From the monthly archives: "June 2012"

 Have not had a ‘real’ vacation in a long time…so this is therapeutic. There’s a lot happening in the world and we will discuss…there are some interesting developments. Woohoo!

 First ran across this story in After reading through the presentations and watching some of the video presentations, I was initially very skeptical. After thinking about it a while, it strikes me that this seems very sound approach even if the exact implementation for a commercial wireless networking infrastructure is different than what Dr. Amir Khandiani has outlined. So going a step further, I’m going to say this is a legitimate candidate for improving LTE and useful as a cornerstone to a 5G wireless. 

Firstly, there is a patent, Methods for spatial multiplexing of wireless two-way channels 7,817,641that covers most of the technology in this discussion.

From his presentation, the summary of the patent is: 

  • New methods for antenna design
  • New RF and base‐band processing brings degradation in SNR due to self‐interference close to zero.
  • Support for asynchronous clients (superimposed networking)
  • Support for MIMO
  • New applications for full‐duplex wireless
  • Hardware, RF and DSP complexities are virtually the same as half‐duplex units.
The technology is a layered approach that first utilizes a symmetrical antenna design including symmetrical pairings of multiple antennae to create nulls relative to TX and RX signals.

2D Symmetrical Antenna

MIMO Symmetrical Antennae

His presentation shows a null of around -15dB on a scope just for antenna nulls. This deserves a checkmark for simplicity.

The second layer of this technology involves active cancellation that is not-syncronized to the TX. He suggests if using a single TX chain, then just go to active interference cancellation. This is done today in multiple over the air technologies, comparable to Qualcomm’s QLIC etc… For multiple TX he suggests using ‘corrective’ beam forming. Beam forming allows a null (think of it as silence) to be created by the TX at the RX. He also suggests you can possibly have a mode where you use existing MIMO antenna and add an ‘auxiliary’ TX just for the purpose of interference nullling.

The last thing he shows in this layered approach is a final synchronous interference cancellation and equalization step in the base band. Performance example he gives is:

Residual Self Interference to Noise Ratio:

  • Antenna structure alone: about 40dB
  • After corrective beam‐forming: about 2dB
  • After base‐band subtraction: about 0.4dB 
So all in all this bit of technology is similar to, or can be thought of as, creating a electromagnetic set of ear muffs for the transmitter so the receiver can listen for distant signals at the same time the transmitter is singing. While there is nothing earth shattering about that as interference cancellation (IC) schemes are being employed on uplink and downlink in LTE today, it is important to note that this approach is a possible solution to the vexing self interference dilemma (If I shout, I can’t hear you at the same time…) with a repeatable, orderly system of layers. 
Lastly he mentions something I’ve been thinking of for some time, and that’s a shift from source based communications (unique signal stream including MIMO) The best way I can summarize it to be simple is, instead of using an isolated signal for transmission, focus on using the interference.

Media = The universe

Overall you can see the pieces of a wireless evolutionary step. I think the layered IC could be added after 3GPP Release 11 to further increase throughput/capacity and security of wireless transmissions. It’s very compelling if we shift to using mixed TDD/FDD modes and now you have the basis of a new range of applications including super low latency communications, extremely high security and so on. Throw in some cognitive radio and we are really capturing the lightning in a bottle. My hat is tipped to Dr. Amir K. Khandani, he found a good way to tie together different pieces of the puzzle to move the needle forward.

Links: E&CE Department, University of Waterloo, Qualcomm,,,

It may be very worthwhile attending his seminar 2PM on June 18th, 2012.

Dr. Amir K. Khandani
Department of Electrical and Computer Engineering, University of Waterloo

Shaping the Future of Wireless: Two-way Connectivity

Monday, June 18, 2012

2:00 pm

DC 1302

Their summary below.. 


