Over-the-air wireless data frame capture

Patent analysis often involves investigating how a particular solution functions in order to determine the potential for use of a given patented claim, and sometimes this investigation entails analyzing wirelessly-communicated data.

In an earlier post I described how to capture IP packets sent to/from wireless devices by using a Windows OS computer as a wireless hotspot together with Wireshark, a packet capture and analysis software tool. While that technique works well for capturing and analyzing IP packets communicated between a wireless device on the wireless LAN (WLAN) and a remote server, that technique does not capture lower-level point-to-point MAC frames communicated between devices on the WLAN, such as between the hotspot computer and a wireless device or between two wireless devices connected to the WLAN.

Within a WLAN, devices do not need to leverage transport or network packets (e.g., TCP/IP) to communicate with one another since they are on a shared medium and so can use the data link instead. To capture the frames sent on the shared wireless medium, there is another process I can recommend. This process provides for capturing communicated frames, such as between a computer application and a smartphone on the WLAN. The guidance below presumes that you have permission to capture wireless frames transmitted over the wireless network.

  1. Fire up an unencrypted IEEE 802.11g wireless access point on a channel that is free or the least crowded. The “g” aspect is important, because newer protocols such as “n” and “ac” complicate capture due to variables like channel width and spatial streams. Having the access point be passcode-free and unencrypted is important as well because it allows for reading frames in the clear (presuming no other encryption is used for the transported data), though it is possible to use Wireshark to decrypt encrypted channels if you know the credentials — this is not covered herein.
  2. Boot Kali Linux on a computer. Kali is a Linux distribution with tools built in for performing penetration testing.
  3. Connect a wireless adapter that support IEEE 802.11g along with “monitor mode.” An example is Panda’s PAU05 300Mbps Wireless 802.11n USB Adapter — I have found that this particular adapter works well. Some other monitor mode wireless adapters that may function well are listed here and here.
  4. Use Kali built-in tools like airmon-ng and airodump-ng to monitor Wi-Fi channels and capture data while your devices under test are communicating. This further article on passive Wi-Fi connection sniffing provides alternate, but similar, techniques in deep detail.
  5. Once you have captured the sequence of data you wish, discontinue the capture and open the resulting “PCAP” file in Wireshark, which is conveniently preloaded in the Kali Linux distribution. In Wireshark you can analyze the data there.

Obviously much more could be written about each of the tools and protocols above, and indeed, books have been written about each. However, here you have a short list of high-level steps to perform for passive Wi-Fi data sniffing, along with a complete set of the hardware and software you will need.

For potential future discussion is packet capture in a wired network, such as via Ethernet.


EPO Patent Information Conference

For the past few years I have enjoyed attending the European Patent Office’s (EPO) annual Patent Information Conference, which is held in a different European city each year. In 2015 it was based in Copenhagen, and in 2016 it was held in Madrid. This year (2017) it is held in Sofia, Bulgaria. There are several training sessions along with discussion rounds covering a variety of topics, such as patent-related searches, freedom to operate assessments, patent analytics, patent asset monitoring, and of course patent information and evaluation tools. As described in an earlier post about European patents, as a US-based patent analyst I find it beneficial to continue to stay informed about the latest developments in European patent law and data. This annual conference provides me with the opportunity to learn, and I also have met many great patent professionals at these conference events. Additionally, there are dozens of excellent exhibitors showing off their latest patent information and analysis software and services.

Europe is my home away from home, and I love spending time there and exploring new cities, as well as learning from peers. This conference is also relatively inexpensive compared to most patent conferences in the US.

Please let me know if you plan to attend this year’s (or any future year’s) EPO Patent Information Conference, and I can plan to meet you for a chat.

European Patents

In my patent analysis practice, I continue to see an increase in requests to review European (EP) patents. This is likely due to a variety of reasons, including case law decisions in the United States in recent years, along with the promise of a European Unified Patent Court (UPC). In any case, I find it advantageous as a US-based patent analyst to be familiar with European patent practice because there are many differences from US practice, and of course there are different resources available for European patent review.

