Description
Title of Invention
COMMUNICATION APPARATUS, COMMUNICATION SYSTEM AND
5 COMMUNICATION METHOD
Technical Field
[OOOl]
The present disclosure relates to a communication apparatus, a
10 communication system and a con~municationm ethod.
Background Art
[0002]
Recently, wireless communication technologies in which various types of
15 data are h-dnsmitted and received through close proximity ~virelessc ommunication
have been developed.
[0003]
For example, TransferJet (registered trademark) is used in digital cameras
and personal computers (PCs) as a close proximity wireless comn~unications cheme,
20 and used to build an ecosystem for data communication among inforination
processing apparatuses. Specifications of TransferJet were standardized by the
TransferJet Consortium, and almost the same international standards as the
specifications according to the TransferJet Consoriium are registered as ECMA 398
disclosed in the following Non-Patelit Literature 1.
25 [0004]
In addition, in Patent Literature 1, a method of efficiently establishing,
maintaining and releasing a wireless connection in wireless communication
teclmology is disclosed.
30
Patent Literature
Citation List
[OOOS]
Patent Literature 1 : JP 4840043B
Non-Patent Literature
[0006]
5 Nott-Patent Literature 1: ECMA-398 (http:/l~~w.ecrnai
n t e r n a t i o n a l . o r S / p ~ ~ b l i c a t i o t ~ s / f i l e s ~
Summary of Invention
Technical Problem
10 [0007]
In both technologies disclosed in the above Patent Literature and Non-
Patent Literature, wireless communication is performed through half-duplex
communication channels. However, in recent years, with the increase of
applications for which full-duplex communication is necessary, support of full-
15 duplex cotnmunication through half-duplex communication channels is necessary.
[OOOS]
In view of the above circumstance, the present disclosure proposes a
cotnmunication apparatus, a cotnmunication system and a communication method
which are novel and improved and through which it is possible to support full-duplex
20 communication over half-duplex cotnmunication chant~els.
Solution to Problem
[0009]
According to the present disclosure, there is provided a co~ntnunication
25 apparatus including: a switch unit configured to switch data communication to be
performed with another con~munication apparatus on a transmission side or a
reception side; and a conmmunication unit cotlfigured to transmit transmission data to
the other cotnmunication apparatus and receive a response ~vlteu the data
co~nmunication is performed on the trattsmissiot~ side, and receive reception data
30 from the other co~nnlunication apparatus and transmit a response when the data
conununicatiou is performed on the reception side. The s~vitch unit performs
switching from the transmission side to the reception side when the response
received by the comnmtniication unit includes a switching instruction.
[OO 101
According to the present disclosure, there is provided a cotnmunication
5 spstem including: a first comniunication apparatus configured to perform data
commnnication on a transn~issio~sli de and a second communication apparatus
configured to perform data comtnunication on a reception side. The first
comnlunication apparatus includes a first switch unit configured to perform
switching from the transtnission side to the reception side, and a first comnlunication
10 unit configured to transmit transmission data to the second conlmunication apparatus
and receive a response. The second communication apparatus includes a second
switch unit configured to performn switching from the reception side to the
transmission side, and a second conununication unit configured to receive the
tsansmission data from the first communication apparatus and transmit the response.
15 The second switch unit performs switching from the reception side to the
transmission side when the response including a switching inst~~ictioisn t ransmitted
by the second communication unit, and the first switch unit performs switching from
the transmission side to the reception side when the response is received by the first
communication unit.
20 [OOlI]
According to the present disclosure, there is provided a communication
method including: switching data communication to be performed with another
communication apparatus on a transmission side or a reception side; transmitting
transmission data to the other communication apparatus and receiving a response
25 when the data commnnication is perfornled on the transmission side and receiving
reception data from tlie other communication apparatus and transmitting a response
when the data con~mmiication is performed on the reception side; and performing
switching from the transmission side to the reception side when the received
response includes a switching instruction.
30
Advantageous Effects of Invention
[OO 121
According to the present disclosure described above, it is possible to support
full-duplex communication over half-di~plexc onx~~u~~icacthiaonnn els. Also, the
above effects are not necessarily limited, but along with tile effects or instead of the
5 effects, any effect shown in this specification or other effects that may be understood
fio~nth is specification may be achieved.
Brief Description of Drawings
[00 131
10 [FIG. 11 FIG. 1 is a diagram schematically illustrating two devices of a
communication system according to an embodiment of the present disclosure.
[FIG. 21 FIG. 2 is a diagram illustrating a protocol stack of TransferJet.
[FIG. 31 FIG. 3 is a diagram for describing an inter frame space in TransferJet.
[FIG. 41 FIG. 4 is a block diagram illustrating a configuration of a communication
15 apparatus according to a first embodiment.
[FIG. 51 FIG. 5 is a diagram illustrating a format of an ACK frame of TransferJet.
[FIG. 61 FIG. 6 is a diagram illustrating a format of a management f?ame of
TransferJet.
[FIG. 71 FIG. 7 is a diagram illustrating a format of a frame body of a managenlent
20 frame of TransferJet.
[FIG. 81 FIG 8 is a diagram illustrating an example of a transmission right arbitrating
operation according to the first embodiment.
[FIG. 91 FIG. 9 is a diagram illustrating an example of a transmission right arbitrating
operation according to the first embodiment.
25 [FIG. 101 FIG. 10 is a diagram illustrating an example of a sleep operation according
to the first enlbodiment.
[FIG. 1 I] FIG. 11 is a flowchart slowing operations of the con~munication apparatus
according to the first embodiment.
Hereinafter, (a) preferred embodiment(s) of the present disclosure will be
described in detail with reference to the appended drawings. In this specification
and the drawings, elenlents that have substantially the same fimction and structure
are denoted with the same reference signs, and repeated explanation is omitted.
5 [0015]
The description will proceed in the following order.
1. Overview of communication system according to an e~nbodiment of the present
disclosure
2. First embodiment
10 2-1. Configuration of communication apparatus
2-2. Arbitration of transmission right
2-2-1. Axbitration by ACK frame
2-2-2. Arbitration by token ft-ame
2-2-3. One example of transmission right arbitrating operation
15 2-3. Sleep for very sho~ttim e
2-4. Operating process
3. Summary
[0016]
4. Overview of communication system according to an embodiment of the present
20 disclosure>
First, an ovel-view of a cornmnnication system according to an embodiment
of the present disclosure will be described with reference to FIGS. 1 and 2.
Specifically, an ove~~lieowf a communication system based on TransferJet will be
described.
25 [0017]
FIG. 1 is a diagram schematically illustrating two devices (communication
apparatuses) of the communication system according to an embodiment of the
present disclosure. As illustrated in FIG. 1, the conlmunication system according to
the present embodiment includes a co~nmunication method whose object is to
30 transmit and receive data between a pair of devices aud wirelessly transnlits and
receives data between the devices at a short distance. The two devices have a role
of a responder or an initiator. The initiator is a "side at which a connection request
is issued" and the responder is a "side at ~vhich a connection request is received."
In the present enibodiment, one to one (P2P) conn~~unicatiiso p~e~rf onlied. At the
time of connection, the initiator issues a connection request and the respo~~diesr i n a
5 standby state: However, their roles are different only during the connection, and the
devices have the same configuration related to the connection. Examples of the
initiator include a PC, a portable device, and an electronic card. Examples of the
responder include devices such as a PC, a portable device, and an electronic card.
[0018]
10 FIG. 1 schematically illustrates a state in which devices of the present
embodiment wirelessly communicate with each other through physical layers thereof.
While close proximity wireless communication is performed through a physical layer
using TransferJet in the present embodinietit, the physical layer is not limited thereto,
but a general-purpose physical layer for con~municationc an be applied. Since the
15 phj~sicall ayer using TransferJet uses a connection layer service data unit (CSDU), it
is pa~ticularly appropriate for communication of a large amount of data such as
photos and videos.
