U.S. patent application number 13/740020 was filed with the patent office on 2013-05-23 for method and system for contention-based medium access schemes for directional wireless transmission with asymmetric antenna system (aas) in wireless communication systems.
This patent application is currently assigned to SAMSUNG ELECTRONICS CO., LTD.. The applicant listed for this patent is SAMSUNG ELECTRONICS CO., LTD.. Invention is credited to Chiu Ngo, Huai-Rong Shao.
Application Number | 20130128839 13/740020 |
Document ID | / |
Family ID | 42319043 |
Filed Date | 2013-05-23 |
United States Patent
Application |
20130128839 |
Kind Code |
A1 |
Shao; Huai-Rong ; et
al. |
May 23, 2013 |
METHOD AND SYSTEM FOR CONTENTION-BASED MEDIUM ACCESS SCHEMES FOR
DIRECTIONAL WIRELESS TRANSMISSION WITH ASYMMETRIC ANTENNA SYSTEM
(AAS) IN WIRELESS COMMUNICATION SYSTEMS
Abstract
A method and system for wireless communication in an asymmetric
antenna system (AAS) communication system is provided. A wireless
station performs carrier sensing by sensing a wireless
communication channel for ongoing communications in one or more
directions. Upon detecting that the wireless communication channel
is idle, the station transmits a frame preamble on the channel to a
receiving wireless station in more than one transmit direction, and
transmits a frame payload on the channel to the receiving wireless
station in one transmit direction.
Inventors: |
Shao; Huai-Rong; (San Jose,
CA) ; Ngo; Chiu; (San Francisco, CA) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
SAMSUNG ELECTRONICS CO., LTD.; |
Suwon |
|
KR |
|
|
Assignee: |
SAMSUNG ELECTRONICS CO.,
LTD.
Suwon
KR
|
Family ID: |
42319043 |
Appl. No.: |
13/740020 |
Filed: |
January 11, 2013 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
12628792 |
Dec 1, 2009 |
8385362 |
|
|
13740020 |
|
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|
61143635 |
Jan 9, 2009 |
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Current U.S.
Class: |
370/329 |
Current CPC
Class: |
H04W 74/0808
20130101 |
Class at
Publication: |
370/329 |
International
Class: |
H04W 74/08 20060101
H04W074/08 |
Claims
1. A method of wireless communication, comprising: carrier sensing,
by a wireless station sensing a wireless communication channel for
ongoing communications in one or more directions, wherein carrier
sensing comprises sensing the wireless communication channel in a
number of receive directions such that receive directions cover at
least transmit directions; upon detecting that the wireless
communication channel is idle: transmitting a frame preamble on the
channel to a receiving wireless station in more than one transmit
direction; and transmitting a frame payload on the channel to the
receiving wireless station in one transmit direction.
2. The method of claim 1 further comprising: upon detecting the
channel is idle: transmitting a request to send (RTS) frame on the
channel to the receiving wireless station in a number of transmit
directions which cover the expected receive direction in addition
to an expected transmit direction.
3. The method of claim 2 further comprising: upon receiving a clear
to send (CTS) frame from the receiving wireless station in response
to the RTS frame, transmitting the frame preamble to the receiving
wireless station in the number of transmit directions which cover
the expected receive direction in addition to the expected transmit
direction; and transmitting the frame payload to the receiving
wireless station in the expected transmit direction only.
4. The method of claim 3 further comprising maintaining a Short
Inter-Frame Space period between transmission of an RTS frame and a
CTS frame in a transmission direction.
5. The method of claim 1, wherein transmitting the frame preamble
further comprises periodically transmitting a frame mid-amble in a
number of transmit directions which cover an expected receive
direction in addition to an expected transmit direction.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This application is a continuation of U.S. patent
application Ser. No. 12/628,792 filed Dec. 1, 2009, which in turns
claims priority from U.S. Provisional Patent Application Ser. No.
61/143,635 filed on Jan. 9, 2009, incorporated herein by
reference.
