leave power on the table while the power amplifier is capable of delivering yet under utilized by the system.

Augment ORTENGA in your analysis, design and development team to architect transmitter in such a way that can benefit from PA efficiency and utilize every Watts or power in the system.

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Posted on February 8, 2020 

DAC Dynamic Range and Resolution for SLL Management Algorithm for 5G NR, LEO and Radar

SLL management Algorithms relies on tapering the waveform or antenna array excitations.  This is typically achieved with Digital to Analog Converter, DAC, in advance systems.  The DAC dynamic range depends on maximum to minimum ratio of the excitations or waveform, which may or may not impact resolution depending on the topology of tapering. 

In some cases, it may be sufficient to require DAC ENOB based on the dynamic range. 

On the other hand, there are scenarios for optimum performances; the ENOB is driven by the actual resolutions and noise suppression requirements of tapering.

Augment ORTENGA in your Beamforming, Beam Steering, and SLL Management Algorithms to design appropriate HW as well as required algorithms.

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Posted on February 7, 2020 

5G mmW Antenna Design

The high data rates required for the 5G standards leads to the need for greater band­widths. This has moved the required operating frequency bands up into the millimeter wave range for the 5G communication systems.

The mmWave antenna design for 5G has the following important aspects: the beamforming and synthesizing antenna arrays, designing the antenna elements; designing the feeding network, the effect of the coupling between the adjacent antenna elements, the effect of surrounded materials on the radiation characteristics of the antennas and power consumption, and the thermal dissipation.

The beamform is designed in order to maximize each user’s received signal power while minimizing the interference signal power from the other users.

The antenna design for 5G mmWave communication systems include design antennas for smart phones, indoor small-cell networks, and the base stations.

The antenna design for the above problems focuses on design of ultrawideband (UWB), wide scanning, and dual-polarized phased arrays that shall scan the beam electronically. Examples of this design are arrays of patch antennas (Figure 1), planar dipoles, or bowtie antennas with two orthogonal feeding mechanisms to excite horizontal and vertical modes for each element. In addition matching networks should be designed to improve the impedance matching. The distances between the patches in the arrays design are λ/2 center to center which are 5 mm at 30 GHz and 3 mm at 50 GHz.

Figure 1: Example of planar patch array with orthogonal feedings (Feeding 1 and Feeding 2). Note that the boxes of “Feeding 1” and “Feeding 2” are just block diagrams that take different shapes and locations based on the design.

Implementing this design for the orthogonal modes is challenging because the difficulty of integrating the orthogonal feeds and the existence of resonance modes from the conductors surrounding the antennas.

Reconfigurable antenna design is used in order to switch between different 3D radiation patterns of the antenna and different polarization settings. 

The reflection coefficient should be simulated when the antenna excited by the practical feeding structure over a wide frequency range covers e.g. the FR2: 24.25-52.6 GHz. The radiation pattern and the directivity level should be simulated and the stability of the radiation pattern should be tested over the operating frequency band and the symmetry in co-polar and cross-polar components should be inspected.

Over the air testing (OTA) requirements, such as the size of the chamber and the positioner choice, should be determined based on the size of the antenna structure and the radiation pattern characteristics. If the size or the position of antenna is unknown then we use white box dimensions which is a box include the electronic circuits with the antenna to determine the chamber size. In addition, we decide whether we use direct far field measurements or compact antenna test. In the direct far field measurements, the measurements of the field magnitude are performed in the far-field zone of the antenna while in the compact antenna test the measurements of the complex field are performed in the radiated near-field and then a near-field to far-field transform software is used.

Simulation of massive array of tightly coupled antennas with the feeding network over an UWB, e.g. the FR2: 24.25-52.6 GHz is challenging.

We can design the antenna arrays for the FR2 including the mutual coupling between the antennas, the feeding and impedance matching network, and analyze the effect of the surrounding metals and materials on the antenna performance.

We can solve such kind of problems and develop or choose which method and software is the best for your design.  

