Media convergence into the living room has taken significant steps, with digital TVs (DTVs) becoming more affordable and further fueled by the increase in popularity of digital/personal video recorders (DVRs/PVRs) like TiVo and ON DEMAND video streaming services. And with both Microsoft and Apple fielding home entertainment products into the market, it seems that the advent of a high-tech family room is becoming more imminent. Because of this paradigm shift, remotes are now expected to take on more than simply controlling just one piece of equipment.

Infrared & Its Limitations
Although remote controls were first introduced to the world in the 1950s, it wasn't until the use of infrared (IR) signals as the communication medium in the early 1980s that started the revolutionary adoption of remote controls in consumer electronics. IR gave manufacturers a simple yet low-cost way of uniquely mapping buttons to specific tasks, controlling a seemingly infinite assortment of brands, models and types of equipment. Universal Electronics and Universal Remote Control are two testimonies of IR's staying power after 20-some-odd years, as a portion of their revenue stream comes solely from the licensing libraries of remote control commands, or "codes".

However, there are several drawbacks to IR " the most obvious one being its reliance on line-of-sight in order to be operational. Left for many years without a reasonable alternative, consumers have adapted, albeit begrudgingly. One first needs to figure out where the tiny IR receiver window is on the equipment being controlled to point the remote at. Then after some getting used to, muscle memory subconsciously stretches the hand out at the correct angle to aim and fire. To further complicate matters, interior design and furniture is taking more of a Zen-like simplistic form, tucking components in recessed walls and behind oak cabinets, out of infrared's reach.

And how often do you find yourself hitting the same button multiple times to make sure the signal gets through? Though chipset manufacturers like Vishay and Panasonic are known for designing quality receivers, the infrared link is unidirectional and is not set up to have error detection/correction capabilities. Some of the energy radiated from plasma TVs is in the infrared range of the electromagnetic spectrum and hence can be a source of interference and impair the communication between a remote control and its host " a legitimate concern since DTV sales this year are expected to be on par with regular TVs. Compact fluorescent lights, or CFLs, are also another source of infrared interference and may prove to have more of an impact in the not-too-distant future. Within the last three months, Canada and Australia announced the banning of incandescent light bulbs, with the European Union and seven states in America soon to follow suit. And even though newer remote controls and receivers may have filters that lessen the impact of noise generated by these surrounding components, the link is just not robust enough. Simply put, infrared does not provide a reliable connection.

RF = Reliability and Freedom
RF = Reliability and Freedom.
In essence, infrared bears the same qualities of visible light and thus can only travel in a straight line. Alternatively, remote controls can use Radio Frequency (RF) as the medium of wireless transport and, in so doing, penetrate opaque objects and solid obstacles. Because of this inherent property, RF remote control users will also experience a new found freedom and mobility with the much improved operating range. Imagine being able to mute the TV without having to frantically run back to the living room when the phone rings!

Wireless communication is defined by both its hardware and protocol layers. From a hardware perspective, RF devices today are likely to be transceivers and thus have the ability to both send and receive information, as opposed to most infrared systems which are limited to unidirectional data transfer. In addition, RF systems typically incorporate some form of networking protocol to further enhance the robustness of the communication link. Protocols can vary in complexity " from simple acknowledgments to industry-defined protocols like 802.11 " and provide failsafe mechanisms for data error detection and correction. With such an infrastructure in place, RF can improve the overall user experience in a myriad of ways with a more dependable two-way interface. Plasma TVs and CFLs will no longer pose as an interference problem to remote controls and despite the fact that RF may be affected by different noise sources, automated recovery algorithms in protocols should insure button presses are always delivered to the host component.

Data acknowledgment is just one example of how a bidirectional link can be used to better remote controls. This two-way pipe should be further exploited to allow metadata to be sent from the host to the remote. A fine example of this is Microsoft's SideShow, one of the main attractions of Windows Vista. SideShow is an application that gives the user easy access with the use of a secondary display to emails, music collection, photo albums... you name it. It sends data to a variety of devices via mini programs called gadgets, and those devices can relay control commands back to the application on the PC. For example, an Outlook gadget can send the last five received e-mail message headers to an auxiliary display on a remote control or any other peripheral. Another even more exciting gadget is the Media Center gadget as it gives users access to the TV guide and even schedules recordings. SideShow is fast turning heads in the PC and peripheral market with nifty products like in-lid displays on notebook PCs and LCD-equipped laptop messenger bags. And because Microsoft has made gadget development opened to the public, the possibilities for metadata displays are endless. Finally! An RF remote control that will allow users to view the programming guide and scroll through their massive MP3 and WMA collections at the tip of their fingers!