Two-way (True Full-duplex) Connectivity: The Future of Wireless

Amir K. Khandani 
[email protected], 519-8851211×35324



Current wireless systems are one-way (similar to walkie-talkies), meaning that disjoint time or frequency segments are used to transmit and to receive. Realization of two-way wireless has challenged the research community for many years, generally believed to be impossible. This talk establishes the theory and presents practical realization of two-way wireless. In contrast to the widely accepted beliefs, it is shown that two-way wireless is not only possible, but is fairly simple, with virtually no degradation in signal-to-noise-ratio. More importantly, it is shown that two-way wireless can do much more than just doubling the rate. The innovation is in the antenna design and multiple levels for cancelling self-interference. Methods are developed to support multiple antenna (MIMO) two-way transmission, and asynchronous two-way links (useful in networking applications). These findings are expected to have a profound impact on wireless transmission, networking and security in the near future, more significant than other major breakthroughs in the last few decades.A number of new applications are introduced, showing that two-way wireless: (1) Facilitates wireless networking. (2) Enhances security through “desirable jamming”. (3) Provides the ground to realize unbreakable security (beyond computational or information theoretical security). (4) Enables a new method of wireless communications (to be introduced in this talk) based on embedding data in the transmission media by changing its RF properties in contrast to embedding data in the transmitted signal, and thereby significantly exceeding some of the known theoretical limits on channel capacity. (5) Enables realizing multi-node distributed & collaborative networking, which has been topics of extensive research in the context of Network Information Theory, but still far from practice. (6) Doubles the point-to-point throughput.

The developed hardware uses off-the-shelf components, antennas have a simple structure, are omnidirectional, do not suffer from bandwidth limitations, have a small size/spacing (comparable to current one-way systems), and the increase in signal processing complexity vs. one-way is virtually zero.

BIO: Amir K. Khandani is a professor of electrical and computer engineering at the University of Waterloo. He received his degrees from Tehran University, Iran, and McGill University, Canada, in 1984 and 1992, respectively. He joined uWaterloo in 1993. He currently holds the RIM-NSERC Industrial Research Chair on Network Information Theory and a Canada Research Chair (Tier I) on Wireless Systems. Prior to the RIM-NSERC Chair, he held an NSERC Industrial Research Chair funded by Nortel. He has supervised more than 40 PhD students, 30 master’s students, 30 post-doctoral fellows and 10 research engineers. His former team members have successful careers in industry and academia across the globe.



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There are 2 LTE stories here, with 1 bow tied neatly around. See this…

 So I was reading about the Dish Networks deal with Qualcomm that starts with Dish has 40MHz of S band (~2GHz) that it wants to use for LTE. Then I read that they did the smart thing and signed a deal with Qualcomm because let’s face it, Dish’s ambitions are not going to get much traction without devices. That all makes sense to me and although I can’t say I think getting this to market by 2016 will make them the dominant LTE service provider for the ages. IntoMobile has a good story on this.

Next, I read that Verizon is forming The 4G Venture Forum for Connected Cars with partners like BMW, Honda, Hyundai Motor Company, Kia Motors and Toyota Motor Sales, Inc. Looks like the goal is to foster ecosystem to grow infotainment and telematics over Verizon’s LTE network. Again, this makes a lot of sense to me and without going into tremendous detail, I will say I think this is where the Verizon’s of the world will make the real money from LTE, not from you and I directly, but as channel partners to the connected world. So they will need to work on safety issues, standards blah, a good step.

So hmmm… Why doesn’t Dish use it’s Lower 700MHz E block spectrum to operate a TDD-LTE, Multimedia Broadcast Multicast Service? More specifically Multimedia Broadcast Multicast Single Frequency Network (MBMSFN) and MBMS What is this MBMSFN you ask?

Good Article: eMBMS for More Efficient Use of Spectrum

Good Overview Document: Broadcast and Multicast Service for LTE and Advanced

The Multimedia Broadcast Multicast Service shares resource blocks so that a single unit of data is conservatively shared between multiple UEs therefore not committing separate resources for each UE. Further, the MSMSFN mode of operation simulcasts the same data, synchronously over multiple cells, and since over the air combining is possible, the  Signal to Noise Ratio (SINR) is improved a great deal. This is ideal for broadcasting media. Think in car movies for example. This would be cost effective and easy to achieve. What about Pandora audio or even digital signage ads (read the UICC from the UE and now we have a Minority Report style service)?

