U.S. patent application number 10/446565 was filed with the patent office on 2004-12-02 for multiple mode support in a wireless local area network.
Invention is credited to Stephens, Adrian P..
Application Number | 20040240402 10/446565 |
Document ID | / |
Family ID | 33451064 |
Filed Date | 2004-12-02 |
United States Patent
Application |
20040240402 |
Kind Code |
A1 |
Stephens, Adrian P. |
December 2, 2004 |
Multiple mode support in a wireless local area network
Abstract
Briefly, in accordance with one embodiment of the invention, an
access point may provide multiple access to a single medium by
providing time division multiple access to the medium. During a
first phase to communicate with devices of a first type, the access
point may transmit a beacon to indicate to devices of a second type
not to communicate during the first phase. During a second phase to
communicate with devices of the second type, the access point may
transmit a beacon to indicate to devices of the first type not to
communicate during the second phase. In one particular embodiment,
the access point may transmit a medium reservation packet to
indicate reservation of the medium for affected devices. Phases may
be adaptively extended by transmitting additional medium
reservation packets until it is desired to end the present phase
and transition to the second phase.
Inventors: |
Stephens, Adrian P.;
(Cambridge, GB) |
Correspondence
Address: |
BLAKELY SOKOLOFF TAYLOR & ZAFMAN
12400 WILSHIRE BOULEVARD
SEVENTH FLOOR
LOS ANGELES
CA
90025-1030
US
|
Family ID: |
33451064 |
Appl. No.: |
10/446565 |
Filed: |
May 27, 2003 |
Current U.S.
Class: |
370/310 ;
370/338 |
Current CPC
Class: |
H04W 48/02 20130101;
H04W 28/10 20130101 |
Class at
Publication: |
370/310 ;
370/338 |
International
Class: |
H04B 007/00; H04Q
007/24 |
Claims
What is claimed is:
1. A method, comprising: during a first phase in which to
communicate with devices of a first type, transmitting a first
beacon to indicate to devices of a second type not to transmit
during the first phase; and communicating with devices of the first
type during the first phase.
2. A method as claimed in claim 1, further comprising, during a
second phase in which to communicate with devices of a second type,
transmitting a second beacon to indicate to devices of the first
type not to transmit during the second phase; and communicating
with devices of the second type during the second phase.
3. A method as claimed in claim 1, wherein devices of the first
type include devices to operate in compliance with a first
communications standard, and wherein devices of the second type
include devices to operate in compliance with a second
communications standard.
4. A method as claimed in claim 1, wherein devices of the first
type are unable to communicate with devices of the second type.
5. A method as claimed in claim 1, wherein devices of the first
type operate at approximately the same frequency as devices of the
second type.
6. A method as clamed in claim 1, wherein the beacon is
periodically transmitted.
7. A method as claimed in claim 1, wherein the beacon indicates to
devices of three or more types of devices not to transmit during
phases that do not correspond to devices of the three or more
types; and further comprising communicating with devices of the
three or more types during phases that correspond to devices of a
respective one of the three or more types.
8. A method, comprising: during a first phase in which to
communicate with devices of a first type, transmitting a medium
reservation packet to indicate to devices of a second type not to
transmit during the first phase; and communicating with devices of
the first type during the first phase.
9. A method as claimed in claim 8, further comprising: determining
whether to continue the first phase; and in the event it is
determined to continue the first phase, transmitting an additional
medium reservation packet to indicate to devices of the second type
not to transmit during first phase; and continuing said
communicating with devices of the first device during the first
phase.
10. A method as claimed in claim 8, further comprising: during a
second phase to communicate with devices of the second type,
transmitting a medium reservation to indicate to devices of the
second type not to transmit during the second phase; and
communicating with devices of the second type during the second
phase.
11. A method as claimed in claim 10, further comprising:
determining whether to continue the second phase; and in the event
it is determined to continue the second phase, transmitting an
additional medium reservation packet to indicate to devices of the
first type not to transmit during second phase; and continuing said
communicating with devices of the second type device during the
second phase.
12. A method as claimed in claim 8, wherein devices of the first
type include devices to operate in compliance with a first
communications standard, and wherein devices of the second type
include devices to operate in compliance with a second
communications standard.
13. A method as claimed in claim 8, wherein devices of the first
type are unable to communicate with devices of the second type.
14. A method as claimed in claim 8, wherein devices of the first
type operate at approximately the same frequency as devices of the
second type.
