U.S. patent application number 11/873643 was filed with the patent office on 2008-02-14 for network control apparatus, wireless terminal and communication control method.
This patent application is currently assigned to KABUSHIKI KAISHA TOSHIBA. Invention is credited to Yutaka Asanuma, Takayoshi Ito, Ryoko Matsuo, Shuichi Sekine, Hiroki Shoki.
Application Number | 20080037492 11/873643 |
Document ID | / |
Family ID | 32705911 |
Filed Date | 2008-02-14 |
United States Patent
Application |
20080037492 |
Kind Code |
A1 |
Matsuo; Ryoko ; et
al. |
February 14, 2008 |
NETWORK CONTROL APPARATUS, WIRELESS TERMINAL AND COMMUNICATION
CONTROL METHOD
Abstract
A wireless control apparatus which performs a wireless
communication with a plurality of wireless terminals, comprising:
an evaluation signal receiver configured to receive evaluation
signals relating to received signals in the respective wireless
terminals, which are transmitted from the plurality of wireless
terminals; a supplement signal deciding unit which decides a
supplement signal necessary to supplement the received signals in
the plurality of wireless terminals; and a supplement signal
transmitter configured to transmit the supplement signal decided by
the supplement signal deciding unit, to the plurality of wireless
terminals.
Inventors: |
Matsuo; Ryoko; (Tokyo,
JP) ; Sekine; Shuichi; (Kanagawa-Ken, JP) ;
Ito; Takayoshi; (Kanagawa-Ken, JP) ; Shoki;
Hiroki; (Kanagawa-Ken, JP) ; Asanuma; Yutaka;
(Tokyo, JP) |
Correspondence
Address: |
OBLON, SPIVAK, MCCLELLAND MAIER & NEUSTADT, P.C.
1940 DUKE STREET
ALEXANDRIA
VA
22314
US
|
Assignee: |
KABUSHIKI KAISHA TOSHIBA
Tokyo
JP
|
Family ID: |
32705911 |
Appl. No.: |
11/873643 |
Filed: |
October 17, 2007 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
10721466 |
Nov 26, 2003 |
7295541 |
|
|
11873643 |
Oct 17, 2007 |
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Current U.S.
Class: |
370/338 |
Current CPC
Class: |
H04W 84/18 20130101;
H04W 28/18 20130101; H04W 99/00 20130101; H04W 84/005 20130101 |
Class at
Publication: |
370/338 |
International
Class: |
H04Q 7/24 20060101
H04Q007/24 |
Foreign Application Data
Date |
Code |
Application Number |
Nov 27, 2002 |
JP |
2002-344418 |
Claims
1-20. (canceled)
21. A wireless apparatus which performs a wireless communication
with a plurality of wireless terminals, comprising: a first
receiver which receives evaluation signals relating to received
signals in the respective wireless terminals, which are transmitted
from said plurality of wireless terminals; a signal generator
configured to generate a supplement signal necessary to supplement
deficient part of the received signals in said plurality of
wireless terminals, using the evaluation signal; and a signal
transmitter which transmits the supplement signal decided by said
signal generator, to said plurality of wireless terminals, wherein
the evaluation signals are signals which indicate at least one of
deficient part of the received information signal at said wireless
terminals, propagation environment and capability of wireless
terminals; and the supplement signal is a signal instructed to a
wireless terminal capable of correctly receiving information
signal, to receive the information signal instead of a wireless
terminal not being able to correctly receive the information
signal.
22. The wireless apparatus according to claim 21, wherein the
supplement signal is a signal which indicates information to be
cooperatively received by said plurality of wireless terminals.
23. The wireless apparatus according to claim 21, further
comprising a terminal information signal register unit configured
to register terminal information signal including at least one of
transmission speed, propagation environment, processing state and
request information signal for said plurality of wireless
terminals.
24. The wireless apparatus according to claim 21, further
comprising: a second receiver which receives the information signal
received based on the supplement signal by said plurality of
wireless terminals; and a supplement information signal transmitter
which transmits the information signal received by said second
receiver to said plurality of wireless terminals.
