U.S. patent application number 15/065466 was filed with the patent office on 2016-06-30 for method and apparatus for accessing wireless sensor network.
The applicant listed for this patent is Huawei Technologies Co., Ltd.. Invention is credited to Yongjun LIU, Yong XU, Mu ZHAO.
Application Number | 20160192285 15/065466 |
Document ID | / |
Family ID | 44860890 |
Filed Date | 2016-06-30 |
United States Patent
Application |
20160192285 |
Kind Code |
A1 |
XU; Yong ; et al. |
June 30, 2016 |
METHOD AND APPARATUS FOR ACCESSING WIRELESS SENSOR NETWORK
Abstract
A method and apparatus for accessing a wireless sensor network
are provided in embodiments of this invention. The technical
solution provided in embodiments of this invention includes: when
receiving a first beacon frame, stopping channel scan temporarily,
and establishing a new channel scan sequence according to operating
channels of a current wireless sensor network recorded in the
beacon frame. Non-operating channels are not included in the new
channel scan sequence. Time for performing subsequence channel scan
is reduced, so that the process of accessing the current wireless
sensor network of a device node expecting for network can be
accelerated.
Inventors: |
XU; Yong; (Shenzhen, CN)
; LIU; Yongjun; (Beijing, CN) ; ZHAO; Mu;
(Shenzhen, CN) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Huawei Technologies Co., Ltd. |
Shenzhen |
|
CN |
|
|
Family ID: |
44860890 |
Appl. No.: |
15/065466 |
Filed: |
March 9, 2016 |
Related U.S. Patent Documents
|
|
|
|
|
|
Application
Number |
Filing Date |
Patent Number |
|
|
13664203 |
Oct 30, 2012 |
9319969 |
|
|
15065466 |
|
|
|
|
PCT/CN2011/073589 |
May 3, 2011 |
|
|
|
13664203 |
|
|
|
|
Current U.S.
Class: |
370/329 |
Current CPC
Class: |
H04W 72/085 20130101;
H04W 74/04 20130101; H04W 84/18 20130101; H04W 48/16 20130101 |
International
Class: |
H04W 48/16 20060101
H04W048/16; H04W 74/04 20060101 H04W074/04; H04W 72/08 20060101
H04W072/08 |
Foreign Application Data
Date |
Code |
Application Number |
Apr 30, 2010 |
CN |
201010165632.5 |
Claims
1. A method for accessing a wireless sensor network, comprising:
performing, by a device node, channel scan from a first channel
according to a predefined channel scan sequence; pausing, by the
device node, the channel scan when receiving a first beacon frame
returned sent from a beacon sending node during the channel scan,
wherein the beacon frame carries with includes operating channels
of a current wireless sensor network; deleting, by the device node,
channels except the operating channels from the predefined channel
scan sequence; constructing, by the device node, a new channel scan
sequence; scanning, by the device node, for operating channels that
have not been scanned according to the new channel scan sequence;
receiving, by the device node, beacon frames during the scan of
operating channels that have not been scanned; determining, by the
device node, a parent node for accessing the wireless sensor
network according to the first beacon frame and the beacon frames
received during the scan of operating channels that have not been
scanned; and selecting, by the device node, an operating channel to
access the wireless sensor network on the operating channel through
the parent node.
2. The method according to claim 1, wherein the first beacon frame
further comprises a first channel link quality parameter of an
operating channel where the beacon frame comes from; the beacon
frames received during the scan of operating channels that have not
been scanned further comprises channel link quality parameters of
corresponding operating channels; wherein, determining a parent
node for accessing the wireless sensor network according to the
first beacon frame and the beacon frames received during the scan
of operating channels that have not been scanned comprises:
determining the parent node for accessing the wireless sensor
network according to the first channel link quality parameter
contained in the first beacon frame and channel link quality
parameters of corresponding operating channels contained in the
beacon frames received during the scan of operating channels that
have not been scanned.
3. The method according to claim 1, wherein the selecting an
operating channel for the device node expecting for network
comprises: synchronously switching channels with the parent node
according to the new channel scan sequence to complete a
second-round channel scan; determining an operating channel for the
device node expecting for network according to second channel link
quality parameters carried on beacon frames received during the
second-round channel scan process.
4. The method according to claim 3, wherein the synchronous switch
comprises: performing channel scan on the same channel
synchronously by the device node expecting for network and the
parent node according to the new channel scan sequence, and
performing channel scan through synchronously switching to a next
identical channel according to the new channel scan sequence until
completing channel scan of channels in the new channel scan
sequence.
5. The method according to claim 3, wherein determining an
operating channel for the device node expecting for network
according to second channel link quality parameters carried on
beacon frames received during the second-round channel scan process
comprises: selecting a channel having the best channel quality
according to the second channel link quality parameter values as
the operating channel for the device node expecting for
network.
6. An apparatus, comprising: a readable storage medium comprising
instructions to: perform channel scan from a first channel
according to a predefined channel scan sequence; pause the channel
scan when receiving a first beacon frame returned sent from a
beacon sending node during the channel scan, wherein the beacon
frame includes operating channels in of a current wireless sensor
network; delete channels except the operating channels from the
predefined channel scan sequence; construct a new channel scan
sequence; scan channels that have not been scanned according to the
new channel scan sequence; receive beacon frames during the scan of
operating channels that have not been scanned; determine a parent
node for accessing the wireless sensor network according to the
first beacon frame and the beacon frames received during the scan
of operating channels that have not been scanned; select an
operating channel; and a processor coupled with the readable
storage medium, configured to execute the instructions retained in
the readable storage medium, and access a wireless sensor network
on the operating channel through the parent node.