15. A method as claimed in claim 8, wherein the medium reservation
packet indicates to devices of three or more types of devices not
to transmit during phases that do not correspond to devices of the
three or more types; and further comprising communicating with
devices of the three or more types during phases that correspond to
devices of a respective one of the three or more types.
16. An article comprising a storage medium having stored thereon
instructions that, when executed by a computing platform, result in
providing multiple access to a medium in a wireless local area
network by: during a first phase in which to communicate with
devices of a first type, transmitting a first beacon to indicate to
devices of a second type not to transmit during the first phase;
and communicating with devices of the first type during the first
phase.
17. An article as claimed in claim 16, wherein the instructions,
when executed, further result in providing multiple access to a
medium in a wireless local area network by, during a second phase
in which to communicate with devices of a second type, transmitting
a second beacon to indicate to devices of the second type not to
transmit during the second phase; and communicating with devices of
the second type during the second phase.
18. An article as claimed in claim 16, wherein devices of the first
type include devices to operate in compliance with a first
communications standard, and wherein devices of the second type
include devices to operate in compliance with a second
communications standard.
19. An article as claimed in claim 16, wherein devices of the first
type are unable to communicate with devices of the second type.
20. An article as claimed in claim 16, wherein devices of the first
type operate at approximately the same frequency as devices of the
second type.
21. An article as clamed in claim 16, wherein the beacon is
periodically transmitted.
22. An article as claimed in claim 16, wherein the beacon indicates
to devices of three or more types of devices not to transmit during
phases that do not correspond to devices of the three or more
types; and wherein the instructions, when executed, further result
in providing multiple access to a medium in a wireless local area
network by communicating with devices of the three or more types
during phases that correspond to devices of a respective one of the
three or more types.
23. An article comprising a storage medium having stored thereon
instructions that, when executed by a computing platform, result in
providing multiple access to a medium in a wireless local area
network by: during a first phase in which to communicate with
devices of a first type, transmitting a medium reservation packet
to indicate to devices of a second type not to transmit during the
first phase; and communicating with devices of the first type
during the first phase.
24. An article as claimed in claim 23, wherein the instructions,
when executed, further result in providing multiple access to a
medium in a wireless local area network by: determining whether to
continue the first phase; and in the event it is determined to
continue the first phase, transmitting an additional medium
reservation packet to indicate to devices of the second type not to
transmit during first phase; and continuing said communicating with
devices of the first device during the first phase.
25. An article as claimed in claim 23, wherein the instructions,
when executed, further result in providing multiple access to a
medium in a wireless local area network by: during a second phase
to communicate with devices of the second type, transmitting a
medium reservation to indicate to devices of the second type not to
transmit during the second phase; and communicating with devices of
the second type during the second phase.
26. An article as claimed in claim 25, wherein the instructions,
when executed, further result in providing multiple access to a
medium in a wireless local area network by: determining whether to
continue the second phase; and in the event it is determined to
continue the second phase, transmitting an additional medium
reservation packet to indicate to devices of the first type not to
transmit during second phase; and continuing said communicating
with devices of the second type device during the second phase.
27. An article as claimed in claim 23, wherein devices of the first
type include devices to operate in compliance with a first
communications standard, and wherein devices of the second type
include devices to operate in compliance with a second
communications standard.
28. An article as claimed in claim 23, wherein devices of the first
type are unable to communicate with devices of the second type.
29. An article as claimed in claim 23, wherein devices of the first
type operate at approximately the same frequency as devices of the
second type.
30. An article as claimed in claim 23, wherein the medium access
reservation packet indicates to devices of three or more types of
devices not to transmit during phases that do not correspond to
devices of the three or more types; and wherein the instructions,
when executed, further result in providing multiple access to a
medium in a wireless local area network by communicating with
devices of the three or more types during phases that correspond to
devices of a respective one of the three or more types.
31. An apparatus, comprising: an omnidirectional antenna; a
transceiver to couple to said antenna; and a baseband processor to
couple to said transceiver, said baseband processor to communicate
with devices of a first type during a first phase by transmitting a
first beacon to indicate to devices of a second type not to
transmit during the first phase.
32. An apparatus as claimed in claim 31, said baseband processor to
communicate with devices of the second type during the second phase
by transmitting a second beacon to indicate to devices of the
second type not to transmit during the second phase.