25. The wireless apparatus according to claim 21, further
comprising: a second receiver which receives at least part of
information signal to be received by at least one of said plurality
of wireless terminals; and a supplement information signal
transmitter which transmits the information signal received by said
information signal receiver to the corresponding wireless terminal,
based on the supplement signal.
26. The wireless apparatus according to claim 21, further
comprising: a distributed wireless network information signal
transmitter which transmits information signal necessary to form a
distributed wireless network, to surrounding wireless terminals
including said plurality of wireless terminals, by every a
prescribed time.
27. The wireless apparatus according to claim 21, further
comprising: a detector which detects a state of forming a
distributed wireless network; and a display unit which displays
information relating to the state of forming the distributed
wireless network.
28. A wireless terminal configured to perform wireless
communication with a wireless apparatus which transmits a
supplement signal necessary to supplement a received signal,
comprising: a transmitter which transmits an evaluation signal
relating to the received signal to said wireless apparatus; a first
receiver which receives the supplement signal; and a second
receiver which receives information signal based on the supplement
signal, wherein said evaluation signal is a signal indicative of at
least one of deficient part of the received information signal,
propagation environment and terminal capability; and the supplement
signal is a signal which indicates to receive information signal
instead of an other wireless terminal which cannot correctly
receive the information signal when it is possible to correctly
receive the information signal to be received.
29. The wireless terminal according to claim 28, further comprising
a supplement information signal communication unit configured to
transmit and receive the information signal received by said second
receiver and the information signal received by the other wireless
terminals based on the supplement signal, with the other wireless
terminals to each other.
30. The wireless terminal according to claim 28, further comprising
a supplement information signal communication unit configured to
transmit the information signal received by said second receiver to
said wireless apparatus, and receive the information signal
received by the other wireless terminals based on the supplement
signal via said wireless apparatus.
31. The wireless terminal according to claim 28, wherein the
supplement signal is a signal indicative of information signal to
be cooperatively received.
32. The wireless terminal according to claim 28, further comprising
a terminal information storage which stores terminal information
including at least one of transmission speed, propagation
environment, processing state and request information.
33. A communication control method which communicates with a
wireless apparatus which performs wireless communication with said
wireless terminals, comprising: receiving evaluation signals at a
first receiver of said wireless apparatus, transmitted from the
respective wireless terminals; generating a supplement signal
necessary to supplement deficient part of the received signals
received at said plurality of wireless terminals, using the
evaluation signal; and transmitting said supplement signal to said
plurality of wireless terminals, wherein said evaluation signals
are signals which indicate at least one of deficient part of the
received information signal at the wireless terminals, propagation
environment and capability of the wireless terminals; and the
supplement signal is a signal instructed to a wireless terminal
capable of correctly receiving information signal, to receive the
information signal instead of a wireless terminal not being able to
correctly receive the information signal.
34. The communication control method according to claim 33, wherein
the supplement signal is a signal which indicates information to be
cooperatively received by said plurality of wireless terminals.
Description
CROSS REFERENCE TO RELATED APPLICATIONS
[0001] This application claims benefit of priority under
35USC.sctn.119 to Japanese Patent Application No. 2002-344418,
filed on Nov. 27, 2002, the entire contents of which are
incorporated by reference herein.
BACKGROUND OF THE INVENTION
[0002] 1. Field of the Invention
[0003] The present invention relates to a network control
apparatus, a wireless terminal and a communication control method
used in a distributed wireless network system, which performs
wireless communication, while a plurality of wireless terminals are
relaying information signal to each other.
[0004] 2. Related Art
[0005] In the distributed wireless network in which a plurality of
wireless terminals communicate with each other, a method for
efficiently downloading by means of downloading in group is
disclosed (for example, see Japanese Laid-open publication No.
2002-132613 (pages 1 to 8, FIG. 1).
[0006] The wireless distributed wireless network has an advantage
in that it is possible to temporarily construct a LAN (Local Area
Network) at a certain range, without connecting to a backbone
network. In a future wireless communication, it is anticipated that
other kinds of communication besides sound signal such as motion
pictures and data will be performed frequently, the quantity of
transmitted signal by the wireless terminals at a spot area or at
mobile environment will rapidly increase, and the transmission rate
will also increase.