For example, while Google Patents provides support for EP patents, there is additional information available from European Patent Office (EPO) websites such as Espacenet (technical information) and European Patent Register (legal information, like the USPTO’s Public PAIR). And once a European patent is granted, it is currently enforced in each separate designated contracting state (nation) after validation procedures (such as providing language translations); renewal fees are also thereafter paid to each contracting state. This makes determining current status more difficult — one must determine in which nations the granted patent is enforceable (a topic for a future blog post).

With regard to European patents, the Chrome browser “Patent Claims Tree” extension has been updated to:

  1. provide a link to both Espacenet and the European Patent Register for a given EP patent, such as when viewed in Google Patents
  2. handle claims viewed in Espacenet
  3. provide enhanced German claim text analysis
  4. fix claims extraction for EP patents in Google Patents (based on updates to Google Patents)


EPO links
Links to Espacenet and Register for EP patents.


Espacenet claims tree
Espacenet claims tree

Google Patents website versions

UPDATE (Jan 15, 2018): Ian and the team at Google have greatly improved the new version of Google Patents. Among other improvements, the sidebar is now collapsible, and there is a search bar on the top. The new figure viewer is very flexible and allows for expanding a figure to the needed width. There has also been a big JavaScript refactor and use of gzip to speed up page loading significantly. Excellent work! I’m now only using the new version of Google Patents.

UPDATE (Sep 25, 2017): The “Google Patents Images” Chrome browser extension only works if there are images available to load. It appears that all the latest patents no longer have images available. Therefore, I now find myself using the new Google Patents instead to be able to see the images. Because of this I have created another Chrome browser extension, “Google Patents Widescreen,” to offer better readability of the new Google Patents presentation.

In a previous post about expedited single-patent analysis I discuss how much I enjoy the layout format of the version of Google Patents available at the URL syntax of https://www.google.com/patents/patent_identifier. I continue to use this site for reviewing patents in my daily work.

There is also a newer version of Google Patents available at the URL syntax of https://patents.google.com/patent/patent_identifier. This newer version of Google Patents has a variety of improvements over the previous version, such as detailed search capability, patent expiration information, and claim text search term highlighting. The image viewer is also different, though not necessarily better, depending upon the circumstances (as detailed below).

That said, for several reasons I find myself continuing to prefer the previous version of Google Patents, which as of this writing is still available. These reasons include issues with the newer version, which were communicated to the Google Patents development team in 2016, albeit to no reply as of this writing:

  1. Unnecessary Search Column: It would be helpful to be able to collapse the left-most column containing the search fields. Often, when one is reviewing a particular patent, there’s no desire to perform more searches. I admit that I sometimes work from a Chromebook with an 11-inch display, so having that left column go away would provide more precious real estate for the specification content, or possibly allow for images to be shown on the right side.
  2. Small Images Viewer: For the drawings/images/figures, they are presented in a very small area when using a smaller display device, especially when centered with the rest of the content. I often cannot sufficiently see them and therefore must open them in a new window. While it’s often helpful to be able to see the images while still viewing the rest of the content, it would be beneficial to be able to open the set of drawings in a superimposed pop-up like is done for the legacy Google Patents — in this way a new window/tab is not needed, and one can scroll through all the figures quickly, all while being able to sufficiently see them.
  3. Less-Accessible Metadata: It would be better to include the “Also Published As” information in the top metadata box instead of linking to a full list at the bottom of the page. The preexisting Google Patents solution has a collapsed list of related patents, and this would be the preferable solution for ease and speed of use. Or even a hover or pop-up box with the information would be helpful. Searchers and analysts very often need to see what family members there are, particularly US family members, and so having to go all the way to the bottom of the page to see this very important metadata is counter-intuitive and slow.
  4. Much Slower Page Load Time: Beyond viewing the information, the speed of loading of a single newer Google Patents page is now painfully slow, especially as compared to the loading of the earlier version. And the newer pages will not completely load until after a browser tab/window is put into focus, as opposed to the legacy version which loads without being in focus. The newer pages have a title of “Result” on the browser tab until viewed.