33. An apparatus as claimed in claim 31, said transceiver to
operate at the same frequency as devices of the first type and at
the same frequency of devices as devices of the second type.
34. A method as claimed in claim 31, wherein the beacon indicates
to devices of three or more types of devices not to transmit during
phases that do not correspond to devices of the three or more
types; said baseband processor to communicate with devices of the
three or more types during phases that correspond to devices of a
respective one of the three or more types.
35. An apparatus, comprising: an omnidirectional antenna; a
transceiver to couple to said antenna; and a baseband processor to
couple to said transceiver, said baseband processor to communicate
with devices of a first type during a first phase by transmitting a
first medium reservation packet to indicate to devices of a second
type not to transmit during the first phase.
36. An apparatus as claimed in claim 35, said baseband processor to
communicate with devices of the second type during the second phase
by transmitting a second medium reservation packet to indicate to
devices of the second type not to transmit during the second
phase.
37. An apparatus as claimed in claim 35, said transceiver to
operate at the same frequency as devices of the first type and at
the same frequency of devices as devices of the second type.
38. An apparatus as claimed in claim 35, said baseband processor to
extend the first phase by transmitting an additional medium
reservation packet to indicate to devices of the second type not to
transmit during the first phase.
39. An apparatus as claimed in claim 35, said baseband process to
extent the second phase by transmitting an additional medium
reservation packet to indicate to devices of the first type not to
transmit during the second phase.
40. A method as claimed in claim 35, wherein the medium access
reservation packet indicates to devices of three or more types of
devices not to transmit during phases that do not correspond to
devices of the three or more types; said baseband processor to
communicate with devices of the three or more types during phases
that correspond to devices of a respective one of the three or more
types.
Description
BACKGROUND OF THE INVENTION
[0001] In advancing wireless technology, many devices will exist
that operate using one or more of various wireless standards. Such
wireless devices may be operating within the same environment and
thereby access the same medium, for example so that legacy devices
may still operate with access points that are developed to
communicate in accordance with newly developed standards.
DESCRIPTION OF THE DRAWING FIGURES
[0002] The subject matter regarded as the invention is particularly
pointed out and distinctly claimed in the concluding portion of the
specification. The invention, however, both as to organization and
method of operation, together with objects, features, and
advantages thereof, may best be understood by reference to the
following detailed description when read with the accompanying
drawings in which:
[0003] FIG. 1 is a block diagram of a wireless local area network
in accordance with one embodiment of the present invention;
[0004] FIG. 2 is a diagram of a beacon medium reservation operation
in accordance with one embodiment of the present invention;
[0005] FIG. 3 is a diagram of a distributed medium access operation
in accordance with one embodiment of the present invention;
[0006] FIG. 4 is a flow diagram of a method to provide multiple
mode support in a wireless local area network in accordance with an
embodiment of the present invention; and
[0007] FIG. 5 is a flow diagram of a method to provide multiple
mode support using a distributed medium access operation in a
wireless local area network in accordance with an embodiment of the
present invention.
[0008] It will be appreciated that for simplicity and clarity of
illustration, elements illustrated in the figures have not
necessarily been drawn to scale. For example, the dimensions of
some of the elements are exaggerated relative to other elements for
clarity. Further, where considered appropriate, reference numerals
have been repeated among the figures to indicate corresponding or
analogous elements.
DETAILED DESCRIPTION
[0009] In the following detailed description, numerous specific
details are set forth in order to provide a thorough understanding
of the invention. However, it will be understood by those skilled
in the art that the present invention may be practiced without
these specific details. In other instances, well-known methods,
procedures, components and circuits have not been described in
detail so as not to obscure the present invention.
[0010] Some portions of the detailed description that follows are
presented in terms of algorithms and symbolic representations of
operations on data bits or binary digital signals within a computer
memory. These algorithmic descriptions and representations may be
the techniques used by those skilled in the data processing arts to
convey the substance of their work to others skilled in the
art.
[0011] An algorithm is here, and generally, considered to be a
self-consistent sequence of acts or operations leading to a desired
result. These include physical manipulations of physical
quantities. Usually, though not necessarily, these quantities take
the form of electrical or magnetic signals capable of being stored,
transferred, combined, compared, and otherwise manipulated. It has
proven convenient at times, principally for reasons of common
usage, to refer to these signals as bits, values, elements,
symbols, characters, terms, numbers or the like. It should be
understood, however, that all of these and similar terms are to be
associated with the appropriate physical quantities and are merely
convenient labels applied to these quantities.
