re: terrestrial use of the 2473-2495 mhz band for low ... microsoft tlps e… · globalstar’s...

Microsoft Innovation & Policy Center Tel 202-263-5900

901 K Street, NW 11th Floor Fax 202-783-0583

Washington, DC 20001 http://www.microsoft.com/

September 12, 2016

Ex Parte

Marlene H. Dortch, Secretary

Federal Communications Commission

445 12th Street SW

Washington, DC 20554

Re: Terrestrial Use of the 2473-2495 MHz Band for Low-Power Mobile Broadband Networks,

IB Docket No. 13-213

Dear Ms. Dortch:

Microsoft Corporation (“Microsoft”) submits this ex parte communication to describe the results of tests

conducted on our Redmond, Washington campus. These tests examined the impact of two different

potential transmitters operating in compliance with Globalstar Inc.’s (“Globalstar”) requested rules for a

terrestrial low power service (“TLPS”) on the operation of an Xbox 360S game console with wireless

controllers in a controlled environment. These tests demonstrate that Globalstar’s proposed service is

likely to have a profound negative impact on consumers’ video game consoles.

In particular, Microsoft measured the frequency with which a button press on a wireless controller failed

to be communicated from the controller to the console, causing the console not to behave correctly in

response to user input (“button loss”). Button loss degrades the game player user experience, and—if

serious enough—can render a game unplayable. The Xbox 360S specification provides, therefore, that

button loss shall not exceed 1 loss in 10 minutes of operation.

Our tests demonstrated, however, that the presence of a TLPS access point causes button loss to greatly

exceed this limit. The test results showed that:

Under a scenario where Wi-Fi is present in the 2.4 GHz band on channels 1, 6, and 11, the effect

on communications between the Xbox 360S controller and console is negligible—2 lost button

events in nearly an hour of continuous use at a rate of 1 button press per second. This is the

case even though Wi-Fi transmitters operated at a 100 percent duty cycle;

The introduction of a nearby Globalstar TLPS transmitter using the IEEE 802.11 protocol leads to

an impactful button loss in Xbox game controllers of over 6 percent, or more than 100 times

over 27 minutes. This is 38 times worse performance than the product specification allows;

Ms. Marlene H. Dortch September 12, 2016 of 9

The introduction of a proximate Globalstar TLPS transmitter using a protocol that does not

include 802.11 listen-before-talk functionality leads to dramatic button loss in Xbox 360S game

controllers of over 26 percent, or nearly 950 times over 59 minutes. This is 160 times worse

performance than the product specification allows; and

The button loss associated with the introduction of a proximate Globalstar TLPS transmitter

using either protocol would render action games—which constitute two-thirds of all best-

selling console games1—unplayable, and would seriously undermine the gaming experience for

games of all types.

The implications of these results are clear. If the Commission grants Globalstar permission to operate

TLPS, or grants even wider use of the frequencies to other services, a broad cross-section of U.S.

consumers will lose functionality of their current gaming devices. Total sales of Microsoft’s Xbox 360S

series of consumer home entertainment consoles are approaching 100 million units worldwide, with

approximately half of the customers residing in North America. Microsoft has no reason to believe that

other game console manufactures operating in the 2.4 GHz ISM band would not be similarly affected.2

Based on experimental data, and given the total number of consumers that would experience harm,

Microsoft therefore requests that the Commission not permit Globalstar TLPS or opportunistic Wi-Fi use

of channel 14 in the 2.4 GHz ISM band.

A primer on Xbox 360S wireless game controllers

At its most fundamental level, video gaming is about the ‘gamer’ solving challenges presented by a

software simulation of events. Game consoles such as Xbox 360S require a human interface (controller)

to interact with the system (console) in a timely manner. The gamer’s reaction and response is central to

the game experience. For gamers, it is the quality of this interaction that creates and determines the

entertainment value of the console and the video game. If a gamer presses a button (“button event”) on

the controller and the expected outcome does not occur (“button loss”), or occurs with an unacceptable

amount of delay (“button latency”), many games become unplayable. Manufacturers therefore place

stringent technical requirements on the communications between the game controller and game

console so that button events are within tolerances. Gamers typically will not be aware of the causes of

their button loss or button latency and will likely assume it is the fault of the console manufacturer and /

or video game developer.

1 See Entertainment Software Association, Essential Facts About the Video Game Industry, 2016 Sales,

Demographic and Usage Data at 10 (2016), at http://www.theesa.com/wp-content/uploads/2016/04/Essential-Facts-2016.pdf (Shooter, Action, Fighting, and Sports game genres comprised 67% of best-selling video game genres in 2015).

