AU2005200862B2 - Wireless communication terminal, wireless communication method and program - Google Patents

Description

AUSTRALIA

Patents Act 1990 COMPLETE SPECIFICATION STANDARD PATENT Applicant NATIONAL INSTITUTE OF INFORMATION COMMUNICATIONS TECHNOLOGY INCORPORATED ADMINISTRATIVE AGENCY Invention Title: WIRELESS COMMUNICATION TERMINAL, WIRELESS COMMUNICATION METHOD AND PROGRAM The following statement is a full description of this invention, including the best method of performing it known to me/us:

DESCRIPTION

)WIRELESS COMMUNICATION TERMINAL, WIRELESS COMMUNICATION METHOD AND PROGRAM

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00 Technical Field The present invention relates to a wireless communication terminal, a wireless communication method and a program.

The present application is a divisional application of Application No. 2002210922.

Background Art Mobile wireless communication systems, such as an analog portable telephone, PDC (Personal Digital Cellular) and PHS (Personal Handyphone System), which execute mobile communications outdoors using a microwave frequency band and quasi-microwave frequency band are becoming popular.

Wireless communication systems, such as cordless telephones, which use a milliwave frequency band have been proposed and their studies and developments are underway.

In wireless communication between mobile units and between a stationary unit and a mobile unit using the milliwave frequency band, the microwave frequency band or H:YPriyankaVKeepVspeciYP56041.doc 24/02/05 Sthe quasi-microwave frequency band, the 2 GHz band, in cI particular, the status of the propagation path between two Soften significantly changes as the position of a mobile unit Sdynamically varies.

In communication in such a frequency band, however, if IND a communication party is hid behind an obstruction, 00 attenuation by the obstruction occurs. Even in case where V) the distance between two becomes longer, the distanceoriginated attenuation is likely to occur. Such attenuation is prominent particularly in the frequency band that is suited for line-of-sight (Line of Sight; LoS) communication.

Therefore, there occurred a problem such that such attenuation would deteriorate the transfer quality and communication itself would become impossible.

Embodiments of the invention attempt to overcome the above-described problem and aim at providing a wireless communication terminal and a wireless communication method which are suitable to be able to ensure communication by carrying out relay even in wireless communication using a frequency band suitable for line-of-sight communication even if an obstruction is present in the path of wireless communication and even if the status of the radio wave propagation path dynamically changes, and a computer readable information recording medium in which a program for achieving them is recorded.

H:VPriyankaVKeepVspeciP5604l.doc 24/02/05 -4 C- Disclosure of Invention

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n- According to one aspect of the invention there is 00 provided a wireless communication method enabling relaying c-i of communication between a second wireless communication terminal and a third wireless communication terminal by a c-i first wireless communication terminal, the method 00 comprising the steps of: receiving by the first terminal a destination data information message including information designating a destination terminal and data information addressed to a 1 destination terminal transmitted by the second terminal; determining by the first terminal whether the destination data information message is addressed to the first terminal or a third terminal: determining by the first terminal whether the first terminal can relay communication from the second terminal to the third terminal, and if so: transmitting a relay offer message to the second terminal; receiving by the second terminal the relay offer message; determining by the second terminal whether the data information message transmitted by the second terminal was received by the third terminal, and if not: transmitting by the second terminal the data information message addressing the third terminal as the destination terminal for relaying by the first terminal; receiving by the first terminal the data information message addressing the third terminal for which a relay offer had been made; and then transmitting by the first terminal the data information message addressing the third terminal According to another aspect of the invention there is provided a first wireless communication terminal adapted to relay communication between a second wireless N W lboumeXC aes Patcnt\49VM49999kP493M I AU I\SpcCIS\ P493 I A U I pecificain 20)06-126 doc 2711K,,7 communication terminal and a third wireless communication Sterminal, the first wireless communication terminal having: 00 an input section adapted to enable information designating a destination terminal and data information addressed to a destination terminal to be input; Sa reception section adapted to receive messages 00 including: an information destination data message including information designating a destination terminal and data information addressed to a destination terminal, and a relay offer message; Sa transmission section adapted to transmit messages including: a destination data information message including information designating a destination terminal and data information addressed to a destination terminal, and a relay offer message; and an output section adapted to enable data received by the first terminal in a destination data information message that is addressed to the first terminal to be output, and also adapted to when a destination data message transmitted by a second terminal and addressing a third terminal is received by the reception section, to relay communication to the third terminal, following the first terminal transmiting a relay offer message to the second terminal, and when the reception section receives a destination data information message addressed to a third terminal for which a relay offer has been made, transmitting by the transmission section the destination data information message including information designating the third terminal.

According to another aspect of the invention there is provided a computer program enabling a computer to function as a wireless communication terminal capable of relaying communication between a second wireless communication terminal and a third wireless communication N\Me boume\Cwes\Patnt49OO1,-491-9'9P493Si AU I'Spci\P493X I AU I Specifiction 201-12-6 doc 27/011)7 6 C terminal, computer program adapted to replicate the Sfunctions of: n- an input section enabling information designating 00 a destination terminal and data information addressed to a destination terminal to be input; a reception section adapted to receive messages including: an information destination data message 00 including information designating a destination terminal and data information addressed to a destination terminal, n 10 and a relay offer message; a transmission section adapted to transmit C1 messages including: a destination data information message including information designating a destination terminal and data information addressed to a destination terminal, and a relay offer message; and an output section enabling data received by the reception section in a destination data information message that is addressed to the terminal being replicated by the computer program to be output, and also adapted to when a destination data message transmitted by a second terminal and addressing a third terminal is received by the reception section, to relay communication to the third terminal, the transmission section then being able to transmit a relay offer message to the second terminal, and also adapted to when the reception section receives a destination data information message addressed to a third terminal for which a relay offer has been made, to be able to transmit by the transmission section the destination data information message including information designating the third terminal Brief Description of Drawings FIG. 1 is an exemplary diagram illustrating the schematic structure of an embodiment of a wireless communication terminal according to the invention.