One issue that arose in 2016 was that on the legacy Google Patents, newer patents’ images were not being shown because the associated image links were broken. Perhaps this is intentional so as to encourage users to the newer Google Patents, or perhaps it’s because the legacy version is no longer being actively supported (or both). In any case, because I prefer the legacy version, I created a Chrome browser extension called “Google Patents Images” which on the fly modifies the image links for legacy Google Patents to use the image links for the newer Google Patents. The extension should work automatically for any legacy Google Patents page after the initial installation of the extension (as long as JavaScript is enabled).

The first issued US patent with broken figure images is 8,856,962 — all patents before that patent work OK. The first broken US pre-grant publication is 2014/0304877, while the first broken US design patent is D715016.

Replacing the images allows for viewing the images, but the controls to go to the previous/next images are still broken — these are controlled in the page’s JavaScript, which cannot be manipulated by a Chrome extension.

Google Patents Images Chrome extension
Google Patents Images Chrome extension

More Patent Analysis Tools

The patent claims tree Chrome browser extension I created in 2012 provides a patent claims tree for a given patent document, and it has become fairly popular, with several hundred users as of this writing. The tool is available at the Chrome Web Store, and is described in more detail here and here.

I have created additional Chrome browser extensions that I have found helpful and that you can use during patent analysis. One provides USPTO patent assignments for any selected text, such as a selected company name. This solution allows you to quickly look up any US patent assignments for a given company name in the USPTO patent assignment database.

UPDATED (May 22, 2017): The other links from a selected patent or patent application identifier on any webpage to the corresponding Google Patents page.

The “Patent Assignments” tool is available at the Chrome Web Store, as is the “Open Google Patents” tool.

Screenshots for each extension are provided below. I hope that you find these applications helpful in your patent analysis.

Patent Assignments - screenshot
Patent Assignments Chrome browser extension


Open Google Patents Chrome extension
Open Google Patents Chrome extension


Quickly Reviewing Prosecution History

Often in the course of analyzing a patent, one or more claim terms are difficult to interpret in light of the patent specification, and so in that case it can sometimes be helpful to review the patent’s prosecution history (aka “file wrapper” or “file history”) to ascertain the proper scope for ambiguous terms. Additionally, during prosecution the applicant or the applicant’s representative may disclaim specific scope, whether through explicitly doing so during arguments and/or through making a narrowing amendment to a claim to overcome an examiner rejection. The patent owner will likely be precluded from invoking the doctrine of equivalents to broaden the scope of the claim to cover subject matter ceded by this narrowing amendment. This is often called “prosecution history estoppel”, and it is an important reason to normally include prosecution history review as part of a complete patent analysis. There are many other reasons to review a patent’s prosecution history, many having to do with review of applicant patent practitioner conduct or procedural issues.

However, when reviewing the prosecution history specifically to facilitate determination of claim interpretation, one can narrow the scope of the review in order to hasten the review process, and this allows for review of only specific documents in the overall history’s collection of documents. I have found through practice that using a browser with search result highlighting, one can quickly gather the relevant prosecution history documents from the USPTO’s Public PAIR system.

For this example, I have picked my handy favorite patent number 7654321 (it’s also in a technology area outside of my comfort zone).

1. Use PAIR to pull up information on the patent under review, then select the “Image File Wrapper” tab.

IFW tab

2. Next use the browser’s search result highlighting to find the prosecution history documents of interest. There are mostly documents that you can safely ignore in this review, and I have found a specific set of keywords that I leverage which are helpful in collecting the relevant documents. These keywords are “claim” (for claims and the final index of claims), “amend” (for amendments and arguments), “reject” (for examiner rejection), “allow” (for notice of allowance and the associated examiner feedback), “interview” (for outcome and information pertaining to an interview between the examiner and the applicant), “disclaim” (for a terminal disclaimer, because an applicant might argue claim scope), and “action” (in case an office action was missed through searching for “reject”). The first three keywords will capture everything in the majority of cases. Obviously, for a more thorough prosecution history review, you’ll want to review other documents, such as those pertaining to abandonment, information disclosure statements, petitions, declarations, and the like. However, in a review which concentrates on specific claim term interpretation, only this limited subset of documents will be of particular relevance. For each document of interest, select the associated checkbox in the far right-hand PDF column.