TECHNICAL FIELD
[0002] The present invention relates in general to wireless
communication, and in particular, to directional wireless
communication systems.
BACKGROUND
[0003] In many wireless communication systems, a frame structure is
used for data transmission between wireless stations such as a
transmitter and a receiver. For example, the IEEE 802.11 standard
uses a frame structure in a Media Access Control (MAC) layer and a
physical (PHY) layer. In a typical transmitter, a MAC layer
receives a MAC Service Data Unit (MSDU) and attaches a MAC header
thereto, in order to construct a MAC Protocol Data Unit (MPDU). The
MAC header includes information such as a source address (SA) and a
destination address (DA). The MPDU is a part of a PHY Service Data
Unit (PSDU) and is transferred to a PHY layer in the transmitter to
attach a PHY header thereto to construct a PHY Protocol Data Unit
(PPDU). The PHY header includes parameters for determining a
transmission scheme including a coding/modulation scheme. Before
transmission as a packet from a transmitter to a receiver, a
preamble is attached to the PPDU, wherein the preamble can include
channel estimation and synchronization information.
[0004] Data applications such as Internet web surfing and e-mail
exchange usually require random wireless channel access with bursty
traffic characteristics. Reserving a channel time allocation (CTA)
in advance for these types of data applications may lead to low MAC
layer efficiency. Conventional channel access methods such as
carrier sensing multiple access/collision avoidance (CSMA/CA) and
an optional mechanism of Request To Send/Clear To Send (RTS/CTS) at
a Contention Access Period (CAP), are impractical due to the high
interference and collision probability caused by asymmetric antenna
system (AAS) and directional transmissions.
SUMMARY
[0005] A method and system for wireless communication in an
asymmetric antenna system (AAS) communication system is provided.
In one embodiment, a wireless station performs carrier sensing by
sensing a wireless communication channel for ongoing communications
in one or more directions. Upon detecting that the wireless
communication channel is idle, the station transmits a frame
preamble on the channel to a receiving wireless station in more
than one transmit direction, and transmits a frame payload on the
channel to the receiving wireless station in one transmit
direction.
[0006] These and other features, aspects and advantages of the
present invention will become understood with reference to the
following description, appended claims and accompanying
figures.
BRIEF DESCRIPTION OF THE DRAWINGS
[0007] FIG. 1 shows a block diagram of a wireless asymmetric
antenna system (AAS) communication system including wireless
station devices, according to an embodiment of the invention.
[0008] FIG. 2 shows an example of different number of transmit
directions and receive directions for an AAS communication system,
according to an embodiment of the invention.
[0009] FIG. 3 illustrates an example of interference caused by AAS
with directional transmissions in a conventional wireless
system.
[0010] FIG. 4 shows an example of ordering of requests to send
(RTS) and clear to send (CTS) frames in a number of transmit
directions and receive directions in an AAS communication system,
according to an embodiment of the invention.
[0011] FIG. 5 shows an example of data packet transmission in an
AAS communication system, according to an embodiment of the
invention.
[0012] FIG. 6 shows another example of data packet transmission in
an AAS communication system, according to an embodiment of the
invention.
[0013] FIG. 7 shows a flowchart of enhanced carrier sensing
multiple access/collision avoidance (CSMA/CA) carrier sensing
process implemented by a wireless station in an AAS communication
system, according to an embodiment of the invention.
[0014] FIG. 8 shows a flowchart of an enhanced CSMA/CA with
enhanced RTS/CTS process implemented by a wireless station in an
AAS communication system, according to an embodiment of the
invention.
[0015] FIG. 9 shows a block diagram of a wireless AAS communication
system including wireless station devices, according to an
embodiment of the invention.
DETAILED DESCRIPTION
[0016] The present invention provides a method and system for
contention-based communication medium access schemes for
directional wireless transmission with an asymmetric antenna system
(AAS) in wireless communication systems. Said communication medium
may comprise a wireless communication channel such as a radio
frequency (RF) channel.