Author: Hany A. Raouf, PhD

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Posted on February 6, 2020 

Innovation Recipe – Top down Approach

Any innovation requires challenging the status quo. 

Those, whom are satisfied with the existing solution(s), typically do not seek to enhance the solutions to a problem.

Many companies which are missing out innovating into their products on regular basis or brand new product with features and performances beyond existing market trends have something in common; their design approach flows Bottom up. 

The questions to internal, external, and consultants are around low level blocks in the system and how to enhance it, say mixer in a radio.  The fallacies in that question are that it is already assumed the next generation of radios will embed a mixer.  Perhaps detrimental assumption is that people whom have an extensive background and experiences for that field are in better position to answer that question. 

New ideas come from looking at a problem with a different angle which was missed before.  It is more likely someone without prior knowledge and background that may come up with an innovative solution.  Obviously, the new comer must understand the problem before attempting to solve it.  That burden is on our shoulder to pose an appropriate question.

This is the story of an actress Hedy Lamarr and a composer George Antheil the inventors of Code Division Multiple Access, CDMA, which has enabled Qualcomm to surpass all of its competitors.  While everyone around the globe was working on TDMA or FDMA, in 1985 Qualcomm determined that CDMA will provide ~100x more capacity relative to TDMA and FDMA.  It took approximately 10 years to prove that to remaining industry and show CDMA can be implemented and utilized in cellular market.

It is much better problem solving approach if the system in hand is solved from Top down.  First, gathering constraints and stating requirements for that radio by the product definer, then, attempting to find various architectures that may address those requirements.   

Unfortunately, nowadays many companies big or small utilize Bottom up approach and miss opportunities to lead their own market. 

ORTENGA engineers utilize Top down approach to solve our clients’ problems.

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Posted on January 31, 2020 

PLL Noise Phase Sources

Phased Lock Loop, PLL, is a negative feedback frequency synthesizer of choice for Integrated Circuits, IC.  There are four phase noise sources in any PLL, namely; Crystal Oscillator, XO, Phase Frequency Detector, PFD, Voltage Control Oscillator, VCO, and Divider. 

The analysis of output phase noise can be modeled in steady states as four independent sources for a linear system, shown in color in the above block diagram. 

The Low Pass Filter, LPF, typically does not contribute to the PLL noise.  XO is typically the lowest noise source in the PLL.  For phase noise budget analysis at a system level in a typical design, XO, PFD, and Divider noise sources are lumped together and called PLL noise, whereas VCO noise is singled out independently.  VCO phase noise profile is high pass, while PLL has low pass phase noise profile.

Augment ORTENGA with in your PLL design team for phase noise analysis and line up budget of any radio and design validation.

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Posted on January 29, 2020

Search and Identifications Radar for Smart Train and Smart Helicopter Markets

Radars are used in advanced airplanes as part of Altimeter as well as Search and Identify heading of an airplane using legacy technology.

Civilian Helicopters are typical lack radar due to cost of legacy radar.

Also Trains are rarely use radar for navigation.

With the advance of semiconductor radar System on Chip, SoC, which are designed for Autonomous Vehicle, AV, the cost of realizing such radars are lowered. 

AV radar companies are uniformly focusing on Automotive market, which is a large portion of AV radar market, yet will return investment in several years, 2025 onward for large volumes and later for mass productions. 

There is another untapped market, which is not necessarily being designed for, Smart Train and Smart Helicopter markets, STSHSTSH market can use these radars to navigate in high populations and cities to avoid accident and/or crashes as it becomes evident and painful to hear on too often occasions.

Rest in Peace Kobe Bryant.

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Posted on January 27, 2020

Radar Pulse Compression Techniques and Waveforms

It is well known that radar waveform can either be tailored for range or its resolution.  In other words, the requirements for long range and fine range resolution are contradictory in nature.  In addition, it is also true that range vs. velocity resolution have contradictory design constraints which cannot be met simultaneously, unless more sophisticated waveforms are utilized which are known as Pulse Compression Technique.