Control Freaks
The more tech-savvy living room dwellers become the more control they require " the basic run-of-the-mill remotes that come bundled with the equipment no longer cut it. The Logitech Harmony series of remote controls is a testimony to this, having upped its revenue contribution to Logitech by 60% in 2006 from the year before. In other words, hundreds of thousands of consumers are making a conscious effort to purchase a Harmony remote which costs anywhere from $100 to $1000.

Some observers attribute Logitech's success to the growing number of electronic components in the living room, and Harmony's ability to consolidate the control of three, four even as many as 15 devices within a single remote. Despite the fact that universal remote controls have existed for a while now, there seems to be more interest in them now than ever before. This is mostly due to the exponential rise in personal media content in the last few years. Digital music, photos and video are the biggest culprits of this phenomenon, with consumers typically owning hundreds and sometimes thousands of audio, picture and video files. Compounded by the steady decrease in storage prices and technological advances in memory density, more manufacturers are adding hard drives into consumer electronic devices. As a result, an influx of digital media is being poured into the home and thus users are requiring additional control over the host device, other than just simple play and pause.

Innovation has paved the way for improving this much-sought-after user interaction. It is not uncommon today to see remote controls from Philips, SMK and many others with LCDs and touchscreens. The success of Nintendo's Wii, and its cleverly coined Wiimote motion sensing controller, provides an intuitive way for users to interact, navigate and manipulate items on the screen. It is indeed exciting to witness the unique navigation methods that are being embedded into remote controls " from simple laptop-type trackpads to multilingual voice recognition capabilities. And as these advance features become commonplace, RF as a communications transport, as opposed to infrared, will be even more necessary because of the higher bandwidth and reliability requirements these new features rely upon in order to properly function. Furthermore, RF will have a minimal impact on precious battery life " most RF systems consume an order of magnitude less power than the blinking of infrared LEDs.

Interviewing & Selecting RF Candidates
Interviewing & Selecting RF Candidates
Using RF for remote control connectivity is certainly not a brand new concept and proprietary solutions utilizing the 300-400+ MHz spectrum to tackle on the challenges faced by infrared were always available. However, this legacy approach was not for the faint of heart " only those who had RF expertise could design and develop the appropriate protocol and hardware necessary for the system. And even then, they were often limited to one-way communication links and complicated, expensive component circuitry.

Over the last decade, a slew of wireless technologies have surfaced with the promise of untangling and simplifying the network of wires running into homes, offices and potentially everywhere else. Bluetooth. Certified Wireless USB. Wi-Fi. Z-Wave. ZigBee. Along with a bunch of other proprietary RF solutions in various frequency spectrums. Each technology differs from one another and each is targeted to address particular applications. Each technology has its specific benefits and limitations. So which one makes sense for your remote control? That would greatly depend, first of all, on the type of device you are trying to create.

There are several key design considerations that should be consistent with the product's definition " power supply and battery life, operational range, interference immunity, signal penetration, product globalization, ease of development, user setup experience, wireless topology, interoperability, data throughput, among others. These features are individual topics worthy of a dedicated article in and of themselves. Of course, two other factors that can quickly trump those just listed above are time-to-market and cost. Once all these variables have been taken into consideration, the next logical step is to weigh their importance and use that ranking to determine the best wireless match for your remote control product.

A quick line-up of the usual suspects: Bluetooth has established a brand primarily around wireless headsets for cellular phones and is starting to find its way into cars as well for the same application. However, anyone who has tried Bluetooth out can probably identify the technology's limitations from their previous user experience. Pairing a Bluetooth device to its host can often times be frustrating, even for techies. Also, Bluetooth's power consumption is noticeably high for keyboards, mice, and remote controls which tend to use replaceable batteries; hence, its limited penetration into the Human Interface Device (HID) market, though efforts are apparently underway with a 2.1 version to reduce its current draw. And because Bluetooth resides in the same 2.4GHz unlicensed ISM (Industrial/Scientific/Medical) band as Wi-Fi, cordless phones, and microwaves, it will surely be challenging for a Bluetooth-enabled remote control to operate in a home environment without considerable impact to interactive latency and battery life, due to its interference-prone Frequency Hopping Spread Spectrum (FHSS) avoidance scheme.

