By Dave Bursky, Semiconductor Technology Editor
The use of mm-wave frequencies for 5G radios in cellular handsets and other mobile devices brings the benefit of high-bandwidth multi-Gbit data transfers. However, the high mm-wave frequencies present many design challenges due to the propagation characteristics of mm-wave signals at frequencies of 26 GHz and higher. When used in mobile devices, the placement of the RF front-end modules must consider the position of the hand that holds the device, the materials used to hold the circuitry, and still other factors to ensure the front-end receives a usable signal and can transmit a signal at maximum strength.
Tackling all those challenges to implement mm-wave 5G radio on mobile devices, designers at Qualcomm Technologies Inc., in San Diego, Calif., have developed a fully-integrated RF front end for 5G mm-wave systems. The QTM052 mm-wave modules support bandwidths of up to 800 MHz in the 26.5-29.5 GHz frequency band (n257) as well as the full 27.5-28.35 and 37-40 GHz bands (n261 and n260, respectively). Qualcomm is currently sampling the modules to customers. The company is also working on future modules that will include multiband support to craft a more “universal” solution.
The modules were designed to work in conjunction with the companyʼs Snapdragon X50 5G modem and support features such as advanced beam forming, beam steering, and beam tracking capabilities to considerably improve the range and reliability of the 5G mm-wave signals. Crammed into a package that measures just about 0.75 in. long, 0.3 in. wide and less than 0.1 in. thick, are a 5G NR radio transceiver, a power-management chip, RF front-end components, and an optimized phased antenna array (Figure 1).
Figure 1. A little longer than the diameter of a penny, the 5G mm-wave module developed by Qualcomm (top left) contains a full RF front-end transceiver—power amps, antenna array, switches, multiplexers, power management logic, and still other circuitry. Also shown is the X50 modem chip housed in a BGA package (lower left).
The small size of the module, co-designed in a packaging joint venture with TDK, allows designers to incorporate up to four modules in a smartphone or other mobile device. Why up to four modules rather than just one? The answer has to do with all the negative effects that a human body, the mobile device materials, and the industrial design, thermal effects, surroundings, and regulatory requirements have on the reception and the transmission of mm-wave signals. By using multiple modules positioned in various locations in the mobile device, signal processing circuits in the system can select the module with the best signal from among the modules and actively switch the other modules into a lower power mode.
The mm-wave solution fits best in dense urban areas and crowded indoor situations and provides high-throughput 5G communications. Broader 5G coverage can be achieved using the sub-6-GHz frequency bands. Qualcomm RF modules QPM5650, QPM5651, QDM5650 and QDM5652 allow mobile devices based on the same Snapdragon modem to support 5G NR in the sub 6-GHz bands. These modules include SRS switching to deliver optimum massive MIMO (multiple input/multiple output) solutions and can support the 3.3-4.2 GHz (n77), 33-3.8 GHz (n78), and 4.4-5.0 GHz (n79) sub-6-GHz bands.
Conserving Power in 5G Systems will be Key in Handheld Devices and Base Stations
Energy efficiency in 5G systems is a daunting challenge for handheld systems, base stations, and other infrastructure hardware. Discussing many of the issues and challenges, a full day tutorial sponsored by IEEE Power Electronics Society, IEEE 5G Initiative (new Future Networks Initiative), and the SVC Communications Society, will bring together some of the best and brightest researchers in the world of telecommunications information computing technologies and network power. The tutorial will take place on Wednesday, September 19 at the Texas Instruments facility, Building E, in Santa Clara, Calif. (See registration details at https://goo.gl/1Fuhx2.)
As Brian Zahnstecher, one of the conference chairmen explains, “Even if you think you do not have much interest/involvement in 5G and/or telecom and ICT applications, this special program is focused on all aspects of network power optimization and efficiency opportunities. If you are involved in IoT, wearables, autonomous vehicles, factory automation, medical devices, AR/VR, edge/cloud computing, etc., then this is highly applicable to you. Today’s networks and devices are literally unsustainable (even in the near future) by today’s standards. There is not enough energy in the world to power the billions or trillions of devices predicted to be on the next generation 5G network.”