7. The apparatus according to claim 6, wherein the first beacon
frame further comprises a first channel link quality parameter of
an operating channel where the beacon frame comes from; the beacon
frames received during the scan of operating channels that have not
been scanned further comprises channel link quality parameters of
corresponding operating channels; wherein the readable storage
medium further comprises instructions to: determine the parent node
for accessing the wireless sensor network according to the first
channel link quality parameter contained in the first beacon frame
and channel link quality parameters of corresponding operating
channels contained in the beacon frames received during the scan of
operating channels that have not been scanned.
8. The apparatus according to claim 6, wherein the readable storage
medium further comprises instructions to: synchronously switch
channels with the parent node according to the new channel scan
sequence to complete a second-round channel scan; determine an
operating channel for the device node expecting for network
according to second channel link quality parameters carried on
beacon frames received during the second-round channel scan
process.
9. An apparatus, comprising: a readable storage medium comprising
instructions to: perform a first-round channel scan according to a
predefined channel scan sequence; select a beacon sending node of a
current wireless sensor network as a parent node; determine a
second channel scan sequence according to operating channels in the
current wireless sensor network; synchronously switch channels with
the parent node according to the second channel scan sequence to
perform a second-round channel scan; determine an operating channel
for a device node expecting for network according to second channel
link quality parameters carried on beacon frames received during
the second-round channel scan; and a processor coupled with the
readable storage medium, configured to execute the instructions
retained in the readable storage medium, and access the wireless
sensor network on the operating channel through the parent
node.
10. The apparatus according to claim 9, wherein the readable
storage medium further comprises instructions to: scan from a first
channel according to a predefined channel scan sequence; pause the
channel scan when receiving a first beacon frame sent from a beacon
sending node during the channel scan, wherein, the beacon frame
carries with operating channels in a current wireless sensor
network; delete channels except the operating channels of the
beacon sending nodes from the predefined channel scan sequence;
construct a second channel scan sequence; scan channels that have
not been scanned according to the second channel scan sequence;
receive beacon frames during the scan of operating channels that
have not been scanned; and determine a parent node for accessing
the wireless sensor network according to the first beacon frame and
the beacon frames received during the scan of operating channels
that have not been scanned.
11. The apparatus according to claim 10, wherein the beacon frame
received during the first-round channel scan further comprises a
first channel link quality parameter of an operating channel where
the beacon frame comes from; wherein the readable storage medium
further comprises instructions to: determine the parent node for
accessing the wireless sensor network according to the first
channel link quality parameter contained in the first beacon frame
and channel link quality parameters of corresponding operating
channels contained in the received beacon frames during the scan of
operating channels that have not been scanned.
12. The apparatus according to claim 9, wherein the readable
storage medium further comprises instructions to: perform a
first-round channel scan from a first channel according to a
predefined channel scan sequence, until every channel in the
channel scan sequence has been scanned; construct a second channel
scan sequence according to beacon frames received on operating
channels during the first-round channel scan process, wherein the
beacon frames carry with first channel link quality parameters of
channels where those beacon frames come from; select a beacon
sending node as a parent node from beacon sending nodes sending the
beacon frames according to the first channel link quality
parameters.
13. The apparatus according to claim 12, wherein the readable
storage medium further comprises instructions to: compare operating
channels where the received beacon frames come from with the
predefined channel scan sequence; delete from the predefined
channel scan sequence, channels except the operating channels where
the received beacon frames come from, to construct a second channel
scan sequence.
14. The apparatus according to claim 12, wherein the readable
storage medium further comprises instructions to: store a second
predetermined threshold; select channels having first channel link
quality parameters exceeding the second predetermined threshold
from operating channels of beacon sending nodes in the current
wireless sensor network to construct the second channel scan
sequence.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This application is a continuation of U.S. patent
application Ser. No. 13/664,203, filed on Oct. 30, 2012, which is a
continuation of International Patent Application No.
PCT/CN2011/073589, filed on May 3, 2011, which claims priority to
Chinese Patent Application No. 201010165632.5, filed on Apr. 30,
2010. The afore-mentioned patent applications are hereby
incorporated by reference in their entireties.
TECHNICAL FIELD
[0002] The present invention relates to the field of wireless
sensor technology, and more specifically, to a method and apparatus
for accessing a wireless sensor network.
BACKGROUND
[0003] Wireless sensor networks are widely applied wireless
networks suitable for various practical environments. Wireless
sensor networks have found their extensive applications in
military, medical care and health, environmental protection, public
traffic and other fields due to their advantageous features, such
as, ad hoc, autonomous, self energy saving, high reliability, low
cost, etc.