Claims Highlighted

3. Once all desired documents have been selected, activate the PDF button in the top row and save this PDF file (with whatever name you find helpful) so you can review its contents.

Save PDF


PDF file name


4. Review the downloaded PDF file. While it is helpful to have context of the examiner’s rejection rationale, it is only important what the applicant (or representative) files, argues, and amends.

Index of Claims


The associated PDF file is available for download, if you’d like to see more detail: US7654321 (ser no 11616583) – partial file history.

In this example case, only 20% of the total prosecution history documents need to be acquired and reviewed using the method described above.

Patent Claims Tree tool updates

The patent claims tree Chrome browser extension I created in 2012  provides a patent claims tree for a given patent document, and it has become fairly popular, with several hundred users as of this writing. The tool is available at the Chrome Web Store, and is described in more detail here.

I have recently made a couple of improvements to the tool for EP and WO (PCT/WIPO) patent document handling. For one, claim tree creation is now supported for both EP and WO patent documents on Google Patents. Additionally, rudimentary support for German and French for EP patent documents in Google Patents has been added. While the claim type is not handled for German and French, claim tree creation is now provided. Additionally, it should be noted that Google Patents provides kind code B (i.e., issued patent) claims text for EP patents (while Espacenet does not as of this writing — the kind code B issued claims are only available in a PDF file). See this other PatentAnalyst blog post regarding consideration of kind codes for EP patent documents.

The screenshot below shows a claims tree for an issued EP patent viewed in Google Patents. Noteworthy is that not all formats of multiple dependent claims are fully handled in the Patent Claims Tree tool. These types of claims are more common in EP patent documents than in US patent documents.

Google Patents EP claim tree


Intrinsic and Extrinsic Evidence for Claim Construction

Patent claim construction involves an analysis of intrinsic evidence primarily, and then extrinsic evidence as needed.

Intrinsic evidence includes the following, in this priority order: patented claims, patent specification, and prosecution history. With regard to the prosecution history, this includes not only the prosecution history of the reviewed patent, but also the prosecution histories of all US family members — that is, prior related US applications, prior related CIPs, related US siblings, related US children, and related US grandchildren. For prosecution history review, focus is placed on office actions and office action responses, and reviews look for the possible presence of two types of estoppel: 1) Argument-based prosecution history estoppel where the applicant explicitly indicates claim interpretation through arguments made in office action responses; and 2) Amendment-based prosecution history estoppel where a narrowing amendment is “made for a ‘substantial reason related to patentability’ when the record does not reveal the reason for the amendment.” (Festo) 

Extrinsic evidence includes, for example: dictionaries and expert / inventor testimony. Extrinsic evidence may be considered to inform claim construction based upon the intrinsic evidence, but in most situations intrinsic evidence alone suffices to construe claims, and in many cases it is improper to rely on extrinsic evidence at all.

Patent Claim Terminology

The following is a non-exhaustive set of terms commonly used in patent claim analysis. This list is not meant to be comprehensive, nor is it meant to cover all terminology for patents in general, patenting processes, or patent litigation (e.g., terms like clearance, IDS, post-grant proceedings, licensing, treble damages, etc.). Descriptions have a US-based focus and so are not necessarily applicable for other jurisdictions.

Concentration is placed on those terms most used in the course of patent analysis, where this analysis always focuses on the patented claims. The list will be supplemented over time, and suggestions for additional terms are welcomed.