[0012] Unless specifically stated otherwise, as apparent from the
following discussions, it is appreciated that throughout the
specification discussions utilizing terms such as processing,
computing, calculating, determining, or the like, refer to the
action or processes of a computer or computing system, or similar
electronic computing device, that manipulate or transform data
represented as physical, such as electronic, quantities within the
registers or memories of the computing system into other data
similarly represented as physical quantities within the memories,
registers or other such information storage, transmission or
display devices of the computing system.
[0013] Embodiments of the present invention may include apparatuses
for performing the operations herein. This apparatus may be
specially constructed for the desired purposes, or it may comprise
a general purpose computing device selectively activated or
reconfigured by a program stored in the device. Such a program may
be stored on a storage medium, such as, but is not limited to, any
type of disk including floppy disks, optical disks, CD-ROMs,
magnetic-optical disks, read-only memories (ROMs), random access
memories (RAMs), electrically programmable read-only memories
(EPROMs), electrically erasable and programmable read only memories
(EEPROMs), flash memory, magnetic or optical cards, or any other
type of media suitable for storing electronic instructions, and
capable of being coupled to a system bus for a computing
device.
[0014] The processes and displays presented herein are not
inherently related to any particular computing device or other
apparatus. Various general purpose systems may be used with
programs in accordance with the teachings herein, or it may prove
convenient to construct a more specialized apparatus to perform the
desired method. The desired structure for a variety of these
systems will appear from the description below. In addition,
embodiments of the present invention are not described with
reference to any particular programming language. It will be
appreciated that a variety of programming languages may be used to
implement the teachings of the invention as described herein.
[0015] In the following description and claims, the terms coupled
and connected, along with their derivatives, may be used. In
particular embodiments, connected may be used to indicate that two
or more elements are in direct physical or electrical contact with
each other. Coupled may mean that two or more elements are in
direct physical or electrical contact. However, coupled may also
mean that two or more elements may not be in direct contact with
each other, but yet may still cooperate or interact with each
other.
[0016] It should be understood that embodiments of the present
invention may be used in a variety of applications. Although the
present invention is not limited in this respect, the circuits
disclosed herein may be used in many apparatuses such as in the
transmitters and receivers of a radio system. Radio systems
intended to be included within the scope of the present invention
include, by way of example only, wireless local area networks
(WLAN) devices and wireless wide area network (WWAN) devices
including wireless network interface devices and network interface
cards (NICs), base stations, access points (APs), gateways,
bridges, hubs, cellular radiotelephone communication systems,
satellite communication systems, two-way radio communication
systems, one-way pagers, two-way pagers, personal communication
systems (PCS), personal computers (PCs), personal digital
assistants (PDAs), and the like, although the scope of the
invention is not limited in this respect.
[0017] Types of wireless communication systems intended to be
within the scope of the present invention include, although not
limited to, Wireless Local Area Network (WLAN), Wireless Wide Area
Network (WWAN), Code Division Multiple Access (CDMA) cellular
radiotelephone communication systems, Global System for Mobile
Communications (GSM) cellular radiotelephone systems, North
American Digital Cellular (NADC) cellular radiotelephone systems,
Time Division Multiple Access (TDMA) systems, Extended-TDMA
(E-TDMA) cellular radiotelephone systems, third generation (3G)
systems like Wide-band CDMA (WCDMA), CDMA-2000, and the like,
although the scope of the invention is not limited in this
respect.
[0018] Referring now to FIG. 1, a wireless local area network in
accordance with one embodiment of the present invention will be
discussed. In the wireless local area network (WLAN) system 100
shown in FIG. 1, a first device 110 may include a wireless
transceiver 112 to couple to an antenna 118 and to a baseband
processor 116. Baseband processor 116 in one embodiment may
comprise a single processor, or alternatively may comprise a
baseband processor and an applications processor, although the
scope of the invention is not limited in this respect. Baseband
processor 116 may couple to a memory 114 which may include volatile
memory such as DRAM, non-volatile memory such as flash memory, or
alternatively may include other types of storage such as a hard
disk drive, although the scope of the invention is not limited in
this respect. Some portion or all of memory 114 may be included on
the same integrated circuit as baseband processor 116, or
alternatively some portion or all of memory 114 may be disposed on
an integrated circuit or other medium, for example a hard disk
drive, that is external to the integrated circuit of baseband
processor 116, although the scope of the invention is not limited
in this respect. Likewise, a second device 120 may include a
transceiver 122, baseband processor 126, memory 124, and antenna
128, and access point 140 may include a transceiver 142, memory
144, and baseband processor 146.
