Inductor Guide

Wireless Communications / High-Frequency Inductors: Essential to Automated Driving

1. Major changes are happening to cars

I’m sure I don’t need to tell anyone that cars are going through major changes as we head into an age of automated driving.
Back in the 1980s, there was an American TV series called “Knight Rider”, which was also broadcast in Japan. The kind of “dream car” that appeared in this show is likely to come to reality in 2020 (or perhaps after). (I apologize to those of you too young to remember.)

Right now, we are pursuing the technology needed for the quest to achieve “dream cars.” Auto makers and other related manufacturers (Tier 1 and beyond) are competing to build up their technical strengths. Advanced safety functions such as automatic braking, lane keeping, and automatic parking are being incorporated into actual vehicles and commercialized. In addition to the technology, there are many other concerns to deal with: legal issues (1), social acceptance (2), and international cooperation (3). Quite a few relevant organizations are working on these and other concerns.

Achieving automated driving will be about more than just fulfilling a dream; it will help the world reach its common, greater goal of eliminating fatal traffic accidents. (4)

(1) Many issues still need to be resolved. For example, will it still be the obligation of a human operator to monitor vehicle operation while cruising? (Under current traffic laws, the driver must be able to drive the vehicle at all times; hands-free driving violates the law.) Will the car (system) be held responsible for any accidents? (It is extremely difficult for victims to prove the cause of an accident is on the system side.)
(2) People must become aware of the existence of automated vehicles so that there is nothing to keep the use of such vehicles from spreading. People will have to understand that automated vehicles must keep a certain distance from other vehicles and obey the speed limit to stay in compliance with the law; in other words, automated vehicles will seem slow. Passengers and surrounding people will need to recognize that automated vehicles will frequently operate at reduced speeds or even stop temporarily for the sake of safety. There is also the risk of people deliberately meddling with automated vehicles.
(3) Vehicles imported and exported will have to operate by the system in place in the country of use, and there must be international standards for the technology.
(4) Other aspects include environmental measures that will be made possible by relieving traffic congestion, means of transportation for the elderly, and accident prevention. A particularly large issue to solve with door-to-door automated driving technology is called the “last mile” problem. Door-to-door driving means vehicles must travel not only expressways and major thoroughfares, but also the neighborhood roads where people live.

2. The road to fully automated driving

Different levels of automated driving have been defined, and groups are working on them as milestones on the way to fully automated driving. Until last year, countries and standardization institutes had different definitions, but a movement formed to consolidate to the definitions established by the U.S. Society of Automotive Engineers, Inc. (SAE) at the end of 2016. In the SAE’s system, there are six levels, named Level 0 - Level 5.

Table 1: Automated driving level definitions (draft) 

IT Strategic Headquarters, Cabinet Secretariat, December 7, 2016
Adapted from “Movement Concerning Automated Driving Level Definitions and Response Going Forward (Draft), Reference 3”
*This link is only in Japanese.

Table 1-1: Overview of automated driving level definitions (draft) 

Level Overview

Monitoring for safe
driving, side that is

Human driver performs all or some driving tasks.
SAE Level 0
No Automation
Human driver performs all driving tasks. Human driver
SAE Level 1
Driver Assistance

The system performs sub-tasks to driving tasks related to
vehicle control for either backward / forward or rightward /
leftward motion.

Human driver
SAE Level 2
Partial Automation

The system performs sub-tasks to driving tasks related to
vehicle control for both backward / forward and rightward /
leftward motion.

Human driver
Automated driving system performs all driving tasks.
SAE Level 3
Conditional Automation
・The system performs all driving tasks
(under limited domains).
・There is an expectation that the human driver will
respond appropriately to a request by the system to
intervene in a fallback situation.


(Human driver in
fallback situations)

SAE Level 4
High Automation
・The system performs all driving tasks
(under limited domains).
・There is no expectation that the human driver will
respond in a fallback situation.
SAE Level 5
Full Automation
・The system performs all driving tasks
(under all domains).
・here is no expectation that the human driver will
respond in a fallback situation.

* Domains include not just geographical conditions but also environmental, traffic, speed, and time conditions.

