Obviousness

Obviousness Analysis under 35 U.S.C. § 103 for US Patent 7894385

This analysis identifies combinations of prior art references that would render the claims of US Patent 7894385 obvious to a person having ordinary skill in the art (PHOSITA) at the time of the invention (priority date: June 19, 2006). The motivation to combine these references stems from known problems in wireless mesh networking, particularly concerning mobility, performance, and seamless handovers.

Overview of Independent Claims

US Patent 7894385 has three independent claims:

• Claim 1 (Method): Describes a method for operating a mesh network where a mobile mesh node, equipped with a dedicated scanning radio and at least two relay radios (all on different non-interfering channels), uses the scanning radio for discovery and an uplink relay radio for sampling potential new parent nodes. During sampling, packets are buffered by both the current parent and the mobile node, and sampling times are coordinated via round-robin tokens sent by the common parent. [cite: "1. A method for operating a mesh network having a plurality of mesh nodes, comprising: for at least one mesh node of the mesh network, scanning a Radio Frequency (RF) environment using a dedicated scanning radio to determine a new potential parent mesh node for connecting with said at least one mesh node; wherein said at least one mesh node includes, in addition to said scanning radio, at least two relay radios in each mesh element and wherein said scanning radio and said at least two relay radios operate on different non-interfering channels; wherein said at least one mesh node is moving sufficiently rapidly that it may lose connectivity with its current parent mesh node, and wherein said dedicated scanning radio is utilized for discovery of potential new parent nodes and sampling of discovered potential new parent nodes is performed by an uplink relay radio of said at least one mesh node; wherein while said at least one mesh node samples potential new parent nodes, packets to be sent to said at least one mesh node from its current parent node are buffered by the current parent node, and packets to be sent from said at least one mesh node to its current parent are buffered by said at least one mesh node; and wherein sampling times are coordinated among multiple mesh nodes having a common current parent node whereby the common current parent node sends tokens to each of its children in a round-robin manner."]
• Claim 2 (Apparatus - Mesh Network): Defines a mesh network comprising nodes configured to perform the actions described in Claim 1, including the dedicated scanning radio, multiple relay radios on different channels, buffering during sampling, and token-based round-robin coordination. [cite: "2. A mesh network comprising: a plurality of mesh nodes; wherein at least one mesh node of the mesh network is configured to scan a Radio Frequency (RF) environment using a dedicated scanning radio to determine a new potential parent mesh node for connecting with said at least one mesh node; wherein said at least one mesh node includes, in addition to the scanning radio, at least two relay radios in each mesh element and wherein said scanning radio and said at least two relay radios operate on different non-interfering channels; wherein while said at least one mesh node samples potential new parent nodes, packets to be sent to said at least one mesh node from its current parent node are buffered by the current parent node, and packets to be sent from said at least one mesh node to its current parent are buffered by said at least one mesh node; wherein sampling times are coordinated among multiple mesh nodes having a common current parent node whereby the common current parent node sends tokens to each of its children in a round-robin manner."]
• Claim 3 (Apparatus - Mesh Network with Specific Radio Configuration): Similar to Claim 2 but specifies that each node has at least three radios: a first relay radio for uplink (first RF channel), a second relay radio for downlink (second RF channel), and a dedicated scanning radio (third RF channel) for discovery. It further states that the first relay radio samples after discovery by the scanning radio, with concurrent buffering and token-based coordination. [cite: "3. A mesh network comprising: a plurality of mesh nodes; wherein each node within said plurality of nodes comprises at least three radios further including: a first relay radio operating on a first RF channel at a first point in time and dedicated to uplink connections to a single current parent node; a second relay radio operating on a second RF channel at a first point in time and dedicated to downlink connections to zero or more child nodes; and a dedicated scanning radio operating on a third RF channel at a first point in time and configured to scan a Radio Frequency (RF) environment to discover new potential parent mesh nodes for connecting with said first relay radio; wherein said first, second, and third RF channels are different from each other wherein after said dedicated scanning radio discovers a potential new parent node, said first relay radio samples the RF link to said potential new parent node using its uplink radio and concurrent with said sampling, packets to be sent to the mesh node from its current parent node are buffered by the current parent node, and packets to be sent from the mesh node to its current parent node are buffered by the mesh node wherein sampling times are coordinated among multiple mesh nodes having a common current parent node whereby the common current node sends tokens to each of its children in a round-robin manner."]