[0019] First device 110 and second device 120 may communicate with
access point 140 via wireless communication links 132 and 134,
where access point 140 may include at least one antenna 136.
Alternatively, access point 140, and `optionally ` first device 110
and second device 120, may include two or more antennas to provide
a diversity antenna arrangement, to provide spatial division
multiple access (SDMA), or to provide a multiple input, multiple
output (MIMO) system, or the like, although the scope of the
invention is not limited in this respect. Access point 140 may
couple with network 138 so that first device 110 and second device
120 may communicate with network 138, including devices coupled to
network 138, by communicating with access point 140 via wireless
communication links 132 and 134. Network 138 may include a public
network such as a telephone network or the Internet, or
alternatively network 138 may include a private network such as an
intranet, or a combination of a public and a private network,
although the scope of the invention is not limited in this respect.
Communication between user first device 110 and second device 120
and access point 140 may be implemented via a wireless local area
network (WLAN), for example a network compliant with a an Institute
of Electrical and Electronics Engineers (IEEE) standard such as
IEEE 802.11a, IEEE 802.11b, IEEE 802.15, IEEE 802.16, and so on,
and may for example operate in a basic services set (BSS)
arrangement, although the scope of the invention is not limited in
this respect. In another embodiment, communication between user
system 128 and access point 128 may be implemented via a cellular
communication network compliant with a Third Generation Partnership
Project (3GPP) standard, although the scope of the invention is not
limited in this respect.
[0020] In accordance with one embodiment of the invention, access
point 140 may be a multimode access point (MAP) in that access
point may allow first device 110 and second device 120 to
communicate with access point 140 even though first device 110 and
second device 120 may not be capable of communicating with one
another, for example where first device 110 is arranged to
communicate using a first wireless standard such as the IEEE
802.11a standard, and where second device 120 is arranged to
communicate using a second wireless standard such as a higher
throughput wireless communication standard directed toward, for
example, operation at or near the 5 GHz frequency of the IEEE
802.11a standard, although the scope of the invention is not
limited in this respect. In one embodiment, first device 110,
second device 120, and access point 140 may be arranged to
communicate over an identical or similar frequency band, for
example near 5 GHz, wherein the transceivers 112, 122, and 140 of
first device 110, second device 120, and access point 140 are
arranged to operate on a compatible physical layer, although the
scope of the invention is not limited in this respect. In such
embodiments, first device 110 and second device 120 may not be able
to receive and honor a wireless medium reservation made by the
other device, or may not receive or process medium reservation
packets sent by the other device, although the scope of the
invention is not limited in this respect. In accordance with one
embodiment of the invention, access point 140 may allow both first
device 110 and second device 120 to operate with access point 140
without requiring a modification to the protocol under which the
devices operate, although the scope of the invention is not limited
in this respect.
[0021] As shown in FIG. 1, access point 140 may provide support for
the mixture of two or more devices, such as first device 110 and
second device 120, and may coordinate the operation of wireless
local area network 100. In one embodiment of the invention, access
point 140 may operate to divide time into two phases, phase A and
phase B as shown in FIGS. 2 and 3. Devices of a first type, for
example first device 110, may operate during phase A, and devices
of a second type, for example second device 120, may operate during
phase B. Devices intended to operate during phase A may be referred
to as type A devices, and devices intended to operate during phase
B may be referred to as type B devices, although the scope of the
invention is not limited in this respect. During phase A, type A
devices and access point 140 may be considered as a first
subnetwork, subnetwork A, and during phase B, type B devices and
access point 140 may be considered as a second subnetwork,
subnetwork B, although the scope of the invention is not limited in
this respect. In one particular embodiment of the invention, access
point 140 may initiate frame exchange operations via a poll
mechanism wherein access point 140 may poll devices of type A
during phase A, and may poll devices of type B during phase B,
although the scope of the invention is not limited in this
respect.