N \Meiboume\( wesPalc,,4Wt9tj(K999A)P493X1 AU I\Specrs\P4931 I AU I Specificaiin 200-12-6doc 27/(I0/II 7 C- FIG. 2 is a flowchart illustrating the flow of Scontrol of an operation mode transition process which changes the operation mode of a wireless communication 00 terminal.

FIG. 3 is an explanatory diagram showing how wireless communication terminals, installed on vehicles, detect one another and determine the operation mode.

00 FIG. 4 is an explanatory diagram showing the Sresults of a simulation of how a terminal group is constructed.

SFIG. 5 is an exemplary diagram illustrating the C structure of a slot to be used in transmission of data information.

FIG. 6 is an explanatory diagram showing how transmission from a sender terminal to a destination terminal which belongs to a different terminal group is N \.elbou nc\(:ePaentA900(49999\P4938 I AU Mp-sk?49391 AU I Specifcitaon 2006-12-6 dec 27106/07 LOOW uflf 8Z W9sooW§OOW -9 0 00

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N ',Mel Iou me Cases\Patenl'49(lE4 999'P49K I A U I \Spec is\P4Y)3K IAl 0 Spec ificaiion 20M.1I2.6 dec 27/06/07 carried out.

CI FIG. 7 is an explanatory diagram showing how Stransmission from a sender terminal to a destination terminal which belongs to a different terminal group is carried out via a relay terminal which is a master terminal IND of the destination terminal.

00 SFIG. 8 is an explanatory diagram showing how n transmission from a sender terminal to a destination Sterminal which belongs to a different terminal group is carried out via a relay terminal which is a master terminal of the destination terminal and a sub relay terminal which is a slave terminal of the relay terminal.

FIG. 9 is a graph showing the results of an experiment on the relationship between the input traffic and communication throughput.

FIG. 10 is a graph showing the results of an experiment on the relationship between the input traffic and communication delay.

FIG. 11 is an explanatory diagram showing whether communication among wireless communication terminals succeeds or not depending on whether or not communication power control is executed.

FIG. 12 is an explanatory diagram showing whether communication among wireless communication terminals succeeds or not depending on whether or not communication beam shape control is executed.

FIG. 13 is an explanatory diagram showing whether H:VPriyankaV~eepVspeciVP56041.doc 24/02/05 i communication among wireless communication terminals C succeeds or not depending on whether or not communication Schannel shape control is executed.

FIG. 14 is an exemplary diagram illustrating the schematic structure of a wireless communication terminal IND which performs communication control.

00 tt Best Mode for Carrying Out the Invention Embodiments of the invention will be described below.

The embodiments to be discussed below are to be considered as illustrative and no restrictive and the scope of the invention is not to be limited. Therefore, it would be possible for those skilled in the art to use those individual elements or embodiments in which all the elements are replaced with equivalent ones, but those embodiments should also be included in the scope of the invention.

(First Embodiment) FIG. 1 is an exemplary diagram illustrating the schematic structure of an embodiment of a wireless communication terminal according to the invention. A description will be given below by referring to this diagram.

A wireless communication terminal 101 operates in one of operation modes, an undetermined mode, a master station mode or a slave station mode.

In case were the wireless communication terminal 101 is operating in the undetermined mode, an initial detecting H:VPriyankaVKeepYspeciVP56042.doc 24/02/05 O section 102 of the wireless communication terminal 101 l detects if communication with another wireless communication Sterminal that operates in the master station mode via an antenna 103 is possible.

Further, in case where there are plural communicatable IND wireless communication terminals that operate as a master 00 Sstation, the initial detecting section best propagation path Sas a master station.

SIn case where it is detected by the initial detecting section 102 that communication with another wireless communication'terminal which operates in the master station mode is possible, a slave-mode setting section 104 sets the operation mode to the slave station mode, registers the another wireless communication terminal as a master terminal and transmits subordination information to the effect that the local is subordinate to the master terminal.

The setting of the operation mode is stored in an operation mode storage section 105 and the information on the master terminal is stored in a master terminal storage section 106.

Meanwhile, in case where it is detected by the initial detecting section 102 that communication with the another wireless communication terminal which operates in the master station mode is not possible, a master-mode setting section 107 sets the operation mode to the master station mode.

And, in case where the operation mode is set to the master station mode and subordination information to the H:VPriyankaYKeepYspeciYP56041.doc 24/02/05 effect that the another wireless communication terminal which operates in the master station mode is subordinate to the local is received via the antenna 103, a slave terminal registration section 108 registers the another wireless communication terminal as a slave terminal.

The information on the slave terminal is stored in a slave terminal storage section 109.

In the meantime, when the operation mode is set to the master station mode, while the operation mode is the master station, a master station maintenance detection section 110 regularly detects at every predetermined time period if communication with the slave terminal stored in the slave terminal storage section 109 is possible.