2 See, e.g., Letter from Microsoft Corporation, Nintendo of America Inc., and Sony Interactive Entertainment America, LLC, to Chairman Wheeler and Commissioners Clyburn, Rosenworcel, Pai, and O’Rielly, FCC, IB Docket No. 13-213 (filed June 6, 2016).


Across the industry, consumers have indicated a clear preference for wireless controllers. Game console

manufacturers design controllers to operate in environments shared with other wireless devices. Xbox

360S controllers use the 2.4 GHz band, which is also home to Wi-Fi, Bluetooth, and ZigBee devices. But

even in the crowded 2.4 GHz band, the validated Xbox 360S controller-to-console communications

system specifications for button loss is that one button event lost is allowed for every ten minutes of

active use by the gamer.

This means that even in noisy environments, the button loss experienced by gamers should be a rare

occurrence, relegated to statistical outliers. Game developers have built their games in accordance with

these specifications. Gamers expect this experience. But our research demonstrates that the

introduction of Globalstar TLPS devices would overturn these expectations and cause serious disruption

and consumer dissatisfaction.

Understanding controller-to-console wireless communication protocols

Xbox 360S wireless accessories such as controllers and headsets operate as a Frequency Hopping Spread

Spectrum (“FHSS”) system with time division multiple access (“TDMA”) in the 2.4 GHz ISM band from 2.4

to 2.485 GHz using GFSK modulation. The system segments the 2.4 GHz ISM band space into 40, 2 MHz

wide channels for Xbox 360S accessory communications (2400-2480 MHz). In order to communicate

effectively and meet European regulatory requirements, some 19 channels must be usable in this space

at all times.

When the console is first turned on, each channel is scanned and evaluated for the amount of energy

present. An algorithm selects the 26 channels with the least amount of energy present. The algorithm

also determines a channel sequence based on certain frequency separation requirements between FHSS

hops. The resulting channel list and channel sequence created represents the order of best channels for

controller-to-console communications to be completed. After the controller is turned on, the link

established with the console, and the two devices synchronized, the channel list and channel sequence

is transmitted from the console to the controller.

The game is then selected and begins. When the gamer initiates a button event on the controller, a

(frequency hopping) signal is emitted and directed towards the console. The Xbox 360S console is

constantly searching for an available channel from the channel list in sequence by which to receive the

signal from the controller. The system’s highest priority is ensuring successful button events. The design

philosophy for the check and correction mechanisms is ‘try until you die.’

Under scenarios where all three independent Wi-Fi channels are in operation, the only guaranteed safe

operational region for Xbox 360S accessories is in the 11 MHz upper guard band between the top of

channel 11 and the end of the defined public ISM band at 2.485 GHz, which is also the lower half of

channel 14. Additionally, Xbox 360S peripheral communications may also be able to access the guard

bands below channel 1, between channel 1 and channel 6, and between channel 6 and channel 11. And


as Wi-Fi traffic tends to be ‘bursty’ rather than continuous, the Xbox 360S controller-to-console

communications can sometimes use the 2 MHz-wide channels overlaying occupied Wi-Fi channels when

the Wi-Fi channel is not in use. This occurs in real-time and depends on the operational parameters of

the nearby Wi-Fi access points such as load factor, duty cycle, data type, etc. As a result, Xbox 360S

channels outside of channel 14 have varying degrees of impairment, which manifests itself as latency

between the controller-to-console communications.

In attempting to complete the communication with the controller, the console will cross off channels

from the initial list of 26, the first ones coinciding with its own Wi-Fi communications (if in use). Next,

the console will disable any channel where it experiences a loss of communications from either end of

the connected link. Typically, such an action would occur because of an in-band interferer. And finally,

the console will prohibit channels that exhibit noise energy such as adjacent channels in the Wi-Fi bands.

The console stops eliminating difficult channels when it gets down to 19.

All this happens very quickly as the system will first try to beat the 16 millisecond latency design limit. If

noise disrupts the communications, the controller retries until the button data gets through. The

controller will continue to retransmit a button event multiple times (~ every 10 milliseconds) until it is

successfully received or another button event is triggered. If the communication is so damaged it cannot

complete this in 100 milliseconds, the system will try to find an alternative channel sequence to

complete the transactions and the button data from the previous button event is lost. In short, the

latency increases to the point where the button event is never completed.

Potentially the entire link (between the controller and console) can be lost where a significant time

delay occurs and the controller loses the synchronization signal from the console. If the controller does

become disassociated from the console, the console will need to evaluate the channel space and

identify a new channel list and channel sequence. While the controller is disconnected from the console

the game will stop working until it reconnects, which is both disruptive to the end user and greatly

impacts their ability to use the console.

