Takavar Saremi, Sr. RF Design Engineer, SpaceX

The biggest challenge by far has been the age old trade-off between (power amplifier) efficiency and linearity.  To date, despite all of the advances made in area of linearization, we are simply in a situation where we cannot end up with the efficiency of a compressed amplifier when amplifying modulated waveforms with appreciable peak to average ratios at frequencies and bandwidths typically employed for satellite communications.

David Goins, CTO, Windfreak Technologies

The biggest challenge facing a designer of wireless applications is not necessarily the RF part of the design. That’s what some people call the “Black Magic” portion of wireless devices. 

In my experience, the RF portion of the circuit complexity has been getting easier and easier. Over the years, there has been massive integration of features into fewer and fewer chips. My last project was a dual channel, USB-controlled, RF signal generator that operates from 55 MHz to 13.6 GHz. The RF circuits were all 50 ohms in / 50 ohms out. I actually got good results on an FR4 printed circuit board all the way up to 13.6 GHz. Other than some isolation issues, the first prototype worked well and required little time.

The most challenging part of designing a wireless device is definitely programming. The RF circuits in the SynthHD USB-based RF signal generator are serially programmed by an onboard microprocessor that needs to do 64-bit math.  There are 15- 32-bit registers that need to be calculated for the RF circuit, plus some D/As for controlling circuit gain. The processor also needs to communicate via USB to a personal computer. Therefore, I selected a 32-bit ARM microcontroller from Freescale.

For the first shippable units, the firmware that went into the processor was greater than 3,000 lines of code including comments. Since the first shipments, more lines have been written for expanded features and bug fixes. Firmware and software development have been 95% of the work involved in the development of the RF signal generator—it also promises to be 95% of the sustaining work for that product in the future.  Clearly this is the biggest challenge to designing wireless applications.

Jeff Shamblin, Chief Scientist, Ethertronics

Speed, range, product design, efficiency and reliability from mobile phones to Wi-Fi and the Internet of Things are key challenges designers face for wireless applications and devices.

Multiple use cases with mobile devices continue to develop driving advances in technology. These devices must support a wide range of other services that consumers have become dependent upon such as text messaging, MMS, email, Internet access, short-range wireless communications like Bluetooth and Wi-Fi, business applications, gaming and photography. Wireless application design must adapt to the changing environment.

Video streaming has become more popular with applications such as YouTube and video integrated into everything, furthering the demand to deliver high quality video to maximize the user experience. Continuous design improvement is needed in order to limit disruption, improving overall wireless performance.

In terms of product design, the demand to have consumer devices maintain a thin, sleek profile has increased, causing the space inside smartphones and devices to decline 25 percent annually. This trend compounds the challenge of finding room for all of the antennas required to support Multiple Input Multiple Output (MIMO) and multiple bands, especially the lower frequencies preferred by operators (700MHz), which require physically larger antennas. LTE devices such as smartphones also need antennas for GPS, Wi-Fi, Bluetooth and NFC, plus 2G/3G fallback. A thin form factor places constraints on the functionality and performance due to wireless capacity limitations. The challenge becomes identifying performance requirements, as well as application usage and connectivity to help determine the volume of the application before designing.

Common to all of these challenges is the performance of the antenna which is a major bottleneck in today’s Wi-Fi networks. Designers will need to deploy smart antenna system solutions to meet the range, throughput, design and reliability needs of today’s wireless users. One example is the Active Steering Antenna System from Ethertronics which improves Wi-Fi connectivity, for range and reliability, resulting in a 50 percent improvement in coverage and signal quality.

Peder Rand, Applications Manager, Wireless Connectivity Solutions, Texas Instruments

The first and sometimes the biggest challenge you face is choosing the right wireless technology. There are lots of good options available, but they all have limitations and it’s important to uncover them before you are too far down the path of implementation. A common pitfall is choosing a wireless technology that is unnecessarily complex for the application. Implementation using a complex protocol may still be relatively quick, but the testing phase can be very demanding with many modalities and corner cases.

The second challenge is getting the range that you want without spending too much power or violating any regulatory requirements. There are some very real physics that dictate how well a signal on a certain frequency propagates through a body, house or building. A well-defined worst-case supported use case should always be defined up front and that will dictate choices on frequency, antenna, output power and sensitivity. Meshing helps if and only if you can count on evenly distributed routing nodes.

For battery-operated applications, getting the battery life you need requires thoughtful planning of all component choices, connections and power states. Use a published or measured power profile from actual application use to calculate your energy requirements rather than relying on data sheet numbers.

Security requirements are very application dependent, but good off-the-shelf solutions exist for both encryption and authentication. It’s important to consider key management in the whole lifetime of the product through production/programming, initial connection to its network and eventual re-commissioning to a new network.