[0004] There are two kinds of wireless sensor networks described in
existing sensor network standards: non-beacon enabled networks and
beacon enabled networks. In a beacon enabled network, a
beacon-capable device sends out beacons periodically, through
sending beacons, not only time synchronization with surrounding
nodes, but also network information provision to peripheral nodes
expecting for accessing the network can be realized. For example,
in a superframe-employed network, a coordinator sends beacons to
surrounding nodes, for each superframe period, it begins at the
timing when a beacon is sent out, within the beacon, the duration
of the superframe period, time slot scheduling of the superframe,
and time synchronization for various devices and other information
can be contained. In a non-beacon enabled network, there is no
periodic beacon transmission, and beacons are only transmitted by a
specific device as demand, for example, in network access process
or when time synchronization is necessary. Communications between
the apparatus in a non-beacon enabled network are generally
asynchronous, that is, a transmitting device sends a communication
request when communication is needed to perform inter-device
synchronization coordination and then data transmission.
[0005] Devices in a wireless sensor network usually adopt one
channel to communicate, however, in order to increase network
communication capacity and avoid mutual interference between
devices, network devices can use multiple channels to communicate
simultaneously. In the multi-channel communication mode, various
devices can communicate with each other on their different optimal
channels constantly, or can communicate in a frequency hopping
manner, particularly, including random sequence frequency hopping
and constant sequence frequency hopping. Frequency hopping
communication needs precise time synchronization between devices,
while there is not a high time synchronization requirement in the
case of constant optimal channel communication of devices.
[0006] In existing multi-channel communication networks, various
device nodes generally operate in different channels, and switch to
channels of receiving devices only when communication is needed.
When a device expecting for network joins in a network, instead of
staying on a channel to complete the access process, it enquires on
each potential communication channel according to its own
parameters, that is, to explore on each possible communication
channel to see whether there is an accessible wireless network. In
doing so, the node expecting for network may broadcast a beacon
request frame on a channel and wait for a corresponding period of
time to receive a beacon frame. After sending the beacon request
frame, the device expecting for network only accepts beacon frames
sent from networks, and does not accept data information
transmitted on the channel. If a beacon frame is received, the
device node expecting for network determines whether to join in a
network according to content carried on the beacon frame. When it
is determined to access a wireless network present on the current
channel, the device node expecting for network sends association
information to a device node sending the beacon frame for
subsequent network access process; if the network present on the
current channel is unsuitable for access, the device node discards
the received beacon frame. If no beacon frame is received in a
defined period of time, the device node expecting for network skips
to another channel to repeat the above steps, until each channel
set therein has been detected.
[0007] In the prior art, although the multi-channel communication
method can increase communication resources and avoid communication
collision, a device expecting for network has to send beacon
request frames on various possible channels, and has to wait for a
certain period of time on channels on which beacon request frames
have been sent to acquire network beacon information required to
complete the network access process, consuming a large amount of
time and energy.
SUMMARY
[0008] In view of above, a method and apparatus for accessing a
wireless sensor network is provided in an embodiment of this
invention, capable of achieving fast, effective access to a
wireless sensor network.
[0009] In order to achieve the above purpose, the following
technique solutions are provided in embodiments of this
invention.
[0010] A method for accessing a wireless sensor network,
comprising: [0011] performing channel scan from a first channel by
a device node expecting for network according to a predefined
channel scan sequence; [0012] pausing the channel scan when
receiving a first beacon frame returned from a beacon sending node
during the channel scan, wherein the beacon frame carries with
operating channels of beacon sending nodes in a current wireless
sensor network and a first channel link quality parameter of a
channel on which a current beacon sending node is located; [0013]
comparing the operating channels of beacon sending nodes in the
current wireless sensor network with the predefined channel scan
sequence to delete channels except the operating channels from the
predefined channel scan sequence to construct a new channel scan
sequence; [0014] continuing the channel scan for operating channels
that have not been scanned according to the new channel scan
sequence; [0015] determining a parent node for accessing the
wireless sensor network according to first channel link quality
parameters in received beacon frames of the operating channels;
[0016] selecting an operating channel for the device node expecting
for network to access the wireless sensor network on the operating
channel through the parent node.
[0017] An apparatus for accessing a wireless sensor network,
comprising: [0018] a channel scan unit for performing channel scan
from a first channel according to a predefined channel scan
sequence; [0019] a scan control unit for pausing the channel scan
when receiving a first beacon frame returned from a beacon sending
node during the channel scan, wherein the beacon frame carries with
operating channels of beacon sending nodes in a current wireless
sensor network and a first channel link quality parameter of a
channel on which a current beacon sending node is located; [0020] a
construction unit for comparing the operating channels of beacon
sending nodes in the current wireless sensor network with the
predefined channel scan sequence to delete channels except the
operating channels from the predefined channel scan sequence, and
construct a new channel scan sequence; [0021] wherein, the scan
control unit is further used to continue the channel scan for
channels that have not been scanned according to the new channel
scan sequence; [0022] a determination unit for determining a parent
node for accessing the wireless sensor network according to first
channel link quality parameters in received beacon frames of the
operating channels; [0023] an access unit for selecting an
operating channel for the device node expecting for network to
access the wireless sensor network on the operating channel through
the parent node.
[0024] A method for accessing a wireless sensor network,
comprising: [0025] selecting a beacon sending node of a current
wireless sensor network as a parent node, and determining a second
channel scan sequence constructed according to operating channels
in the current wireless sensor network; [0026] performing a
second-round channel scan while synchronously switching channels
for a device node expecting for network and the parent node
according to the second channel scan sequence; [0027] determining
an operating channel for the device node expecting for network
according to second channel link quality parameters carried on
beacon frames received during the second-round channel scan, and
accessing the wireless sensor network on the operating channel
through the parent node.