[0017] Asymmetric antenna system (AAS) means that a wireless
station uses different antenna systems for transmission and
reception. A wireless station with only one set of antennas used
for both wireless reception and transmission can still include an
AAS if the transmission directions and reception directions are
different due to different configuration settings.
[0018] One embodiment of the invention comprises an enhanced
carrier sensing multiple access/collision avoidance (CSMA/CA)
process with an optional Request To Send/Clear To Send (RTS/CTS)
process, for reducing interference and collision probability while
enabling spatial re-use to improve overall wireless communication
throughput. This embodiment provides a contention-based wireless
channel access method and a data transmission method which reduce
interference and collision probability while enabling spatial
re-use to improve overall wireless system throughput.
[0019] Expected transmit and receive directions for a pair of
wireless stations as used herein mean selected directions in which
each wireless station expects to communicate with the other
wireless station over a wireless channel (based on prior antenna
training and switching). Sensing covers both expected transmit and
receive directions. Sensing in a minimum number of directions
comprises sensing which covers the expected transmission and
receive directions.
[0020] Accordingly, in a wireless communication system including
wireless station devices (DEVs), before a sender station sends
(i.e., wirelessly transmits) packets on a wireless channel in a
particular transmit direction, the sender station first senses the
wireless channel in a minimum number of receive directions which
combined together can cover the transmit direction in addition to
the expected receive direction.
[0021] Then, in one embodiment, the sender station transmits RTS or
CTS in the minimum number of transmit directions which cover its
expected receive direction in addition to the expected transmit
direction. After RTS/CTS negotiation, the sender station transmits
a preamble (or Preamble plus physical/Media Access Control
(PHY/MAC) header) of a data packet in the same way as RTS/CTS in
the minimum number of transmit directions which cover its expected
receive direction in addition to the expected transmit direction.
The remainder of the packet (i.e., the header and the payload (or
payload only)), is transmitted in the expected transmit direction
only.
[0022] In addition, if a packet being transmitted is long
(implementation dependent, typically longer than the time to keep
channel estimation and synchronization from preamble), the process
further involves the sender station periodically inserting
mid-ambles into the packet and transmitting the mid-ambles in the
minimum number of transmit directions which cover its expected
receive direction in addition to the expected transmit direction,
in the same way as the preamble (or Preamble plus PHY/MAC header)
or RTS/CTS. The process can be applied to not only AAS but also
symmetrical antenna systems (SAS) and can be used for both Piconet
Coordinator (PNC)<->DEV and DEV<->DEV
communications.
[0023] An implementation of the invention is now described with
reference to the drawings. FIG. 1 shows a functional block diagram
of a transmitter antenna and receiver antenna system model in a
wireless communication system 10 including wireless station devices
11 such as Device 1 (i.e., DEV1) and Device 2 (i.e., DEV2). As
illustrated in FIG. 1, DEV1 includes M(1, t) transmit antennas and
M(1, r) receive antennas, while DEV2 includes M(2, t) transmit
antennas and M(2, r) receive antennas. A transmit/receive direction
mapping/switching control module 12 implements embodiments of the
invention described herein. The module 12 may be implemented in
many ways, such as program instructions for execution by a
processor, as software, microcode, as computer program product on
computer readable media, as logic circuits, as application specific
integrated circuits, as firmware, etc. Further, embodiments of the
invention can take the form of an entirely hardware embodiment, an
entirely software embodiment, or an embodiment containing both
hardware and software elements.
[0024] In AAS, transmission and receiving can involve different
number of antennas or other different configuration settings. For
example, a wireless station device j may have I(j, t) transmission
directions ("t" indicating transmission), wherein transmission
configuration at kth direction is Q.sub.k-1.sup.(j,t); and the
wireless station device j may have I(j, r) receiving directions
("r" indicating receiving), wherein receiving configuration at kth
direction is Q.sub.k-1.sup.(j,r).