There is nothing that is unachievable with present technology, if you consider Dish is already reaching out to add the S band to chipsets and TDD is already being realized in the market. Dish already has a user experience expectation and backseat car infotainment is not something they are not trying to serve already. Seems like a slam dunk to me.



Links: Verizon Wireless, IntoMobile, Alcatel Lucent, Wikipedia, AddPac, 4GwirelessJobs

From Wikipedia:

3GPP technical specifications

MBMS Bearer Service (Distribution Layer):

  • 3GPP TS 22.146 Multimedia Broadcast/Multicast Service (MBMS); Stage 1
  • 3GPP TS 23.246 Multimedia Broadcast/Multicast Service (MBMS); Architecture and functional description
  • 3GPP TS 25.346 Introduction of the Multimedia Broadcast/Multicast Service (MBMS) in the Radio Access Network (RAN); Stage 2
  • 3GPP TS 25.992 Multimedia Broadcast Multicast Service (MBMS); UTRAN/GERAN Requirements
  • 3GPP TS 43.246 Multimedia Broadcast/Multicast Service (MBMS) in the GERAN; Stage 2
  • 3GPP TR 25.803 S-CCPCH performance for Multimedia Broadcast/Multicast Service (MBMS)

MBMS User Service (Service Layer):

  • 3GPP TS 22.246 Multimedia Broadcast/Multicast Service (MBMS) user services; Stage 1
  • 3GPP TS 26.346 Multimedia Broadcast/Multicast Service (MBMS); Protocols and codecs
  • 3GPP TR 26.946 Multimedia Broadcast/Multicast Service (MBMS) user service guidelines
  • 3GPP TS 33.246 3G Security; Security of Multimedia Broadcast/Multicast Service (MBMS)
  • 3GPP TS 32.273 Telecommunication management; Charging management; Multimedia Broadcast and Multicast Service (MBMS) charging


Full Verizon PR on 4G Venture Forum below:

Verizon Joins With Leading Global Auto Companies To Establish 4G Venture Forum for Connected Cars

BASKING RIDGE, N.J., June 6, 2012 /PRNewswire/ — Verizon today announced the formation of the 4G Venture Forum for Connected Cars, a group of leading global automotive companies brought together by Verizon to accelerate the pace of innovation across the automotive and telematics 4G LTE ecosystem.

BMW, Honda, Hyundai Motor Company, Kia Motors and Toyota Motor Sales, Inc. are joining Verizon as the initial members of the Forum.  Professor Sanjay Sarma of the Massachusetts Institute of Technology also joins the Forum, providing members a link to track important advancements in related academic research.  The group will collaborate and explore ways to deliver connectivity to vehicles of all types, by leveraging open standards and discussing ways to accelerate development of the 4G LTE ecosystem across automotive OEMs, suppliers, device manufacturers, application developers and content publishers.

“There are many challenges to designing next generation telematics and infotainment solutions, including supporting safe and responsible driving, advancing vehicle-to-vehicle solutions and improving sustainability, among others,” said Tami Erwin, chief marketing officer for Verizon Wireless.  “As an innovator in the technology industry, Verizon is a natural impetus for this collaboration, which we all expect will include other companies and spur results that will benefit not only the industry, but millions of consumers around the world.”

Telematics is a growing opportunity that integrates telecommunications and information into vehicles to provide functionality to drivers and passengers.  The 4G Venture Forum for Connected Cars will help discover ways to increase the value of services, ranging from embedded cloud-connected solutions to mobile applications; help define features and explore safety systems; and encourage third-party developers in this space.

Verizon has a strong commitment to collaboration and innovation through its Innovation Program, and through the 4G Venture Forum, which was created in 2009 to identify and support new ideas related to advanced wireless networks and to provide market validation for innovative companies.  The 4G Venture Forum for Connected Cars complements and extends the approach of the 4G Venture Forum, focusing exclusively on the automotive space to address the specific needs of this growing market.