[00 191
Here, TransferJet is a near field wireless communication scheme using a
20 4.48 GHz band. When a comn~t~nicatiopnr otocol (TransferJet) thereof is used,
radio waves of 4.48 GHz are used at -70 dBm/MHz and below and high-speed near
field data communication of a maximum of 560 Mbps can be implemented. In
addition, when a communication distance in near field wireless comtnunication is
limited to several cm, it is possible to perform a communication process at a high
25 speed, imple~nent a con~munication apparatus in a small size, and reduce power
consumption. Next, a protocol stack of TransferJet will be described with reference
to FIG. 2.
[0020]
FIG. 2 is a diagram illustrating a protocol stack of TsansferJet. As
30 illustrated in FIG. 1, the protocol stack of TransferJet includes a physical layer (PHY
layer) 10, a comlection layer (CNL layer) 20, a protocol conversion layer (PCL layer)
30, and an application (user applicatio11) 40.
[0021]
The PHY layer 10 is a layer that actually perfornls wireless communication,
and perfornls half-duplex (unidirectional) commnt~nication. The CNL layer 20 is a
5 layer that performs one-to-one control or media access control and is optimized for
half-duplex con~munication. The PCL layer 30 has a function of mapping the
application 40 to the CNL layer 20, and converts existing interface specifications, for
example, Small Computer System Interface (SCSI) and OBject Exchange (OBEX).
The application 40 uses existing interface specifications, for example, SCSI and
10 OBEX.
[0022]
When TransferJet was initially introduced, half-duplex protocols such as
SCSI and OBEX were used in the application 40. However, in recent years, fullduplex
(bidirectional) protocols such as Transnlission Control ProtocoWIt~ternet
15 Protocol (TCP/IP) or universal asynchronous receiver transmitter WART) of Serial
have been increasingly used.
[0023]
However, since the CNL layer 20 perfor~ns half-duplex communication,
when the application 40 uses the full-duplex protocol, collisions of packets nxay
20 occur over a wireless transmission channel, \vhich may decrease the throughput.
Such collisions of packets will be described in detail below with reference to FIG. 3.
[0024]
FIG. 3 is a diagram for describing an inter fiame space (IFS) in TransferJet.
As illustrated in FIG. 3, the inter frame space represents a time interval between a
26 previous frame and the next frame. As illustrated in FIG. 3, in TransferJet, frames,
an ACK franie (an ACK Frame Tx), a CSDU frame of the initiator (DATA (CSDU)
Tx (initiator)), a CSDU frame of a responder (DATA (CSDU) Tx (responder)), a
management frame of the initiator (Management (exception C-Req) TX (initiator)), a
management frame of the responder (Management (except C-Acc) TX (responder)),
30 a connection request management frame (Management (C-Req) Tx), and a
connection accept response management frame (Management (C-Acc) Tx), are
defined. The frame illustrated in FIG. 3 has a configuration in which a preamble
(Pre), synchronization S (Sync), and a physical layer leader (PI-IY) are included in
colmnon, and a fsame body is subsequent thereto. For example, in the CSDU frame,
a maximum of two CSDUs are stored in a frame body. The comtnunication system
5 can exchange data passed from the upper layer by the CSDU frame.
LO0251
As illustrated in FIG. 3, transmission of the ACK frame is started at an SIFS
interval from the previous frame. Similarly, transmission of the CSDU frame and
the management frame of the initiator is started at an IIFS interval. Here, the IIFS
10 interval and the SIFS interval are the same. In addition, the CSDU fsame and the
management frame of the responder are transmitted at an RIFS interval that is only
Tbst longer than SIFS. In addition, the com~ectionr equest is normally transmitted
at an interval of 100 psec. However, w11en a frame transmitted by another
apparatus is detected in the wireless transmission channel at a timing at which the
15 connection request is transmitted, transmission is performed at an interval that is only
two Tbsts longer than SIFS fsom the frame transmitted by the other apparatus. The
connection accept response is transmitted at an interval that is two Tbsts and a
random backoff (an integer multiple of Tbst) longer than SIFS. Specific values of
SIFS, IES, RIFS, and Tbst are shown in the following Table 1.
20 [0026]
[Table 11
Pwanictcr Valuc I>cscription
name . .
-.. -- -- -. -- -- -,
1 1 ; i ~ - l l : 8.5 spi.cc 1 11 .S psec
IIFS 1 minimum: 8.5 [tsec 1 Initiator minimum inter frame
8 psec*lO% I Slot time
RIFS
[0027]
As illustrated in FIG. 3, the initiator can transmit the CSDU frame after the
IIFS shall be greater or equal
to SIFS
minin~um: 15.7 psec
RIFS shall be greater or equal
to SlFStTbst
space
Responder minimum inter frame
space
IIFS elapses after the previous frame. That is, as shoo\vn in Table 1, the initiator
acquires a tra~~smissiornig ht after the IIFS (a minimum of 8.5 psec (microseconds))
elapses in an idle state of wireless media. 011 the other hand, as illustrated in FIG. 3,
the responder can transmit the CSDU frame after the RIFS elapses after the previous
5 frame. That is, as shown in Table 1, the responder acquires a transmissiot~ right
after the RIFS (a minimum of 15.7 psec) elapses in at1 idle state of the wireless
media.
[0028]
Therefore, when an idle period of the wireless media has reached the RIFS,
10 both of the initiator and the responder have the transmission right. Therefore, when
both simultaneously stat tratlsniission of the CSDU frame, frames collide over the
wireless media.
[0029]
Accordingly, the communication system according to an embodiment of the
15 present disclosure has been created in view of the above circumstances. The
communication system accordit~gt o the present embodiment can support full-duplex
communicatio~~o ver a half-duplex communication channel. Since the
communication system according to the present embodiment supports full-duplex
communication in which fill1 duplex control is performed, it is possible to prevent
20 frames from colliding and the throughput from decreasing as described above.
[0030]
In this specification, an example in which technology according to an
embodiment of the present disclosure is applied in TransferJet will be described as
exemplary wireless technology. Hereinafter, a conmunication process defined in
25 ECMA-398 (Non-Patent Literature 1) will be referred to as a comparison scheme,
and a communication process in which technology accordir~g to an embodiment of
the present disclosme is applied will be referred to as a proposed scheme.
[003 11
The overview of the comtnnnication system according to an embodiment of
30 the present disclosure has been described above. Next, content of the
conmunication system according to an embodiment of the present disclosure will be
described in detail.
[0032]
12. First embodimenp
[2-1. Configuration of comnlunicatiotl apparatus]
5 FIG. 4 is a block diagram illustrating a configuration of a commullication
apparatus 1 according to a first embodiment. As illustrated in FIG. 4, the
communication apparatus 1 includes a coritrol unit 2, a switch unit 3, and a
commut~icationu nit 4. The comnunication apparatus 1 communicates with another
communication apparatus according to any role of the responder and the initiator.
10 The cotnmunication apparatus 1 and the other communication apparatus that
communicates with the communication apparatus 1 and has the same configuration
as the communication apparatus 1 are referred to as a communication system below.
[0033]
(Control unit 2)
15 The control unit 2 serves as an arithmetic processing unit and a control
device, and controls overall operations of the communication apparatus 1 according
to various progranams. The control unit 2 is iinplen~ented by, for example, a central
processing unit (CPU) and a microprocessor. The control unit 2 may also include a
read only memory (ROM) configured to store programs and calculation parameters
20 to be used and a random access memory (RAM) co&gured to temporarily store
parameters that are appropriately changed.
[0034]
111 the present embodiment, the control unit 2 is connected to the
communication unit 4 and controls transmission and reception of various types of
25 data performed with another communication apparatus connected through the
comnunication unit 4. In addition, the control unit 2 is contlected to the switch unit
3 and performs switching of a talker and a listener to be described below though the
switch unit 3. The other communication apparatus connected tlirough the
communication unit 4 is sinlply referred to as a partner device below.