Opening the tutorial event will be a keynote presentation by Jaafar Elmirghani, the director of the institute of integrated information systems at the University of Leeds. In his keynote “GreenTouch – Yesterday, Today & Tomorrow,” he will introduce and discuss a number of measures for reducing the power consumption of cloud and virtualized communications networks, presenting methods for the optimum use of renewable energy in these networks to shrink the carbon footprint at a given power consumption level. Following the keynote, Chih-Lin I, the chief scientist for wireless technologies at China Mobile, will examine “5G’s Green Journey and More” from the perspective of a carrier. Deploying and operating the world’s largest mobile network with efficiency in mind has been an ongoing pursuit of China Mobile through each and every generation. She will provide an overview of China Mobile’s Green Action program that has led to the greenest 4G network from the first day of its deployment, and the world’s first multi RAT (radio access technology), multi-vendor plug-and-play energy saving solution. In addition, the presentation will highlight China Mobile’s 5G R&D themes (Green & Soft) that led to an end-to-end soft 5G architecture and how this has been reflected in the 5G NR specifications.
The telecom industry has gone through a major transformation when it comes to reducing energy consumption of cellular infrastructure nodes, according to Yiva Jading, a senior specialist at Ericsson Research. Her presentation titled “From Always On to Always Available” will highlight a successful change journey based on innovation and trustful collaboration between several companies and research organizations involving many R&D engineers. Our journey, started from the EARTH project, identifyed and shared best practice for LTE-product development, thus creating increased technology potential for low-energy operation with the 5G standard. The next presentation, “5G Densification and Network Power Efficiency,” by Apruv Mathur, a principal architect at Nokia, provides an overview of the future directions of different types of small-cell 5G RAN network deployments (e.g. indoor, outdoor). Additionally, he will highlight the tradeoffs linked to energy efficiency and usage of the spectrum and network resources. The session will also cover some of the energy savings and optimization techniques that are in play for RAN devices.
From the infrastructure component supplier’s point of view, Doug Kirkpatrick, the CEO of Eridan Communications, will examine “Mitigating Thermal and Power Limitations to Enable 5G.” In 3GPP, 5G-NR was defined with a modulation that inherently reduces energy efficiency of linear transmitters. This causes thermal problems from the dissipated power, which is a particular difficulty for massive-MIMO arrays. Temperature rise from transmitter power dissipation limits the array size that can be safely built. Achieving the multiple business objectives for 5G installations requires solving this problem. Sampling technologies are showing great promise. This presentation considers the physical basis of this thermal problem and shows how the sampling operation of the switch-mode mixer modulator (SM3) solves not only the thermal problem but also how, using the SM3, signal bandwidth efficiency is increased to 14 bits per symbol (16,384-QAM) with modulation within 0.5% of ideal.
Examining RF front-end design, Arniban Bandyopadhyay, Director, RF Strategic Applications and Business Development at Global Foundries, will discuss the technology challenges to meet both RF performance and power consumption requirements. His tutorial, “Silicon Technology Solutions to Address Power and Performance Requirements for Sub-6-GHz and MM Wave 5G Radio Interfaces,” will dive into RF front-end module architecture changes from current 4G to sub-6-GHz and mm-wave 5G radio interfaces. The focus will be to discuss how these technology challenges can be addressed by different silicon technology choices like partially-depleted and full-depleted silicon-on-insulator, SiGe and bulk RF CMOS. He will conclude by comparing the above technologies for different use cases.
Wrapping up the tutorial conference, Bruce Nordman, a research scientist at Lawrence Berkeley National Laboratory, will examine “Networked Electricity” – a generic technology solution that allows base stations to automatically adapt to any and changing power contexts, thus reducing costs, increasing efficiencies, improving performance, and enabling more use of renewables and storage. Networked electricity can also enable more graceful system degradation when power is in short supply. As systems move to more small cells, local power distribution (LPD) can offer diverse powering options, including the ability to draw on host site power and/or service provider power, with the mixture changing dynamically. LPD can make integration of local energy storage easier. This tutorial will describe LPD and highlight some ways that it intersects technology directions enabled by 5G technology, both for base stations and end devices.
(For the detailed program go to https://5g.ieee.org/education/ieee-5g-learning-series/ieee-5g-learning-series-bay-area-energy-efficiency-edition.)