[0025] FIG. 2 illustrates an example where different number of
transmit directions and receive directions for AAS are shown for
DEV1 (bold lobes indicate receive directions, and normal lobes
indicate transmit directions). As illustrated by example in FIG. 2,
DEV1 has four transmit directions (transmit lobes) and three
receive directions (receive lobes). Transmit directions and receive
directions may cover different spatial areas around DEV1. A special
case of AAS is symmetric antenna system (SAS) in which the same
antenna array, and also the same configuration setting, is used for
transmitting (transmission) and receiving (reception), and for a
symmetric wireless channel between two wireless station devices.
For SAS, transmit directions and receive directions cover the same
spatial areas.
[0026] In wireless networks operating at 2.4 GHz or 5 GHz, data is
always transmitted omni-directionally. CSMA/CA provides
contention-based communication medium access control since a
wireless station in such networks can easily detect whether there
are ongoing transmissions on a wireless channel within its
transmission range.
[0027] However, for 60 GHz AAS with directional transmission, even
if a wireless station detects that the wireless channel is free in
its receive direction, interference with ongoing communications of
other stations may still occur when that wireless station transmits
a packet on the wireless channel in its transmit direction (such
directional transmission may involve e.g., transmission using
directional antennas, beamforming transmissions, etc.).
[0028] FIG. 3 illustrates an example of interference caused by AAS
with directional transmissions in a conventional wireless system
including three wireless station devices DEV1, DEV2, DEV3. When
DEV1 wishes to communicate with DEV2, DEV1 first senses the
wireless channel at its receive direction. If the channel is free
in the receive direction, DEV1 starts to directionally transmit a
packet at its transmit direction on the channel and DEV2 receives
the packet at its receive direction. However, DEV3 cannot detect
the packet transmitted by DEV1 at receiving direction of DEV3 and
might transmit a packet to DEV2 which causes collisions at DEV2
with packets from DEV1. Conventional RTS/CTS mechanisms (i.e., DEV1
sends RTS at its transmit direction to DEV2, and DEV2 sends CTS at
its transmit direction to DEV1) cannot solve the collision problem
caused by DEV3 in an AAS system since the transmit direction and
receive direction cover different areas for AAS.
Enhanced Carrier Sensing
[0029] According to an embodiment of the invention, an enhanced
CSMA/CA and RTS/CTS process (i.e., enhanced carrier sensing) is
provided to reduce/eliminate the interference problem caused by AAS
while still allowing spatial re-use (i.e., proximate wireless
stations perform simultaneous directional transmissions without
interference with each other). Without loss of generality, in this
embodiment, it is assumed that two wireless station devices have
already trained their antennas and found the directions to each
other using known antenna training techniques, before they use
contention-based medium access control to exchange data on a
wireless channel.
[0030] Enhanced carrier sensing according to the invention
comprises channel sensing by a wireless station (device), covering
the transmit direction to be used for a new transmission in
addition to the expected receive direction. Before a sender
wireless station transmits packets on the wireless channel in a
particular transmit direction, the wireless station first senses
the channel in a minimum number of receive directions which
combined together can cover the transmit direction in addition to
the expected receive direction at the wireless station. As shown by
example in FIG. 2, if wireless station Device 1 (i.e., DEV1)
desires to transmit a packet in a transmit direction
Q.sub.3.sup.(1,t) and receive packets in a receive direction
Q.sub.2.sup.(1,r), then DEV1 senses the wireless channel in the
receive directions of Q.sub.0.sup.(1,r) and Q.sub.2.sup.(1,r). The
switching time for sensing between different directions is
implementation specific, for example, can be every 2
microseconds.
[0031] A wireless station may determine which receive directions
can cover one transmit direction in different ways. An example is
that during a Quasi-omni direction training stage, such as
specified in sub-section 8.6.6 of the IEEE 802.15.3c specification
draft and the beamforming antenna training stage such as specified
in section 13 of the IEEE 802.15.3c specification, a device may
determine the relationships between its transmit directions and
receive directions.