Button Loss Tests The purpose of the tests was: (1) to show that in a controlled environment the Xbox 360S performed

within specification in a worst case scenario when Wi-Fi access points operating on channels 1, 6, and 11

were operating at 100 percent duty cycle; and (2) to determine what effects, if any, there are to Xbox

360S operations resulting from adding TLPS operations on channel 14 using either an IEEE 802.11

protocol or a protocol that did not incorporate listen-before-talk features, but was still consistent with

Globalstar’s requested operating parameters.3 There were four different test cases run (Attachment B

Slide 2).

3 Additional detail regarding the tests is set forth in Attachment A, Declaration of Mark W. Casebolt.


The tests were conducted June and July 2016 on Microsoft’s Redmond, WA campus in a shielded

chamber.

Test Set-Up

The Xbox 360S console and the Xbox 360S wireless controller were located on the left side of the

chamber (Attachment B Slide 3). The controller (Attachment B Slide 4) was located six feet from the

console (Attachment B Slide 5). The Xbox 360S has built-in 802.11n wireless networking capability in the

2.4 GHz band, but Microsoft did not activate this feature during the tests.

The Xbox 360S model tested ran the retail Xbox 360S operating system software. In addition, the Xbox

360S was modified to run a test application called ‘Thruput’ that allowed a Universal Serial Bus (“USB”)

analyzer to capture and redirect button presses to continuously read traffic between the main Xbox

360S motherboard and the ‘accessory’ radio front panel board. The Xbox 360S USB interface to the

accessory radio was connected to a Teledyne LeCroy PC-based USB analyzer running on a Windows PC.

The USB analyzer was set up to capture button event traffic as it was forwarded to the Xbox 360S

motherboard.

A BK Precision Arbitrary Waveform function generator was used to provide a 1 second periodic button

press stimulation with a 50 percent duty cycle and a 3 Volt peak signal for the measurement. An Xbox

360S controller (independent and battery powered) was modified to accept this input and transmit

wireless button event messages to the Xbox 360S host. The button event as initiated by the waveform

generator was tallied by a Sestos 3CE 24 Volt 6-digit scale counter. This signal was also used to window

signal conditioner logic supporting accurate receive event counts. The wireless controller output power

was 5 dBm, the value used in retail units.

A second Sestos 3CE 24 Volt 6-digit scale counter was used to tally button event counts received by the

Xbox 360S from the controller. The Sestos 3CE 24 Volt 6-digit scale counters were powered by a Keithley

2303 PS High Speed Precision Power Supply operating at 15 Volts. The detect signal conditioner logic

was powered by an Agilent E3640 PS power supply.

On the right side of the chamber were the MediaTek Wi-Fi cards and the Ruckus 7352 Access Point

(pictured) or Microsoft Research’s software defined radio (“SORA”) transmitters4 (Attachment B Slide 6).

MediaTek 7662 Wi-Fi radios used in Microsoft products were mounted on USB evaluation ‘interposers’

and controlled via a Windows PC to transmit on Wi-Fi channels 1, 6 & 11 at 7.5 dBm conducted power.

Resulting EIRP due to mismatch was on the order of 5 dBm (Attachment B Slide 7).

4 Microsoft, Microsoft Research Software Radio (SORA), https://www.microsoft.com/en-

us/research/project/microsoft-research-software-radio-sora/.


A modified Ruckus Model 7352 Access Point5 and a Nook HD+ were operated on channel 14 where the

iPerf network bandwidth measurement tool was used to generate traffic at a rate of 11 Mbps. The

Ruckus AP has a maximum power rating of 23 dBm according to its specification sheet. The AP

dynamically adjusted its power levels as needed to extend its range, but since the unit was in the same

room it was not transmitting at maximum power. Based on spectrum analyzer traces, the Ruckus AP was

transmitting at just slightly above that of the MediaTek units (8.0-9.0 dBm). As a consequence of

operating at the lower power levels, the TLPS signal on channel 14 did not fill in the full 20 MHz channel,

effectively creating a 3 MHz guard band between Wi-Fi channel 11 and TLPS, where there would not be

one if the transmitters were all operating at maximum power.

The Microsoft SORA radio was configured to transmit using LTE in a 20 MHz channel at 10 dBm on

channel 14 (Attachment B Slide 8). The LTE signal filled up the 20 MHz of channel 14. Exact EIRP

reduction due to efficiency mismatch was not measured.