Further, when the operation mode is set to the slave station mode, while the operation mode is the slave station, a slave station maintenance detection section 111 regularly detects at every predetermined time period if communication with the master terminal stored in the master terminal storage section 106 is possible.

And, an undetermined-mode setting section 112 sets the operation mode to the undetermined mode in any of the following cases.

A case where it is detected by the master station maintenance detection section 110 that communication with the slave terminal is not possible.

A case where it is detected by the slave station maintenance detection section 111 that communication with H:VPriyankaYKeepspcciYP56041.doc 24/02/05 Sthe master terminal is not possible.

CI A case where the operation mode is set to the Smaster station mode and a predetermined time has elapsed with no wireless communication terminal registered as a slave terminal.

IND In the meantime, a transmission section 113 transmits a 00 message to another wireless communication terminal.

n Further, a reception section 114 receives a message from another wireless communication terminal.

Although the illustration of a bandpass filter, a modulator/demodulator and the like which are used in an ordinary wireless communication terminal is omitted in this diagram, the wireless communication terminal 101 can be realized by using ordinary well-known techniques.

The operation mode storage section 105, the master terminal storage section 10 and the slave terminal storage section 109 can be realized by a RAM (Random Access Memory) or the like.

The slave-mode setting section 104, the master-mode setting section 107 and the undetermined-mode setting section 112 can be realized by a CPU (Central Processing Unit; central processing unit) which controls the wireless communication terminal 101.

The initial detecting section 102, the slave terminal registration section 108, the master station maintenance detection section 110, the slave station maintenance detection section 111, the transmission section 113 and the H:VPriyankaVIeeVspeciVP5604l.doc 24/02/05 reception section 114 can be realized by the cooperation of CI the CPU and an ordinary mobile communication unit.

SIn the embodiment, stable communication can be ensured Sby using, as the condition for "communicatable" with another terminal, the condition such that not only communication is 1-1 possible but also the carrier power v.s. noise power ratio 00 0 (hereinafter called "CN ratio") exceeds a predetermined Sthreshold value. For the sake of easier understanding, that communication is possible and the CN ratio is greater than a predetermined threshold value is simply said to be "communication is possible" in the following description.

(Operation Mode Changing Process) FIG. 2 is a flowchart illustrating the flow of control of an operation mode transition process which changes the operation mode of the wireless communication terminal 101.

A description will be given below by referring to this diagram.

The wireless communication terminal 101 is set to the undetermined mode immediately after power is given. First, it is checked if communication with another terminal which operates in the master station mode is possible (step S201) In case where communication with another terminal which operates in the master station mode is possible (step S201; Yes), the operation mode is set to the slave station mode (step S202). At this time, the master terminal is registered and subordination information is sent to the master terminal. Then, after standing by for a H:VPriyankaeepyspeciYP56O4.doc 24/02/05 Spredetermined time (step S203), it is checked if Oc communication with the master terminal is possible (step d9 S204), and, if possible (step S204; Yes), the process returns to step S203. If it is not possible (step S204; No), the operation mode is set to the undetermined mode (step

(N

IND S205). This allows the process to return to step S201.

00 In case where communication with another terminal which

(N

V' operates in the master station mode is not possible (step C, S201; No), the operation mode is set to the master station mode (step S206). While the operation mode is the master station mode, when subordination information is received from another terminal, that terminal is registered as a slave terminal.

Then, after standing by for a predetermined time (step S207), it is checked if there is a terminal registered as a slave terminal (step S208), and, if not possible (step S208; No), the operation mode is set to the undetermined mode (step S210) and the process returns to step S201.

If there are terminals registered as a slave terminal (step S208; Yes), it is checked if communication with them is possible (step S209), and, if communication is possible (step S209; Yes), the process returns to step S207 whereas if it is not (step S209; No), the operation mode is set to the undetermined mode (step S210) and the process returns to step S201.

The standby time in step S203 and step S207 may be 0.

Further, the detection of the communicatable/non- H:VPriyankaVKeepyspeciVP56041.doc 24/02/05 b communicatable status and the moment of the status change c may be processed by interruption.

4 (How Operation Mode Is Determined) FIG. 3 is an explanatory diagram showing how wireless communication terminals of this embodiment are installed on IND vehicles, detect one another and determine the operation 00 mode. A description will be given below by referring to Sthis diagram.

FIG. 3(a) shows five wireless communication terminals, A, B, C, D and E, in the order of detection. It is assumed that any of A, B, C, D and E is in the initial state and their operation modes are not set (or are set to the slave station mode). A and B can communicate with each other, and C, D and E can communicate with one another.

Here, as A performs detection, it can communicate with B and can see that B is not a master station. So, the operation mode of A is set to the master station. FIG. 3(b) shows the situation.

Then, as B performs detection, it can see that it can communicate with A or master station. So, the operation mode of B becomes the slave station and B gives a notification to that effect to A. A registers B as a slave terminal and B registers A as a master terminal. FIG. 3(c) shows that situation.

Further, as C performs detection, it can see that communication with both D and E is possible but neither is a master terminal. So, the operation mode of C is set to the H:VPriyankaVYeepVspeciVP56041.doc 24/02/05 b master station. FIG. 3(d) shows the situation.

c' Then, as D performs detection, it can see that it can 4 communicate with C or a master station. So, the operation mode of D becomes the slave station and D gives a notification to that effect to C. C registers D as a slave 1O terminal and D registers C as a master terminal. It is to 00 be noted that while D is also communicatable with E, it does n not select E because E is not a master terminal.