[0028] An apparatus for accessing a wireless sensor network,
comprising: [0029] a preprocess unit for selecting a beacon sending
node of a current wireless sensor network as a parent node, and
determining a second channel scan sequence constructed according to
operating channels in the current wireless sensor network; [0030] a
second-round scan unit for synchronously switching channels for a
device node expecting for network and the parent node according to
the second channel scan sequence to perform a second-round channel
scan; [0031] an access unit for determining an operating channel
for the device node expecting for network according to second
channel link quality parameters carried on beacon frames received
during the second-round channel scan, and accessing the wireless
sensor network on the operating channel through the parent
node.
[0032] It can be seen that a method and apparatus for accessing a
wireless sensor network is provided in embodiments of this
invention. According to technique solutions provided in embodiments
of this invention, when a first beacon frame is received, the
channel scan is paused, a predefined channel scan sequence is
adjusted according to operating channels of a current wireless
sensor network recorded in the beacon frame, the non-operational
channels are deleted from the channels, so that channel scan time
can be saved, and the process of accessing to the current wireless
sensor network by a device node expecting for network can be
accelerated.
BRIEF DESCRIPTION OF THE DRAWINGS
[0033] For a more explicit description of the technical solutions
of embodiments of this invention, a brief introduction of
accompanying drawings to be used in the description of these
embodiments will be given below. Obviously, accompanying drawings
described below are merely some embodiments of this invention, for
those skilled in the art, other accompanying drawings can be
derived from these ones without any creative efforts.
[0034] FIG. 1 is a flowchart of a method provided in an embodiment
of this invention;
[0035] FIG. 2 is a schematic structure diagram of an apparatus
provided in an embodiment of this invention;
[0036] FIG. 3 is a schematic structure diagram of a unit of the
apparatus provided in an embodiment of this invention;
[0037] FIG. 4 is a schematic structure diagram of a unit of the
apparatus provided in another embodiment of this invention;
[0038] FIG. 5 is a flowchart of a method provided in another
embodiment of this invention; and
[0039] FIG. 6 is a schematic structure diagram of an apparatus
provided in an embodiment of this invention.
DESCRIPTION OF EMBODIMENTS
[0040] For a better understanding of technical solutions of this
invention for those skilled in the art, a clear and complete
description of technical solutions of embodiments of this invention
will be given in connection with accompanying drawings of
embodiments of this invention. Obviously, embodiments described
herein are merely some embodiments of this invention, but not all
of them. Based on those embodiments of this invention, other
embodiments can occur to those skilled in the art without any
creative efforts, all of which fall within the scope of this
invention.
[0041] Referring to FIG. 1, a network access method provided in an
embodiment of this invention comprises the following steps. [0042]
S101. A device node expecting for network performs channel scan
from a first channel according to a predefined channel scan
sequence; [0043] S102. Pause the channel scan when receiving a
first beacon frame returned from a beacon sending node during the
channel scan; wherein the beacon frame carries with operating
channels of beacon sending nodes in a current wireless sensor
network and a first channel link quality parameter;
[0044] The first channel can be any channel of the predefined
channel scan sequence.
[0045] In the method provided in the embodiment of this invention,
before joining in a network by a device node expecting for network,
a range of operating channels is generally predefined according to
its own system for scanning, not exceeding beyond the number of
operable channels in a range of its operating frequencies, such as
16 channels available for selection in the range of 2.4 GHz. Once a
range of scan channels has been determined, for example, 13
channels can be selected from the 16 available channels as scan
channels and scanned by a certain order. For example, channels 1-13
can be selected, and the channel scan sequence can be defined as
from channel 1 to channel 13. After the determination of channels
to be scanned and their channel scan order, a channel scan sequence
can be formed for the channels to be scanned according to the
channel scan order. Then, recorded channels are scanned in turn
according to the channel scan sequence.
[0046] The channel scan process comprises: sending a beacon request
frame on a scan channel by the device node expecting for network,
and then waiting a predetermined period of time.
[0047] For the convenient of description, assume that a channel X
is now being scanned by the device node expecting for network
according to the current predefined channel scan sequence. The
device node expecting for network sends a beacon request frame on
channel X. In practical applications, the device node expecting for
network may add its predefined channel scan sequence in the beacon
request frame with a frame format particularly shown in Table 1. As
shown in Table 1, four bytes in the third column are used to record
a predefined channel scan sequence.
TABLE-US-00001 TABLE 1 Byte: 1 1 4 Frame head Command frame
identifier Channels to be scanned
[0048] The device node expecting for network waits a predetermined
period of time on channel X. If there is a beacon sending node
capable of sending a beacon frame on channel X, the beacon sending
node sends a beacon frame to the device node expecting for network
after receiving the beacon request frame transmitted from the
device node expecting for network. In general, upon receiving a
beacon frame on a channel, the device node expecting for network
will switch to a next channel in the predefined channel scan
sequence to continue its channel scan process; if there is not a
beacon sending node on channel X, no beacon frame can be sent after
the device node expecting for network has sent a beacon request
frame, in this case, after waiting a time exceeding a predetermined
time threshold on channel X, the device node expecting for network
switches to a next channel in the predefined channel scan sequence
to continue its channel scan process.