Test Results

The first series of tests was qualitative. The engineering staff involved in the technical work played an

action video game on the Xbox 360S when the three Wi-Fi radios operating on channels 1, 6, and 11

were operating at 100 percent duty cycle. The staff did not note any degradation of their gaming

experience. With the introduction of the Ruckus Access Point on channel 14, they did note a number of

occurrences of pressing a button on the controller with no action or delayed action occurring in the

game. The frequency of button pressing with no actions or noticeably delayed actions increased when

the Ruckus Access point was replaced with the Microsoft SORA radio emulating an LTE signal on the

same channel.

The second series of tests was quantitative. Microsoft tested the instrumented Xbox 360S console and

controller. The device constantly sent button events (1 button/second) under the four interference

scenarios listed below to simulate the user experience of an action game.

5 Ruckus Wireless, Inc., ZoneFlex™ 7352, 802.11N Smart Wi-Fi Access Points, Data Sheet (2012),

http://en.ruckuswireless.com/assets/pdfs/products/zoneflex-7352.pdf.


Button Events

Test # Test Scenario Sent Received Lost (#)

Lost (%)

Lost (per 10 min.)

1 No Wi-Fi 1805 1805 0 0.0 0

2 Wi-Fi on channels 1,6, and 11 3493 3491 2 0.06 0.3

3 Wi-Fi on channels 1,6, 11, and TLPS using IEEE 802.11 on channel 14

1689 1583 106 6.28 38

4 Wi-Fi on Channels 1,6, 11, and TLPS using LTE under full requested technical rules on channel 14

3541 2593 948 26.77 160

As expected, Test 1 found no button loss when no Wi-Fi channels were in operation. At 1 button press

per second, the 1805 button events represent a run time of a little over 35 minutes. Attachment B Slide

9 is a snapshot of the Frequency Hopping Spread Spectrum system used for controller-to-console

communications across the 2.4 GHz ISM band. The signals were 2 MHz wide across their base.

Test 2 was the worst case scenario for Xbox 360S operations in the presence of Wi-Fi under the

Commission’s current rules. Here Wi-Fi radios were operating on channels 1, 6, and 11 at 100 percent

duty cycle during the Xbox 360S operation. Still there was only a slight increase in button loss observed

with loss reaching only 0.06 percent, or 2 button losses out of 3493 button events (Attachment B Slide

10). At 1 button press per second, the 3493 button events represent a run time of slightly under 1 hour.

The spectrum analyzer trace showed that the Xbox 360S signals that reached the console were in the

gaps between Wi-Fi channels and above Wi-Fi channel 11 (Attachment B Slide 11).

Over the course of 10 minutes (600 seconds) at 1 button event per second, the gamer would experience

1 button loss out of 600 button events, well within Microsoft’s operational specifications.6 Our

experience is that action gamers can operate at up to 5 button events per second for a period of time.

Assuming that they can maintain that rate for 10 minutes, which is a possibility, the test data would still

predict an average of less than 2 button losses.7

It is clear that the communications between the Xbox 360S controller and console were able to operate

with almost 100 percent success, even in the worst case Wi-Fi environment possible.

Test 3 introduced the Ruckus TLPS AP operating on channel 14 using an IEEE 802.11 b/g/n protocol. iPerf

was used to saturate the channel. The result was a loss of 106 of 1689 button events—or 6.28 percent

6 0.06 percent button loss * 600 button events = 0.36 button losses.

7 0.06 percent button loss *3000 button event = 1.8 button losses.


(Attachment B Slide 12). At 1 button press per second, the 1689 button presses represent a run time of

about 27 minutes. The spectrum analyzer trace showed that communications between the Xbox 360S

controller and console occurred on frequencies between Wi-Fi channels and in the artificial gap created

between channel 11 and channel 14 as a result of the TLPS access point operating at low power – a gap

that would not be present if the TLPS was operating at its full power. (Attachment B Slide 13). We noted

that, because the Ruckus AP incorporates the IEEE 802.11 carrier sense multiple access (“CSMA”)

protocol, it performed listen-before-talk followed by exponential back off in response to Xbox 360

controller-to-console communications. Consequently, the Xbox 360S controller-to-console

communication channels overlaid on the lower half of channel 14 experience various degrees of

impairment similar to what occurs when these channels are overlaid on Wi-Fi operations on channels 1,

6, and 11. Although this behavior likely limited the impact of TLPS, the impact remained serious, and

would have been easily noticeable by a gamer. The Xbox 360S controller-to-console communication was

designed under the assumption that these 2-MHz wide channels would be available without impairment

on the lower half of channel 14. These channels will now be impaired with co-channel TLPS operations.

Over the course of 10 minutes (600 seconds) at 1 button event per second, the gamer would experience

38 button losses out of 600 button events. These button losses are not at regular time intervals but are

often clustered in time, increasing the disruption to the user. Again, in an action game, where gamers

can achieve up to 5 button events per second, the test data would predict 180 button losses per 10

minutes of playing, making the game unplayable.