[0022] Referring now to FIG. 2, a diagram of a beacon medium
reservation operation in accordance with one embodiment of the
present invention will be discussed. In wireless local area network
100, access point 140 may periodically transmit a beacon to provide
privileged access to the medium for access point 140. Although the
beacon medium reservation operation shown in FIG. 2 is discussed
with respect to using privileged access by way of example, the
invention is not limited in this respect. In one embodiment, the
beacon medium reservation operation of FIG. 2 may be referred to as
a privileged access operation to provide privileged access to the
wireless medium for access point 140, although the scope of the
invention is not limited in this respect. As shown in FIG. 2,
access point 140 may transmit a beacon that is received by devices
of subnetwork A, beacon A, at the start of phase B. Likewise,
access point 140 may transmit a beacon that is received by devices
of subnetwork B, beacon B, at the start of phase A. The transmitted
beacons, beacon A and beacon B, may include a privileged medium
reservation for access point 140 to prevent devices of the other
phase from operating during the present phase. For example, first
device 110 may be designated as able to operate during phase A and
may be generally referred to as a type A device, and second device
120 may be designated as able to operate during phase B and may be
referred to as a type B device, although the scope of the invention
is not limited in this respect. The beacon for phase A, beacon A,
may be received by type A devices and may contain a medium
reservation to prevent type A devices, e.g., first device 110, from
transmitting during phase B. Type B devices may access the medium
and access point 140 during phase B because type B devices have not
received and acted upon the medium reservation contained in beacon
A. Similarly, the beacon for phase B, beacon B, may be received by
type B devices and may contain a medium reservation to prevent type
B devices, e.g., second device 120, from transmitting during phase
A. Type A devices may access the medium and access point 140 during
phase A because type A devices have not received and acted upon the
medium reservation contained in beacon B, although the scope of the
invention is not limited in this respect. The beacon medium
reservation operation as shown in FIG. 2 may allow wireless local
area network 100 to operate using time division multiple access,
although the scope of the invention is not limited in this
respect.
[0023] Referring now to FIG. 3, a diagram of a distributed medium
access operation in accordance with one embodiment of the present
invention will be discussed. In one embodiment of the invention,
wireless local area network 100 may be based on carrier sense
multiple access/collision avoidance (CSMA/CA) with medium
reservation packets, although the scope of the invention is not
limited in this respect. In such an embodiment, access point 140
may gain access to the medium prior to phase A, and may transmit a
medium reservation in a medium reservation packet, reserve B, where
the medium reservation packet may be honored by type B devices, for
example second device 120, but may not be received or honored by
type A devices, for example first device 110. As a result of the
medium reservation packet, reserve B, type A devices may continue
to operate under a CSMA/CA protocol during phase A, and type B
devices do not attempt to transmit during phase A. Access point 140
may extend the duration of phase A by transmitting additional
medium reservation packets, reserve B continuation, that are
honored only by type B devices, thereby allowing type A devices to
continue to operate during phase A, although the scope of the
invention is not limited in this respect.
[0024] At the end of phase A, access point 140 may gain access to
the wireless medium and may transmit a medium reservation in a
medium reservation packet, reserve A, at the start of phase B,
where the medium reservation packet may be honored by type A
devices, but may not be received or honored by type B devices. As a
result, type B devices may continue to operate under a CSMA/CA
protocol during phase B, and type A devices do not attempt to
transmit during phase B. Access point 140 may extend the duration
of phase B by transmitting additional medium reservation packets
that are honored only by type A devices, thereby allowing type B
devices to continue to operate during phase B, although the scope
of the invention is not limited in this respect.
[0025] As shown in FIG. 3, access point 140 may transmit a medium
reservation that is honored by type B devices, thereby permitting
type A devices to operate during phase A. The use of a continuation
reservation is also shown in phase A. After the completion of phase
A, at the start of phase B, access point 140 may transmit a medium
reservation that is honored by type A devices. Type B devices then
are able to access the medium during phase B. In the example shown
in FIG. 3, although there may be periods of inactivity for type B
devices in phase B, devices of type A may be prevented from
accessing the medium because of the medium reservation packets,
reserve A, transmitted by access point 140, although the scope of
the invention is not limited in this respect. Likewise, though
there may be periods of inactivity of for type A devices in phase
A, devices of type B may be prevented from accessing the medium
because reservation packets, reserve B, transmitted by access point
140, although the scope of the invention is not limited in this
respect. The distributed medium access operation as shown in FIG. 2
may allow wireless local area network 100 to operate using adaptive
time division multiple access by adjusting the duration of the
phases, phase A and phase B, according to the load it observes in
the corresponding subnetworks, subnetwork A and subnetwork B,
although the scope of the invention is not limited in this
respect.