C Further, as E performs detection, it can see that it can communicate with C or a master station. So, the operation mode of E becomes the slave station and E gives a notification to that effect to C. C registers E as a slave terminal and E registers C as a master terminal. It is to be noted that while E is also communicatable with D, it does not select D because D is not a master terminal. FIG. 3(e) shows that situation.

As a result, A registers B as a slave terminal and C registers C D a slave terminal.

Apparently, more than zero slave stations are subordinate to a single master station. Therefore, group separation is carried out master station by master station.

In this manner, the relationship between a master station and a slave station is set autonomously. Update of them can be executed by each wireless communication terminal 101 at an independent timing.

The autonomous group separation in the embodiment guarantees that a master station and a slave station H:VPriyankaKeepspeciVP56O41.doc 24/02/05 Ssubordinate to it have a good communication therebetween.

Further, communication between a master station and Sanother master station is not good in most cases. This is because that if it is good, one should become a slave station to the other one.

1-1 Communication between slave stations belonging to 00 different groups may or may not be good. This differs V)depending on the situation.

FIG. 4 is an explanatory diagram showing the results of a simulation of how the relationship between a master terminal (Master Terminal) and slave terminals (Slave Terminal) subordinate to the former and a terminal group (Terminal Group) constituted by them in a case where there are twenty wireless communication terminals 101.

FIG. 4 shows the passage of time in the order of and and how the wireless communication terminals 101 have moved accordingly. It is seen from this diagram that a terminal group is autonomously constructed and, what is more, that terminal group is maintained for a substantial time.

Therefore, efficient message transmission becomes possible by using a message relay scheme to be discussed later.

(Slot Structure) In the embodiment, a message which is exchanged between the transmission section 113 and the reception section 114 is time-divided and transmitted slot by slot. FIG. 5 is an exemplary diagram illustrating the structure of a slot which is used in this embodiment.

H:VPriyankaWKeepVspeciVP56041.doc 24/02/05 0 A single slot 501 can be separated into two times, a

C

control signal period 502 and a data transfer period 503.

r~ In the control signal period 502, the following control l signals are transmitted.

.Destination message (Call Notification) which notifies

(N

information of a destination to be designated and to that 00 effect that data information is to be transmitted to the

(N

Sdestination.

q Acknowledge message (ACK) which notifies to that effect that data information has been transmitted to the designated destination or a relay to the destination.

*Not-acknowledge message (NACK) which notifies to that effect that a destination message has arrived but data information has not been transmitted.

-Relay-offer message (Relay Offer) which notifies to that effect that transmission of data information may be relayed to the destination.

*Inquiry message (Authentication Confirm). A slave station asks a master station to which it is subordinate if the destination is also subordinate.

*Relay-approval message (Authentication Reply). A slave station gives a master station to which it is subordinate a notification to that effect the destination is also subordinate.

In the data transfer period 503, a data information signal is transmitted. While data information to be sent is transmitted by a data information signal, information, such H:VPriyankaVKeepVspeciVP5604l.doc 24/02/05 as destination information or relay information, may be CI added and transmitted.

SBecause the amount of information to be transmitted in the control signal period 502 is small and the time is short, the instantaneous transmission power in the control signal IND period 502 may be made large. This can make the 00 O transmission distance for Call Notification or the like n longer.

Because a relatively large amount of information is transmitted in the data transfer period 503, the maximum value of the instantaneous transmission power is limited and the distance of arrival is shorter than signals to be transmitted in the control signal period 502.

The following will discuss as an example the situation where data information is transmitted from a wireless communication terminal P (sender terminal) subordinate to another wireless communication terminal in a terminal group 1 to a wireless communication terminal (destination terminal) Q which is subordinate to both a wireless communication terminal Q and a wireless communication terminal R in a terminal group 2. Note that the following description can also be applied to a case where the wireless communication terminal P is a master terminal.

FIG. 6 is an explanatory diagram showing how a message is exchanged in case where data could be transmitted directly from the wireless communication terminal P (sender terminal) to the wireless communication terminal Q H:YPriyankaYKeepVspeciYP56041.doc 24/02/05 S(destination terminal) CI First, the wireless communication terminal P broadcasts Call Notification and then directly transmits data n information (Direct Transmission).

Under this circumstance, because the wireless 1-1 communication terminal Q could receive the directly 00 transmitted data information, it returns ACK to the wireless V' communication terminal P.

As it is received, transmission of the data information in the wireless communication terminal P has completed successfully.

FIG. 7 is an explanatory diagram showing how a message is exchanged in case where data could be transmitted from the wireless communication terminal P (sender terminal) to the wireless communication terminal Q (destination terminal) via the wireless communication terminal R (relay terminal).

First, the wireless communication terminal P broadcasts Call Notification and then directly transmits data information (Direct Transmission). This is the same as done in the example illustrated in FIG. 6.

In case where the wireless communication terminal Q could receive Call Notification but failed receiving data information, the wireless communication terminal Q transmits NACK to the wireless communication terminal P. In case where the wireless communication terminal Q could receive neither Call Notification nor data information, nothing would be transmitted.

H:VPriyankaVKeepVspeciYP56O4l.doc 24/02/05 i In sucha case, in case where the wireless Cl communication terminal P could not receive ACK from the Swireless communication terminal, it checks if there is Relay n Offer from another wireless communication terminal.