Test 4 introduced a Microsoft SORA TLPS AP on channel 14 operating at 10 dBm using LTE. The test

device therefore did not use listen-before-talk or back off if it sensed another device attempting to

access the medium. Instead, the TLPS device simply turned on if the signal strength of devices operating

in its vicinity were transmitting below the threshold set for its clear channel assessment. This was an

appropriate test because Globalstar has opposed any FCC rule that required it to use an 802.11 protocol.

In fact, Globalstar has not even committed to using a protocol that incorporated the rudimentary clear-

channel assessment functionality employed in this test.

In this test, button loss increased even further. The recorded button loss was 948 out of 3541 button

events, or 26.77 percent (Attachment B Slide 14). At 1 button press per second, 3541 button events

represent a run time of slightly under an hour. The spectrum analyzer trace showed that the only

communication to get through in this particular snapshot was that between Wi-Fi channels 1 and 6

(Attachment B Slide 15). At this level of button loss, a wide cross section of video games beyond action

games would be seriously degraded.

Over the course of 10 minutes, the games would experience 160 button losses. Extrapolating this to 5

button events per second leads to a completely debilitating 800 button losses per 10 minutes, or 800

times worse than the worst case acceptance specification.


Illustrative Example

A button loss is comparable to a lost character in a text. Consider what a loss of 6.28 percent of a text,

including spaces, means in terms of loss of information. Next consider the impact of the loss of 26.77

percent of characters. Attachment C provides an illustration.

Future Testing

Based on the results of these controlled tests, Microsoft intends to perform the same button loss tests

and button latency tests outside of a testing chamber on our campus, and then ultimately in a multi-

tenant dwelling with real users and test equipment to measure the results.

Additionally, we intend to assess the impact of TLPS on button latency. Attempts to measure latency in

the tests described above were largely frustrated by very high button loss.

Conclusion

The controlled testing showed that the communication between the Xbox 360S controller and console is

designed to not be affected in situations where Wi-Fi radios are operating on channels 1, 6, and 11, each

at a 100 percent duty cycle. The concurrent operation of either the modified Ruckus AP using the IEEE

802.11n protocol or the Microsoft SORA system using the LTE protocol causes an unacceptable degree

of button loss to the gamer that significantly degrades the gaming experience.

Sincerely,

/s/ Paula Boyd

Paula Boyd

Director, Government Relations and Regulatory Affairs

Michael Daum

Technology Policy Strategist

MICROSOFT CORPORATION

Attach.

ATTACHMENT A

Before the

FEDERAL COMMUNICATIONS COMMISSION

Washington, D.C. 20554

In the Matter of )

)

Terrestrial Use of the 2473-2495 MHz Band for ) IB Docket No. 13-213

Low-Power Mobile Broadband )

Networks )

DECLARATION OF MARK W. CASEBOLT

1. My name is Mark Casebolt. I am a Principal Engineer at Microsoft Corporation. I

received a BSEE degree from Oregon State University, and worked at University of Washington

towards my MSEE before engaging in entrepreneurial technology development as Vice President

and Chief engineer at Rapid Systems—an instrumentation company. I have over 40 years of

experience designing, analyzing and measuring the performance of electronics systems including

both intentional and unintentional wireless systems in both lab and operating environments.

2. Prior to joining Microsoft, I was Vice President and chief engineer at Rapid Systems and

am a Principal partner in Paragon Manufacturing Corporation. Exclusive of trade secret

technologies, I have developed successful wireless products in my technology developments in

Military, Aerospace, Industrial, Medical, and Consumer product areas, and have been awarded

23 patents.

3. In my position as Electrical Engineering Manager at Microsoft Hardware Group, I

developed wireless solutions while managing a broad variety of technological innovations

including consumer wireless peripherals, Networking, and integrated wireless solutions

operating in ISM bands.

4. As wireless Architect in the Microsoft XBOX organization, my key work relating to

wireless coexistence and desense interference have led to some 20 adjunct associated wireless

2

patent disclosures with 7 direct filings and 2 awards to date. My work on the coexistence of four

simultaneous consumer class wireless media streams in close proximity with current operating

sensitivity thresholds in the -90 dB RSSI range makes me well suited to evaluate the similar

coexistence challenges presented by a Globalstar interferer and its effects on a proximate

consumer wireless ecosystem.