Verizon Wireless has the largest 4G LTE network, now available in 258 markets and covering more than two-thirds of the U.S. population.  The Forum may support and fund advancements regardless of underlying network technology; companies will not be obligated to work with Verizon and are not precluded from working with other service providers.

March 21st FCC kicked off an industry discussion with their FCC Docket No. 12-69

Promoting Interoperability in the 700 MHz Commercial Spectrum

Last Friday, (1st of June), Qualcomm shoots over some comments to the FCC in response. Specifically, a document titled:

Promoting Interoperability in the 700 MHz Commercial Spectrum

Interoperability of Mobile User Equipment
Across Paired Commercial Spectrum Blocks in the 700 MHz Band

12-69 06-01-2012 QUALCOMM Incorporated 7021921420

So normally I see things like this come and go and I don’t utter a word, however I would like to point out a few things about Qualcomm’s position that I feel like should be made more clear.

Below is a diagram of the lower 700MHz spectrum. A key problem for everyone today is there are DTV broadcasts in many urban areas with extremely high power transmitters. The current FCC requirements allow DTV stations on Channel 50 and 51 to spew interference into the lower portions of the 700MHz spectrum (See Channel A, B and C.) Furthermore, there are 2 blocks, the D and E block in the lower 700MHz that also allow high power (think 50KW of RF power) to be broadcast. For LTE this could be a huge issue to both devices and base stations. Fundamentally, this is an unfair situation to those that purchased spectrum in the lower 700MHz areas and ultimately a problem for end users due to the limitations this places on what we can or can’t do now.

OK so Qualcomm didn’t create this problem but they are aware of it as they have been working on providing components to handset OEMs that utilize this spectrum. So they are trying to facilitate the use of multiple radio bands into the devices we love so dearly but it’s complicated. See their list of spectrum’s they are interesting in building to:

  • 700 MHz 3GPP bands (Band Classes 12, 13, 14, 17);
  • 850 MHz cellular band (Band Class 5);
  • Original PCS band (Band Class 2);
  • PCS Block G (Band Class 25);
  • AWS-1 band (Band Class 4);
  • Potential AWS-4 band (Band Class 23);
  • Original 800 MHz iDEN band (Band Class 26); and
  • BRS band (Band Class 41). 
So Band 12 is the original band plan, that is channels A, B and C of lower 700MHz that 3GPP put into their specification to allow the use of this portion of the spectrum. ATT later came back and requested/received a different plan. The just happened to purchase mostly B and C channels in the auctions, so their proposal was to create a band around B and C called Band 17. The 3GPP approved it so it’s part of the build specifications in the devices. Unfortunately it’s not fashionable to support Band 17 and Band 12. Qualcomm’s document to the FCC explains their logic on why this can’t happen. Therefore, components from Qualcomm today support Lower 700MHz Band 17 (ATT), Upper 700MHz (VZW) and now Band 25 (Sprint), with AWS support (Band 4) for others like Metro etc… If you are not ATT, VZW, Sprint, or AWS spectrum holder, you are not supported for LTE essentially.
Qualcomm developed more stringent filter requirements for Band 17 than Band 12, partially by utilizing the Channel A/Band 12 as a guard band of 6MHz, but there is more to it than just that. 
Their justification looks like this:
Qualcomm’s tests and analyses demonstrate that consumer devices operating on the Lower B and/or C blocks using the Band 12 filter will suffer harmful interference from E Block and Channel 51 signals, while the Band 17 filter provides these devices with an effective defense. More specifically, these comments will show that without the Band 17 filter:
  • High-power E Block signals would cause blocking interference to consumer devices seeking to receive a 5 MHz signal on the B Block or a 10 MHz signal on the B and C Blocks;
  • High-power E Block signals would cause intermodulation interference to consumer devices seeking to receive a 5 MHz signal on the B or C Block or a 10 MHz signal on the B and C Block; and
  • Channel 51 television signals would cause reverse intermodulation interference to consumer devices seeking to receive a 5 MHz signal on the C Block or a 10 MHz signal on the B and C Blocks.

