Healthcare Wireless and Device Connectivity

WLAN Convergence on a DAS and IEC 80001

Medical devices of which includes infusion pumps and patient monitoring and also other monitoring modalities as pulse oximetry, are in an increasing fashion moving their applications across the WLAN (Wireless LAN).  As a result of this there will be an increasing need to develop the correct deployment model to scale the x number of medical wireless enabled devices (no matter the bandwidth); and further how they will establish the correct QoS, and also to exist within the right quality of service (QoS) for all applications. Also has to be factored into how these life critical applications will exist with other needed data and voice requirements on the WLAN, i.e. quality of service, as stated.

All medical device manufactures with WLAN client adapters do have to be tested and validated not only the described quality of service or should; but have to submit their testing data to internal regulatory, and finally pass muster with entire FDA process.  This testing and design process of the WLAN has been based upon the well established and proven micro-cellular or proven (WLAN) architecture.  Many of these medical device companies have relied upon www.veriwave.com as Veriwave is the gold standard in the industry for this type of testing  Oh yes, the majority of WLAN companies use Veriwave for testing their internal radio designs.

Their seems to be discussions regarding the use model of these regulated WLAN devices that were validated on a industry best of designs for the WLAN industry to be utilized in a DAS infrastructure (Distributed Antenna System) architecture.

Several caveats need to potentially looked at or evaluated.

• Will the end hospital client or infrastructure provider assume the risk for the deviation from the approved and regulated model, that is the micro-cellular architecture (WLAN)?
• How will this infrastructure impact the proven quality of service model, and how acceptable will this be the the end user?
•  What is the overall initial cost and total cost of ownership to go against a proven industry standard micro-cellular architecture (WLAN) of those companies that control a plus 85% of the WLAN industry?
• End users should get several quotes of which includes a converged design, a stand alone WLAN cost model, and a stand alone DAS model.  They will be surprised at the cost deltas regarding a converged model, that is WLAN with a DAS.
• If the end client or infrastructure provider decides to drive this model, they should assume the costs of the additional infrastructure and any changes going forward, and yes what risks are involved?
•  Finally, one has to ask themselves how a DAS will ever support 802.11n or MIMO, and what implications this has for cost of changes of DAS infrastructures that were originally designed for 802.11a/b/g. Not that medical devices are incorporting 802.11n now, but this is the natural migration.
• DAS designs are normally non-diversity, so how will this impact the S/N (signal to noise ratio) or help negate multi-path occurences that can be overcome with a diversity or MIMO micro-cellular infrastructure.

See of which is attached a most excellent article touching on several of the aforementioned topics by Dr. Steve Baker. Steve and I have authored an article before and I consider him one of; if not the most respected authority on challenging the correct use model of medical devices in the WLAN industry.

 

Download Wimd2225-baker1_authors_version
 

802.11n MIMO is the threshold reached with convergence on a DAS?

While I have never been an advocate of overlaying WLAN on a DAS, in theory and some practice this could be done with 802.11/b/g and even (a); however everything comes with a price.  Engineering to -85dB for data for 802.11a/g, while not diversity  this may or could be done. Adding capabilities for voice (voice over IP), and you have another dimension such as an increased signal strength requirement of -65dBm. Then when you add 802.11a, amplification of the signal is needed either at the antenna element or in the IDF (to meet the link budget.  DAS systems work well for what they were intended to do. That is transmitting broadband signals such as traditional cellular at 850MH and PCS at 1900MHz. At these frequencies you have a approximate coverage pattern of 10,780 sq. ft. per antena element. At the VHF or UHF range this dramatically increase to 34,375 sq. ft. However to to meet the link budget requirement when WLAN is combined on a DAS, this decreases coverage to 3,520 ft per antenna element.  Adjustments also have to made for 1/2" coaxial cable loss.  Going back to 850MHz and 1900MHz, you will have 2.5db of loss for every 100ft at 850MHz and 4.0 db of loss at 1900MHz.  At 5.750GHz, this loss increases dramatically to 8.0 db for every 100ft.  Now moving to 802.11n and the use of MIMO. The race is on between Verizon and LTE oer 700MHz and Sprint with WIMAX.  Not doubt LTE will probably take the edge because of Verizon's major footprint and the fact that a huge build-out is not required as required for WIMAX.  DAS companies tend to claim support of 802.11n because of the inherent portended support of MIMO for WIMAX. Again, the question begs to mind how the heck will this work?  Oh yes, and how much will this actually cost? Remember MIMO needs multiple antenna pathwyas (in and out x 2). If the AP(s) are in the IDF, will you need four independent runs of coaxial cable or do you extend the AP(s), out on the floor and then come up with a way to run ethernet over coaxial? MIMO should be preserved as it takes advantage of multi-path to increase throughput in theory up to 600MB/sec, realistically 300MB/sec. My suggstion for any enterprise customer that is looking for 802.11n and a DAS is pretty simple.  Get a DAS quote for all the broadband services, i.e. cellular, PCS, UHF/VHF, etc. Then get a quote for a discrete (stand alone), WLAN, i.e. 802.11a/b/g/n.  Then get a quote from the DAS supplier for broadband services and WLAN services (to include 802.11n). Compare pricing of all quotes two discrete systems versus combined. Finally get in writing as a part of the contract documents that 802.11n will be fully supported in all it's features and functionality. In addition, contact your WLAN provider of 802.11n, and obtain in writing that they have tested and that they approve the use of their specific 802.11n AP and controllers with a DAS.