5. In the time period June – July 2016, I and engineers under my direction at Microsoft

Main Studios Campus, Building 123, conducted a series of tests to observe what, if any, impacts

to the performance and the user experience of the Microsoft Xbox 360S consumer product can

be expected when wireless local area networks using TLPS access points operating on channel

14 using either the IEEE 802.11 or LTE protocol are deployed in environments when Wi-Fi is

operating on channels 1, 6, and 11—a common situation in multi-tenant dwellings, mixed use

development, and on college campuses.

6. In this declaration I provide a statement regarding the facts and parameters of the

demonstration network, describing the compatibility measurements executed with the purpose of

assessing the impact of Globalstar’s proposed TLPS operating in proximity to existing Wi-Fi

networks in a dense urban environment, and specifically with Microsoft’s Xbox 360S gaming

console and controller devices utilizing the 2.4 GHz Industrial, Scientific and Medical band.

Summary of Deployment

7. There were four scenarios tested. All the tests were conducted in a shielded chamber.

8. In the first scenario, the button loss of an Xbox 360S in the 2.4 ISM band was determined

with no other operations in the band.

9. In the second scenario, the button loss of the Xbox 360S was determined in the presence

of Wi-Fi operations on channels 1, 6, and 11. One MediaTek 7662 card was tuned to transmit on

3

Wi-Fi channel 1, one MediaTek 7662 card was tuned to transmit on Wi-Fi channel 6, and one

MediaTek 7662 card was tuned to transmit on Wi-Fi channel 11. Each of the MediaTek cards

was operated at 7.5 dBm, a bandwidth of 20 MHz, and at a 100 percent duty cycle. The 100

percent duty cycle represents the worst case scenario. EIRP (the Equivalent Isotropic Radiation

Power or the energy into the air) from these radios was reduced in this configuration due to

inefficiency loss by 1-4.5 dB.

10. In the third scenario, the button loss of the Xbox 360S was determined in the presence of

Wi-Fi operation on channels 1, 6, and 11; and a single Ruckus model 7352 access point, with

manufacturer supplied hardware and software modifications which allows it to operate on

channel 14 using the IEEE 802.11 b/g/n protocol, representative of one potential type of

Globalstar TLPS access point. The Ruckus access point was streaming data to a client device,

either a laptop or media player client device.

11. One MediaTek 7662 card was tuned to transmit on Wi-Fi channel 1, one MediaTek 7662

card was tuned to transmit on Wi-Fi channel 6, and one MediaTek 7662 card was tuned to

transmit on Wi-Fi channel 11. Each of the MediaTek cards was operated at 7.5 dBm, a

bandwidth of 20 MHz, and at a 100 percent duty cycle. The modified Ruckus access point

operated between 8 and 9 dBm with a bandwidth of 17 MHz.

12. In the fourth scenario, the button loss of the Xbox 360S was determined in the presence

of Wi-Fi operation on channels 1, 6, and 11; and a single OEM Microsoft SORA system,

allowing it to operate on channel 14 using the LTE protocol, representative of one possible type

of Globalstar TLPS access point. The Microsoft SORA access point was streaming data to a

client device, either a laptop or media player client device. No attempt was made to evaluate the

efficiency loss or EIRP of the SORA antenna.

4

13. One MediaTek 7662 card was tuned to transmit on Wi-Fi channel 1, one MediaTek 7662

card was tuned to transmit on Wi-Fi channel 6, and one MediaTek 7662 card was tuned to

transmit on Wi-Fi channel 11. Each of the MediaTek cards was operated at 7.5 dBm, a

bandwidth of 20 MHz, and at a 100 percent duty cycle. The Microsoft SORA access point

operated at 10 dBm with a bandwidth of 20 MHz. The Microsoft SORA access point was

streaming data to a laptop or media player in this environment.

Summary of Results of Compatibility Measurements

14. Test Scenario 1: Of the 1805 sent button events by the Xbox 360S controller to the Xbox

360S console, at one button event per second, there were no lost button events recorded.


360 console, in the presence of Wi-Fi operations on channels 1, 6, and 11 as described above,

there were 2 lost button events, representing 0.06 percent button loss.


360S console, in the presence of Wi-Fi operations on channels 1, 6, and 11, and a modified

Ruckus access point operating on channel 14 as described above, there were 106 lost button

events, representing 6.28 percent button loss.


360S console, in the presence of Wi-Fi operations on channels 1, 6, and 11, and a OEM

Microsoft SORA access point operating on channel 14 as described above, there were 948 lost

button events, representing 26.77 percent button loss.

5

Conclusions

18. The design specification for the Xbox 360S requires there to be no more than one button

loss event in 10 minutes of operation.

19. Test Scenario 1 establishes that there are no lost button events between Xbox 360S

controller and console when the Xbox 360S is the only device operating in the 2.4 GHz ISM

band.