30 [0035]
(Switch unit 3)
In the present embodiment, t~vo conmnication apparatuses whose
communication is established by TransferJet have a role of a talker (a transnlission
side) or a listener (a reception side). The talker is a side at which a transtnission
right is provided and a CSDU fianle is transmitted. The listener is a side at which
5 no transmission right is provided and a CSDU frame is received. The switch unit 3
according to the present embodiment has a function of switchillg the role in data
communication with the partner device to that of the talker or the listener based on
control by the control unit 2. For example, the switch unit 3 switches the talker and
the listener based on whether there is data to be transt~~itteadn d whether a switching
10 instruction (an ACK frame in which a talk flag to be described below is set) from the
partner device is received by the communication unit 4.
[0036]
(Communication unit 4)
The communication unit 4 refers to a communication module configured to
15 perform close proximity wireless communication based on control by the control unit
2. For example, the commum~icatiotu~n it 4 is configured by an induced-electricfield-
coupling type coupler and performs close proximity wireless comtnunication
with an external device according to TransferJet. More specifically, the
communication unit 4 performs close proximity wireless communication with
20 another comtnunication apparatus (a communication apparatus having a close
proximity wireless communication function) that is within a predetermined
comn~ut~icatiorna nge from the communication unit 4. Here, close proximity
wireless communication between the communication unit 4 and the other
communication apparatus is possible only when the con~municationu nit 4 and the
25 other communication apparatus are in a proximity state. Here, the term "proximity
state" refers to, for example, a state in which the communication unit 4 and the other
communication apparatus are within a predetermined range (for example, 3 cm) from
or in contact w i t h each other.
[0037]
30 The comn~unication tunit 4 transmits and receives the franles such as the
ACK fsatlle, the CSDU frame, the management frame, the connection request frame,
and the connection accept response frame, which have been described with reference
to FIG. 3, to and hom the partner device. In particulal; in the present embodiment,
the com~n~~nicatiuonait 4 transmits the CSDU frame (transn~issiond ata) to the
partner device and receives the ACK frame (response) in the case of the talkel:
5 Otherwise, the communication unit 4 receives the CSDU frame (reception data) from
the partner device and transmits the ACK frane (response) in the case of the listenel:
[0038]
The configuration of the communication apparatus 1 according to the
present embodiment has been described above. Next, arbitration of the
10 transmission right by the communicatio~l system according to the present
embodiment will be described with reference to FIGS. 5 to 7.
[0039]
[2-2. Arbitration of transmission right]
The comn~unications ystem according to the present embodiment performs
15 arbitration of the transmission right by the ACK fiame or arbitration of the
transmission right by a dedicated frame (a token frame) for transmission right
arbitration. First, arbitration of the transmission right by the ACK frame will be
described with reference to FIG. 5.
[0040]
20 [2-2-1. Arbitration by ACK frame]
FIG. 5 is a diagram illustrating a format of the ACK frame in TransferJet.
As illustrated in FIG. 5, the ACK frame includes a conmon CNL header and a sub
CNL header.
[0041]
25 As illustrated in FIG. 5, the corlnnon CNL header includes Rx UID, Tx UID,
Rsv., MUX, and HCS. The Rx UID is an 8-byte field in which a unique ID WID)
of a transmission destination is stored. The Tx UID is an 8-byte field in which a
UID of a reception destination is stored. The Rsv. is a 1-byte field serving as a
reserved area. The MUX is a 1-byte field in which a multiplex number of the frame
30 body is stored. The HCS is a 4-byte field in which a header check sequence is
stored.
[0042]
As illustrated in FIG. 5, the sub CNL header includes Attribute, SeqNum,
Rsv., and HCS. The Attribute is a field in which infor~iiationi ndicating an attribute
of a fsame is stored, which will be described in detail below. In addition, the
5 SeqNum is a l-byte field in which a sequence number assigned for frame body
management in the CNL layer is stored. The Rsv. is a 2-byte field serving as a
reserved area. The HCS is a 4-byte field in wliih a header check sequence is stored.
[0043]
Next, content of the Attribute will be described. As illustrated in FIG. 5,
10 the Attribute includes Seq Sync, Rsv., FBT, Reserved, and Frame type. The Seq
Sync is a 1-bit field in which a flag of synchronization is stored. The Rsv. is a 1-bit
field serving as a reserved area. The Fsame Body type (FBT) is a 1-bit field in
which a type of a frame body that indicates, for example, an ACK for the CSDU
fsatne or an ACK for tlie manage~nenft rame, is stored. The Reserved is a 3-bit area
15 serving as a reserved area. The Frame type is a 2-bit area in which a type of a
frame that indicates the CSDU frame, the ACK frame or the management frame is
stored.
[0044]
The co~nmunication system according to the present embodiment uses the
20 Reserved field of the snb CNL header in order to arbitrate the transmission right.
More specifically, the communication system according to the present embodiment
arbitrates the transmission right based on whether a flag (a talk flag) indicating a
request of the transmission right is set in the Reserved field of the ACK fran~e.
[0045]
25 The comtnunication apparatus 1 sets the talk flag in the ACK frame and thus
acquires the transmission right. More specifically, whet1 the communication
apparatus 1 has the role of tlie listener and there is data to be hansmitted, the switch
unit 3 switches the role fsom that of the listener to that of the talker. Accordit~gly,
tlie cotnrllunication unit 4 transmits the ACK frame i~lcluding the talk flag (the
30 s\vitching instruction) to the partner device. Therefore, since the conllnunication
apparatus 1 has the role of tlie talker and the partner device has tlie role of the listenel;
the corin~~unicatiounn it 4 stores data to be transmitted in the CSDU frame and
transinits the frame to the partner terminal.
[0046]
On the other hand, when the ACK fianle in which the talk flag is set is
5 received, the communication apparatus 1 transfers tlie transmission right to the
partner device. More specifically, when the cominutiication apparatus 1 has the role
of the talker and the ACK frame received by the communication unit 4 includes the
talk flag (the switching instruction), the switch unit 3 switches the role of tlie
comtnunication apparatus 1 from that of the talker to that of the listener.
10 Accordingly, since the comnlunication apparatus 1 has the role of the listener and the
partner device has the role of the talker, tlie commuilication unit 4 can receive the
CSDU frame from the partner terminal.
[0047]
If both the coinmunication apparatus 1 and the partner device have data to
15 be transmitted, when the ACK fiame in which the talk flag is set is transmitted after
both receive the CSDU fiame from the partner, the transmission right is acquired and
its own CSDU frame is transmitted. That is, both alternately acquire the
transmission right and transmit the CSDU frame. That is, it is possible to transmit
the CSDU fiame substantially simnltatieously. In this manner, when the
20 communication system according to the present embodiment switclles the role of
communication apparatuses according to arbitration of the transmission right by tlie
ACK frame, it is possible to implement full duplex control.
[0048]
Here, an application (the application 40 in FIG. 2) of an upper layer uses a
25 full-duplex communication specification in some cases. For example, in a TCPIIP
protocol, which is one full-duplex coinmunication specification, the transmission
side performs arrival confirmation when an ACK response is received after data
transmission. On the other hand, when there is no ACK response, the transmission
side delays data transmission and retransmits data.
30 COO491
In the comparison scheme, it is difficult for the responder to transmit the
CSDU frame at an appropriate timing as in the present embodiment. More
specifically, as illustrated in FIG. 3, in order to transmit the CSDU fsanle fro111 the
responder to the initiator, it is necessary that the inter fralue space RIFS have elapsed.
Therefore, while the CSDU frame is transmitted fiorn the initiator to the responder at
5 an IIFS interval, it is difficult to transmit tl~eC SDU fraine in which the ACK
response in the TCPIIP protocol is stored from the responder to the initiator.