 

802.11n and what this means to the macro cellular environment

With the innovations in multi-mode devices such as the I-Phone, just by the huge applications being offered, by default this places huge challenges for ATT for handling such new great innovations such as www.airstriptech.com. While it is felt that this device will provide provide access to these innovative applications outside of the building environment, the applications will only drive further the requirement for a DAS.  It is no longer just the voice side. Also, the desire to download PAC images for consult;  it looks like a perfect storm for 802.11n. (off-load from the macro network to the private WLAN).

Inaugural Medical Device Connectivity Conference and Exhibition

This is the final brochure (actually updated URL which will provide any last minute changes) of the Inaugural Medical Device Connectivity Conference and Exhibition. Integra Systems will speaking on September 11, (Day Two) at 830A.M. Track A "Infrastructure"  Converged Medical Device and Enterprise Networks: Challenges and Best Practices. In addition, we will host a Post Conference Workshop that same day from 2:00-6:00P.M.  The title of this workshop is "Distributed Antenna Systems in Hospitals: Best Practices."

  

 

http://www.tcbi.org/files/brochures/MDC_2009_Brochure.pdf

AAMI Article on DAS (Distributed Antenna Systems)

Integra Systems, Inc. along with www.interface.cc, has been selected to author a design and technology overview article on DAS (Distributed Antenna Systems), for healthcare. The article will be an engineering perspective based upon the collective years of domain experience with the landscape of solution offerings. This copyrighted article will be a publication of www.aami.org and should be coming out in the next circulation of IT Horizons.

  

 

The Most Comprehensive DAS Platform....Yet...By Far.

There is a reason that SOLiD is at the top of this page. It's because they are at the top of their game.  Modular design, exceptional quality, innovative and precise control, all wrapped in a competitively priced solution; it is the total next generation DAS solution that can blow the socks off of existing active or passive designs. Consolidation in the DAS marketplace of companies will occur in 2009 and 2010, just like in the WLAN space.  At the end of the day only the right business DAS model will prevail perhaps without any external funding. You have to be able to execute with the right business channel with the innovative technology at the correct price point. In todays economic climate where technology has been commoditized, it is about execution of the solution at the right economic value. What makes the SOLiD solution for the United States so unique and financially compelling for the enterprise marketplace...especially healthcare?

- The best price/power ratio in the industry. SOLid's high power output requires less hardware and therefore costs less than comparable systems.

- Supports all public safety and cellular services including 700MHz and AWS with just one strand of fiber to each remote.

- A modular design permits you to buy what you need now and then upgrade to new requirements inexpensively later.

- The remote units comply with fire code and NEMA 4 requirements at no additional cost.

- The most precise filtering available in any DAS system on the market.  Eliminates interference issues and permits load balancing among cellular services.