20. Test Scenario 2 establishes that even in the worst case scenario, where there are Wi-Fi

operations on channels 1, 6, and 11, with each operating at 100 percent duty cycle, the average

button loss per 10 minutes of operation is 0.3.

21. Test Scenario 3 shows that when a TLPS access point using a compliant IEEE 802.11

protocol is added to scenario 2, there is a significant increase in button loss. Under the test

conditions, there would be an average of 38 button losses per 10 minutes at 1 button press per

second. Typically for action games, there are periods of operation where a sent button rate of 5

button presses per second is consistently achieved. At this button loss rate, there is going to be

serious degradation of the Xbox 360S game player user experience.

22. Test Scenario 4 shows that when a TLPS access point using a LTE protocol is added to

scenario 2, there would be an average of 160 button losses per 10 minutes at 1 button press per

second. Here the button loss is so significant that action games would be unplayable. In this

environment, players of other types of games will also experience a serious degradation to their

user experience.

23. The two key differences between Test Scenario 3 and Test Scenario 4 are: (1) The

politeness of the TLPS using the IEEE 802.11 protocol allowed the Xbox 360S to access channel

14 when its signal was detected. The TLPS using the LTE protocol just turned on and off

according to its duty cycle. And (2) In Test Scenario 3, presumably due to the lower power used,

6

an internal guard band was created between Wi-Fi channel 11 and TLPS where the Xbox 360S

controller to console communication could operate. In Test Scenario 4, the full 20 MHz was

used. There was no de facto internal guard band created between Wi-Fi channel 11 and TLPS

where the Xbox 360S signal could consistently operate.

24. Cursory measurements of Bluetooth operating gaming controllers in this environment

were observed to operate with similar or somewhat poorer lost button events.

25. The conclusion is clear. The Commission should not permit TLPS or any Wi-Fi

operations on channel 14.

Pursuant to 28 U.S.C. § 1746, I declare under penalty of perjury under the laws of the United

States that the foregoing is true and correct to the best of my knowledge, information and belief.

Executed on September 12, 2016.

Mark W. Casebolt

ATTACHMENT B

Xbox 360 Button Event Interference Test Setup & Results

4 Different Test CasesXBOX 360

Console to Wireless Controller Test Number

XBOX 360Console to Wireless Controller

Test Scenario

1 No Wi‐Fi

2 Wi‐Fi on Channels 1, 6, and 11

3 Wi‐Fi on Channels 1, 6, 11, and unlicensedIEEE 802.11 on Channel 14

4 Wi‐Fi on Channels 1, 6, 11, and unlicensed LTE on Channel 14

Slide 2

Test Setup – Left Side of Room

Xbox 360Sconsole

Tektronix MSO 4004 Mixed Signal Oscilloscope

BK Precision Arbitrary Waveform function generator

Xbox 360S wirelessController—6 feet from console

Sestos 3CE 24V 6 digit scale counters

Slide 3

Test Setup – Xbox 360S Console

Xbox 360S console

Teledyne Lecroy Mercury T2 USB analyzer wired inline with Xbox controller radio

board

Slide 4

Test Setup – Xbox Controller Xbox 360S wireless controller

Wires from controller to BK Precision Arbitrary Waveform function generator is used to provide a 1 second

periodic button press stimulation

Controller indicator showing connection to console as controller 1

Slide 5

Test Setup – Right Side of Room

MediaTek 7662 cards, 3 active

Agilent spectrum analyzer

Spectrum analyzer probe placed between all the Wi‐Fi devices

Ruckus 7352 Access point (modified by manufacturer to run on

Channel 14) transmit

power 23 dBm

Windows laptop running Iperf plugged into Ruckus AP

Slide 6

Test Setup – Wi‐Fi Channels 1, 6 & 11MediaTek 7662 cards to transmit on Channels 1, 6 and 11 at 7.5 dBm

EIRP

They were set to transmit at full buffer (100% duty cycle)

Slide 7

Test Setup – SORA Software Defined Radio

Detailed docs https://www.microsoft.com/en‐us/research/project/microsoft‐research‐software‐radio‐sora/

SORA unit with MS designed radio front endTx power 10dBm

Slide 8

Spectrum Analyzer View – Test Case 1No Wi‐Fi Xbox controller to console communication

Note: Same picture in both sides of slide. Scale set from 2400 MHz to 2500 MHz so each gridline is 10 MHz.