Accordingly, in the conlparison scheme, when it is not possible to receive the ACK
response at an appropriate timing after an application of the initiator transmits a
TCPIIP packet, data transmission is delayed and data is retransmitted.
10 [0050]
On the other hand, in the communication system according to the present
embodiment, even when the initiator performs data transmission in order to perform
the full duplex control described above, the responder can transmit the CSDU fsame
in which the ACK response in the TCPAP protocol is stored. Therefore, since the
15 initiator can perform a~~ivcaoln furnation according to the ACK response, there is no
need to delay data transmission or retransmit data. Accordingly, when the
application of the upper layer uses the full-duplex communication specification, the
communication system according to the present embodiment can implement a higher
transmission rate than the comparison scheme.
20 [OOSl]
In addition, since the communication system according to the present
embodiment performs arbitration of the transn~ission right by the ACK frame, as
described with reference to FIG. 3 and Table 1, no situation in which both have the
transmission right occurs, and thus no collision of frames occu~.s. In addition, the
25 communication system according to the present embodiment performs full duplex
control by arbitration of the transmission right using a reserved area of an existing
frame configuration. Accordingly, hen the co~nmunication system according to
the present embodiment adds a dedicated frame for performing arbitration of the
transmission right, it is possible to prevent the thsoughput from decreasing.
30 [0052]
Arbitration of the transmission right by the ACK fiame has been described
above. Next, arbitration of the transmission right by the token fraune will be
described.
[0053]
[2-2-2. Arbitration by token fia~ne]
5 The conlmunication system according to the present embodiment starts a
procedure of exchanging a dedicated fiame (a token fcame) for performing
arbitration of the transmission right only when data communication is not performed.
Since the token frame is exchanged while data communication is not performed,
there is no influence on the throughput due to exchange of the token frame.
10 [0054]
The token frame is inlplemented using an existing management frame.
First, the existing management frame of Transferjet will be described with reference
to FIG. 6.
[0055]
15 FIG. 6 is a diagram illustrating a format of a management frame of
Transferjet. As illustrated in FIG. 6, the management frame includes a common
CNL headel; a sub CNL header, a frame body, and an FCS. Since the common
CNL header is the same as that described with reference to FIG. 5, detailed
description thereof will be omitted herein. The frame body is a 32-byte field in
20 which control information is stored. The FCS is a 4-byte field in which a frame
check sequence is stored.
[0056]
As illustrated in FIG. 6, the sub CNL header includes Attribute, SeqNum,
Length, and RCS. The Attribute is a field in which information indicating an
25 attribute of a frame is stored, which will be described below in detail. The Length
is a 2-byte field in wvhich a length of a frame body is stored. Note that, since the
HCS and the SeqNum are the satne as those described with reference to FIG. 5,
detailed descriptions thereof will be omitted herein.
[0057]
30 Next, content of the Attribute w i l l be described. As illustrated in FIG. 6,
the Attribute includes Seq Sync, ACK type, Frame Body type, Reserved, and Frame
type. The ACK type is a 1-bit field in which infornlation indicating either an
ItiACK for which an ACK response is necessary or a NoACK for wliich an ACK
response is not necessary is stored. Also, since the Seq Sync, the Frame Body type,
the Reserved, and the Frame type are the same as those described with reference to
5 FIG. 5, detailed descriptions thereof will be omitted herein.
[OOSS]
The format of the management frame of TransferJet has been described
above. Next, an exemplary configuration of the management frame for
implementing the token frame will be described with reference to FIG. 7.
lo [a0591
FIG. 7 is a diagram illustrating a format of a frame body of a nxanagenlent
frame of TratisferJet. As illustrated in FIG. 7, the frame body includes LiCC
Version, LiCC, two Reseiveds, Own UID, and LiCC information. The link control
command (LiCC) is a 1-byte field in which a command for connection control is
15 stored. The LiCC type is a 1-byte field in which a version thereof is stored. The
Reserved is a 1-byte field serving as a reserved area. The Own UID is an 8-byte
field in which an own UID is stored. The LiCC it~formation is a 20-byte field in
which various types of infornlation about a command (LiCC) for connection control
are stored.
20 [0060]
Next, content of the fsame body in the management frame and relevant
setting information are shown in Table 2.
The con~munication system according to the present embodiment assigns,
5 for example, "OxOB," to the LiCC type as a value for the token fiame. The ACK
type in the tokenfimne is ImACK for which an ACK response is necessary. That is,
the co~nmunicatio~syls tem according to the present embodiment uses a management
fiame in which the ACK type of the sub CNL header is set as ImACK and the LiCC
of the frame body is set to OxOB as the dedicated frame (the token frame) for
10 arbitration of the transmission right.
The exemplary configuration of the token fiame has been described above.
The communication system according to the present embodiment performs
15 arbitration of the transmission right by the token frame described above. The ACK
type of the token frame is ImACK for which an ACK response is necessary.
Accordingly, when neither the talker nor the listener has data to be transmitted, the
conununication system according to the present e~nbodimentp erforms arbitration of
the transmission right by continuously performing transmission of the token fiame
20 and the ACK response.
More specifically, when the cotn~nunication apparatus 1 has the role of the
talker and there is no data to be transtnitted, the communication unit 4 transmits a
token frame (a transmission right arbitration frame) in place of the CSDU frame
(trans~nission data) to the partner device and receives the ACK frame. When no
5 talk flag is set in the received ACK fiame, the comnlunication unit 4 continuously
transmits the token fratne. Then, \vhen data to be transmitted is generated while the
ACK frame in which the talk flag is set is not received, the commurlication unit 4
transmits the CSDU fsame.
[0066]
10 On the other hand, when the communication apparatus 1 has the role of the
listener and there is no data to be transmitted, the communication unit 4 transmits the
ACK frame in which no talk flag is set to the partner device as a response to the
token frame. Then, when data to be transmitted is generated, the communication
unit 4 acquires the transmission right by transmitting the ACK frame in which the
15 talk flag is set to the partner device.
[0067]
In this manner, the communication system according to the present
embodiment continuously performs transmission of the token frame and the ACK
response when there is no data to be transmitted, and performs arbitration of the
20 transmission right within a framework of such an exchange when data to be
transmitted is generated. Therefore, unlike the comparison scheme, as described
with reference to FIG. 3 and Table 1, since both do not have the transmission right
after a predetermined time in an idle state, collision of frames does not occur.
[0068]
25 Here, the comm~~nicatioapnp aratus 1 has three states, a transmission state in
which any frame is transmitted, a reception state in wluc11 any frame is received, and
a frame detection operation state in which a preamble serving as a header of a fiame
is detected wvithout performing transmission and reception. In an electronic circuit
used in the communication apparatus 1, the fsatne detection operation state has
30 higher power consuti~ption than the other states in some cases. In particular, in
TransferJet, since transmission power for perfonning cotnmut~icationi n a proximity
state of about 3 cm is low and power for reception is also low, the frame detection
operation state has higher power consumption than the other states in many eases.
In this regard, in the communication system according to the present embodinlent,
since the conlmunication apparatus 1 and the partner device are usually in either the
5 transmission state or the reception state as the talker or the listener, it is possible to
avoid the frame detection operation state, thereby reducing power consumption.
[0069]
In addition, in a general wireless conlmunication specification, in order to
prevent interference, communication is stopped when there is no transmission data.
10 However, in TsansferJet, a risk of interference is low since communication is
performed with low transmission power in a proximity state of about 3 cm, and thus
it is possible to perform transmission and reception constantly by applying
technology according to the present embodiment.
[0070]
15 Arbitsation of the transmission right by the token fiame has been described
above. Next, an example of a transmission right arbitrating operation will be
described with reference to FIGS. 8 and 9.