Enhanced RTS/CTS
[0032] After determining which receive directions can cover one
transmit direction, an enhanced RTS/CTS process according to an
implementation of the invention overcomes interference and hidden
node problems caused by AAS and directional transmissions.
Accordingly, instead of sending out RTS/CTS in one particular
transmit (TX) direction or in all transmit directions, a wireless
station transmits the RTS or CTS in a minimum number of transmit
directions which cover its expected receive (RX) direction in
addition to the expected transmit direction.
[0033] For example, as shown in FIG. 2, if Device 1 (i.e., DEV1)
desires to receive packets in the receive direction
Q.sub.0.sup.(1,r) and transmit packets in the transmit direction
Q.sub.0.sup.(1,t), then DEV1 sends RTS or CTS in the transmit
directions of Q.sub.0.sup.(1,t) and Q.sub.3.sup.(1,t), which
combined together can cover the receive direction
Q.sub.0.sup.(1,r). With this approach, the interference and hidden
node problem are reduced/eliminated, while spatial re-use is
maintained. The switching of RTS/CTS transmission between different
directions at a wireless station is implementation specific, for
example, can be symbol based or multiple symbol based.
[0034] Further, packet-based switching may be performed at a
wireless station wherein the entire RTS/CTS is transmitted in one
direction first before switching to another direction. However, the
RTS is transmitted in the expected transmit direction as the last
direction and the CTS is transmitted in the expected transmit
direction as the first direction, in order to maintain a MAC
protocol Short Inter-Frame Space (SIFS) period between RTS and
CTS.
[0035] Referring to the example scenario in FIG. 4, DEV1 wishes to
transmit RTS in the transmit directions of Q.sub.0.sup.(1,t) and
Q.sub.3.sup.(1,t), but its expected transmit direction for actual
data is only Q.sub.0.sup.(1,t). Further, DEV2 wishes to reply with
CTS in the transmit directions of Q.sub.1.sup.(2,t) and
Q.sub.2.sup.(2,t) but its expected transmit direction for actual
data is only Q.sub.2.sup.(2,t). The RTS/CTS transmission at
different directions is implemented as shown with ordering of RTS
and CTS in different directions under packet based repetition,
maintaining a SIFS period between RTS and CTS transmissions. DEV1
transmits RTS in transmit directions Q.sub.3.sup.(1,t) and
Q.sub.0.sup.(1,t). After a SIFS period, DEV2 transmits responsive
CTS in transmit directions Q.sub.2.sup.(2,t) and
Q.sub.1.sup.(2,t).
[0036] In this example, the requirement for order of transmissions
in RTS/CTS negotiations is that there is at least a SIFS period in
between RTS transmission by DEV1 in the expected transmission
direction Q.sub.0.sup.(1,t) and CTS transmission by DEV2 in the
expected transmission direction Q.sub.2.sup.(2,t).
Enhanced Data Packet Transmission
[0037] Further, according to the invention, an enhanced data packet
transmission is implemented to prevent other types of collisions.
After RTS/CTS negotiation between a transmitting wireless station
and a receiving wireless station, during a reserved transmission
opportunity (TXOP) when a data packet is being transmitted at a
particular transmit direction from the transmitting station, it is
still possible that a newly joining station or (a station waking up
from a sleep state) interferes with the ongoing transmission by
transmitting a packet after sensing channel idle in certain
directions. As illustrated in FIG. 5, according to an embodiment of
the invention, to reduce this type of interference or collision
probability, the preamble (or Preamble plus PHY/MAC header) of a
data packet is transmitted by a wireless station the same as
RTS/CTS in the minimum number of transmit directions which cover
its expected receive direction, in addition to the expected
transmit direction. The remainder of the packet (i.e., header and
the payload (or payload only)), is transmitted in the expected
transmit direction only.
[0038] One special case is that the preamble (or Preamble plus
PHY/MAC header) can be transmitted omni-directionally. The
switching of transmission between different directions at a
wireless station is implementation specific and can be, for
example, symbol based or multiple symbol based. The remainder of
the packet (i.e., header and the payload (or payload only)), is
transmitted in the expected transmit direction only.