Finally, it should be said that designing for wireless applications used to be a lot more challenging. These days you generally get good reference designs and sample implementations that are functionally very close to your end application. You start out from something that works, and have good guides to do your customization. Our office periodically runs 24-hour innovation events where we get very close to end product functionality before we rip a new page off the calendar.

Sol Jacobs, VP and General Manager, Tadiran Batteries

One of the main challenges in designing a truly wireless device is choosing the right power supply.

If extended service life is required, then the ideal solution usually involves an industrial grade bobbin-type lithium thionly chloride (LiSOCl2) battery, with certain cells having been proven to deliver 40-year battery operating life.

If the application involves energy harvesting, then you may want to consider the use of an industrial grade Lithium-ion (Li-ion) rechargeable battery, which can operate for up to 20 years and 5,000 recharge cycles, far exceeding consumer grade Li-ion batteries that work for approximately 5 years and 500 recharge cycles. Consumer grade batteries are generally recommended if the wireless device is easily accessible for battery replacement and in relatively mild operating environments.

When choosing among industrial grade batteries, start by comparing the annual self-discharge rate. Remote wireless sensors often consume more power as a result of annual self-discharge than through actual energy consumption, so even a relatively small improvement in the battery’s annual self-discharge rate can translate into decades of extended operating life. Ruggedness and reliability are also important considerations, as is an extended operating temperature range, especially if the wireless device is being deployed in extreme environments.

Product miniaturization is best achieved through a battery that delivers high energy density and high voltage, thus creating the possibility of using fewer cells to power the device. Also be mindful of total lifetime cost calculations, as the low initial cost of a consumer grade battery can be highly misleading once you factor in the all the ‘hidden’ costs associated with multiple battery replacements, as labor expenses can far exceed the cost of the batteries themselves. Application-specific requirements will ultimately dictate your ideal power supply.

Cees Links, GreenPeak Technologies

Designers of wireless applications for the Smart Home are facing a bevy of challenges. How do you make it small enough, how do you make it secure enough and maintenance free, how do you ensure that your new application will communicate with other wireless applications – both those currently available as well as what may appear in the future. How do you create a smart home device that will be successful?

To solve these questions, one needs to understand what customers really want – what the industry is truly looking for. Many companies today are making the mistake of thinking that simply connecting a device is good enough – it is not. They need to understand that Smart Home customers want services – not just connected devices. They are looking for services that make their live safer, more secure, and more convenient, and more efficient.

To be successful, wireless device developers need to create a network of devices, actuators and controllers - often called sentrollers – that incorporates intelligence and the ability to learn. It is no longer enough to be connected, it has to be smart.

A the recent CES event in las Vegas, the new Family@Home system from GreenPeak Technologies garnered a lot of attention from retailers, service providers and customers alike. They all wanted a system that connected a wide range of services, ensuring family safety and comfort, to monitoring and managing the home’s internal environment and energy consumption. Wireless device developers need to think big – consider the entire ecosystem – not just connecting an appliance, device or a sensor to the internet and remotely managing it.

Alan Grau, President, Icon Labs

Battery life, size and price constraints are driving many IoT sensor deployments. With the sheer number of endpoints being deployed, small differences in price can have a major impact on the viability of an IoT initiative.  Extending battery life is an even more critical requirement in IoT systems.  Replacing sensors in the field is obviously an expensive task. 

In the drive to meet these challenges, security is often overlooked or neglected.  However, this doesn’t have to be case.  Finding the balance between size, price and battery life, on one hand, and security on the other hand, is a key challenge for Wireless IoT developers.  Scalable solutions are available, both in the form of hardware security modules and software security frameworks.  Balancing these requirements will be critical to creating the Internet of Secure Things.

Roger Schroder--Engineering Manager, Stahlin Non-Metallic Enclosures

Wireless enables easy communication between device sensors. The simplification of this connectivity allows for additional sensors to monitor machinery so that far more data can be collected.

However, the challenge with wireless data transmission, such as radio, is that the proportion of energy received becomes critical if it is too low for the signal to be distinguished from the background noise. Radio receivers retrieve all signals on the frequency at which the receiver is set, and in the case of WiFi, it’s 2.4 GHz. For data transmission to occur, the WiFi signal must be at least 20 dBm greater than the signal level of background noise or spurious transmissions. If a signal is shielded, the signal-to-noise ratio (SNR) diminishes and the signal level drops below the 20-dbm threshold. Data transmission errors occur as a result.

Hence, process facility designers with the opportunity to select their enclosure material should investigate and determine that selections are appropriate for wireless data transmission in the intended environment.

In general, metallic enclosures for WiFi components have proven somewhat ineffective unless there is an external antenna. Unfortunately, external antennas have many downsides including vulnerability to environmental elements such as corrosion, ferrous-oxide deterioration, and natural ambient interference coming from environmental forces. This is why many designers are making the switch to non-metallic materials because they allow for free transmission of electronic signals and antennas can be placed securely inside the enclosure.