[0071]
[2-2-3. One example of transmission right arbitrating operation]
20 FIG. 8 is a diagsam illustrating an example of a transmission right arbitrating
operation according to the first embodiment. FIG. 8 illustrates an example in which
a comnlunication apparatus 1-1 (a first cotnmunication apparatus) and a
eomnlunieation apparatus 1-2 (a second communication apparatus) perform data
communication while performing arbitration of the transmission right. Note that
25 the communication apparatus 1-1 co~sespondsto the initiatol; and the communication
apparatus 1-2 coisesponds to the responder. Roles 5-1 and 5-2 show roles (a talker
and a listener) of the communication apparatuses 1-1 and 1-2. Transmission buffers
6-1 and 6-2 show amounts of remaining data to be transmitted by the conlmunication
apparatuses 1-1 and 1-2. One square of the trans~nission buffers 6-1 and 6-2
30 corresponds to two CSDUs. Note that the star sy~llbols" *"i n the drawing indicate
parts different from the comparison scheme.
[0072]
As illustrated in FIG. 8, first, the comtnunication apparatus 1-1 sewing as
the talker translnits a CSDU frame 101 in which two CSDUs of sequence numbers
#1 and #2 are stored to the comtnunication apparatus 1-2 sewing as the listener.
5 [0073]
Next, the comtnunication apparatus 1-2 trausmits an ACK frame 103
indicating reception up to the CSDU of sequence number #2 to the communication
apparatus 1-1 as a response to the CSDU frame 101. In this case, since the
transmission buffer 6-2 has data to be transmitted, the communication apparatus 1-2
10 sets the talk flag it1 the ACK frame 103. Accordingly, the co~nmunicationa pparatus
1-2 changes the role 5-2 from that of the listener to that of the talker. In addition,
the communication apparatus 1-1 that has received the ACK fiame 103 in which the
talk flag is set changes the role 5-1 fiom that of the talker to that of the listener. In
addition, the communication apparatus 1-1 deletes data that has been completely
15 transmitted fiom the transmission buffer 6-1 with the reception of the ACK frame
103.
[0074]
Next, the communication apparatus 1-2 serving as the talker transmits a
CSDU frame 105 in which two CSDUs of sequence numbers #I05 and #I06 are
20 stored to the communication apparatus 1-1 serving as the listener.
100751
Next, the comnunication apparatus 1-1 transmits an ACK frame 107
indicating reception up to the CSDU of sequence number #lo6 to the comm~unication
apparatus 1-2 as a response to the CSDU frame 105. In this case, since the
25 transmission buffer 6-1 has data to be transmitted, the communication apparatus 1-1
sets the talk flag in the ACK frame 107. Accordingly, the comtnunication apparatus
1-1 changes the sole 5-1 to that of the talker. It1 addition, the commnication
apparatus 1-2 changes the role 5-2 to that of the listener and deletes data that has
been completely transmitted fro~nth e bansmission buffer 6-2 with the reception of
30 the ACK frame 107 in which the talk flag is set.
[0076]
In this manner, when both the con~munication apparatus 1-1 and the
conltnunication apparatus 1-2 have data to be transmitted, the CSDU kame is
alternately transmitted.
[0077]
5 Next, the cotnmunication apparatus 1-1 serving as the talker transmits a
CSDU frame 109 in which two CSDUs of sequence numbers #3 and #4 are stored to
the communication apparatus 1-2 s e ~ ~ iansg th e listener
[0078]
Next, the communication apparatus 1-2 transmits an ACK frame 111
10 indicating reception up to the CSDU of sequence number #4 to the cormnunication
apparatus 1-1 as a response to the CSDU frame 109. In this case, since the
transmission buffer 6-2 has no data to be transmitted, the communication apparatus
1-2 does not set the talk flag in the ACK fsame 11 1. The communication apparatus
1-1 deletes data that has been completely transmitted from the transmission buffer 6-
15 1 with the reception of the ACK frame I1 1.
[O079]
Next, the communication apparatus 1-1 serving as the talker continuously
transmits a CSDU frame 113 in which two CSDUs of sequence numbers #5 and #6
are stored to the communication apparatus 1-2 serving as the listener. In this
20 manner, when the ACK fsame in which no talk flag is set is received, the talker can
consecutively transmit the CSDU frame.
[OOSO]
Next, the communication apparatus 1-2 transmits an ACK frame 115
indicating reception up to the CSDU of sequence number #6 to tlie communication
25 apparatus 1-1 as a response to the CSDU frame 113. In this case, since the
transmission buffer 6-2 has no data to be transmitted, the cormnunication apparatus
1-2 does not set the talk flag in the ACK frame 115. The cornmutlication apparatus
1-1 deletes data that bas been completely transmitted from the transn~issionb uffer 6-
1 with the reception of the ACK frame 115.
30 [0081]
Next, since the role 5-1 is that of the talker and the transmission buffer 6-1
has no data to be transmitted, the cotm~lunication apparatus 1-1 transmits a token
frame 117 in place of the CSDU frame.
[O082]
Next, the communication apparatus 1-2 transmits an ACK frame 119 to the
5 communication apparatus 1-1 as a response to the token frame 117. In this case,
since the transmission buffer 6-2 has no data to be transmitted, the comn~i~nication
apparatus 1-2 does not set the talk flag in the ACK frame 119. Also, in this case,
data to be transmitted is generated in the communication apparatus 1-1.
[OO83]
10 Next, the comnr~nication apparatus 1-1 serving as the talker contini~~ously
transmits a CSDU frame 121 in which two CSDUs of sequence numbers #7 and #8
are stored to the comn~unicatioat~pp aratus 1-2 serving as the listener.
[OO84]
Next, the communication apparatus 1-2 transmits an ACK fiame 123
15 indicating reception up to the CSDU of sequence number #8 to the communication
apparatus 1-1 as a response to the CSDU kame 121. In this case, since the
transmission buffer 6-2 has no data to be transmitted, the communication apparatus
1-2 does not set the talk flag in the ACK frame 123. The connnunication apparatus
1-1 deletes data that has been completely transmitted from the transmission buffer 6-
20 1 with the reception of the ACK frame 123.
[OO85]
Next, since the role 5-1 is that of the talker and the transmission buffer 6-1
has no data to be transmitted, the comn~unicationa pparatus 1-1 transmits a token
frame 125 in place of the CSDU frame. Also, in this case, data to be transmitted is
25 generated in the communication apparatus 1-2.
[O086]
Next, the connnunicatiori apparatus 1-2 transmits an ACK frame 127 to the
colnmunication apparatus 1-1 as a response to the token fra~i~1e2 5. In this case,
since the transmission buffer 6-2 has no data to be transmitted, the communication
30 apparatus 1-2 sets the talk flag in the ACK frame 127. Accordingly, the
connnunication apparatus 1-2 changes the role 5-2 to that of the talker. In addition,
the commu~~icatioanp paratus 1-1 that has received the ACK frame 127 in which ihe
talk flag is set changes the role 5-1 to that of the listener.
[0087]
Next, the comnlunication apparatus 1-2 serving as the talker transmits a
5 CSDU fiame 129 in which two CSDUs of sequence numbers #I07 and #I08 are
stored to the comtnunication apparatus 1-1 serving as the listener.
[0088]
Next, the communication apparatus 1-1 transmits an ACK frame 131
indicating reception up to the CSDU of sequence number #lo8 to the comtnunication
10 apparatus 1-2 as a response to the CSDU frame 129. In this case, since the
transmission buffer 6-1 has no data to be transmitted, the comnlunication apparatus
1-1 does not set the talk flag in the ACK frame 131. Thk communication apparatus
1-2 deletes data that has been completely transmitted from the transmission buffer 6-
2 with the reception of the ACK frame 13 1.
15 [0089]
Next, since the role 5-2 is that of the talker and the transmission buffer 6-2
has no data to be transmitted, the conlmunication apparatus 1-2 transmits a token
fiame 133 in place of the CSDU frame.