[0049] In the embodiment of this invention, the device node
expecting for network performs channel scan from a first channel of
a predefined channel scan sequence, until a first beacon frame is
received. When a first beacon frame is received by the device node
expecting for network, instead of switching to a next channel in
the predefined channel scan sequence to continue channel scan as
that in existing channel scan process, the channel scan is paused.
If no beacon frame returned on the scanned channel is received by
the device node expecting for network, channel scan is performed
continuously according to the predefined channel scan sequence,
until each channel of the predefined channel scan sequence has been
scanned.
[0050] The beacon frame sent from the beacon sending node generally
comprises a current network ID, time synchronization, and other
information. Because the beacon sending node operates in the
current multi-channel wireless sensor network, operating channels
of its surrounding beacon sending nodes might have been recorded in
its communications with those surrounding beacon sending nodes; or
operating channels of various surrounding beacon sending nodes
might have been counted in advance. That is, the beacon sending
node may acquire operating channels of beacon sending nodes in the
current wireless sensor network. In the embodiment of this
invention, the beacon sending node can add operating channels of
beacon sending nodes in the current wireless sensor network into
the beacon frame and feed it back to the device node expecting for
network. A beacon frame format of an embodiment of this invention
is shown in Table 2.
TABLE-US-00002 TABLE 2 8-bit 1 4/10 0/5/6/10/14 4 4 variable 2
byte: 2 Frame Sequential Address Auxiliary Time Network Beacon FCS
control No. field security synchronization channel payload field
field field use list Frame head MAC payload MFR
[0051] The channel link quality parameter may be RSSI (Received
Signal Strength Indication). Since the channel link quality
parameter contained in the beacon frame has time dependency,
channel link quality parameters received at different times
generally differ from each other even for the same channel. Thus,
terms such as first channel link quality parameter and second
channel link quality parameter are used in embodiments of this
invention to distinguish channel link quality parameters at
different times.
[0052] S103. Establish a new channel scan sequence according to
beacon sending nodes of the current wireless sensor network.
[0053] Particularly, the operating channels of beacon sending nodes
of the current wireless sensor network can be compared with the
predefined channel scan sequence, and a new channel scan sequence
is formed through deleting channels except those in the operating
channels from the predefined channel scan sequence.
[0054] S104. Scan operating channels that have not been scanned in
sequence according to the new channel scan sequence.
[0055] S105. Determine a parent node for accessing the wireless
sensor network according to first channel link quality parameters
in received beacon frames of the operating channels.
[0056] In the embodiment of this invention, a first channel link
quality parameter is used to represent a channel link quality
parameter carried in the first beacon frame during this channel
scan process, and channel link quality parameters carried in
received beacon frames during the scan process of operating
channels that have not been scanned according to the new channel
scan sequence. After receiving a beacon frame, the device node
expecting for network may be aware of channel use information of
the network according to information carried on the channel frame.
The device node expecting for network may establish a new channel
scan sequence according to operating channel information contained
in the beacon frame. For example, in an embodiment, operating
channels of beacon sending nodes of the current wireless sensor
network can be compared with the predefined channel scan sequence,
and then channels except those in the operating channels are
deleted from the set channel scan sequence to establish a new
channel scan sequence.
[0057] In subsequent channel scan, the device node expecting for
network continue to scan channels that have not been scanned
according to new channel scan sequence. Non-operating channels are
excluded from the new channel scan sequence, and thus scanning
according to the new channel scan sequence can save time otherwise
wasted in the scan of non-operating channels. The newly constructed
channel scan sequence is more optimal than the original predefined
channel scan sequence, so that time required for subsequent channel
scan is fundamentally reduced.
[0058] Continuing with the above example, in an embodiment of this
invention, the predefined channel scan sequence is channel 1 to
channel 13. The device node expecting for network begins channel
scan from channel 1, assume that a first channel frame is received
in the scan of channel 2, the channel scan process is then paused.
From information carried on the beacon frame, it is determined that
the current network comprises operating channels 2, 3, 4, 6, 9, 10,
13, 15 and 16. After comparing the operating channels in the
current network with the predefined scan channels, channels except
the operating channels are deleted, that is, the channels that
originally would be scanned 5, 7, 8, 11 and 12 are deleted, to
establish a new channel scan sequence, including 2, 3, 4, 6, 9, 10,
13. Because channels 1, 2 have been scanned, it is sufficient to
continuously scan other operating channels that have not been
scanned (channels 3, 4, 6, 9, 10 and 13) according to the new
channel scan sequence.
[0059] When all operating channels in the new channel scan sequence
have been scanned, through beacon frames returned on various
operating channels, a parent node for accessing the wireless sensor
network can be determined according to first channel link quality
parameters carried on those beacon frames. For example, a beacon
frame sending node with the best channel link quality parameter can
be selected as the parent node for accessing the wireless sensor
network.
[0060] S106. Select an operating channel for the device node
expecting for network to access the wireless sensor network on the
operating channel through the parent node.
[0061] After determining a parent node for wireless sensor network
access, it is also necessary for the device node expecting for
network to determine an operating channel, so that it can access
the wireless sensor network on that operating channel through the
parent node.
[0062] In an embodiment of this invention, any existing channel can
be selected as the operating channel of the device node expecting
for network; alternatively, an operating channel can be directly
selected for the device node expecting for network according to the
first channel link quality parameters.