[0007] When the information signal quantity increases or the
transmission rate increases, there may be the possibility that the
whole information signal cannot be received accurately with only
one wireless terminal. Particularly, when the wireless terminal is
moving at a high speed as in a train or a bus, or in a place where
the wireless environment is bad, this problem is serious. In order
to handle this problem, the present applicant has proposed a method
in which when a wireless terminal requests reception of information
signal in a large quantity, the wireless terminal cooperates with
other wireless terminals in the same distributed wireless network
to receive the desired information signal, the reception requesting
terminal coordinates the information signal received by the
respective wireless terminals, and the coordinated information
signal is distributed to the wireless terminal which has requested
reception (see Japanese Patent Application No. 2002-127282).
[0008] However, this method has two problems described below.
[0009] 1. One of the wireless terminals in the distributed wireless
network collects the information signal received by the respective
wireless terminals and coordinates the information signal as single
information signal. However, the processing becomes a large load
according to the capacity of the terminal which performs
processing.
[0010] 2. Since the function and capacity are different for each
wireless terminal in the distributed wireless network, if the
reception processing is allocated to each terminal under the same
condition, the processing time of the terminal having small
capacity affects other wireless terminals.
[0011] Moreover, if it is assumed that the distributed wireless
network is constructed in trains or buses, it is expected that the
access to the distributed wireless network by the wireless
terminals is too frequent. In such a case, the system in which a
plurality of terminals simply cooperate with each other would never
be preferable.
SUMMARY OF THE INVENTION
[0012] In view of the above situation, it is an object of the
present invention to provide a network control apparatus, a
wireless terminal and a communication control method, which can
improve the communication quality and communication efficiency of a
plurality of wireless terminals forming a distributed wireless
network.
[0013] A wireless control apparatus according to one embodiment of
the present invention which performs a wireless communication with
a plurality of wireless terminals, comprising:
[0014] an evaluation signal receiver which receives evaluation
signals relating to received signals in the respective wireless
terminals, which are transmitted from said plurality of wireless
terminals;
[0015] a supplement signal generating unit configured to generate a
supplement signal necessary to supplement deficient part of the
received signals in said plurality of wireless terminals, using the
evaluation signal; and
[0016] a supplement signal transmitter which transmits the
supplement signal decided by said supplement signal generating
unit, to said plurality of wireless terminals.
[0017] Furthermore, a wireless terminal according to one embodiment
of the present invention configured to performs wireless
communication with a wireless control apparatus which transmits a
supplement signal necessary to supplement deficient part of a
received signal, comprising:
[0018] a transmitter which transmits an evaluation signal relating
to the received signal to said wireless control apparatus;
[0019] a supplement signal receiver which receives the supplement
signal; and
[0020] a supplement information receiver which receives information
based on the supplement signal.
[0021] Furthermore, a communication control method which
communicates with a wireless control apparatus which performs
wireless communication with said wireless terminals,
comprising:
[0022] receiving evaluation signals at an evaluation signal
receiver of said wireless control apparatus, transmitted from the
respective wireless terminals;
[0023] generating a supplement signal necessary to supplement
deficient part of the received signals received at said plurality
of wireless terminals, using the evaluation signal; and
[0024] transmitting said supplement signal to said plurality of
wireless terminals.
BRIEF DESCRIPTION OF THE DRAWINGS
[0025] FIG. 1 is a diagram showing a network configuration
according to a first embodiment of a distributed wireless network
system.
[0026] FIG. 2 is a diagram showing a network configuration
according to a second embodiment of a distributed wireless network
system.
[0027] FIG. 3 is a diagram showing a network configuration
according to a second embodiment of a distributed wireless network
system.
[0028] FIG. 4 is a block diagram indicating one example of the
internal configuration of the control terminal 12 according to the
second embodiment.
[0029] FIG. 5 indicates one example of the database in the memory
24, which stores data such as bit rates, propagation environments,
processing state and request information signal of the respective
wireless terminals.