[0090]
20 Next, the comn~unicatioa~pl paratus 1-1 transmits an ACK frame 135 to the
communicaiion apparatus 1-2 as a response to the token frame 133. In this case,
since the transmission buffer 6-1 has no data to be transmitted, the communication
apparatus 1-1 does not set the talk flag in the ACK frame 135.
[0091]
25 The example of the transmission right arbitrating operation has been
described above. Next, the inter frame space in the transmission right arbitrating
operation described above with reference to FIG. 8 will be described with reference
to FIG. 9.
[0092]
30 FIG. 9 is a diagram illustrating an example of a transmission right arbitrating
operation according to the first embodiment. As illustrated in FIG. 9, all of the inter
frame spaces after a connection between the communication apparatus 1-1 and the
coll~municatiotl apparatus 1-2 is established are SIFS. That is, regardless of
whether they are the initiator or the responder, and regardless of whether they are the
talker or the listener, the co~nmunicationa pparatuses 1-1 and 1-2 transmit a frame
5 using the same inter frame space.
[0093]
Here, as described above with reference to FIG. 3 and Table 1, in TransferJet
of the comparison scheme, the inter frame space of the responder has an interval that
is only Tbst longer than the inter frame space of the initiator. Therefore, when data
10 is transmitted from the responder, a longer time is necessary than when data is
transmitted fiom the initiatol: In this regard, in the proposed scheme, as illustrated
in FIG. 9, since the inter frame space is uniformly set as SIFS, a transmission time
when data is tsansmitted from the responder is reduced, and it is possible to obtain
the same transmission rate as when data is transmitted fsom the initiator.
15 [0094]
The example of the transmission right arbitrating operation has been
described above.
[0095]
[2-3. Sleep for very short time]
20 The communication system according to the present embodiment sleeps for
a very short time while data communication is not performed by the CSDU frame
and thus decreases power consumption and implenients a high-speed response.
Specifically, the talker sets a sleep time in the token frame and notifies the listener of
the time. The listener that has received a notification of the sleep time through the
25 token frame performs a sleep operation for the notified time after the ACK frame is
transmitted for the token frame. In addition, the talker that has transmitted the
token frame in which the sleep time is set performs a sleep operation for the notified
time after the ACK frame is received fsom the listene~
[0096]
30 The co~nmunication apparatus 1 according to the present embodiment
notifies of the sleep time using an LiCC information field in the fsame body of the
token frame. An exemplary configuratiotl of the frame body in the token frame is
shown in the following Table 3.
[0097]
[Table 31
[Byte 04, Bit 61: Own UID [62]
[Byte 04, Bit 01: Own UID [56]
[Byte 05, Bit 71: Owl UID [55]
5 [0098]
As shown in Table 3, in a sleep period of byte 31 of LiCC infoimation, the
sleep time is set. A detailed setting example of the sleep period is shown in the
following Table 4.
[0099]
10 [Table 41
The exemplary configuration of the frame body in the token frame has been
.
described above.
[OIOl]
15 When the con~mu~licatioun it 4 sets sleep period information indicating the
~ ;57zi;I.,, ~ ><,+
,~~ .. ~,.~ ~~ ~...~<,5.~.:;::-..v< +2,G:<:z: *:;> ;z:7;gz
; ~~ . ..~~~. ~:.. ~.:. ..~ ~ : ~ ~ + ~ ~ ~ ~ ~ ; Indicate sleep time
unit: 10 psec
0: no sleep
1 : sleep for 10 psec
. . .
255: sleep for 2550 psec
.:~~;.:~ ~:~~.~ ,~-;.~.~ ~ :.~~. .~'~."< <,~~=..-.~i'.~"- ...-~.. . :~<.. .. ~:. :~.:~:~~. .;. !.?....: ~s;:~; .:, <: .~:.:.~. : ..:.i~.~ :~a~ete~jnam.i:ez$$:$~$?::~g~~al:~;~-:: :;;;;$:; ~~~~ .~ .~. .~~... .
sleep time shonn in Table 4 in the token fran~ea nd transmits the fiame to the partner
[OlOO]
Sleep period 0 to 255
device, the com~nunication apparatus 1 pauses cot~ullunication until the sleep time
elapses after the ACK fsatne for the token frame is received. In addition, when the
token frame in which the sleep period shown in Table 4 is set is received, the partner
terminal pauses comtn~~nicatiofnor a time indicated by the sleep period after the
5 ACK frame is transtnitted. Also, when the ACK frame in which the talk flag is set
is transmitted with respect to the token kame in which the sleep time is set, the
communication system may cancel the sleep operation.
[O 1021
I-Iere, diverse methods of setting the sleep time and a notification timing of
10 the sleep time by the communication apparatus I serving as the talker can be
considered. Accordingly, the method of setting the sleep time and the notification
timing of the sleep time will be described in detail.
[0103]
The communication apparatus 1 may set any sleep time. In order to reduce
15 power consumption, it is preferable to set as long a time as possible. When a
response time assumed by the application (the application 40 in FIG. 2) of the upper
layer is known, the communication apparatus 1 sets a time equal to or less than the
response time assumed by the upper layer as the sleep time. This is because, when
the sleep operation is performed for the response time assumed by the application of
20 the upper layer or longer, there is a possibility of a time out occulring in the
application. On the other hand, when the response time assumed by the application
of the upper layer is unknown, the con~munication apparatus 1 should set the sleep
time as a very short time.
[0104]
25 In addition, the communication apparatus 1 can notify the partner device of
the sleep time at any timing. Here, two notification timings mrill be described as
examples.
[OlOS]
The first notification timing is a timing at which the token frame is
30 transmitted a predetermined number of times. specific all^: the communication
apparatus 1 transmits the token frame in ~vhich the sleep time is set after the token
fsatne is transmitted N times. Accordingly, when data transmission and reception
by the application of the upper layer are intempted for a predeter~nined time or more,
the co~mnunications ystem can perform the sleep operation.
[0 1061
5 The second notification timing is any timing at which the token fsame is
transmitted. Specifically, the communication apparatus 1 normally sets the sleep
time in the token frame. Accordingly, when data transmission and reception by the
application of the upper layer are slightly interrupted, the comtnunication system can
perform the sleep operation. Also, in order to perfor~n the sleep operation even
10 when an interruption period of data transmission and reception by the application is
unknown, the sleep time should be set as a very short time.
[O 1071
In this manner, while data communication by the CSDU frame is not
performed, the cornniunication system according to the present embodiment can
15 implement the sleep operation for a very short time using the token fiame and reduce
power consumption. Further, when a minimum value of the sleep time in the
comparison scheme is 5 milliseconds (msec), it is possible to implement the sleep
operation for a range of several psec (microseconds) as shown in Table 4 in the
proposed scheme. Accordingly, the comnlunication system according to the present
20 embodiment can reduce a delay time from when data transmission is requested until
sleep is released and data transmission is started, and increase responsiveness.
[0108]
The method of setting the sleep time and the notification timing of the sleep
time by the communication apparatus 1 have been described above. Next, an
25 example of a sleep operation by the conlmunication system according to the present
embodiment will be described with reference to FIG. 10.
[0 1091
FIG. 10 is a diagram illustrating an example of a sleep operation according
to the first embodiment. FIG. 10 illustrates an example in which the token frame is
30 transmitted once, the sleep time is then notified of by the second token frame, and the
sleep operation for 100 psec is performed.
[OllO]
As ill~~strateind FIG. 10, first, the con~municationa pparatus 1-1 serving as
the talker transmits a CSDU fran~e2 01 to the con~nnnicationa pparatus 1-2 serving
as the listener.
5 [0111]
Next, the con~n~unicatioanpp aratus 1-2 transmits an ACK frame 203 to the
coln~nunicationa pparatus 1-1 after the SIFS elapses from when the CSDU frame 201
is received.
(01121
10 Next, the communication apparatus 1-1 transmits a first token frame 205 to
the communication apparatus 1-2 after the SIFS elapses from when the ACK frame
203 is received.