The following diagram illustrates various Analog and Digital Pulse Compression Waveforms which are utilized by Radar Waveform designers to optimize range and its resolutions.

Pulse Compression and MIMO radar can be utilized to design appropriate waveform constraints for range, range resolution, and velocity resolution.

Augment ORTENGA with in your design team to deliver radar product for Autonomous Vehicle, eHealth, Smart Home, Smart City, or other applications.

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Posted on January 25, 2020

Phase Shifting Mechanism for Beamforming and Beam Steering Radio Front End Module

Any beamforming and beam steering radio front end utilizes phase shifting mechanism to point and steering the beam by changing inter-element phase shift among array of antennas.

Depending on the center frequency, fractional bandwidth, and required radio metrics of the front end, there are two topologies available, passive or active phase shifting mechanism.

5G mmW bands starts at 24 GHz and eventually allocated bands up and near 110 GHz.

Here are some options that may be applicable to your new radio.

  1. Embedded Transmission Lines and RF switches; they could provide around ~10% fractional BW. For example, at 24 GHz, 10% fractional BW is 2.4 GHz, which is more than enough.
  2. Active phase shifters, they have embedded RF switches and smaller foot print, also with approximately 10% fractional BW.

Keep in mind as the frequency increases, this 10% fractional BW would even produce more of absolute BW.  For instance, for 52 GHz band, the absolute BW could be as wide as 5.2 GHz.

On the other hand, if your new radio operates at lower frequency, say 10 GHz, then absolute BW could be as wide as 1 GHz, although wide yet may not be adequate to achieve VHT requirements.

Some of the design considerations could be such as; phase angle resolution, phase angle field of view, switching speed, settling time, insertion loss, etc.  Process control is also should be considered. 

Augment ORTENGA with your design team to determine the requirements for phase shifting mechanism and implement it within radio front end module.

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Posted on January 24, 2020

MIMO Application in SATCOM

Multi Input Multi Output, MIMO, is well known technique in Mobile Terrestrial Wireless Communications to enhance Throughput, Range, and Reliability via Spatial Diversity.

MIMO takes advantage of multipath between transmitter and receiver and combines multiple received replicas of the signals via DSP to enhance SINR.  The environment where MIMO flourish is multi independent path radio channel.  That environment typically exists when Transmitter, Receiver, or both are mobile and there are objects between them to instigate multipath.

Typical GEO SATCOM applications are for fixed communication links between transmitter and receiver.

In the case of mobile receiver in GEO network, there could be additional SINR improvement if multiple receiver antennas are utilized.

LEO SATCOM networks will be utilizing mobile satellites which handover the signal every several seconds. The receiver can be fixed or mobile.  For instance by using two receive antennas which are properly located at the UT, theoretically an additional of ~3dB SINR may be realized depending on implementation loss of the UT and if it is properly specified for receiver sensitivity.  Therefore, there could be some merits using MIMO techniques, so long as it is cost effective. 

Partner with ORTENGA for design and development of radio algorithms and implementations in your new product.

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Posted on January 13, 2020

SLL Management Algorithm Flow

Side Lobe Level, SLL, are undesired radiation characteristic of any antenna or antenna arrays.

Many companies spent significant amount of time and resources during the prototype development phase to mitigate SLL and qualify/certify the radiation pattern by FCC.  The issue which remains is two folds even after they succeed to meet FCC and regulatory requirements.

First, the SLL mitigation technique used are not optimum design performances and typically sacrifice antenna gain and power efficiency of Power Amplifier to meet regulations.  This in turn translates to lower C/N and/or Eb/N0, therefore lower throughput.  In other words, the transmitter suffers power efficiency as well as optimum throughput, two critical metrics for any transmitter in exchange for mitigating SLL, which should have been part of original design to begin with, hence lack of optimum design. 

Spending resources to design efficient power amplifier, yet backing off from efficiency sweet spot of Power Amplifier due to undesired and uncontrolled SLL defeats the purpose of the overall system metrics; that power efficiency and throughput, both of which impact bottom lines of the network operator.