[0039] If a packet being communicated between two wireless stations
is long, another wireless station which joins or wakes up after the
preamble (or Preamble plus PHY/MAC header) of that long packet may
still interfere with the ongoing packet communication. As
illustrated in FIG. 6, according to an embodiment of the invention,
to reduce this type of interference or collision probability,
mid-ambles are inserted into the packet by a transmitting station
and transmitted in a minimum number of transmit directions which
cover the expected receive direction at that station, in addition
to the expected transmit direction (similar to the preamble (or
Preamble plus PHY/MAC header) or RTS/CTS). One special case is that
the mid-ambles can be transmitted omni-directionally. The switching
of transmission between different directions at the station is
implementation specific and can be, for example, symbol based or
multiple symbol based. The periodically inserted mid-ambles can
also be used for beam-tracking purposes if phased array antennas
are used.
Combinations
[0040] The enhanced carrier sensing process according to the
invention, can be used alone to reduce interference and collision
probability. In addition, the enhanced carrier sensing can be
combined with enhanced data packet transmission according to the
invention, to further reduce interference and collision
probability. Further, enhanced carrier sensing can be combined with
said enhanced RTS/CTS according to the invention, to further reduce
interference and collision probability. Still further, enhanced
carrier sensing and enhanced RTS/CTS can be combined to further
reduce interference and collision probability.
Symmetrical Antenna System (SAS)
[0041] SAS is a special case for AAS. For SAS, since expected
transmit direction and the receive direction are the same, carrier
sensing only needs to be performed in the expected receive
direction; RTS/CTS only need to be transmitted in the expected
transmit direction; and the preamble (or Preamble plus PHY/MAC
header) or mid-amble of data packets only need to be transmitted in
the expected transmit direction, the same as data payload.
Process Implementations
[0042] A contention-based channel access method and data
transmission process according to the invention reduces
interference and collision probability while enabling spatial
re-use to improve overall system throughput. FIGS. 7 and 8 show
flowcharts of example implementations of the invention for IEEE
802.11 wireless communication systems. Specifically, FIG. 7 shows a
flowchart of enhanced CSMA/CA carrier sensing process 50
implemented by a wireless station, according to an embodiment of
the invention, comprising: [0043] Block 51: Check that the network
allocation vector (NAV) is zero before attempting to transmit an
information frame on a wireless carrier channel. If not, proceed to
block 52, else proceed to block 53. [0044] Block 52: Back off from
the transmission attempt for a time period, proceed to block 51.
[0045] Block 53: Sense the channel for ongoing communications in
minimum number of receive directions which cover its expected
receive direction in addition to the expected transmit direction.
[0046] Block 54: If the channel is idle, proceed to block 55, else
proceed to block 52. [0047] Block 55: Transmit frame preamble
(mid-amble) in minimum number of transmit directions which cover
its expected receive direction in addition to the expected transmit
direction, transmit frame payload in the expected transmit
direction. [0048] Block 56: If acknowledgment (ACK) is received
from a receiving station, then transmission is successful, else
proceed to block 52.
[0049] FIG. 8 shows a flowchart of an enhanced CSMA/CA with
enhanced RTS/CTS process 100 implemented by a wireless station,
according to an embodiment of the invention, comprising: [0050]
Block 101: Check that the network allocation vector (NAV) is zero
before attempting to transmit an information frame on a wireless
carrier channel. If not, proceed to block 102, else proceed to
block 103. [0051] Block 102: Back off from the transmission attempt
for a time period, proceed to block 101. [0052] Block 103: Sense
the channel for ongoing communications in minimum number of receive
directions which cover its expected receive direction in addition
to the expected transmit direction. [0053] Block 104: If the
channel is idle, proceed to block 105, else proceed to block 102.