In this case, the wireless communication terminal R has 1-1 transmitted Relay Offer to the effect that "transmission to 00 the wireless communication terminal Q may be relayed" to the V) wireless communication terminal P.

The wireless communication terminal R understood that the wireless communication terminal Q was its own slave terminal as a result of having seen the information of the destination (wireless communication terminal Q) included in Call Notification sent in the broadcasting and that relay there would be possible, and thus returned Relay Offer.

Therefore, the wireless communication terminal P transmits data, information addressed to the wireless communication terminal Q to the wireless communication terminal R. In the embodiment, a direct transmission system, not broadcasting system, is used in the transmission of data information.

The wireless communication terminal R returns ACK to the wireless communication terminal P, notifying that this data information has been received. This completes transmission in the wireless communication terminal P successfully.

Further, the wireless communication terminal R performs direct transmission of Call Notification and data H:VPriyankaVKeepVspeciVP56041.doc 24/02/05 Sinformation to the wireless communication terminal Q, and Cl transmission in the wireless communication terminal P is Scompleted successfully as ACK is returned to the wireless n communication terminal R from the wireless communication terminal Q.

1-1 At the same time, as the wireless communication 00 terminal Q returns ACK (Finish) to the wireless V) communication terminal P, the entire relaying completes successfully.

In this manner, ACK(Finish) is also returned to the wireless communication terminal P from the wireless communication terminal Q. This is because, as described above, signals to be transmitted in the control signal period 502 have a long distance of arrival, ACK can be returned even though data information cannot be transmitted.

This can allow the sender to confirm that data information has been transmitted to the destination as done in the TCP (Transfer Control Protocol) Although Relay Offer is returned only from the wireless communication terminal R in the diagram, the wireless communication terminal P may receive a plurality of Relay Offers. The one that has the maximum transmission power is selected from among them and data information is directly transmitted only to that party and the party is allowed to relay it.

FIG. 8 is an explanatory diagram showing how a message is exchanged in case where data could be transmitted from H:VPriyankaV~eepVspeciVP5641.doc 24/02/05 the wireless communication terminal P (sender terminal) to cI the wireless communication terminal Q (destination terminal) Svia the wireless communication terminal S (sub relay terminal) and the wireless communication terminal R (relay terminal) ND First, the wireless communication terminal P broadcasts 00 Call Notification and then directly transmits data information (Direct Transmission). This is the same as done Sin the example illustrated in FIG. 6 and FIG. 7.

In case where the wireless communication terminal Q could receiveCall Notification but failed receiving data information, the wireless communication terminal Q transmits NACK to the wireless communication terminal P. In case where the wireless communication terminal Q could receive neither Call Notification nor data information, nothing would be transmitted.

In such a case, in case where the wireless communication terminal P could not receive ACK from the wireless communication terminal, it waits for Relay Offer from another wireless communication terminal.

Meanwhile, the wireless communication terminal S that has received Call Notification makes an inquiry "Is the wireless communication terminal Q a slave terminal of the wireless communication terminal to the wireless communication terminal R (Authentication Confirm) In response to that, the wireless communication terminal R returns "As the wireless communication terminal Q H:VYPriyankaVKeepVspeciYP56041.doc 24/02/05 Sis the slave terminal of the wireless communication terminal CI R, transmission to the wireless communication terminal Q may Sbe relayed" (Authentication Reply) to the wireless n communication terminal P.

Accordingly, the wireless communication terminal S IND transmits Relay Offer to the effect that "transmission to 00 the wireless communication terminal Q may be relayed" to the n wireless communication terminal P.

Then, the wireless communication terminal P transmits data information addressed to the wireless communication terminal Q to the wireless communication terminal R.

The wireless communication terminal S returns ACK to the wireless communication terminal P, notifying that this data information has been received. This completes transmission in the wireless communication terminal P successfully.

Further, the wireless communication terminal S performs direct transmission of data information to the wireless communication terminal R, and relaying during this period is completed successfully as ACK is returned to the wireless communication terminal S from the wireless communication terminal R.

Furthermore, the wireless communication terminal R performs direct transmission of data information to the wireless communication terminal Q, and relaying is completed successfully as ACK is returned to the wireless communication terminal R from the wireless communication H:YPriyankaVKeepspeciP5641.doc 24/02/05 terminal Q.

At the same time, as the wireless communication terminal Q returns ACK (Finish) to the wireless communication terminal P, the entire relaying completes successfully.

Communication within the same terminal group can be realized by applying the above-described transmission system similarly.

It is possible to employ such an embodiment in which the sender terminal does not wait for ACK returned from the destination that is located at the relayed terminal in case where relaying is carried out. For example, although data transmission to the wireless communication terminal Q is completed successfully as the wireless communication terminal P receives ACK(Finish) last in the modes shown in FIG. 7 and FIG. 8, the embodiment is such that data transmission from the wireless communication terminal P is made to any wireless communication terminal and data transmission is completed successfully as ACK from that wireless communication terminal is received.

Such data transmission does not guarantee, as in the UDP (User Datagram Protocol), that a packet reliably reaches the party, but has a characteristic such that fast transmission is possible.

Although a data information message and other messages are transmitted in a time-divisional manner in this embodiment, the above-described scheme can be applied H:VPriyankaKeepYspeciP56041.doc 24/02/05 Ssimilarly even in the frequency division or code division cI and those embodiments are included in the scope of the Sinvention.

n (Experimental Results) FIGS. 9 and 10 are graphs which respectively show the INO results of experiments on the relationship among the input 00 traffic (Input Traffic), communication throughput n (Normalized Throughput) and communication delay (Normalized Delay) in the case where the scheme of the embodiment is used (Proposed) and in the case where the conventional scheme is used (Conventional) It is seen that the use of the embodiment has improved the communication throughput and shortened the communication delay.