[0063] In another embodiment of this invention, a second-round
channel scan can be performed through synchronously switching
channels with the parent node according to the new channel scan
sequence. Particularly, the synchronous switch process comprises:
performing channel scan on the same channel according to the new
channel scan sequence by the device node expecting for network and
the parent node simultaneously, then synchronously switching to a
next channel to scan, until all channels in the new channel scan
sequence have been scanned. The channel scan process may comprise:
sending a beacon request frame on a channel by the device node
expecting for network; returning a beacon frame to the device node
expecting for network by the parent node after receiving the beacon
request frame; receiving the beacon frame by the device node
expecting for network, wherein a second channel link quality
parameter is carried on the beacon frame.
[0064] An operating channel of the device node expecting for
network is determined according to second channel link quality
parameters carried on beacon frames received during the
second-round channel scan. For example, a channel with the best
second channel link quality parameter can be selected as the
operating channel of the device node expecting for network.
[0065] The second channel link quality parameter is used to
represent channel link quality parameters of operating channels
carried on beacon frames received during the second-round channel
scan.
[0066] Note that during the first-round channel scan, the first
channel link quality parameters are carried on beacon frames
received by the same device node expecting for network, which are
sent on different operating channels by beacon sending nodes on
those different operating channels, representing channel quality of
those different operating channels; while the second channel link
quality parameters are carried on beacon frames received by the
same device node expecting for network sent during the second-round
channel scan process, which are sent by the parent node on
different operating channels, representing channel quality of
different operating channels on which the parent node sends beacon
frames. Thus, compared to the first channel link quality parameter,
the second channel link quality parameter is more suitable to
reflect differences between channels.
[0067] This invention does not have limitations on the method of
operating channel determination, which can be selected as required
in practice.
[0068] For example, if channel 6 is determined as having the best
channel link quality according to first channel link quality
parameters in beacon frames, a beacon sending node on channel 6 is
selected as the parent node for the device node expecting for
network to access the wireless sensor network, at the same time,
channel 6 can be selected as the operating channel of the device
node expecting for network to access the current wireless sensor
network on channel 6 through the parent node.
[0069] According to the method provided in an embodiment of this
invention, when a first beacon frame is received, channel scan is
paused, and a new channel scan sequence is constructed according to
operating channels of a current wireless sensor network recorded in
the beacon frame, wherein non-operating channels are excluded from
the new channel scan sequence, so that the time required for
subsequence channel scan can be reduced, and the access to the
current wireless sensor network by the device node expecting for
network can be accelerated.
[0070] Referring to FIG. 2, an apparatus for accessing a wireless
sensor network is also provided in an embodiment of this invention,
which is located in a device node expecting for network,
comprising: [0071] a channel scan unit 201, for performing channel
scan from a first channel according to a predefined channel scan
sequence; [0072] a scan control unit 202, for pausing the channel
scan when receiving a first beacon frame returned from a beacon
sending node during the channel scan, the beacon frame carrying
with operating channels of beacon sending nodes in a current
wireless sensor network and a first channel link quality parameter;
[0073] a construction unit 203, for comparing the operating
channels of beacon sending nodes in the current wireless sensor
network with the predefined channel scan sequence to delete
channels except the operating channels from the predefined channel
scan sequence to construct a new channel scan sequence; [0074]
wherein, the scan control unit 202 is further used to continue the
channel scan for the channels that have not been scanned according
to the new channel scan sequence; [0075] a determination unit 204,
for determining a parent node for accessing the wireless sensor
network according to first channel link quality parameters in
received beacon frames of the operating channels; [0076] an access
unit 205, for selecting an operating channel for the device node
expecting for network to access the wireless sensor network on the
operating channel through the parent node.
[0077] In an embodiment of this invention, referring to FIG. 3, the
access unit 205 comprises: [0078] a synchronous scan subunit 301,
for completing a second-round channel scan through synchronous
channel switch with the parent node according to the new channel
scan sequence; [0079] a determination subunit 302, for determining
an operating channel for the device node expecting for network
according to second channel link quality parameters carried on
beacon frames received during the second-round channel scan
process; [0080] an access subunit 303, for accessing the wireless
sensor network on the operating channel through the parent
node.
[0081] Referring to FIG. 4, in another embodiment of this
invention, the access unit 205 comprises: [0082] a selection
subunit 401, for selecting any existing channel as the operating
channel of the device node expecting for network; or selecting the
operating channel of the device node expecting for network
according to the first channel link quality parameters in the
beacon frames. [0083] an access subunit 402, for accessing the
wireless sensor network on the operating channel through the parent
node.
[0084] According to the apparatus provided in an embodiment of this
invention, when a first beacon frame is received, channel scan is
paused, and a new channel scan sequence is constructed according to
operating channels of a current wireless sensor network recorded in
the beacon frame, wherein non-operating channels are excluded from
the new channel scan sequence, so that the time required for
subsequence channel scan can be reduced, and the access to the
current wireless sensor network by the device node expecting for
network can be accelerated.
[0085] Referring to FIG. 5, another method for accessing a wireless
sensor network is provided in an embodiment of this invention,
comprising the following steps.
[0086] S501. Select a beacon sending node of a current wireless
sensor network as a parent node, and determine a second channel
scan sequence constructed according to operating channels in the
current wireless sensor network.
[0087] S502. Synchronously switch channels for a device node
expecting for network and the parent node according to the second
channel scan sequence to perform a second-round channel scan.