[0054] Block 105: Transmit RTS frame in minimum number of transmit
directions which cover its expected receive direction in addition
to the expected transmit direction. [0055] Block 106: If CTS is not
received from a receiving station, then proceed to block 102, else
proceed to block 107. [0056] Block 107: Transmit frame preamble
(mid-amble) in minimum number of transmit directions which cover
its expected receive direction in addition to the expected transmit
direction, transmit frame payload in the expected transmit
direction. [0057] Block 108: If acknowledgment (ACK) is received
from the receiving station, then transmission is successful, else
proceed to block 102.
[0058] Enhanced carrier sensing according to the invention provides
that before a wireless station transmits packets on the channel in
a particular transmit direction, it first senses the channel in a
minimum number of receive directions which combined together can
cover the transmit direction in addition to the expected receive
direction. A station transmits the RTS or CTS in the minimum number
of transmit directions which cover its expected receive direction
in addition to the expected transmit direction. After RTS/CTS
negotiation, the station transmits the preamble (or preamble plus
PHY/MAC header) of a data packet as the same as RTS/CTS in the
minimum number of transmit directions which cover its expected
receive direction in addition to the expected transmit direction.
The remainder of the packet, i.e., Header and the payload (or
payload only), is transmitted in the expected transmit direction
only.
[0059] If a packet being transmitted is long, the station
periodically inserts mid-ambles into the packet and transmit the
mid-ambles in the minimum number of transmit directions which cover
the expected receive direction for a device in addition to the
expected transmit direction, the same as the preamble (or Preamble
plus PHY/MAC header) or RTS/CTS. The station can reduce RTS/CTS
overhead since RTS/CTS overhead is transmitted at only necessary
directions. Further, spatial re-use is enabled since RTS/CTS is
transmitted only at necessary directions instead of all
directions.
[0060] The invention provides a general wireless communication
scheme which can be applied to directional communication between
two wireless stations or between a station and a coordinator, in a
wireless network or communication system. FIG. 9 shows a block
diagram of an example AAS wireless communication system 200,
implementing an embodiment of the present invention. The system 200
includes wireless stations such as a wireless station 202 and
wireless station 204, for data communication, such as transmission
of data, audio/video information over a wireless channel 201. The
wireless devices in FIG. 1 are examples of such wireless
stations.
[0061] The station 202 includes a PHY layer 206, a MAC layer 208
and an application layer 210. The PHY layer 206 includes a radio
frequency (RF) communication module 207 which transmits/receives
signals under control of a baseband process module 230. The
baseband module 230 allows communicating control information and
video information.
[0062] The application layer 210 includes an audio/visual (A/V)
pre-processing module 211 for packetizing video streams, which are
then converted to MAC packets by the MAC layer 208. The application
layer 210 further includes an audio/visual controller (AV/C)
control module 212 which sends stream transmission requests and
control commands to access the channel for transmission of packets.
An example data packet frame format transmitted between the
transmitter station 202 and the receiver station 204 is as shown in
FIG. 6.
[0063] The station 204 includes a PHY layer 214, a MAC layer 216
and an application layer 218. The PHY layer 214 includes an RF
communication module 213 which transmits/receives signals under
control of a base band process module 231. The application layer
218 includes an A/V post-processing module 219 for de-packetizing
into streams the video information in the MAC packets, received by
the MAC layer 216. The de-packetizing is reverse of the
packetization. The application layer 218 further includes an AV/C
control module 220 which handles stream control and channel
access.
[0064] Directional transmissions such as beamforming transmissions
are performed over the channel. The MAC/PHY layers perform antenna
training and beaming switching control. An example application of
the present invention in FIG. 9 is for millimeter Wave (mmWave)
wireless networks, such as 60 GHz frequency band wireless networks.
In one example, for each of stations 202, 204, the invention may be
implemented in their respective MAC layers. Specifically, for
implementation, the MAC layer controls the PHY layer to perform
channel sensing at different directions, transmit RTS/CTS at
different directions, and transmit a data packet at one or
different directions, etc. A transmit/receive direction
mapping/switching control module 12 (FIG. 1) is provided in the MAC
layer of one or more wireless stations to implement the above steps
such as in FIGS. 7-8.