Prior Art References for Obviousness Analysis

The following prior art references, cited in US7894385, are relevant for this analysis:

• US5633876A (Eon Corporation): "Store and forward repeater" [cite: "US5633876A ( en ) * 1992-10-26 1997-05-27 Eon Corporation Store and forward repeater"] – Teaches buffering/store-and-forward mechanisms.
• US20040264413A1 (Oren Kaidar): "Device, system and method for channel scanning" [cite: "US20040264413A1 ( en ) * 2003-06-26 2004-12-30 Oren Kaidar Device, system and method for channel scanning"] – Teaches channel scanning, potentially with a dedicated scanning unit.
• US20050074019A1 (Nortel Networks Limited): "Method and apparatus for providing mobile inter-mesh communication points in a multi-level wireless mesh network" [cite: "US20050074019A1 ( en ) * 2003-10-03 2005-04-07 Nortel Networks Limited Method and apparatus for providing mobile inter-mesh communication points in a multi-level wireless mesh network"] – Directly addresses mobility and handover in mesh networks.
• US20060077985A1 (Microsoft Corporation): "System and method for establishing a wireless mesh network using multiple frequency bands" [cite: "US20060077985A1 ( en ) * 2004-10-09 2006-04-13 Microsoft Corporation System and method for establishing a wireless mesh network using multiple frequency bands"] – Teaches multi-frequency operation in mesh networks to avoid interference.
• US7164667B2 (Belair Networks Inc.): "Integrated wireless distribution and mesh backhaul networks" [cite: "US7164667B2 ( en ) * 2002-06-28 2007-01-16 Belair Networks Inc. Integrated wireless distribution and mesh backhaul networks"] – Discloses multi-radio mesh networks, including backhaul and access, often on different frequencies.

Obviousness Combinations and Motivation to Combine

A person having ordinary skill in the art (PHOSITA) in wireless mesh networking, at the time of the invention, would have been motivated to combine the teachings of the cited prior art to improve the performance, reliability, and seamless operation of mobile nodes within multi-radio mesh networks, particularly to address the challenges of maintaining connectivity during rapid movement and handovers.

Combination for Claims 1, 2, and 3

The claims of US7894385, whether directed to a method or an apparatus, would be rendered obvious by a combination of:

• US20050074019A1 (Nortel Networks),
• US20040264413A1 (Kaidar),
• US7164667B2 (Belair Networks),
• US20060077985A1 (Microsoft), and
• US5633876A (Eon Corporation).

Motivation for Combination:

1. Establishing a Foundation for Mobile Mesh Networking: US20050074019A1 (Nortel Networks) clearly teaches the need for and mechanisms of "mobile inter-mesh communication points" and handovers within multi-level wireless mesh networks. [cite: "US20050074019A1 ( en ) * 2003-10-03 2005-04-07 Nortel Networks Limited Method and apparatus for providing mobile inter-mesh communication points in a multi-level wireless mesh network"] This provides the fundamental problem context of a rapidly moving mesh node that may lose connectivity. [cite: "wherein said at least one mesh node is moving sufficiently rapidly that it may lose connectivity with its current parent mesh node"]
2. Enhancing Network Performance with Multi-Radio, Multi-Channel Design: A PHOSITA, aiming to improve the throughput and reduce latency in mesh networks (as recognized in US7894385's background section), would look to US7164667B2 (Belair Networks) and US20060077985A1 (Microsoft). Belair Networks discloses multi-radio mesh backhaul for integrated wireless distribution. [cite: "US7164667B2 ( en ) * 2002-06-28 2007-01-16 Belair Networks Inc. Integrated wireless distribution and mesh backhaul networks"] Microsoft explicitly teaches using "multiple frequency bands" for different communication types (e.g., access and backhaul) to avoid contention and interference. [cite: "US20060077985A1 ( en ) * 2004-10-09 2006-04-13 Microsoft Corporation System and method for establishing a wireless mesh network using multiple frequency bands"] It would be obvious to incorporate at least two relay radios (for uplink and downlink) operating on different, non-interfering channels into a mobile mesh node to prevent self-interference and enhance overall communication efficiency. [cite: "wherein said at least one mesh node includes, in addition to said scanning radio, at least two relay radios in each mesh element and wherein said scanning radio and said at least two relay radios operate on different non-interfering channels"]
3. Enabling Efficient Discovery of Potential Parents: To facilitate seamless handovers for mobile nodes (as in Nortel), continuous discovery of potential new parent nodes is crucial. US20040264413A1 (Kaidar) describes a "device, system and method for channel scanning" which includes a "scanning unit" that "scans frequencies... to find a new communication channel." [cite: "US20040264413A1 ( en ) * 2003-06-26 2004-12-30 Oren Kaidar Device, system and method for channel scanning"] A PHOSITA would be motivated to integrate such a dedicated scanning radio into the mobile mesh node (from Nortel/Belair/Microsoft) to perform discovery. To avoid interference with the active relay radios, it would be obvious to operate this dedicated scanning radio on a different, non-interfering channel, consistent with the multi-channel teachings of Microsoft and Belair. This dedicated scanning radio would perform initial discovery of potential parent nodes.
4. Optimizing Link Sampling for Accurate Handover Decisions: Once potential parent nodes are discovered by the dedicated scanning radio, the decision of which parent to switch to requires accurate link quality measurement. US7894385 itself acknowledges that "if the antennas on the uplink differ from those on the scanning radio, then the conclusions made by the scanning radio may be inaccurate." A PHOSITA would be motivated to use the actual uplink relay radio (one of the "at least two relay radios" from Belair/Microsoft) to "sample the throughput performance" of discovered potential new parent nodes, as this provides a more accurate assessment of the link that will actually carry data. [cite: "wherein said dedicated scanning radio is utilized for discovery of potential new parent nodes and sampling of discovered potential new parent nodes is performed by an uplink relay radio of said at least one mesh node"]
5. Ensuring Data Integrity During Handover/Sampling: During the period when the uplink relay radio is sampling potential new parent nodes, it is temporarily unavailable for regular data transmission with the current parent. To prevent packet loss, the "store and forward" mechanism disclosed in US5633876A (Eon Corporation) would be a well-known and obvious solution. [cite: "US5633876A ( en ) * 1992-10-26 1997-05-27 Eon Corporation Store and forward repeater"] Implementing buffering at both the current parent node (for downlink packets) and the mobile mesh node (for uplink packets) during this sampling phase is a standard and obvious engineering practice to maintain data integrity during transient network states like handovers. [cite: "wherein while said at least one mesh node samples potential new parent nodes, packets to be sent to said at least one mesh node from its current parent node are buffered by the current parent node, and packets to be sent from said at least one mesh node to its current parent are buffered by said at least one mesh node"]
6. Coordinating Multiple Mobile Clients: In a scenario where a common parent node serves multiple mobile child nodes, and each child needs to sample potential new parents, uncoordinated sampling could lead to contention or overload the parent's buffering capacity. Therefore, a PHOSITA would be motivated to implement a coordination mechanism. The use of a token-based, round-robin manner for scheduling resource access is a fundamental and widely known technique in computer science and networking for managing shared resources fairly and efficiently. [cite: "wherein sampling times are coordinated among multiple mesh nodes having a common current parent node whereby the common current parent node sends tokens to each of its children in a round-robin manner."] Applying this standard scheduling approach to coordinate sampling times among child nodes would be an obvious design choice for managing network efficiency.

For Claim 3, the specific enumeration of "at least three radios" (first relay radio, second relay radio, and dedicated scanning radio) each on different RF channels is a direct combination of the multi-radio mesh architectures from Belair (US7164667B2) and Microsoft (US20060077985A1), with the dedicated scanning radio concept from Kaidar (US20040264413A1), operating on separate non-interfering channels to optimize performance. [cite: "wherein each node within said plurality of nodes comprises at least three radios further including: a first relay radio operating on a first RF channel at a first point in time and dedicated to uplink connections to a single current parent node; a second relay radio operating on a second RF channel at a first point in time and dedicated to downlink connections to zero or more child nodes; and a dedicated scanning radio operating on a third RF channel at a first point in time and configured to scan a Radio Frequency (RF) environment to discover new potential parent mesh nodes for connecting with said first relay radio; wherein said first, second, and third RF channels are different from each other"] The motivation for these specific configurations remains the same: to achieve robust, high-performance mobile connectivity with minimal disruption.

Therefore, the combination of these prior art references would lead a PHOSITA to the claimed inventions of US7894385 with a reasonable expectation of success, driven by the known desire to improve the functionality and performance of mobile nodes in wireless mesh networks.