[0088] After determining the parent node, the device node expecting
for network and the parent node synchronously switch channels
according the second channel scan sequence to complete the
second-round channel scan for adjusted channels. In this
embodiment, the purpose of the second-round channel scan is to
determine an operating channel for the device node expecting for
network, that is, to determine on which channel the device node
expecting for network will operate.
[0089] Particularly, synchronously switching channels according the
second channel scan sequence by the device node expecting for
network and the parent node to complete the second-round channel
scan for adjusted channels particularly comprises: according to the
second channel scan sequence, switching to the same channel by the
parent node and the device node expecting for network; after
switching to the same channel by both of the parent node and the
device node expecting for network, sending a beacon request frame
by the device node expecting for network on a current channel to
the parent node; returning a beacon frame by the parent node when
receiving the beacon request frame; after receiving the beacon
frame, switching to a next channel in the second channel scan
sequence by the device node expecting for network along with the
parent node to continue channel scan, until a beacon frame is
received by the device node expecting for network on the last
channel of the second channel scan sequence, after which the
second-round channel scan process ends.
[0090] S503. Determine an operating channel for the device node
expecting for network according to second channel link quality
parameters carried on beacon frames received during the
second-round channel scan, and access the wireless sensor network
on the operating channel through the parent node.
[0091] In the embodiment of this invention, the second channel link
quality parameters carried in the beacon frames may be RSSI.
According to RSSI, an operating channel most suitable to its
operation can be determined by the device node expecting for
network. For example, a channel with the maximum RSSI can be
selected as the operating channel. After determining the operating
channel, the wireless sensor network can be accessed on the
operating channel through the parent node.
[0092] In the method provided in the embodiment of this invention,
a second channel scan sequence is constructed according to
operating channels in a current wireless sensor network, a parent
node is selected from beacon sending nodes, the parent node and a
device node expecting for network synchronously switch channels
according to the second channel scan sequence to complete a
second-round channel scan process to acquire second channel link
quality parameters of various channels, an operating channel of the
device node expecting for network is selected according to the
second channel link quality parameters, on which the wireless
sensor network is accessed through the parent node. Because the
second channel scan sequence is determined according to operating
channels in the current wireless sensor network in which
non-operating channels are excluded, time consumed on non-operating
channels during the second-round channel scan process of the device
node expecting for network can be avoided, so that time and energy
consumed by the device node expecting for network to acquire
channel status data can be fundamentally reduced, and the
efficiency of device node expecting for network to access a
wireless sensor network can be improved.
[0093] In an embodiment of this invention, step S501 can be
realized through the following steps, particularly comprising:
[0094] performing channel scan from a first channel by a device
node expecting for network according to a predefined channel scan
sequence; [0095] pausing the channel scan when receiving a first
beacon frame returned from a beacon sending node, wherein the
beacon frame carries with operating channels of beacon sending
nodes in a current wireless sensor network and a first channel link
quality parameter of a channel on which a current beacon sending
node is located; [0096] comparing the operating channels of beacon
sending nodes in the current wireless sensor network with the
predefined channel scan sequence to delete channels except the
operating channels from the predefined channel scan sequence and
construct a second channel scan sequence; [0097] continuing the
channel scan for operating channels that have not been scanned
according to the second channel scan sequence; [0098] determining a
parent node for accessing the wireless sensor network according to
first channel link quality parameters in received beacon frames of
the operating channels.
[0099] In another embodiment of this invention, step S501 can be
realized through the following manner, comprising: [0100]
performing a first-round channel scan from a first channel by a
device node expecting for network according to a predefined channel
scan sequence, until all channels in the channel scan sequence have
been scanned; [0101] constructing a second channel scan sequence
according to beacon frames received on operating channels during
the first-round channel scan, wherein the beacon frames carry with
first channel link quality parameters of channels where these
beacon frames come from; [0102] selecting a beacon sending node as
a parent node from the beacon sending nodes sending the beacon
frames according to the channel link quality parameters.
[0103] When constructing the second channel scan sequence,
operating channels corresponding to beacon frames received can be
compared with the predefined channel scan sequence; channels except
those in the operating channels are deleted from the predefined
channel scan sequence to construct the second channel scan
sequence; in other embodiments of this invention, channels having
first channel link quality parameters exceeding a second
predetermined threshold can be selected from operating channels
corresponding to the received beacon frames to construct the second
channel scan sequence.
[0104] The second predetermined threshold is an upper limit of the
channel link quality parameters, if the channel link quality
parameter of a channel reaches or even exceeds the second
predetermined threshold, it is indicated that the channel has
better channel link quality, and is suitable for the device node
expecting for network as an operating channel.
[0105] After determining the second channel scan sequence, channels
having first channel link quality parameters failed to meet a first
predetermined threshold can be further deleted from the second
channel scan sequence.
[0106] The first predetermined threshold is a lower limit of the
channel link quality parameters, if the channel link quality
parameter of a channel fails to meet the first predetermined
threshold, it is indicated that the channel is unsuitable for the
device node expecting for network as an operating channel.