Table 1-2:Expected time to achieve marketing and service (draft) (compared to technical examples in Government-Private Sector ITS Concept Road Map 2016)

Level Technology expected to be achieved (examples) Expected time line for marketing
SAE Level 2

Automatic lane changing
“Semi auto-pilot”
Driverless automated driving service
(for remote areas; limited to specific regions)

By 2020
By 2020
SAE Level 3 “Auto-pilot” 2020 goal
SAE Levels 4/5

Driverless automated driving mobility services
(in dedicated spaces; limited to specific regions)
Fully automated driving systems

By 2020
2025 goal




(Automated cruising mode for expressways; driver is responsible.
Equipped with functions to deliver system notices to driver based on cruising conditions.) 

(Automated cruising mode under certain conditions, such as expressways; system is responsible.
Driver responds if requested by system.)

Cars being sold today (February 2017) are Level 1 or 2 shown here.

Level 1 or 2 cars have one or more sensors (camera, millimeter-wave radar, laser radar, etc.) that capture surrounding conditions and motions. A computer determines whether those conditions and motions are a danger under pre-established standards, and if so, automatically causes one or more actions, such as applying the brakes. 

These are referred to as autonomous systems, since certain actions (recognition, judgment, and operations) are completed solely by systems built into the car. Such systems are called Advanced Driver Assistance Systems (ADAS) (5).

At these levels, the human driver still has an obligation to monitor driving and operate the vehicle; the system supports the human driver when conditions make it necessary.

Fig. 1: Illustrative figure of automated vehicles and systems

Japan Patent Office, February 2014
FY2013 Patent Application Technology Trend Survey Report (Overview)
Adapted from “Fig. 1-1: Scope of survey (illustrative figure and technology bird’s eye view figure) <self-driving automobile illustrative figure>”
*This link is only in Japanese.

At Level 3 and up, the system is in charge of driving, so the degree of difficulty is said to be very different. Issues that must be addressed include improving the image recognition accuracy of ADASs by using artificial intelligence (AI) (deep learning), accurately and safely operating the vehicle even as conditions change, and ensuring safety when making the handover from automated driving to the human driver (6).

Other items being considered are how to forecast dangers that the ADAS alone cannot protect against, and how to incorporate preventive safety.To give an example, let’s assume the ADAS has detected a danger and caused the automatic brake to operate. Even if the system manages to avoid a collision in front, it means nothing if the car gets hit from behind.

To give a separate example, the system also must respond safely when a car or person is in the camera or radar’s blind spot.

To deal with situations like that, certain information is needed, as follows:

  • Information between vehicles; by sharing information, vehicles can maintain a safe distance from each other.
  • Information on the motion of vehicles and people approaching intersections, as provided by sensors installed on traffic lights and other road equipment; this information would be conveyed to vehicles outside the camera or radar’s range of detection (including blind spots).

A scheme is necessary that allows the above information to be shared and anticipated so the system can forecast and avoid dangers. A cooperative ITS (intelligent transport [or transportation] system) is such a mechanism. Referred to as V2X (a general term for V2V, V2I, etc.) (7), schemes that would use an established communications protocol are under review.

Japan has decided on the standard ARIB STD-T109 (760 MHz band) as its transport system communications protocol, while Europe and the United States have adopted IEEE 802.11.P (5.9 GHz band). On the ADAS side, auto manufacturers are competing against each other on the merits of their technical strengths. V2X, in contrast, is largely being developed as part of the public transit infrastructure.

Telematics service (8), using a mobile communications standard such as LTE or 5G, is also being considered. Such service would take the place of car navigation. The service under consideration would create high-precision maps and 3D maps (9) and stay constantly connected to the cloud to provide timely map updates (a process known as dynamic mapping) (10). This feature would make automated driving accurate and safe. Authorities have also begun to look at other data and information services.

Recently we hear the term “connected car” frequently, and when these integrate with the aforementioned high-level ADAS and automated driving is perfected, this is what Level 5 Full Automation driving will look like.

As you can tell from the above, wireless communications will have a major role to play in Levels 3-5. When the day comes that fully automated driving technology is established and widespread, it’s easy to imagine that communications systems will take the place of today’s traffic lights, and will control the flow of vehicles so that there are no accidents or traffic congestion.

