US 9,854,547 B2 · Method and apparatus for synchronizing timing among devices in a wireless local area network (WLAN)

Abstract

A wireless communication device including a first media access control device and a first transceiver. The first media access control device is configured to selectively generate a first timestamp having a first length and a second timestamp having a second length. The first timestamp indicates a first synchronization time of the wireless communication device, the second timestamp indicates only a first portion of the first synchronization time, and the first synchronization time is used by a client station to synchronize timing between the wireless communication device and the client station. The first media access control device is further configured to generate a beacon including either the first timestamp or the second timestamp, and an indication of whether the beacon includes the first timestamp or the second timestamp. The first transceiver is configured to transmit the beacon from the wireless communication device to the client station.

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Claims16

Dependent claims

A wireless communication device, comprising:

a first media access control device configured to
selectively generate (i) a first timestamp having a first length, and (ii) a second timestamp having a second length, wherein the first length and the second length are different, wherein the first timestamp indicates a first synchronization time of the wireless communication device, wherein the second timestamp indicates only a first portion of the first synchronization time, and wherein the first synchronization time is used by a client station to synchronize timing between the wireless communication device and the client station, and
selectively generate beacons having a first beacon type, a second beacon type, and a third beacon type, wherein (i) the first beacon type corresponds to a full beacon including the first timestamp having the first length, (ii) the second beacon type corresponds to a short beacon having a first configuration including, in a timestamp field, the first timestamp having the first length, and (iii) the third beacon type corresponds to a short beacon having a second configuration including, in the timestamp field, the second timestamp having the second length,
wherein, to generate the short beacon of the second beacon type and the third beacon type, the first media access control device is configured to
selectively generate the second beacon type corresponding to the short beacon having the first configuration including the first timestamp having the first length, and
selectively generate the third beacon type corresponding to the short beacon having the second configuration including the second timestamp having the second length,
wherein, in each of the second beacon type and the third beacon type, the short beacon includes a timestamp indication field including an indication of whether the timestamp field includes the first timestamp having the first length or the second timestamp having the second length;
and
a first transceiver configured to transmit the short beacon from the wireless communication device to the client station.

6 more elements

A method of operating wireless communication device, the method comprising:

selectively generating (i) a first timestamp having a first length, and (ii) a second timestamp having a second length, wherein the first length and the second length are different, wherein the first timestamp indicates a first synchronization time of the wireless communication device, wherein the second timestamp indicates only a first portion of the first synchronization time, and wherein the first synchronization time is used by a client station to synchronize timing between the wireless communication device and the client station;
selectively generating beacons having a first beacon type, a second beacon type, and a third beacon type, wherein (i) the first beacon type corresponds to a full beacon including the first timestamp having the first length, (ii) the second beacon type corresponds to a short beacon having a first configuration including, in a timestamp field, the first timestamp having the first length, and (iii) the third beacon type corresponds to a short beacon having a second configuration including, in the timestamp field, the second timestamp having the second length,
wherein generating the short beacon of the second beacon type and the third beacon type includes
selectively generating the second beacon type corresponding to the short beacon having the first configuration including the first timestamp having the first length, and
selectively generating the third beacon type corresponding to the short beacon having the second configuration including the second timestamp having the second length,
wherein, in each of the second beacon type and the third beacon type, the short beacon includes a timestamp indication field including an indication of whether the timestamp field includes the first timestamp having the first length or the second timestamp having the second length;
and
transmitting the beacon from the wireless communication device to the client station.

5 more elements

Dependencies are inferred from the claim text.

Description5,259 words

Summary718 words

#The present disclosure relates to timing synchronization in wireless local area networks.

#Wireless local area networks (WLANs) may include an access point (AP) and one or more client stations. Various operating standards for WLANs include, but are not limited to, Institute for Electrical and Electronics Engineers (IEEE) 802.11a, 802.11ac, 802.11af, 802.11ah, 802.11b, 802.11g, and 802.11n.