[0026] In one alternative embodiment, the multiple access operation
of wireless local area network 100 using a poll mechanism may
generally be extended to any number of device types, N device types
by dividing time into N phases, phase A, phase B, up to phase N and
operating the appropriate protocol during its respective phase,
although the scope of the invention is not limited in this respect.
In another alternative embodiment, the multiple access operation of
wireless local area network 100 using privileged access using a
beacon medium operation as shown in FIG. 2 likewise may be extended
to N device types by overlapping medium reservations signaled in
beacons so that each device type may see precisely one contiguous
period during which access point 140 has not reserved the medium to
itself, although the scope of the invention is not limited in this
respect. In alternative embodiments, the beacon need not be
transmitted using any privilege. In a further alternative
embodiment, the multiple access operation of wireless local area
network 100 using a distributed medium access operation as shown in
FIG. 3 likewise may be extended to N device types by permitting
operation of a single device type during its corresponding phase
through the transmission of medium reservation packets for all
other device types at the start of the corresponding phase. For
example, in a three phase case, the access point 140 may transmit
medium reservation packets for device types B and C at the start of
phase A, although the scope of the invention is not limited in this
respect.
[0027] Referring now to FIG. 4, a flow diagram of a method to
provide multiple mode support using a beacon medium reservation
operation in a wireless local area network in accordance with an
embodiment of the present invention will be discussed. Method 400
may be implemented by access point 140 and may be tangibly embodied
as a instructions stored on memory 144 of access point 140,
although the scope of the invention is not limited in this respect.
Method 400 may initiate by starting phase A at block 410. At the
start of phase A, access point 140 may transmit beacon B at block
412 where beacon B may include a privileged medium reservation to
indicate to type B devices to not transmit during phase A. As a
result, access point 140 may communicate with type A devices at
block 414 without interference from type B devices. After a
predetermined period, phase B may start at block 416 at which time
access point 140 may transmit beacon A where beacon A may include a
privileged medium reservation to indicate to type A devices to not
transmit during phase B. As a result, access point 140 may
communicate with type B devices at block 420 without interference
from type A devices. After a predetermined period, method 400 may
continue with phase A at block 410, although the scope of the
invention is not limited in this respect.
[0028] Referring now to FIG. 5, a flow diagram of a method to
provide multiple mode support using a distributed medium access
operation in a wireless local area network in accordance with an
embodiment of the present invention will be discussed. Method 500
may be implemented by access point 140 and may be tangibly embodied
as a instructions stored on memory 144 of access point 140,
although the scope of the invention is not limited in this respect.
Method 500 may initiate by starting phase A at block 510. At the
start of phase A, access point 140 may transmit reservation packet
B at block 512 to indicate to type B devices not to transmit during
phase A. As a result, access point 140 may communicate with type A
devices at block 514 without interference from type B devices. At
block 516, access point 140 may determine whether to continue phase
A, and if so, the access point 140 may transmit an additional
reservation packet B at block 512 to extend phase A and to continue
with method 500 at block 512. In the event access point 140
determines at block 516 not to continue phase A, phase B may start
at block 518. At the start of phase B, access point may transmit a
reservation packet A to indicate to type A devices not to transmit
during phase B. As a result, access point may communicate with type
B devices at block 522 without interference from type A devices. At
block 524, access point 140 may determine whether to continue phase
B, and if so, the access point 140 may transmit an additional
reservation packet A at block 524 to extend phase B and to continue
with method 500 at block 524. In the event access point 140
determines at block 524 not to continue phase B, phase A may start
again at block 510, and method 500 may continue at block 510,
although the scope of the invention is not limited in this
respect.
[0029] Although the invention has been described with a certain
degree of particularity, it should be recognized that elements
thereof may be altered by persons skilled in the art without
departing from the spirit and scope of the invention. It is
believed that the wireless local area network supporting multiple
modes of the present invention and many of its attendant advantages
will be understood by the forgoing description, and it will be
apparent that various changes may be made in the form, construction
and arrangement of the components thereof without departing from
the scope and spirit of the invention or without sacrificing all of
its material advantages, the form herein before described being
merely an explanatory embodiment thereof, and further without
providing substantial change thereto. It is the intention of the
claims to encompass and include such changes.
* * * * *