Because the security aspect of Bluetooth is greatly improved and newer technologies counter the RF interference often caused by wireless overcrowding, Bluetooth is becoming a much more trustworthy connectivity solution even in hospitals and other healthcare facilities.
Hospital Settings And Its Effect on Connectivity
Hospital settings are both hectic and fast-paced. The evolution of connectivity technologies greatly enhances a hospital’s ability to successfully deliver vital services, but there are a multitude of RF obstacles inherent to a hospital or other medical settings. The following are just a few of these obstacles.
- Challenging Physical Environment:
Walls, electronic equipment, and people are obstacles to efficient and reliable wireless communication. With so much inherent water, human body can both reflect and absorb RF energy which means that, the busier the hospital, the more likely the disruption of radio signals.
- Unpredictable Capacity:
When the hospital faces an influx of patients, this means not only an increased use of wireless medical devices used to treat the patients, but a significant increase of associated non-medical devices as well. The patients and their accompanying family members or friends bring their own devices and their own bandwidth. With the ever-growing reliance on wireless communication and the sheer number of wireless devices, it’s important that hospitals can handle the varying bandwidth needs without sacrificing critical connectivity.
- Unique Sites or Situations:
Although hospitals in general serve a common purpose, there is no one-size-fits-all connectivity solution for healthcare facilities. Each situation or site is unique and requires a custom solution. Understanding the physicality of the site as well as predicted network needs.
Understanding Bluetooth Technologies
This section delves into coexistence issues that may arise with the use of Bluetooth (and ways to mitigate them) as well as Bluetooth mesh technology which can greatly boost its connectivity performance.
Coexistence Between Bluetooth and Wi-Fi Technologies:
Within a hospital setting, there is a wide variety of both medical and non- medical equipment that can create RF interference. While Bluetooth and Wi-Fi often use the same frequency band, they are practically non-competing technologies. Each has its own specific applications and, oftentimes, these applications even require that both technologies co-exist in the same network and sometimes even in the same system. To ensure that Bluetooth and Wi-Fi technologies are not hindered by one another’s presence, engineers must not overlook coexistence or collocation when designing RF systems that include both Bluetooth and Wi-Fi.
Bluetooth Low Energy:
Bluetooth LE is ideal for applications that intermittently send small amounts of data – applications we see, for example, in a wide variety of medical devices such as blood glucose monitors and pumps, pulse oximeters, asthma inhalers, fitness trackers, blood pressure monitors, and more. For reliable operation in the crowded 2.4 GHz frequency band, Bluetooth LE utilizes frequency-hopping spread spectrum methods that involve what’s called a channel map update procedure. This procedure can be utilized with both non-adaptive channel blocking and Adaptive Frequency Hopping (AFH).
Spread spectrum signaling offers two main benefits. First, a wideband signal is far less susceptible to intentional blocking (jamming) and unintentional blocking (noise or interference) than a narrowband signal. Second, a wideband signal sometimes can be perceived as a part of the noise floor (static interference) and thereby remain undetected. The two most popular spread spectrum signal structuring techniques are Frequency Hopping Spread Spectrum (FHSS) and Direct Sequence Spread Spectrum (DSSS). Bluetooth uses FHSS whereas Wi-Fi uses DSSS. Given that both technologies operate in the same frequency band, this use of differing techniques is the heart of potential Wi- Fi/Bluetooth coexistence issues. FHSS devices and DSSS devices perceive each other as noise—Wi-Fi and Bluetooth are mutual interferers.
Channel Map Update
Although the 5 GHz frequency band has absorbed some of the RF congestion, Bluetooth coexists on the 2.4 GHz band with Wi-Fi, ZigBee, and other commercial applications. It is important that Bluetooth devices can mitigate the interference and communicate effectively on this crowded frequency band. The channel map update procedure allows peer devices to determine (or agree on) which channels are best to use – which ones are not hindered by interference.
At the most basic level, channel map updates simply involve any of the associated Bluetooth devices detecting a channel with high interference and ‘suggesting’ that it not be used. The master device then disables this ‘bad’ channel and it remains disabled for the remainder of the current connection. If the interference dissipates, the channel still remains disabled until the devices are disconnected and a new connection is made.
There are two general methods to improve upon this most basic version of channel map updates: proprietary algorithms or Adaptive Frequency Hopping (AFH). For Bluetooth, AFH involves scanning for busy channels and, when found, altering the channel map to avoid them. The key difference is that, with AFH, it is a dynamic process – the communication devices constantly monitor and can continuously change the channel map to mitigate the interference. Bad channels are excluded only until they are no longer congested. In addition, AFH involves the ability for the selected channel to frequently change to allow the transmission of data over a wider collection of channels to avoid interference and perform better in busy radio environments.
Throughput and Range Tradeoffs in Bluetooth LE
To adjust to difficult environments where Bluetooth connectivity might be challenged, Bluetooth 5 offers two new physical layer schemes that each have their own advantages. Your choice depends on whether you need greater throughput or greater reliability in range.
Better Range with LE Coded PHY
LE Long Range/ Coded PHY provides increased range not by increasing the output power but by using bit expansion using Forward Error Correction (FEC) coding. It sends each bit in the data packet as coded 2- or 8-bits in order to give more devices at farther distances the opportunity to successfully receive transmissions. Testing by the Laird Connectivity team and other organizations show that LE Long Range/Coded PHY can successfully increase range up to 4 times while also improving sensitivity of receiving devices by 4 or 12 dB.
Higher Throughput with LE 2M PHY
Bluetooth 5 adds support for an 2 Mbps PHY, known as LE 2M PHY. It allows data to be transmitted at the higher two Mbps symbol rate, which achieves around 1.5x the final throughput of the original 1 Mbps modulation. Both 2M PLY and LE Coded PHY achieve their results without an increase in power, and both have their advantages and disadvantages. In general, if higher throughput isn’t a requirement for your application, LE Coded PHY provides an obvious advantage. Connectivity in medical applications is critical, and LE Coded PHY provides a reliability boost, especially considering the densely populated environment of a hospital.
As Bluetooth security has been enhanced using asymmetric cryptography, major security concerns have been addressed (especially beginning with BT 4.2) and adoptions of Bluetooth in medical have increased. Pairing modes prior to Bluetooth 4.2 are now known as legacy pairing. Since Bluetooth 4.2, pairing now involves LE Secure Connections based on Elliptic Curve Diffie-Hellman (ECDH) cryptography. By incorporating ECDH into Simple Secure Pairing, Bluetooth now uses private and public key pairs that are extraordinarily difficult to break. Once paired, Bluetooth LE modules within devices are extremely secure.
Some of the other enhancements since Bluetooth 4.2 include: connection orientated isochronous communication and mode 3 security for LE audio; enhanced attribute protocol to require encrypted connection to transmit data; configurable minimum key size to ensure connections have a baseline level of security; 2M PHY for faster and easier OTA updates.
As Bluetooth technology has evolved to be more secure, more and more applications that leverage this technology have come into play, even in medical spaces. With its low-power consumption ability, prolific global use, and scalability, Bluetooth is a great add-on to wireless infrastructures that support critical healthcare settings.
About Laird Connectivity:
Laird Connectivity simplifies wireless connectivity with market-leading RF modules, system-on-modules, internal antennas, IoT devices, and custom wireless solutions. Our products are trusted by companies around the world for their wireless performance and reliability. With best-in-class support and comprehensive product development services, we reduce your risk and improve your time-to-market. When you need unmatched wireless performance to connect your applications with security and confidence, Laird Connectivity Delivers – No Matter What.
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