(Second Embodiment) This embodiment is to further change the transmission mode of a signal in accordance with the status of the radio wave propagation path at the time each wireless communication terminal transmits a signal, in addition to the above-described embodiment.

The status of the radio wave propagation path can be expressed by parameters which indicate the following information.

-Reception power -Distance and direction between the sender terminal and receiver terminal *Use status of the frequency channel H:VPriyankaVKeepVspeciP56041.doc 24/02/05 *Designation by user CI The transmission mode can be expressed by parameters Swhich indicate the following information.

Transmission power .Frequency channel to be used in transmission INO .Modulation type 00 -Beam shape SWhile a single master terminal and a plurality of slave Sterminals form a terminal group having a star-like relationship in the embodiment, it is expected that they have a radio wave propagation path better than a predetermined reference.

It is therefore possible to suppress consumption of the transmission power as much as possible and ensure reliable transmission by adequately grasping the status of the radio wave propagation path between a terminal group and a terminal group and changing the transmission mode according to the status.

Specifically, at the time each terminal sends out Relay Offer in response to Call Notification, the status of the radio wave propagation path at the time of receiving the Call Notification is measured first. Then, information of the reception status parameter that expresses the measuring result is designated in the Relay Offer and is returned to the sender terminal.

The sender terminal acquires the reception status parameter designated in the received Relay Offer and sends a H:YPriyankaVKeepVspeciVP56041.doc 24/02/05 Smessage using a transmission parameter corresponding to the cI reception status parameter to request relaying to the sender Sof the Relay Offer.

3 In the embodiment, broadcasting is used for transmission of Call Notification and direct transmission is 1-1 used for the accompanied transmission of data information.

00 0 Therefore, the former has greater transmission power than V) the latter. In the embodiment, therefore, the transmission power at the time of direct transmission is made as low as possible.

It is fine if direct transmission succeeds with the minimum transmission power required, but in case where direct transmission has failed, transmission is carried out using the transmission mode according to the the status of the radio wave propagation path between the sender terminal and the relay terminal. For example, the transmission power may be changed in proportional to the reception power designated in Relay Offer or according to the reception power, the beam shape may be changed to the direction designated in Relay Offer or a frequency channel other than the "frequency channel currently in use" designated in Relay Offer may be used.

Therefore, the communication capacity of the entire system can be improved in addition to reduction of the consumption power.

FIG. 11 is an explanatory diagram of the comparison between a case where transmission power control is not H:VPriyankaVXeepYspeciVP56041.doc 24/02/05 used and a case where transmission power control is used.

CI The circles in the diagram indicate the ranges over which Sradio waves reach, and the terminal A has already n communicated with the terminal B and the terminal C is trying to communication with the terminal D.

1-1 In the case where transmission power control is not 00 used, as shown in FIG. the radio wave from the n terminal A has also reached the terminal D, and it becomes Sinterference to communication from the terminal C to the terminal D. Therefore, communication from the terminal C to the terminal D will not succeed.

In the case where transmission power control is used, as shown in FIG. on the other hand, the terminal A makes transmission with the minimum transmission power required, so that the radio wave from the terminal A does not reach the terminal D. Therefore, communication from the terminal C to the terminal D will succeed. That is, the communication capacity of the entire system has been improved.

FIG. 12 is an explanatory diagram in a case where the beam shape is changed in accordance with the position of a terminal to be communicated, and FIG. 13 is an explanatory diagram in a case where the frequency channel to be used is changed in accordance with the use status of the current communication channel. Although the case where control is not performed and the case where control is performed are illustrated in them, it is understood, as in the above- H:VPriyankaVKeepYspeciVP56041.doc 24/02/05 b described example, that the communication capacity of the entire system has improved in the case where control is Sperformed as compared with the case where control is not C performed.

FIG. 14 is an exemplary diagram illustrating the IND schematic structure of a wireless communication terminal 00 which performs the communication control of the embodiment n that has been described above. The wireless communication C-i terminal illustrated in the diagram is applied in a case where the invention is adaptedto other wireless communication terminals than the above-described embodiment.

A description will be given below by referring to this diagram.

A wireless communication terminal 1401 has an input section 1402, a transmission section 1403, a reception section 1404, an output section 1405, an antenna 1406, and a directional coupler 1407. The transmission section 1402 transmits various kinds of messages via the directional coupler 1407 and the antenna 1406. The reception section 1404 receives various kinds of messages via the antenna 1406 and the directional coupler 1407.

First, the input section 1402 accepts inputting of a destination terminal and data information addressed to the destination terminal.

Then, the transmission section 1403 transmits a destination data information message which designates the destination terminal, whose input has been accepted by the H:YPriyankaVleepVspeciVP56041.doc 24/02/05 O input section 1402, and data information addressing that as I a destination terminal using a predetermined transmission Sparameter (including the parameter of transmission power, Sthe parameter of the frequency channel to be used in transmission, the parameter of the modulation system, the IND parameter of the beam shape), 00 SIn this transmission using the predetermined n transmission parameter, as described above, of the message, the portion that designates the destination terminal is transmitted in broadcasting, and Sthe portion that designates data information is transmitted with the minimum transmission power required.