[0065] As is known to those skilled in the art, the aforementioned
example architectures described above, according to the invention,
can be implemented in many ways, such as program instructions for
execution by a processor, as software modules, microcode, as
computer program product on computer readable media, as logic
circuits, as application specific integrated circuits, as firmware,
etc. Further, embodiments of the invention can take the form of an
entirely hardware embodiment, an entirely software embodiment or an
embodiment containing both hardware and software elements.
[0066] The terms "computer program medium," "computer usable
medium," "computer readable medium", and "computer program
product," are used to generally refer to media such as main memory,
secondary memory, removable storage drive, a hard disk installed in
hard disk drive, and signals. These computer program products are
means for providing software to the computer system. The computer
readable medium allows the computer system to read data,
instructions, messages or message packets, and other computer
readable information from the computer readable medium. The
computer readable medium, for example, may include non-volatile
memory, such as a floppy disk, ROM, flash memory, disk drive
memory, a CD-ROM, and other permanent storage. It is useful, for
example, for transporting information, such as data and computer
instructions, between computer systems. Furthermore, the computer
readable medium may comprise computer readable information in a
transitory state medium such as a network link and/or a network
interface, including a wired network or a wireless network that
allow a computer to read such computer readable information.
Computer programs (also called computer control logic) are stored
in main memory and/or secondary memory. Computer programs may also
be received via a communications interface. Such computer programs,
when executed, enable the computer system to perform the features
of the present invention as discussed herein. In particular, the
computer programs, when executed, enable the processor multi-core
processor to perform the features of the computer system.
Accordingly, such computer programs represent controllers of the
computer system.
[0067] The flowcharts and block diagrams in the figures illustrate
the architecture, functionality, and operation of possible
implementations of systems, methods and computer program products
according to various embodiments of the present invention. In this
regard, each block in the flowchart or block diagrams may represent
a module, segment, or portion of code, which comprises one or more
executable instructions for implementing the specified logical
function(s). It should also be noted that, in some alternative
implementations, the functions noted in the block may occur out of
the order noted in the figures. For example, two blocks shown in
succession may, in fact, be executed substantially concurrently, or
the blocks may sometimes be executed in the reverse order,
depending upon the functionality involved. It will also be noted
that each block of the block diagrams and/or flowchart
illustration, and combinations of blocks in the block diagrams
and/or flowchart illustration, can be implemented by special
purpose hardware-based systems that perform the specified functions
or acts, or combinations of special purpose hardware and computer
instructions.
[0068] The terminology used herein is for the purpose of describing
particular embodiments only and is not intended to be limiting of
the invention. As used herein, the singular forms "a", "an" and
"the" are intended to include the plural forms as well, unless the
context clearly indicates otherwise. It will be further understood
that the terms "comprises" and/or "comprising," when used in this
specification, specify the presence of stated features, integers,
steps, operations, elements, and/or components, but do not preclude
the presence or addition of one or more other features, integers,
steps, operations, elements, components, and/or groups thereof.
[0069] The corresponding structures, materials, acts, and
equivalents of all means or step plus function elements in the
claims below are intended to include any structure, material, or
act for performing the function in combination with other claimed
elements as specifically claimed. The description of the present
invention has been presented for purposes of illustration and
description, but is not intended to be exhaustive or limited to the
invention in the form disclosed. Many modifications and variations
will be apparent to those of ordinary skill in the art without
departing from the scope and spirit of the invention. The
embodiment was chosen and described in order to best explain the
principles of the invention and the practical application, and to
enable others of ordinary skill in the art to understand the
invention for various embodiments with various modifications as are
suited to the particular use contemplated.
[0070] Though the present invention has been described with
reference to certain versions thereof; however, other versions are
possible. Therefore, the spirit and scope of the appended claims
should not be limited to the description of the preferred versions
contained herein.
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