  • Antecedent basis: A claim term (word or phrase) is referred to in a definite form using “the” or “said” and has been been previously introduced in the current claim or in an ancestor claim using the same term. Lack of antecedent basis can lead to claim scope being indefinite. Also, the patent specification (per 35 USC 112) needs to provide guidance on the meaning of claim terms (i.e., support or antecedent basis), although the same words need not be used therein.
  • Anticipation: A specific type of description or event which demonstrates that a claimed invention does not meet legal novelty requirements for patenting. Anticipation is determined on a claim-by-claim basis, and a single prior art reference (e.g., a printed publication) or event (such as a sale) must disclose every claimed limitation, whether explicitly or inherently.
  • Beauregard: A claim type that claims an article of manufacture embodied as a computer-readable medium (CRM) and associated instructions. The name originates from a Federal Circuit case  In re Beauregard (1995). However, a more recent case at the Federal Circuit in 2012 (Digital-Vending Services International, LLC v. The University of Phoenix, Inc.) interpreted Beauregard claims as method claims rather than as apparatus or composition of matter claims. Further complicating scope interpretation of Beauregard claims is that the USPTO now instructs examiners to reject Beauregard claims because computer-readable media can include signals, which were found to not be patentable subject matter under 35 USC 101 in the Federal Circuit case of In re Nuijten (2007). To get around this type of invalidity, the computer-readable media should explicitly be limited to be “non-transitory”.
  • Body: The portion of a patent claim which recites claimed elements and describes how these elements interoperate in order to form a claimed invention. The claim body follows the preamble (introduction) and the transition phrase (link).
  • Claim construction: Interpretation and determination of the meaning of a patent claim. Construing the proper meaning of a claim is a necessary step prior to determination of potential use.
  • Claim type/category: A category covered by a given claim. 35 USC 101 indicates the following basic categories as statutory classes: “process, machine, manufacture, or composition of matter”. A claim covering an activity (process or method) is often referred to as a “process claim”, a “method claim”, or a “use claim”. A claim covering a physical entity such as a product or apparatus (e.g., machine, article, composition, device, system, etc.) is often referred to as a “product claim” or an “apparatus claim”. My Patent Claims Tree tool attempts to determine the type/category of claim for each independent claim based on semantic analysis of language used within the claims. The claim category for a given claim determines its scope and coverage of use.
  • Dependent claim: A claim which depends upon at least one other claim and which inherits limitations from its ancestor claims. A dependent claim provides additional specificity and claims a narrower embodiment.
  • Direct infringement: This occurs when a party makes, uses, sells, offers to sell, or imports a patented invention in the United States during the term of the associated patent. See also “Indirect infringement” and “Divided use/infringement”.
  • Divided use/infringement (multi-actor): Joint infringement when two or more different parties together make, use, sell, or offer to sell a solution that would be judged to infringe upon a patented claim.
  • Doctrine of claim differentiation: A rule that every claim in a patent is presumed to have different scope from every other claim. This doctrine means that if a dependent claim of a parent claim specifically has narrower limitations, then the parent claim must necessarily be different – that is, it has a broader interpretation. As an example, for an independent claim that recites a chair with a plurality of legs, with the independent claim having an associated dependent claim requiring a chair with 4 legs, the independent claim is therefore not limited to what is recited in the dependent claim. The dependent claim in this example protects chairs with 4 legs specifically, and therefore the independent claim must logically cover chairs not only with 4 legs, but also chairs having any number of legs greater than one (i.e., a “plurality”). It would be improper to read the 4-leg limitation into the independent claim.
  • Doctrine of equivalents: A legal rule that allows a court to hold a party liable for patent infringement even when every element of a patented claim does not literally read on a product or process. Equivalents can be determined when alterations are “insubstantial”, though there are many limitations to the doctrine of equivalents.
  • Element: A component of the claim body indicating a part, step, structure, substance, etc. that together with the other claim elements forms the process, machine, article of manufacture, or composition of matter named in the claim preamble.
  • Extrinsic evidence: Evidence and support from sources external to the patent itself and its associated prosecution history. Extrinsic evidence may include expert or inventor testimony/opinion, dictionaries, and the like. Normally, review of intrinsic evidence alone suffices to resolve any ambiguity in a claim term, but extrinsic evidence may in some cases inform claim construction based upon the intrinsic evidence.
  • Independent claim: A standalone claim that does not refer to or depend upon another claim. An independent claim may have zero or more dependent claims which inherent limitations from it. An independent claim is therefore broader than all its dependent claims.