[0113]
Next, the commt~nicationa pparatus 1-2 transmits an ACK fiame 207 to the
15 communication apparatus 1-1 after the SIFS elapses fiom when the token fiame 205
is received.
(01141
Then, the comnunication apparatus 1-1 transmits a second token frame 209
to the communication apparatus 1-2 after the SIFS elapses from when the ACK
20 frame 207 is received. In this case, since the token frame is transmitted a second
time, the cornmunication apparatus 1-1 sets 100 psec as the sleep time in the sleep
period of the LiCC information field in the frame body of the token frame.
[0115]
Next, the co~nmunication apparatus 1-2 transmits an ACK frame 211 to the
26 communication apparatus 1-1 after the SlFS elapses fiom when the token frame 209
is received.
[0116]
Then, the communication apparatus 1-1 that has received the ACK frame
21 1 performs the sleep operation for a sleep time of 100 psec notified of by the token
30 frame 209. In addition, the communication apparatus 1-2 that has transmitted the
ACK frame 2 11 performs the sleep operation for a sleep time of 100 psec notified of
by the token frame 209.
[0117]
After 100 psec elapses, the comnlunication apparatus 1-1 is restored from
the sleep operation, and transmits a first token frame 213 to the colnmunication
5 apparatus 1-2.
[0118]
Next, the cotnmunication apparatus 1-2 hansmits an ACK frame 215 to the
conununication apparatus 1-1 after the SIFS elapses from when the token frame 213
is received.
10 [0119]
Then, the communication apparatus 1-1 transmits a token fsame 217 in
which a sleep period of 100 psec is set to the communication apparatus 1-2 as a
second token fsame after the SIFS elapses from when the ACK frame 215 is received.
[0120]
15 Next, the cotnmunication apparatus 1-2 transmits an ACK frame 219 in
which the talk flag is set to the con~municatiolia pparatus 1-1 after the SIFS elapses
from when the token frame 217 is received. Accordingly, the communication
apparatus 1-2 can cancel the sleep operation.
[0121]
20 Next, the co~nnlunication apparatus 1-2 transmits a CSDU fsame 221 after
the SIFS elapses from when the ACK frame 219 is transmitted.
[O 1 221
The exenlplary sleep operation by the communication system according to
the present embodiment has been described above. Next, operations of the
25 communication apparatus 1 according to the present embodiment will be described
with reference to FIG. 11.
[0123]
[2-4. Operating process]
FIG. 11 is a flowchart showing operations of the communication apparatus 1
30 according to the first embodiment. As illustrated in FIG. 11, first, in Step S102, the
co~~lrnunicatioatpi paratus 1 deter~ninesw hetlier its role is that of the talker or the
listener. Specifically, tlie control unit 2 detern~ines the role as that of the talker if
the initiator is set when conlnlunication starts and determines the role as that of the
listener if the responder is set when coninlunication starts. Then, the control unit 2
determines a role with reference to settings in Steps S114, S116, S126, and S128 to
5 be described below.
[0 1241
When it is determined that the coillmunication apparatus 1 has the role of
the talker (talker in S102), in Step S104, the communication apparatus 1 determines
whether there is data to be transmitted. Specificall): the control unit 2 determines
10 whether there is data to be transmitted based on whether the transmission buffer has
data to be transmitted.
[Ol25]
When it is determined that there is data to be transmitted (YES in S104), in
Step SIO6, the communication apparatus 1 transmits tlie CSDU frame. Specifically,
15 the communication unit 4 stores data in the transmission buffer in the CSDU frame
and transmits the data to the partner device serving as the listener.
[0 1261
On tlie other hand, when it is determined that there is no data to be
transmitted (NO in S104), in Step S108, the communication apparatus 1 transmits the
20 token frame. Specifically, the communication unit 4 transmits the management
frame in which the ACK type of the sub CNL header is set as ImACK and the LiCC
of the frame body is set to OxOB to the partner device as the token frame.
[0 1271
Next, in Step S110, the communication apparatus 1 receives the ACK frame.
25 Specifically, the communication unit 4 receives the ACK frame from the partner
device as a response to the CSDU frame transmitted in Step S106 or the token frame
transmitted in Step S108.
[0128]
Next, in Step S112, tlie communication apparatus 1 deternlines whether the
30 talk flag is set in the ACK frame. Specificall>: the coiltrol unit 2 determines
whether the talk flag is set in the Reserved field of the ACK frame received in Step
S110.
[O 1291
When it is detennitied that the talk flag is set (YES in S112), in Step S114,
tlie conimunication apparatus 1 sets its own role as that of tlie listene~ Specifically,
5 tlie switch unit 3 switches the role of the co~inlllunicationa pparatus 1 from that of the
talker to that of tlie listene~ Then, the process returns to Step S102 again.
[0130]
On the other hand, when it is determined that no talk flag is set (NO in
S112), in Step S116, the colnmunication apparatus 1 sets its own role as that of the
10 talker. Specifically, the switch unit 3 keeps the role of the conmunication apparatus
1 as that of the talkec Then, the process returns to Step S102 again.
[0131]
When it is determined in Step S102 that the conununication apparatus 1 has
the role of the listener (listener in S 102), in Step S 11 8, the communication apparatus
15 1 receives the CSDU frame or the token frame. Specifically, the communication
unit 4 receives the CSDU fiame or the toketi frame from the partner device serving
as the talker.
[0132]
Next, in Step S120, the comtnunication apparatus 1 deter~ilines whether
20 there is data to be transmitted.
[0133]
When it is determined that there is data to he transmitted (YES in S120), in
Step S122, the communication apparatus 1 sets the talk flag and transmits the ACK
frame. Specifically, the cotnmunication unit 4 transmits the ACK fratne in which
25 the talk flag is set in the resewed field to tlie partner device. Then, in Step S126,
the cottlmunicatioti apparatus 1 sets its own role as that of tlie talker. Then, the
process returns to Step S102 again.
[0134]
On the other hand, when it is determined that there is no data to be
30 tra~ismitted( NO in S120), in Step S124, the commtlication apparatus 1 transmits the
ACK frame without setting tlie talk flag. Specificallj: the cotlullnnication unit 4
tra~lsmits the ACK frame in which no talk flag is set in the reserved field to the
paltner device. Then, in Step S128, the com~~lnnicatioanp paratus 1 sets its own
role as that of the listener. Then, the process returns to Step S102 again.
[0135]
5 The operations of the communication apparatus 1 according to the present
embodiment have been described above.
[0136]
<3. Sumnlaty>
As described above, the conllnunication system according to the present
10 embodiment can stupport full-duplex communication over a half-duplex
communication channel. Specificall]; the communication system according to the
present embodiment can implement full-duplex communication without decreasing
the throughput according to arbitration of the transmission right using the ACK
fiame in the TransferJet specification. Here, since the communication system
15 according to the present embodiment implements full-duplex comn~nnication by
control in the CNL layer, arbitration of the transmission right in a layer higher than
the CNL layer is unnecessaly. Therefore, the communication system according to
the present embodiment can increase the throughput with the decrease in a load on
the upper layer.
20 [0137]
In addition, the comnlunication system according to the present embodiment
can reduce power consu~nptiona nd prevent fiame collision without influencing the
throughput according to arbitration of the transmission right by the token frame.
Further, the communication system according to the present embodiment can
25 decrease power consumption and implement a high-speed response by the sleep
operation for a very short time.
[0138]
The preferred enlbodiment(s) of the present disclosore haslhave been
described above with reference to the acconlpanying drawings, whilst the present
30 disclosme is not limited to the above examples. A person skilled in the art may find
various alterations and modifications within the scope of the appended claims, and it
should be understood that they will naturally come under the technical scope of the
present disclosure.
