Prior art — US Patent 7193986

Analysis of Prior Art for U.S. Patent 7,193,986

This analysis covers the prior art references cited by the USPTO examiner during the original prosecution of U.S. Patent 7,193,986. The core of the invention in the '986 patent, particularly in independent claims 1 and 9, is a master-slave wireless network where some data packets transmitted by the master contain a pointer. This pointer indicates the relative time remaining until a special "designated packet" (e.g., a beacon) is transmitted. The designated packet, in turn, contains scheduling information for the slave devices, telling them when to transmit. This mechanism is designed to allow slave devices to quickly synchronize and save power by sleeping until the next designated packet.

The following five references were considered by the examiner.

1. U.S. Patent 6,088,337 A

Full Citation: "Method access point device and peripheral for providing space diversity in a time division duplex wireless system." Assignee: Motorola, Inc.
Dates: Filed: October 20, 1997. Published: July 11, 2000.
Brief Description: This patent details a time division duplex (TDD) wireless system with a central access point (master) and multiple peripherals (slaves). The access point broadcasts a beacon signal that contains system timing and frame structure information. Peripherals periodically wake from a low-power state to listen for this beacon to maintain synchronization and receive scheduling information, such as the address of a peripheral scheduled to transmit. The primary focus is on using multiple antennas (space diversity) to combat signal fading.
Potential Anticipation of Claims: This reference discloses a master-slave TDD system where a beacon is used for synchronization and scheduling, which covers many elements of claims 1 and 9. However, it does not appear to teach the key element of a pointer within a regular data packet that indicates the relative time until the next beacon. Instead, the '337 patent describes a system where peripherals wake up at predetermined intervals based on a known frame structure. Therefore, it likely does not anticipate the claims.

2. U.S. Patent 6,498,936 B1

Full Citation: "Methods and systems for coding of broadcast messages." Assignee: Ericsson Inc.
Dates: Filed: January 22, 1999. Published: December 24, 2002.
Brief Description: This patent relates to the Bluetooth communication standard, describing a master-slave piconet structure. It focuses on methods for efficiently encoding and transmitting broadcast messages from the master to all slaves. These broadcast messages can contain control and scheduling information. The '986 patent itself acknowledges Bluetooth as prior art and aims to improve its power efficiency.
Potential Anticipation of Claims: The Bluetooth system described has a master-slave, time-slotted architecture with broadcast packets containing control information, aligning with several elements of claims 1 and 9. However, standard Bluetooth protocols do not include a dynamic pointer in general data packets to indicate the timing of a future broadcast. Power-saving modes in Bluetooth, such as "sniff mode," rely on a pre-negotiated fixed interval for communication, not a per-packet relative time pointer. The '986 patent's invention is presented as a specific improvement over this existing Bluetooth method. Thus, this reference does not appear to anticipate the claims.

3. U.S. Patent 6,795,418 B2

Full Citation: "Wireless MAC protocol based on a hybrid combination of slot allocation, token passing, and polling for isochronous traffic." Assignee: Koninklijke Philips Electronics N.V.
Dates: Filed: March 31, 2000. Published: September 21, 2004.
Brief Description: This patent describes a MAC protocol for a wireless network managed by a central coordinator (master). The coordinator transmits a beacon to start a "superframe." This beacon contains detailed scheduling information, allocating specific time slots for different types of traffic and different stations (slaves). The system allows stations to enter a power-saving mode and wake up just in time to receive the next beacon.
Potential Anticipation of Claims: This reference is strong prior art for a beacon-based scheduling system in a master-slave network. The beacon acts as the "designated packet" containing slave scheduling information (claims 1 and 9). However, like the other references, it appears to lack the specific teaching of a pointer in other data packets that provides a countdown to this beacon. The power-saving mechanism relies on the slave knowing the beacon interval and waking at the next expected beacon time, not on information from an intermediate packet. Therefore, it does not fully anticipate the claims.

4. U.S. Patent 6,947,446 B2

Full Citation: "Slot format and acknowledgement method for a wireless communication system." Assignee: Motorola, Inc.
Dates: Filed: January 16, 2001. Published: September 20, 2005.
Brief Description: This patent outlines a TDD communication system with an access point (master) and subscriber units (slaves). The system uses a defined frame structure with downlink (master-to-slave) and uplink (slave-to-master) portions. The master transmits control messages, such as a "Downlink MAP," which explicitly schedule the transmission times for subscriber units in the subsequent uplink portion of the frame.
Potential Anticipation of Claims: This reference discloses a master-controlled, time-slotted network where the master sends scheduling messages. The "Downlink MAP" functions similarly to the "designated packet" of the '986 patent. However, the timing is inherent in the rigid frame structure; subscriber units know to look for the MAP at a specific point in each frame. The reference does not describe a pointer in an arbitrary data packet that indicates the relative time to a future MAP message.

5. U.S. Patent Application Publication 2002/0115458 A1

Full Citation: "Radio communication system." Assignee: Nippon Telegraph And Telephone Corporation.
Dates: Filed: February 21, 2001. Published: August 22, 2002.
Brief Description: This application describes a system where a control station (master) broadcasts control information on a broadcast channel (BCCH) within a superframe. This BCCH informs communication stations (slaves) of the frame structure and available resources. Slave stations can operate in a power-saving mode by waking up only to receive the BCCH in a predetermined cycle.
Potential Anticipation of Claims: This system uses a master-broadcasted control channel (BCCH) as the "designated packet" for scheduling, as recited in claims 1 and 9. The power-saving method is based on a "predetermined cycle," implying the slave knows the fixed interval between BCCH transmissions. It does not teach the use of a pointer in other data packets to dynamically indicate the time remaining until the next BCCH, which is the specific mechanism claimed in the '986 patent.