[0107] In the method provided in the embodiment of this invention,
after determining the parent node and the second channel scan
sequence consisted of operating channels, the parent node and a
device node expecting for network synchronously switch channels to
complete a second-round channel scan process according to the
second channel scan sequence to acquire second channel link quality
parameters of various channels, an operating channel of the device
node expecting for network is determined according to the second
channel link quality parameters, on which the wireless sensor
network is accessed through the parent node. Because the second
channel scan sequence consists of operating channels, in which
non-operating channels are excluded, it is not necessary to scan
every channel in the predefined channel scan sequence, time and
energy consumed by the device node expecting for network to acquire
channel status data during the second-round channel scan can be
reduced, and the efficiency of device node expecting for network to
access a wireless sensor network can be improved.
[0108] Referring to FIG. 6, an apparatus for accessing a wireless
sensor network is further provided in an embodiment of this
invention, which is in a device node expecting for network,
comprising: [0109] a preprocess unit 601 for selecting a beacon
sending node of a current wireless sensor network as a parent node,
and determining a second channel scan sequence formed according to
operating channels in the current wireless sensor network; [0110] a
second-round scan unit 602 for completing a second-round channel
scan through making device node expecting for network and the
parent node to synchronously switch channels according to the
second channel scan sequence; [0111] an access unit 603 for
determining an operating channel for the device node expecting for
network according to second channel link quality parameters carried
on beacon frames received during the second-round channel scan, and
accessing the wireless sensor network on the operating channel
through the parent node.
[0112] Wherein, in an embodiment of this invention, the preprocess
unit 601 comprises: [0113] a first scan subunit for performing
channel scan from a first channel by a device node expecting for
network according to a predefined channel scan sequence; [0114] a
scan control subunit for pausing the channel scan when receiving a
first beacon frame returned from a beacon sending node, wherein,
the beacon frame carries with operating channels of beacon sending
nodes in a current wireless sensor network and a first channel link
quality parameter of a channel on which a current beacon sending
node is located; [0115] a first construction subunit for comparing
the operating channels of beacon sending nodes in the current
wireless sensor network with the predefined channel scan sequence
to delete channels except the operating channels from the
predefined channel scan sequence, and construct a second channel
scan sequence; [0116] wherein the scan control subunit is further
used to continue the channel scan for channels that have not been
scanned according to the second channel scan sequence; [0117] a
determination subunit for determining a parent node for accessing
the wireless sensor network according to first channel link quality
parameters in beacon frames received on the operating channels.
[0118] In another embodiment of this invention, the preprocess unit
601 comprises: [0119] a second scan subunit for performing a
first-round channel scan from a first channel by a device node
expecting for network according to a predefined channel scan
sequence, until every channel in the channel scan sequence has been
scanned; [0120] a second construction subunit for constructing a
second channel scan sequence according to beacon frames received on
operating channels during the first-round channel scan process,
wherein the beacon frames carry with first channel link quality
parameters of channels where those beacon frames come from; [0121]
a selection subunit for selecting beacon sending node as a parent
node from beacon sending nodes sending the beacon frames according
to the channel link quality parameters.
[0122] Wherein, the second construction subunit may further
comprise: [0123] a second comparison module for comparing operating
channels corresponding to the received beacon frames with the
predefined channel scan sequence; [0124] a second deleting module
for deleting channels except the operating channels corresponding
to the received beacon frames from the predefined channel scan
sequence to construct a second channel scan sequence.
[0125] In practical applications, the second construction subunit
may further comprise: [0126] a storage module for storing a second
predetermined threshold; [0127] a construction module for selecting
channels having first channel link quality parameters exceeding the
second predetermined threshold from operating channels of beacon
sending nodes in the current wireless sensor network to construct
the second channel scan sequence.
[0128] Optionally, the second deleting module is further used to
delete channels having first channel link quality parameters failed
to meet a first predetermined threshold from the second channel
scan sequence.
[0129] The apparatus provided in the embodiment of this invention
realizes network access for a device node expecting for network
through two rounds of channel scan. A first-round channel scan
process is performed according to a predefined channel scan
sequence; non-operating channels are deleted from the predefined
channel scan sequence according to beacon frames received during
the first-round channel scan, to form a second channel scan
sequence. Then a parent node is selected from beacon sending nodes
capable of sending beacon frames; the parent node and the device
node expecting for network synchronously switch channels according
to the second channel scan sequence to complete a second-round
channel scan process, to acquire second channel link quality
parameters of various channels, and determine an operating channel
for the device node expecting for network according to the second
channel link quality parameters, on which the wireless sensor
network is accessed through the parent node. Because the second
channel scan sequence is determined through adjustment according to
beacon frames received during the first-round channel scan, in
which non-operating channels are deleted, it is not necessary to
scan every channel in the predefined channel scan sequence, time
and energy consumed by the device node expecting for network to
acquire channel status data during the second-round channel scan
can be reduced, and the efficiency of device node expecting for
network to access a wireless sensor network can be improved.
[0130] This invention can be described in the context of computer
executable instructions executed by a computer, for example,
program modules. In general, those program modules comprise
routines, programs, objects, components, data structures, etc for
carrying out specific tasks or realizing specific abstract data
structures. This invention also can be implemented in distributed
environments, in which tasks are carried out by remote devices
connected through communication networks. In distributed
environments, program modules can be located on local and remote
computer storage mediums, including storage devices.
[0131] What described above is merely preferred embodiments of this
invention, it should be indicated that, for those skilled in the
art, many improvements or modifications can be made without
departing from the principle of this invention, which should be
treated as being covered in the scope of this invention.
* * * * *