[0139]
For example, while the communication apparatus 1 performs close
5 proximity wireless communication according to tlie TransferJet specification in tlie
above embodiment, the present teclinologp is not limited thereto. For example, the
conununication apparatus 1 may communicate with the external device through
Bluetooth (registered trademark), Zigbee (registered trademark) or Ultra Wide Band
(UWB).
10 [0140]
In addition, a computer program for implementing the same functions as
respective configurations of an information processing device is also created in
hardware such as a CPU, a ROM and a RAM to be installed in the information
processing device. In addition, a recording medium in which the computer program
15 is recorded is provided.
[0141]
In addition, the effects described in tlie present specification are merely
illustrative and demonstrative, and not limitative. In other words, the technology
according to the present disclosure can exhibit other effects that are evident to those
20 skilled in the art along with or instead of the effects based on the present
specification.
[0142]
Additionally, the present technology may also be configured as below.
(1)
A communication apparatus including:
a switch unit configured to switch data commnunication to be perfonned with
another commu~iicationa pparatus on a transmissioi~s ide or a reception side; and
a communication unit cot~figured to transmit tra~ismission data to the other
commutiication apparatus and receive a response when the data cotilmunication is
30 performed on the tratismission side, and receive reception data from the other
cornnu~nicationa pparatus and transmit a response wlien tlie data communication is
performed on the reception side,
wherein the switch unit performs switching from the trans~llissions ide to the
reception side when the response received by the con~nninication unit includes a
switching instruction.
5 (2)
The commnnication apparatus according to (I),
wherein the communication unit cotnmunicates with the other
cotimunication apparatus through close proximity wireless communication.
(3)
10 The comniu~licationa pparatus according to (I) or (2),
wherein the co~mnunication unit transmits a transmission right arbitration
frame in place of the transmission data to the other communication apparatus and
receives the response.
(4)
The communication apparatus according to (3),
wherein the conmunication unit transmits the transmission right arbitration
frame to the other co~nmunicationa pparatus when the communication apparatus is
on the transmission side and there is no data to be transmitted.
(5)
The communication apparatus according to any one of (1) to (4),
wherein the communication unit transmits the response including the
s~vitchingin st~uctionto the other connnunication apparatus.
(6)
The communication apparatus according to (5),
26 wherein the switch unit performs switching from the reception side to the
transmission side when the communication apparatus is on the reception side and
there is data to be transmitted, and
wherein the communication unit transmits the transtnission data to the other
cotnmunication apparatus after the response including the switching instr~lction is
30 transmitted.
(7)
The co~n~nunicatioanp paratus according to (3) or any one of (4) to (6)
dependent from (3),
wherein the communication unit sets information indicating a sleep time in
the trai~s~nissionri ght arbitration frame, transmits the frame to the other
5 conununicatioi~ apparatus, and pauses communication until the sleep time elapses
after the response is received.
(8)
The cornnlunication apparatus according to any one of ( 1 ) to (7),
wherein the comnunication apparatus is either a responder or an initiator,
10 and
wherein the communication unit transmits the transmission data using a
same inter fiaine space regardless of whether the communication apparatus is the
responder or the initiator.
(9)
A communication system including:
a first communication apparatus configured to perform data communication
on a transmission side and a second communication apparatus configured to perform
data cotnmunication on a reception side,
wherein the first communication apparatus includes
20 a first switch unit configured to perform switching from the
transmission side to the reception side, and
a first conlmunication unit configured to transmit transmission data
to the second communication apparatus and receive a response,
wherein the second communication apparatus includes
25 a second switch unit configured to perfornl switching from the
reception side to the transmission side, and
a second co~i~munication unit configured to receive the
transmission data fiom the first communication apparatus and transmit the response,
and
30 wherein the second switch unit perforlns switching from the reception side
to the transmission side when the response including a switching instruction is
transmitted by the second communication unit, arid the first switch unit perfornls
switching from the tra~isnlission side to the reception side when the response is
received by the first conimunication unit.
(10)
5 A comnlunication method including:
switching data communication to be perfonned with another colnmunication
apparatus on a transmission side or a reception side;
transmitting transtnission data to the other cotminuication apparatus and
receiving a response when the data communication is performed on the transmission
10 side and receiving reception data from the other communication apparatus and
transmitting a response when the data communication is performed on the receptiotl
side; and
perfonning switching from the transmission side to the receptiotl side when
the received response includes a switching instruction.
Reference Signs List
[O 1431
1, 1-1, 1-2 communication apparatus
2 control unit
20 3 switch unit
4 cotnmunication unit
5-1,5-2 role
6-1, 6-2 transmission buffer
10 PHY layer
25 20 CNL layer
30 PCL layer
40 application
CLAIMS
Claim 1
A cotnmnnication apparatus comprising:
a switch unit configured to switch data conlmunication to be performed with
5 another cornnlunication apparatus on a transmission side or a reception side; and
a communication unit configured to transmit transmission data to the other
comnlunication apparatus and receive a response when the data connnnnication is
performed on the transmission side, and receive reception data fioin the other
communication apparatus and transmit a response when the data communication is
10 performed on the reception side,
wherein the switch unit performs switching from the transmission side to the
reception side when the response received by the communication unit includes a
switching instruction.
15 Claim2
The communication apparatus according to claim 1,
wherein the communication unit communicates with the other
comnlunication apparatus though close proximity wireless communication.
20 Claim 3
The com~nunicationa pparatus according to claim 1,
wherein the communication unit transmits a transmission right arbitration
fsame in place of the translnission data to the other co~nmunicationa pparatus and
receives the response.
25
Claim 4
The conlmunication apparatus ac;ording to claim 3,
wherein the colnmunication unit transmits the transmission right arbitration
fiame to the other conmnication apparatus when the communication apparatus is
30 on the transn~issious ide and there is no data to be transmitted.
Claim 5
The comnlunication apparatus according to claim 1,
wherein the communication unit transnlits the response including the
switching instruction to the other communication apparatus.
5
Claim 6
The communication apparatus according to claim 5,
wherein the switch unit performs switching from the reception side to the
transmission side when the communication apparatus is on the reception side and
10 there is data to be transmitted, and
wherein the comtnunication unit transmits the transmission data to the other
com~nunication apparatus after the response including the switching instruction is
transmitted.
15 Claim7
The communication apparatus according to claim 3,
wherein the comm~~nicatiounn it sets information indicating a sleep time in
the transmission right arbitration frame, transmits the frame to the other
communication apparatus, and pauses communication until the sleep time elapses
20 after tlie response is received.
Claim 8
The communication apparatus according to claim 1,
wherein tlie communication apparatus is either a responder or an initiator,
25 and
wherein the communication unit transmits the transmission data using a
same inter frarne space regardless of whether tlie communication apparatus is the
responder or the initiator.
30 Claim 9
A comnlunication system comprising:
a first communication apparatus configured to perforn~d ata communication
on a transmission side and a second communication apparatus configured to perform
data commr~nicationo n a reception side,
wherein the first communication apparatus includes
a first switch unit configured to perform switching from the
transmission side to the reception side, and
a first communication unit configured to transmit transmission data
to the second communication apparatus and receive a response,
wherein the second communication apparatus includes
a second switch unit configured to perform switching from the
reception side to the transmission side, and
a second communication unit configured to receive the
transmission data fiom the first communication apparatus and transmit the response,
and
15 wherein the second switch unit perfotms switching from the reception side
to the transmission side when the .response including a switching instruction is
transmitted by the second communication unit, and the first switch unit performs
switching from the transmission side to the reception side when the response is
received by the first communication unit.
20
Claim 10
A communication method comprising:
switching data communication to be performed with another communication
apparatus on a transmission side or a reception side;
25 transmitting transmission data to the other communication apparatus and
receiving a response when the data conununication is performed on the transmission
side and receiving reception data from the other communication apparatus and
transmitting a response when the data communication is performed on the reception
side; and
30 performing switching from the transmission side to the reception side when
the received response includes a switching instruction.