 

The Technical Rationale of a DAS (Distributed Antenna System) for Healthcare

Beyond the business rationale for distributed antenna systems in healthcare, there are very valid technology reasons from a user model perspective.  Much has been written about cell phones interfering with medical equipment.  This is one area that is very much mis-understood.  A cellular site (tower) will have an output power of approximately 20W per carrier and there will be multiple carriers being broadcast or radiated. The antenna elements will have a gain of at least 17dB. The overall effective isotropic radiated power is 1000W per carrier (60dBm). Most of the new construction using reflective glass for LEED environments will provide 20dB attenuation.  It is likely that the tower is not next to the hospital but more than estimated to be a mile or more away. From a mile, the free space path loss is 95dB, thus the signal entering the building is -35dBm per carrier, which is around 1/1,000,000W.  Due to older and the newer LEED construction, hospitals have become very bad multi-path environments. So dealing with this minute signal, the cellular device many times has a hard time to keep the sufficient signal strength (-85dBm or 5 "bars"). In order for the mobile device to achieve the uplink, the power control algorithms boost the power of the mobile device. (The simple reason why your battery drains faster when you have poor coverage).  Cellular devices also can transmit at relatively high power levels (perhaps 1W for short periods of time such as during the ring cycle). However if the mobile device has adequate coverage via a DAS, the path loss between the cell phone and the indoor DAS, will be much lower than the cellular device and the actual cell site.  The power control algorithms within the cellular network will cause the cell phone to transmit at much lower levels, (potentially under 5mW), which really is not a problem.  The result is the power control algorithms will reduce the power required for the uplink which increases battery life and decreases drastically the concern for any EMI.

Infrastructure Cost Considerations for DAS

While Distributed Antenna Systems (DAS), have a great place in healthcare, there are also many considerations of the technology offerings in the marketplace. These are some of the questions to perhaps ask?

1. Generally single mode fiber based designs are more cost-effective in areas over 200,000 sq. ft. (Link Budget considerations go into effect as over long distances fiber is a better transport medium than coaxial cable) So the question comes up should I use a passive or active design?

2. How many single mode fiber (strands) are required from the MDF to each IDF?  Less fiber runs, less cost.

3. Is the remote unit modular?  This allows for a building block approach, starting out with a public safety requirement then cellular and/or PCS. This saves costs over the life of the DAS.

4. How much power does the remote unit provide?  Higher composite power simple means you save costs by less number of remote units, versus one in each IDF.

5. Can the DAS proposed support all services such as the requirement for 700MHz, public safety and AWS?  This ensures support of all services going forward without a rip and replace strategy.

6. Is 802.11a/b/g or 802.11n being discussed?  If so, how will the DAS support MIMO of which is a requirement of 802.11n?  Does the WLAN vendor support this in their technical design guides?

7. What design tools are used?

DAS Article for Publication Forthcoming

Integra Systems, Inc. has been selected again by one of the leading publications in healthcare to author an article on Distributed Antenna Systems.  This should be coming out in the next couple of months.  It will go in depth on the nuances of passive/active designs, what is a BDA, the link budget, challenges of incorporating 802.11a/b/g/n, and what the future holds for these solutions in healthcare.

SOLiD and Integra Systems

Integra Systems, Inc. "blog" is non-biased educational content and is not endorsed or paid for by any technology provider.  The intent of this content is to educate and give opinions about new and otherwise forward looking technology in the mobility, wireless, and medical connectivity space.  The end goal is to provide a better informed audience of these spaces from one who has been in the field and these industries multiple decades; actually being hands on..making things work.  Further this is also based upon many years of distinct knowledge and hands on technical design experience in the DAS marketplace.

It has recently surfaced by documented and retained emails by futher third party entities that is has been suggested that Integra Systems, Inc. has been employed by or solicited funds from SOLiD for any content as provided on this blog. This is because or perhaps of recent or certain "blogs" discussing the merits of their forward looking DAS (Distributed Antenna Systems), design.

Let it be known that Integra Systems, Inc. "HAS NOT BEEN EMPLOYED BY SOLiD, or RECEIVED ANY FINANCIAL RENUMERATION FROM SOLiD". The only intent of this blog and provided postings has been to point out the uniqueness of what  seems is a next gen offering  i.e. fiber fed DAS, both from a technology and financial ROI perspective. These types of discussions it is felt will only help the overall DAS marketplace, and provide better solutions to enhance the future in-building wireless experience. At the end of the day it our goal to provide best user experience at the right price point. The fact that this creates this discussion, it is great. I only helps the end user make the right decision.

Integra Systems, Inc. will to this date will ascertain currently to  pursue all legal recourse to ensure that the content of this blog is not misrepresented, and to further protect the professional reputation of Integra Systems, Inc.