#An access point periodically transmits a beacon frame at a target beacon transmission time (TBTT) and/or, in some 802.11 operating standards, a short beacon frame at a target short beacon transmission time (TSBTT). Each of the beacon frame and the short beacon frame may include a timestamp used for a timing synchronization function (TSF). For example, each client station in a basic service set (BSS) of the WLAN may use the timestamp in a beacon frame to synchronize timing between the AP and the client station. FIG. 1A shows an example beacon frame 100. FIG. 1B shows an example short beacon frame 104. FIG. 1C shows an example timing diagram 108 of transmission of the beacon frames 100 at TBTTs 110 and the short beacon frames 104 at TSBTTs 112.

Brief description of the drawings7 figures

#FIG. 1A is an example beacon frame.

#FIG. 1B is an example short beacon frame.

#FIG. 1C is an example timing diagram of transmission of beacon frames and short beacon frames.

Detailed description4,471 words

#In the drawings, reference numbers may be reused to identify similar and/or identical elements.

#An 8 byte timestamp field in a frame body of a beacon frame indicates a transmission time, as transmitted from an access point (AP), of a first bit of the 8 byte timestamp field. The transmission time corresponds to a timing synchronization function (TSF) time. The 8 byte timestamp field corresponds to a non-information embedding (IE) field. For example, a media access control (MAC) layer of the AP transmitting the beacon frame may set the 8-byte timestamp field. Conversely, a client station receiving the beacon frame is configured (e.g., in a MAC layer of the client station) to perform the TSF based on the 8 byte timestamp field. For example, the client station is configured to set a timer based on the 8 byte timestamp field.

#In some IEEE 802.11 standards (e.g., 802.11ah), an AP may selectively transmit a beacon frame (i.e., a full beacon frame) and/or a short beacon frame. The short beacon frame may only include a 4 byte timestamp. For example only, an AP may transmit the short beacon frame only at a target short beacon transmission time (TSBTT), or at both the TSBTT and a target beacon transmission time (TBTT).

Facts

Application

14/539,130Filed 12 Nov 2014 · us provisional application

Priority

12 Nov 2013

Published

US 2015/0131628 A114 May 2015

Granted

26 Dec 2017

Term ends

18 Jul 2035

Estimated · how

20 years from earliest known nonprovisional domestic filing plus recorded patent term adjustment, including 248 days of adjustment. Maintenance-fee lapses, terminal disclaimers and statutory extensions have not been checked. The continuity chain may be incomplete; this is not an enforceability determination.

Classification6 codes

H04W 56/001
Synchronisation arrangements: synchronization between nodes
H04W 56/0015
Synchronization between nodes: one node acting as a reference for the others
H04W 72/0446
Based on the type of the allocated resource: resources in time domain, e.g. slots or frames
H04W 40/244
Connectivity information management, e.g. connectivity discovery or connectivity update: using a network of reference devices, e.g. beaconing

Family

Application61/902,963Us provisional application · filed 12 Nov 2013

Application61/928,728Us provisional application · filed 17 Jan 2014

Application61/974,940Us provisional application · filed 3 Apr 2014

US 2015/0131628 A1Pre-grant publication · published 14 May 2015

US 9,854,547 B2This patent

From the US filing history. Foreign family members aren’t listed.

Timeline

12 Nov 2013Priority claimedParent application 61/902,963
12 Nov 2014Application filedUS 14/539,130
14 May 2015PublishedUS 2015/0131628 A1
9 Sep 2015Assigned to Marvell Semiconductor, Inc.assignment of assignor's interest
9 Sep 2015Assigned to Marvell International Ltd.assignment of assignor's interest
9 Sep 2015Assigned to Marvell World Trade Ltd.assignment of assignor's interest
9 Sep 2015Assigned to Marvell International Ltd.license
26 Dec 2017GrantedUS 9,854,547 B2
29 Jan 2020Assigned to Marvell International Ltd.assignment of assignor's interest
20 Feb 2020Assigned to Cavium Internationalassignment of assignor's interest
12 Oct 2026TodayWithin its term
18 Jul 2035Term endsEstimated, includes 248 days of adjustment

Method and apparatus for synchronizing timing among devices in a wireless local area network (WLAN)

Life of this patent

Method and apparatus for synchronizing timing among devices in a wireless local area network (WLAN)

Life of this patent

Life of this patent

Abstract

Drawings

Drawings

Claims16

Description5,259 words

Drawings

Classification6 codes

Life of this patent

Description5,259 words