(5) ADAS (Advanced Driver Assistance System)
ADASs are on the market today, although manufacturers have their own names for them:“-------- Pilot,” “Safety --------,” “-------- Sensing,” and the like.
(6) The question is, when these systems encounter a situation they cannot deal with and responsibility for driving suddenly shifts to the human driver, is the driver ready to respond?
There are experimental results suggesting that humans need about four seconds to react once they get a system warning. It is said that today’s ADASs come with automatic stop functions in case the human driver does not respond despite a warning.
(7) V2V (vehicle to vehicle [inter-vehicle]) communications, V2I (vehicle to infrastructure) communications, etc., collectively known as V2X (vehicle to everything): In future, communications systems like these are expected to be obligatory in automobiles.
(8) Even now, telematics services are being provided. Automated driving, however, will require 5G, a transmission standard that offers high capacity with little delay. Services will also likely connect to the automobile IoT.
(9) Automated driving will require map data with centimeter-level detail and 3D maps capable of recognizing multi-level crossings. One way to make high-precision maps containing even neighborhood streets is to use sensor-equipped vehicles that pick up road information and share it with other vehicles through the cloud. It’s also very important that vehicles know their own position with great precision. In Japan, a variety of approaches are under study, including a method that uses the Michibiki Quasi-Zenith Satellite.
(10) Road conditions can change day to day (even moment by moment) because of accidents and construction. Therefore, studies are considering systems that constantly update to the latest information.
Fig. 2: Automated driving system development scenario

Ministry of Internal Affairs and Communications, June 3, 2016
Radio Policy Vision Council 2020 (No. 3)
Reference 3-1: Service Working Group Summary, Overview
Image processed from “Scenario for Development to Realize Connected Cars and an Automated Driving System”
*This link is only in Japanese.

3. High-frequency inductors for automobiles

As previously mentioned, wireless communications technology will be heavily involved in assuring vehicle safety once automated driving becomes reality. 

It may sound grandiose, but communications technology will have to be one element of safety for transportation in society as a whole. To meet society’s safety requirements, Murata Manufacturing Co., Ltd. is taking a fresh look at the reliability of each of its components and, as a basic rule, is committed to following the AEC-Q200 standard for automobiles. We are working actively to make sure our components meet expectations for infotainment devices and equipment where even greater reliability is essential, such as power trains and safety devices.

High-frequency inductors, in particular, are electronic components that have demonstrated enormous growth up to now for smartphones (and will continue to do so). Until now, they have had fairly limited application for automobiles, such as TV and radio signal receivers for car navigation systems, car audio, and other infotainment devices. Now, as we foresee an age of automated driving, we are building our lineup of reliable high-frequency inductors for safety functions (devices outlined in blue in Fig. 3).

One by one, we are working with the products in our LQP, LQG, and LQW series (Fig. 4) and series currently used widely in smartphones and consumer devices to enhance the reliability of each. Even in those cases where we are adapting design from consumer devices to on-board safety devices, we are working to bring out highly reliable high-frequency inductors that can be put to use without any major design changes.

Fig. 3: Places where automotive high-frequency inductors are used

High-frequency inductors by Murata
Details here.


Our automotive lineup is evolving! See our technical columns for more information about high-frequency inductors.

Lineup of LQW Series of Wire Wound Type RF (Radio Frequency) Inductors

Basic Facts about Inductors [Lesson 2] Roles of Inductors 1- "Inductors for high-frequency range"

Basic Facts about Inductors [Lesson 4] Roles of Inductors - "Structure of inductors"

Basic Facts about Inductors [Lesson 5] Technology for mounting inductors onto products

Wire-Wound ( LQW Series )

Film ( LQP Series )

Multilayer ( LQG Series )

*The information provided here only covers some aspects of automated driving. We have written it to be as easy as possible to understand. The development of automated driving technology, however, is keenly competitive right now, and the relevant information is constantly changing. Be aware that details may change between the time of this writing and the time of product release.


Sadao Kotera
Product Engineering Section, Product Engineering Department, EMI Filter Division
Murata Manufacturing Co., Ltd.

The information presented in this article was current as of the date of publication. Please note that it may differ from the latest information.

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