[0030] FIG. 6 is a flowchart indicating the processing procedure in
the second embodiment of the distributed wireless network
system.
[0031] FIG. 7 is a diagram showing a network configuration
according to the third embodiment of the distributed wireless
network system.
[0032] FIG. 8 is a diagram showing the network configuration when
the control terminal requests transmission of information signal
relating to a deficient part in a wireless terminal.
[0033] FIG. 9 is a diagram showing another network configuration
according to the third embodiment of the distributed wireless
network system.
[0034] FIG. 10 is a diagram showing a network configuration
according to the fourth embodiment of the distributed wireless
network system.
[0035] FIG. 11 is a flowchart showing the processing procedure
according to the fourth embodiment.
[0036] FIG. 12 is respectively illustrations showing a network
configuration in modified examples of the fourth embodiment.
[0037] FIG. 13 is respectively illustrations showing a network
configuration in modified examples of the fourth embodiment.
[0038] FIG. 14 is a diagram showing a network configuration in the
fifth embodiment of the distributed wireless network system.
[0039] FIG. 15 illustrates a case in which the number of the
wireless terminals existing in the vehicle is large.
[0040] FIG. 16 illustrates an example in which information signal
transmitted from the control terminal 12 to the wireless terminals
for each fixed time or as required.
[0041] FIG. 17 is a diagram showing an example in which a wireless
terminal newly entering at a range of a distributed wireless
network acquires information signal relating to the distributed
wireless network.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0042] The network control apparatus, the wireless terminal and the
communication control method will be described specifically, with
reference to the drawings.
First Embodiment
[0043] FIG. 1 is a diagram showing a network configuration
according to a first embodiment of a distributed wireless network
system. The distributed wireless network system in FIG. 1 has
wireless terminals 1 to 5 respectively held by a plurality of
persons in a vehicle such as a train or bus, a base station 11
which is installed outside of the vehicle and transmits various
information signal to the respective wireless terminals 1 to 5, and
a control terminal 12 installed at a position where the propagation
environment is relatively good, such as a ceiling of the
vehicle.
[0044] The wireless terminals 1 to 5 and the control terminal 12
form the distributed wireless network. Here, the distributed
wireless network stands for a network in which the respective
terminals have a relay function, and the respective terminals
cooperate with each other to transmit information signal between
the base station 11 and the respective wireless terminals.
[0045] It is assumed here that the wireless terminals 1 to 4
request reception of information signal in a large quantity from
the base station 11.
[0046] It is assumed here that the wireless terminals 1 to 3
correspond to a cellular system or a wireless LAN, which receives
information signal via the base station 11 such as CDMA, PDC
(Personal Digital Cellular) and PHS (Personal Handy Phone System),
and also correspond to the distributed wireless network, and are
so-called multi-system type terminals. On the other hand, the
wireless terminal 4 corresponds only to the distributed wireless
network.
[0047] At first, after having received information signal (1) from
the base station 11 individually, the wireless terminals 1 to 3
transmit information signal for identifying the respective wireless
terminals 1 to 3 (hereinafter referred as individual terminal
information signal (2)), and a signal indicating a part deficient
in received information signal, propagation situation, terminal
capability and the like (hereinafter, referred as an evaluation
signal (3)), to the control terminal 12.
[0048] The wireless terminal 4 transmits the evaluation signal (3)
indicating that the information signal (1) has not been received to
the control terminal 12 together with the individual terminal
information signal (2).
[0049] Here, it is assumed that the wireless terminal 3 can
normally receive the information signal (1) because the propagation
situation is good, or the terminal capability is high, and the
wireless terminals 1 and 2 have a part deficient in the received
information signal (hereinafter, referred as "deficiency
information signal"). In this case, the control terminal 12
transmits a signal indicating a part to be supplemented by the
respective terminals (hereinafter referred as a supplement signal
(4)) to the respective wireless terminals, based on the deficiency
information signal in the evaluation signal (3) transmitted from
the respective wireless terminals.