  • Indirect infringement: Here, a party induces another party to directly infringe a patent (inducement) or the party contributes to the direct infringement of the patent by another party (contributory infringement). A party is a contributory infringer only if the party provides a component of a patented invention, and the party knew that the combination for which the component was especially designed was both patented and infringing, and the component must not be a staple article or commodity of commerce suitable for substantial non-infringing use.
  • Interpretation: Determination of the meaning of a patent claim. Construing the proper meaning of a claim is a necessary step prior to determination of potential use. See also “Claim construction” and “Markman”.
  • Intrinsic evidence: Evidence and support from 1) Claims, 2) Specification, 3) Prosecution History, in that priority order, for determining claim interpretation. With regard to #3, the prosecution history (aka file history, file wrapper, etc.), this includes not only the prosecution history of the specific patent, but also the prosecution histories of all its US family members — i.e., prior related US applications, prior related CIPs, related US siblings, related US children, and related US grandchildren.
  • Invalidity: A determination that a patent claim should not have issued due to the associated claimed invention not having been novel or nonobvious, requiring clear and convincing evidence because there is a presumption of validity bestowed on an issued patent. Claims can also be found invalid through other means beyond anticipation or obviousness.
  • Limitation: A limitation often refers to an adjective, adverb, or other phrase that modifies a claim element. However, many patent professionals use the term “limitation” interchangeably with the term “element”.
  • Markman: A pretrial hearing in which a judge determines appropriate patent claim interpretations as a matter of law.
  • Means-Plus-Function (MPF or M+F): A type of claim language which claims a structure only in terms of its functionality. In the US, means-plus-function claims are provided for in 35 USC 112, paragraph 6. Whereas this type of claim was often used to broadly encompass various structures, MPF claims are now construed much more narrowly, encompassing only those structures defined within the patent specification, along with equivalents with insubstantial difference. As a result, and due to the scope uncertainty of MPF claims, this type of claim has fallen more out of use in recent years. Also, while claim construction is a question of law, a determination of the scope of equivalents under 35 USC 112, paragraph 6 is a question of fact (therefore requiring a jury decision).
  • Non-obviousness: A patentability requirement which mandates that a claimed invention must not be obvious in that a person having ordinary skill in the art would not know how to solve the problem for which the claimed invention is provided by using the same solution. This requirement is of course applied inconsistently and is normally the most difficult to apply or defend against, and there are and have been many different factors and tests applied to determine nonobviousness (e.g., “Graham factors”, “Teaching-Suggestion-Motivation” (TSM), etc.).
  • Novelty: A patentability requirement which mandates that a claimed invention must not have been known to the public before the patent’s priority date (there are some specific date exceptions). Otherwise, the claimed invention is anticipated if one prior art reference or event discloses all the claim elements and limitations and enables a person having ordinary skill in the art to make and use the claimed invention.
  • Preamble: An introductory statement for a patent claim that indicates the type of claim (or statutory class) and that names the product or process claimed.
  • Prior art: Information which was publicly available in any form before a specific date that might be of relevance to the originality (novelty and nonobviousness) of a claim.
  • Prosecution history (file history, file wrapper): Patent prosecution is the interaction between a patent applicant and a patent office with regard to a patent or patent application, and the prosecution history is the collection of these interactions between the applicant (or its representatives) and the office. For the USPTO, the prosecution histories for patents and patent applications is available for retrieval and review through PAIR. Public PAIR provides access to patent histories for published patent documents (usually after 18 months following the priority date), and Private PAIR additionally provides access to prosecution histories for those patent documents that are currently unpublished.
  • Subject matter eligibility: Claimed subject matter is eligible or ineligible to be patented based upon the type of subject matter claimed, independent of requirements pertaining to novelty and non-obviousness. Certain types of subject matter are ineligible for patent protection in the US such as literary works, compilations of data, music compositions, legal documents, forms of energy and signals, natural phenomena, mental processes, and abstract intellectual concepts.
  • Transition: A transitional word or phrase between the claim preamble and the claim body. Usually this word is “comprises” or “comprising”.
  • Transitory signal: Subject matter that is ineligible for patent protection according to the Federal Circuit In re Nuijten (2007) ruling which concluded that articles of manufacture do not include intangible, incorporeal, transitory entities (which the court indicated that signals are).
  • Use / Infringement: A product or process is read upon by a patented claim.
  • Written description: Portion of a patent specification which describes, among other things, inventive embodiments. Claim elements and limitations need to be disclosed in the written description in order to be allowed.