Slide 9

Test 2 Button Counter Results

Button events sent

Button events received

Slide 10

Spectrum Analyzer View – Test Case 2Channels 1, 6 and 11 Wi‐Fi Xbox controller to console communication


Slide 11

Test 3 Button Controller Results

Button events sent


Slide 12

Spectrum Analyzer View – Test Case 3Channels 1, 6, 11, & 14 – IEEE 802.11 Xbox controller to console communication


Slide 13

Test 4 Button Controller Results

Button events sent


Slide 14

Spectrum Analyzer View – Test Case 4Channels 1, 6, 11 Wi‐Fi and 14 LTE Xbox controller to console communication


Slide 15

ATTACHMENT C

ILLUSTRATIVE EXAMPLE: COMPARABLE LOSS OF CHARACTERS

FCC 13-213 Paragraph 1 (1404 characters, including spaces)

By this Notice of Proposed Rulemaking (Notice), the Commission proposes modified rules for

the operation of the Ancillary Terrestrial Component (ATC)1 of the single Mobile-Satellite

Service (MSS) system operating in the Big LEO S band.2 The proposed changes would allow

Globalstar, Inc. (Globalstar) to deploy a low power broadband network. Under the proposals in

this Notice, Globalstar would be able to provide low-power ATC using its licensed spectrum at

2483.5-2495 MHz under certain limited technical criteria, and with the same equipment would

be able to utilize spectrum in the adjacent 2473-2483.5 MHz band pursuant to the applicable

technical rules for unlicensed operations in that band. For all the reasons stated herein, we

believe that Globalstar’s proposal to deploy broadband access equipment should be further

examined and a record developed to determine whether this proposal has the potential to enable

more efficient use of Globalstar’s S-band spectrum and spectrum in the adjacent band. This

action could potentially increase the amount of spectrum available for broadband access in the

United States. At the same time, significant concerns have been raised about potential

detrimental impacts on unlicensed devices. We seek comment on the costs and benefits of the

proposed approach, and on changes to our rules which may facilitate such deployment and

minimize any negative impacts.

FCC 13-213 Paragraph 1 (6.28 percent loss – 88 out of 1404 characters, including spaces)

Byhis Notice of Proposed Rulemaking (Notice), the Commission proposesmodified rules for the

operatn of the ncillary Terrestrial Compnent (AC)1 of he single Mobile-atellite Service(SS)

system operating in the Bi LE S band.2 The proposedchanges would allow obalstar, Inc.

(Gobalstar to eploy a low poer broadban network. Undr the roposals in this Notice, lobalstar

woud be able to prvide low-power ATusing its licensed sectrum at 243.5-495 Hz under certan

limited tecnical crteria, and wih the same quipment would e able to utilizespectrum in the

adjacent24732483.5 MHz ban pursuant to the applicable echnical rules fr unlicensed perations in

that band.For al the reasons stted hereinwebelieve that Globaltar’ proposal to eploy broadband

acces equipment should be furtheexamined and a record eveloped to detemine whether this

prosal has the potntial to enable more efficient use of Globalstar’s -band spectrum andspectrum

in the adjcent band. This actio could potentilly increasethe amount of pectrum available for

brband access in the Unitd Stats. At thesame time, significant concerns have ben raised bout

potential detrimental impacts on licensed devices. We eek coment n the costs and nefits of the

proposed approach, and on hanges to ourules which may facilitate such deployment and

minimize any negative impacts.

FCC 13-213 Paragraph 1 (26.77 percent loss – 376 out of 1404 characters, including spaces)

B ths Ntic of Prposed Ruemaing Notie), themssion propoes oded ruls for theratin of t Anillay

TerestialCoponentAC)o sin MobileatelliteerviceMSSsystemoeratinin the BigE band2hepose

hangs uld allolobalstar, nc. (Glostar) eploy a lw wer brodba networ der thepropoain this

NoticGlobaar wold bable provi low-owr ATuig its licensepectrum at 32495Mz unrcrtainlimted

riteria, andwith sam equipent wold bableilize sptrum inthe adaent 243248 Mz and pursuant the

applicale tehicalules fornlicensedprations inhat bndForallthe resonated herewe beleve tat

loblstars proposa tdeply boaban acessemensold befurtereamind anda recrd deveoped todetermin

whetherthis proosal hasthe tentiato enble mor effient e o Gobast’s Sband sectrum ad spectru in

the adjacen ba.This actin culdpoteialy incrastheamnt of specum availle forboadnd ccess in t Uted

Stte.t thesam te sigificant concers hae beenraid abutottial drimenal impcts onnlicense diceseek

2

cmment onthecosts anenefits of theroposd aproch, ages wch may faciitate suc deoment andmiiize

anngate ipats

re: terrestrial use of the 2473-2495 mhz band for low ... microsoft tlps e… · globalstar’s...

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