That is, the transmission power of the latter is lower than that of the former. Up to this is the first stage in transmission.

In case where transmission has not succeeded through it and the reception section 1404 has received a relay-offer message, the transmission section 1403 transmits the destination data information message to the sender terminal of the relay-offer message using the transmission parameter that is associated with the reception status parameter designated in the relay-offer message.

This is equivalent to the case in the above-described embodiment where Relay Offer is received, a message is transmitted to the terminal which is requested to relay by adjusting the transmission power, beam shape, frequency channel, etc. using the transmission parameter corresponding H:VPriyankaVKeepYspeciVP56O41.doc 24/02/05 to the reception status parameter designated in the relay- CI offer message.

SIn case of performing reception, when the reception n section 1404 has received "a destination data information message addressing the local as a destination terminal", the IND transmission section 1405 outputs the data information.

00 In case where the reception section 1404 has received 3 "a destination data information message addressing another Swireless communication terminal (hereinafter called "relayable terminal") to which the local can relay communication", a "relay-offer message which designates the reception status parameter at the time the destination data information message has been received (including the parameter of reception power, the parameter of the use status of the frequency channel or the parameter of the distance and direction to the sender terminal of the destination data information message) is transmitted.

This is equivalent to the case in the above-described example where communication to another wireless communication terminal in a terminal group to which the wireless communication terminal 1401 belongs is detected and Relay Offer is returned to it.

Thereafter, in case where the reception section 1404 has received a 'destination data information message designating data information addressing, as a destination terminal, "a relayable terminal targeted for the relay-offer message transmitted earlier by the transmission section", H:VPriyankaYKeepVspeciVP56041.doc 24/02/05 35 0 the transmission section 1403 transmits the destination Sdata information message to the relayable terminal for relaying.

00 This is equivalent to the case in the abovedescribed example where if the wireless communication terminal 1401 is a master station, a message is Stransmitted to the relayable terminal directly, and if it 00 is a slave station, a message is relayed via the master Sstation to the relayable terminal.

In this manner, the communication capacity of the O communication system can be improved by adequately C performing communication control in a wireless communication terminal which can relay to another terminal.

Industrial Applicability As described above, the invention can provide a wireless communication terminal and a wireless communication method which are suitable to be able to ensure communication by carrying out relay even in wireless communication using a frequency band suitable for line-of-sight communication even if an obstruction is present in the path of wireless communication and even if the status of the radio wave propagation path dynamically changes, and a computer readable information recording medium in which a program for achieving them is recorded.

In the claims which follow and in the preceding description, except where the context requires otherwise due to express language or necessary N\Melboum\CasesnPate\49OO.4999\P4938 AU I\Specis\P493$I AU I Specificalion doc 27/1(07 implication, the word "comprise" or variations such as C "comprises" or "comprising" is used in an inclusive sense, i.e. to specify the presence of the stated features but not to preclude the presence or addition of further features in various embodiments of the invention.

ND It is to be understood that, if any prior art 00 p publication is referred to herein, such reference does not

(N

constitute an admission that the publication forms a part of -iq the common general knowledge in the art, in Australia or any other country.

H:VPriyankaVKeepVspeciVP56Ol .doc 24/02/05

Claims (2)

1. A wireless communication method enabling relaying of 00 communication between a second wireless communication terminal and a third wireless communication terminal by a first wireless communication terminal, the \0 method comprising the steps of: 00 receiving by the first terminal a destination 0 data information message including information designating a destination terminal and data Sinformation addressed to a destination terminal CI transmitted by the second terminal; determining by the first terminal whether the destination data information message is addressed to the first terminal or a third terminal: determining by the first terminal whether the first terminal can relay communication from the second terminal to the third terminal, and if so: transmitting a relay offer message to the second terminal; receiving by the second terminal the relay offer message; determining by the second terminal whether the data information message transmitted by the second terminal was received by the third terminal, and if not: transmitting by the second terminal the data information message addressing the third terminal as the destination terminal for relaying by the first terminal; receiving by the first terminal the data information message addressing the third terminal for which a relay offer had been made; and then transmitting by the first terminal the data information message addressing the third terminal. N \iMelboulne\Ces\Palcn491XN)U41999\P493I AU I\Sprci\P493K I AL I Specriicaiuon 2I06-12-I doc 27/WIU7