Z-Wave and ZigBee
Z-Wave and ZigBee are wireless protocols aimed at, but not limited to, the automation and sensor network applications. Both have devices in the 900MHz ISM band, with ZigBee offering a 2.4GHz version as well. 900MHz solutions do allow for better signal penetration, but the tradeoff of lower data rate is unacceptable to some. While for others, developing one RF design is complicated enough, let alone different frequencies for the United States (908/915MHz) and Europe (868MHz), and at the end of the day still unable to sell into markets like Japan. Though costlier than Bluetooth and other similarly modest bandwidth technologies, Z-Wave and ZigBee are still attractive solutions for remote controls especially in the custom installer market " which typically service supersized houses " for their lighting control capabilities and mesh network topology.

With the proliferation of broadband internet, Wi-Fi is undoubtedly one of the most familiar wireless technologies today which makes it the least likely to face user adversity. Wi-Fi has more than sufficient bandwidth for not just displaying, but streaming, rich media content onto remote controls, and enough range to satisfy most homes. And while it does seem that Wi-Fi fits the bill as an ideal RF technology, the truth is everything comes at a price and in the case of Wi-Fi there are two: power consumption and system cost. A similar tune can be said of Certified Wireless USB, a cable replacement standard that is touted to be as user-friendly as its wired predecessor. A remote control solution that uses Wireless USB may stand to benefit from the preservation of the underlying architecture, functionality, and datarate of the now-ubiquitous USB, not to mention the engineering development expertise. It will, however, be too expensive to adopt for most device manufacturers who are accustomed to building $1-$2 infrared remotes.

What's In a Standard?
What's In a Standard?
All the technologies discussed above claim to belong to some form of special interest group, alliance, or organizational body, which then gives them the provisional right to be referred to as an industry standard. So for example, a chipset from Broadcom adheres to the same Bluetooth specifications as a device from CSR and by virtue of those requirements, both devices are interoperable, provided that they are official Bluetooth-certified products. This assurance of quality is one of the benefits of being a standard-complying solution. Some device manufacturers will seek that sense of security. Others are committed to a standard for the brand recognition it will bring to their product " these folks believe that having a Wi-Fi logo on the packaging is the stamp of approval needed for their end customer to make the purchase.

The ZigBee Alliance promises similar interoperability and thus a great deal of hype has surrounded it in the last three to four years. However, when one digs deeper into the specification, in order to be truly interoperable, there are hidden costs in terms of stack size, design complexity, and much more. Both chip makers and their customers have concluded that full mesh network systems and full interoperability is overkill in most designs. Furthermore, some prefer to add their special sauce in the mix, to differentiate themselves from their vanilla counterparts. Hence, there are numerous custom profiles and custom software protocol stacks already available and countless more in development. These solutions have essentially become proprietary solutions, but because the underlying PHY layer is still IEEE's 802.15.4-compliant, they continue to align their product positioning with ZigBee. On the other hand, while Z-Wave is recognized by most to be a standard, it is unique because Zensys is currently the sole manufacturer of Z-Wave compliant devices. But as announced in a recent press release, there are plans underway to license Z-Wave to other chipset makers.

Alternatives are available for developers looking to meet their customers' needs for greater remote control functionality while extending battery life and improving immunity to interference. For example, the block diagram shown below shows an implementation example of an RF remote control based on Cypress Semiconductor's PRoC family of system-on-chip (SoC) devices. These devices use Cypress's WirelessUSB radio technology which is embedded in PC input devices like keyboards, mice, and media center remote controls.

Needs Versus Wants
Needs Versus Wants
Like any emerging technology, there are more solutions available in the market than engineering resources can explore or develop, and wireless is no different. The current landscape is divided and segregated into far too many camps. Having said that, Media Center Extenders, Apple TVs, a forecast of 53 million worldwide IPTV subscribers in 2009 and many other forms of internet invasion into the living room may very well be the catalyst needed for a consortium to put together a simple, dedicated RF protocol for remote controls. In the meantime, before chalkboarding your next remote control concept, it is essential to keep in mind what the customer truly needs versus what is perceived as features they (do not really) want. Personally, I'd just like a pager function on my remote so I can buzz for it when my dog, Jordan, hides it away.

About the author
Leon Tan is a Product Manager of the Wireless Solutions team at Cypress Semiconductor. He currently is responsible for the WirelessUSB and PRoC family of RF devices and is the marketing lead for remote controls. A BSE Computer Engineering graduate from University of Michigan, Ann Arbor, Leon enjoys cheering on the Detroit Pistons when taking a breather from learning (pun intended) remote controls. He can be reached at leon.tan@cypress.com.