Second, the additional time which takes for trial and error is reducing the chances of being in the market during the window of opportunity.

ORTENGA SLL Management Algorithm is proactive design and embedded during the development phase to expedite TTM while producing optimum design trade-off Gain vs. SLL, hence power efficiency and throughput, below algorithm flow.

Partner with ORTENGA for design and development of radio algorithms and implementations in your new product.

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Posted on January 12, 2020

Cost Effective Sub 6 GHz gNB Infrastructure

One of the major reasons for 5G NR architecture is reduced cost for given throughput, bps/$.

System Architecture contributes to overall Bill of Materials and cost.  Software Defined Radio, SDR, is cost effective and being utilized for gNB infrastructure SoC.  The removing of transceiver can reduce the BOM significantly for Digital or Hybrid Beamforming architectures.  

In fact, SDR architecture can also be utilized in MIMO radar systems.

Diligent systems definition and requirements enable cost saving architecture for appropriate market.

Partner with ORTENGA for Market analysis and/or Competitor landscape for your new product.

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Posted on January 11, 2020

Very Small Aperture Terminal, VSAT

VSAT are ground SATCOM User Terminals, UT, which have 75 cm to 1.2 m antenna aperture.

Although VSAT are typically utilized for GEO SATCOM Networks market, the growth is in LEO market for the next several years. 

LEO networks will provide higher datarate and lower latency relative to legacy GEO networks, comparable to 4G 3GPP.

Many companies are designing and developing LEO Hub, UT, and/or Satellites, which will be online as early as 2021.

Partner with ORTENGA for Market analysis and/or Competitor landscape for your new product.

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Posted on January 6, 2020

Beam Tracking Algorithm Flow

Beam Tracking Algorithm is utilized when there is beamforming and mobility either at transmitter or receiver.

The following diagram illustrates top level algorithms flow interactions, namely; Beamforming, SLL management, and Beam tracking.

It is worth mentioning that although the high level flow diagram is similar yet actual flow diagram may change depending on the applications and use cases.  For instance, in some use cases or applications, there is need for Target Acquisition Algorithm, before beam tracking algorithm of the target is invoked.

Partner with ORTENGA in design and development of any of the above algorithms for your new product.

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Posted on January 4, 2020

5G, SATCOM, and Radar Filter Requirements

Filters are widely used in radio communications and radar systems. In fact, multiple filters are used across any radio, namely; Preselector Filter, Image Rejection Filter, Channel Select Filter, Anti Aliasing Filter, Digital Filter in Decimation and Interpolation to cover some of them.

As the above filter names indicate, they impact anywhere from linearity, image rejection, resolution of ADC/DAC to DSP systems performances.  There are tradeoffs where to put filter and set its requirements in such a way that optimizes the system performance over all operational conditions.

Filter requirements impact other blocks performance requirements, such as; PA, LNA, Mixer, ADC/DAC, PLL, and Antenna. There are multiple Filter Topologies in Analog or Digital domains, such as; Butterworth, Tchebyshev, Elliptical, Bartlett, Hanning, Hamming, Blackman/Harris, or Kaiser filter.  Analog filters are implemented in the frequency domain, while digital filters are in time domain.

It is challenging task to relate each filter requirements to actual system metrics at radio level.  It requires both understanding of systems as well as impairments caused by lack of adequate filtering to draw and analyze appropriate filtering and implement them at the proper stage in the radio.

These filters are used in UE Mobile Wireless, UT SATCOM, SATCOM HUB, Mobile Infrastructures, and Radar Systems. If your system has Rx Sensitivity, interference, blocker, simultaneous listens and talks, ADC/DAC clipping issues, then it may need additional filtering or filtering at proper stage to mitigate the issues.

Partner with ORTENGA to analyze, drive appropriate Filter requirements, and/or implement the desired filter in Analog or Digital domain for your new product and market.

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Posted on January 1, 2020