38- c 2. A method as claimed in claim 1 wherein a relay offer Smessage includes a reception status parameter for the n- received destination data information message, the 00 reception status parameter including one or more of: an indicator reception power, a frequency channel use status indicator, and an indicator of distance and IN direction of the first terminal relative to the 00 0 second terminal at the time the destination data information message was received. n 3. A method as claimed in claim 2 wherein the second C terminal transmits the destination data information message to the first terminal for relaying to the third terminal in accordance with a predetermined transmission parameter associated with the reception status parameter included in the relay offer message, wherein the transmission parameter includes any one or more of transmission power, frequency channel for transmission, modulation system or beam shape. 4. A method as claimed in claim 3 wherein when the second terminal transmits the destination data information message in accordance with the predetermined transmission parameter, a transmission power used for transmitting the portion in the destination data information message which designates the data information is lower than a transmission power used for transmitting the portion of the destination data information message which designates the destination terminal. A first wireless communication terminal adapted to relay communication between a second wireless communication terminal and a third wireless communication terminal, the first wireless communication terminal having: an input section adapted to enable information N \NeIbo umcCasu\Icit\4IOO4999YP4)381 AU IbSpevc\P493I ALI I SpcC IfiCalon 2006-12. doc 27I/107 39 C designating a destination terminal and data Sinformation addressed to a destination terminal to be ;Z input; 00 a reception section adapted to receive messages including: an information destination data message including information designating a destination Sterminal and data information addressed to a 00 destination terminal and a relay offer message; a transmission section adapted to transmit messages including: a destination data information Smessage including information designating a destination terminal and data information addressed to a destination terminal, and a relay offer message; and an output section adapted to enable data received by the first terminal in a destination data information message that is addressed to the first terminal to be output, and also adapted to when a destination data message transmitted by a second terminal and addressing a third terminal is received by the reception section, to relay communication to the third terminal, following the first terminal transmiting a relay offer message to the second terminal, and when the reception section receives a destination data information message addressed to a third terminal for which a relay offer has been made, transmitting by the transmission section the destination data information message including information designating the third terminal. 6. A wireless communication terminal as claimed in claim wherein when a relay offer message transmitted by a second terminal is received by the reception section and a destination data information message transmitted by the first terminal was not received by N \MeIboumc\CW Le\P niN A90049999\P493J I Al I\Spccrs\P4938I AU I SpecLiiclon 200-6j24) do 27/K/07 C the destination terminal, the transmission section Stransmits the destination data information message ;Z for relaying by the second terminal. 00 7. A wireless communication terminal as claimed in claim 6 wherein a relay offer message includes a reception Sstatus parameter for the received destination data 00 information message, the reception status parameter including one or more of: an indicator reception power, a frequency channel use status indicator, and San indicator of distance and direction of the first r terminal relative to the second terminal at the time the destination data information message was received. 8. A wireless communication terminal as claimed in claim 7 wherein the transmission section transmits the destination data information message to a terminal from which a relay offer has been received in accordance with a predetermined transmission parameter associated with the reception status parameter included in the relay offer message, wherein the transmission parameter includes any one or more of transmission power, frequency channel for transmission, modulation system or beam shape. 9. A wireless communication terminal as claimed in claim 8 wherein when the transmission section transmits the destination data information message in accordance with the predetermined transmission parameter, a transmission power used for transmitting the portion in the destination data information message which designates the data information is lower than a transmission power used for transmitting the portion of the destination data information message which designates the destination terminal. N \Melbou \CaesUalentW\9j-lY41999\P493 I A U I Sp-049381 AU I Speciication 2006I2-12, dc 27/06117 41 0 10. A computer program enabling a computer to function Sas a wireless communication terminal capable of ;Zf relaying communication between a second wireless 00 communication terminal and a third wireless communication terminal, computer program adapted to replicate the functions of: CI an input section enabling information designating 00 a destination terminal and data information addressed to a destination terminal to be input; a reception section adapted to receive messages Sincluding: an information destination data message including information designating a destination terminal and data information addressed to a destination terminal, and a relay offer message; a transmission section adapted to transmit messages including: a destination data information message including information designating a destination terminal and data information addressed to a destination terminal, and a relay offer message; and an output section enabling data received by the reception section in a destination data information message that is addressed to the terminal being replicated by the computer program to be output, and also adapted to when a destination data message transmitted by a second terminal and addressing a third terminal is received by the reception section, to relay communication to the third terminal, the transmission section then being able to transmit a relay offer message to the second terminal, and also adapted to when the reception section receives a destination data information message addressed to a third terminal for which a relay offer has been made, to be able to transmit by the transmission section the destination data information message including information designating the third N \Melboume\Cs Paten\tcOO))Q99\P4938 IAU I\Spews\P4939 I AL I Sp-ckIic-,on 20M-126 do 27/06tO7 -42- terminal. Ill.A computer program as claimed in claim 10 wherein 00 when a relay offer message transmitted by a second terminal is received by the reception section and a destination data information message transmitted by the first terminal was not received by the 00 destination terminal, the transmission section transmits the destination data information message for relaying by the second terminal. C- 12.A computer program as claimed in claim 11 wherein a relay offer message includes a reception status parameter for the received destination data information message, the reception status parameter including one or more of: an indicator reception power, a frequency channel use status indicator, and an indicator of distance and direction relative to the second terminal at the time the destination data information message was received. 13.A computer program as claimed in claim 12 wherein the transmission section transmits the destination data information message to a terminal from which a relay offer has been received in accordance with a predetermined transmission parameter associated with the reception status parameter included in the relay offer message, wherein the transmission parameter includes any one or more of transmission power, frequency channel for transmission, modulation system or beam shape. 14.A computer program as claimed in claim 13 wherein when the transmission section transmits the destination data information message in accordance with the predetermined transmission parameter, a transmission power used for transmitting the portion N \MelbounK\CasesPawl nW49O0O-49N9\P4938 AU I\Specs\P 493I AU I Speciicaion 2006-12-doc 27/0107 43 in the destination data information message which designates the data information is lower than a transmission power used for transmitting the portion of the destination data information message which designates the destination terminal. method as claimed in any one of claims 1 to 4 and substantially as herein described with reference to the accompanying drawings. 16.A wireless communication terminal as claimed in any one of claims 5 to 9 and substantially as herein described with reference to the accompanying drawings. 17.A computer program as claimed in any one of claims to 14 and substantially as herein described with reference to the accompanying drawings. N \MeIbou, \Ca s\PapentI4IO Xn49999\P4938 AU I\Spe~crs\P43I A U I Specriicaio, 2006.12-6 dmc 271607