…blah blah…

In fact, Qualcomm’s innovations and ongoing work with carriers and manufacturers demonstrate that there is no need for any FCC mandate.7 Because of the difficult interference challenges described herein, the fact that existing technology does not offer a solution to these challenges, and Qualcomm’s ongoing innovation and collaboration with all carriers and manufacturers, the Commission should not require mobile equipment to be capable of operating over all paired commercial spectrum blocks in the Lower 700 MHz band

In reviewing their document it’s clear that they are protecting their interests, that is they are developing and have been shipping products around Band 17 and Band 13, where their orders have been coming from. I read it as they (QCOM) are not interested in the 700MHz Band 12 spectrum holder issues as much since these smaller interests represent a greater deal of complexity and will have less payback than serving the larger operators. The issue they hold up as the big fish is the fact a large signal from Channel 51 or D/E block causes blocking and IM at the device receivers.

Sooo naturally

 part of the American experience (IMHO) is the fight for the little guy. If Qualcomm is allowed to ignore Band 12 issues and only sell to the big guys then big business wins and the little guy loses. 

It doesn’t have to be this way, there is a way to get what you want but some things will have to change. 

Let me take a moment to crow, and eat crow. I wrote a series of posts deriding Apple for its design choices regarding the Qualcomm transceivers. I only went off of publicly available information to keep everything on the up and up. 

Apple, I’m sorry for putting it all on you. It wasn’t all your fault. My last post I did say you needed to get off your duff and fight for the little guy by making your own transceiver and or doing some band stitching solutions but it’s not all your fault.
My original Posts:

On the other hand, I was right about everything I said in the corrections on the Qualcomm parts. My assertions are backed up in Qualcomm’s document. The reason I say that is because this story is possible to resolve amicably and my assumptions are built on some truths.

Key point is new components such as Qualcomm’s WTR1605L make Band 12 deployment possible, just not supported without changes to the propagation environment of the broadcasters thanks to Qualcomm not wanting to go any further on the solution development.


  1. FCC doesn’t need to mandate the world to use Qualcomm’s products, much less the WTR1605L, the MDM9615/MFM8930 etc… There’s already a huge challenge getting multiple suppliers in the space and layers and layers IPR issues that haven’t even been made public yet….
  2. The rules on the side skirts of the Channel 51 and D and E block spectrum holders is causing harm to a greater number of people than changes to these rules would. Make the roll off’s sharp such that interference is minimized. Be more fair and only make it an optional mitigation to be whipped out in case an operator actually wants to deploy in the A, B or C blocks (Band 12) and not just for Band 17.
  3. Qualcomm could feel free to improve the Band 12 filter.
  4. Baseband interference cancellation would be a good part of a solution too.
  5. Utilize a small cell strategy to target users very effectively. It’s one thing dealing with interference from a 1000′ tower to the users served by your 200′ tower and another when the device and base station are within 100 meters of each other. I can help you do this if you don’t know how to make it happen.
  6. Lower 700MHz spectrum holders can consider a fixed deployment instead of mobile. It’s less difficult to null out interferers.
  7. If all else fails, just contact me directly. I will sell you TX filters to reduce the transmission of the interference and help you work it out with the broadcasters to boot.

  At the end of the day, it’s up to the little guy to fight the power. People need to voice their opinions on this matter. Do you want better LTE data coverage? Do you want more companies to be able to offer LTE? More devices? Are you completely confident that Verizon and ATT will pass any device savings on to you that they could get from locking out variations?

Contact the FCC and let them know what you think.


BTW, Mariam Sorond, VP of Technology Development at DISH networks states that TX filters are sufficient to allow normal operations and no FCC rule changes like reducing TX power of D/E block (DISH broadcast) is required…. See her response.;jsessionid=f796PTRD1w7bWhL1w1BnJdbpT1jT52XDGhMGQzMqsGvb0QMQxlGj!-1221852939!-1969853125?id=7021921464



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