[0050] In the embodiment shown in FIG. 1, the signal received by
the wireless terminal 3 having excellent propagation situation and
terminal performance is used to supplement signals of other
wireless terminals. The control terminal 12 transmits the
supplement signal (4) instructing to supplement the information
signal (1) from the wireless terminals 3, to the respective
wireless terminals 1 to 5.
[0051] The respective wireless terminals 1 to 5 transmit the
evaluation signal (3) again to the wireless terminal 3, according
to the supplement signal (4). The wireless terminal 3 receives the
deficiency information signal instructed by the evaluation signal
(3) from the wireless terminal 3, and transmits the received
deficiency information signal to other wireless terminals 1, 2, 4
and 5.
[0052] As in this embodiment, when the other wireless terminals 1,
2, 4 and 5 supplement information signal only from the wireless
terminal 3, the evaluation signals for the other wireless terminals
1, 2, 4 and 5 may be transmitted beforehand from the control
terminal 12 to the wireless terminal 3. As a result, the wireless
terminal 3 can understand beforehand which wireless terminal is
deficient in which information signal. Therefore, the wireless
terminals 1, 2, 4 and 5 are unnecessary to transmit the evaluation
signal again to the wireless terminal 3, and can promptly receive
the deficient information signal from the base station 11 to
transmit it to the other terminals 1, 2, 4 and 5.
[0053] As described above, in the first embodiment, the evaluation
signal (3) transmitted from the respective wireless terminals 1 to
5 to the control terminal 12 is transmitted to the wireless
terminal 3 having a good propagation environment, which have
correctly received the information signal (1), and the wireless
terminal 3 receives the deficiency information signal from the base
station 11 and transmits the information signal to the other
wireless terminals 1, 2, 4 and 5. As a result, all wireless
terminals that have not correctly received the information signal
can obtain the deficiency information signal via the wireless
terminal 3, thereby improving the communication reliability.
Second Embodiment
[0054] In the second embodiment, a plurality of wireless terminals
in the distributed wireless network receives information signal
from the base station 11 by cooperating to each other, according to
the instruction from the control terminal 12.
[0055] FIGS. 2 and 3 are diagrams showing a network configuration
according to the second embodiment of the distributed wireless
network system. The distributed wireless network system according
to the second embodiment has wireless terminals 1 to 6 respectively
held by a plurality of persons in a vehicle, a control terminal 12
installed on the ceiling or the like in the vehicle, and a base
station 11 installed outside of the vehicle, similarly to the first
embodiment.
[0056] It is assumed here that the wireless terminal 1 requests
reception of information signal in a large quantity that cannot be
received by the wireless terminal 1 itself to the wireless base
station 11. In this case, as shown in FIG. 2, the wireless terminal
1 transmits the individual terminal information signal (2), and a
cooperative reception request signal & desired received signal
information signal (6), to the control terminal 12.
[0057] Next, the control terminal 12 transmits a cooperation
request signal & received signal information signal (7) to
other wireless terminals 2 to 6 in the distributed wireless
network. The respective wireless terminals 2 to 6 reply an Ack/Nack
(8) indicating whether to cooperate or not to the control terminal
12.
[0058] The control terminal 12 controls as database the information
signal relating to propagation situation and terminal capability of
the other wireless terminals 2 to 6 which cooperate with the
wireless terminal 1, among the evaluation signals (3) received
beforehand from the wireless terminals. The control terminal 12
determines an assignment signal (9) indicating assigned parts to be
received by the wireless terminals 2 to 6, and informs the
respective wireless terminals of the assigned parts.
[0059] As shown in FIG. 3, the wireless terminals having received
the assignment signal (9) individually receive the information
signal from the base station 11, and transmit the received
information signal to other wireless terminals. FIG. 3 illustrates
an example in which the control terminal 12 has not given the
reception request to the wireless terminal 4.
[0060] In this case, the wireless terminal 4 only receives the
information signal from other wireless terminals.
[0061] FIG. 4 is a block diagram indicating one example of the
internal configuration of the control terminal 12 according to the
second embodiment. The control terminal 12 has a RF unit 21 which
performs transmission and reception of an analog wireless signal,
and D/A conversion (from a digital signal to an analog wireless
signal) or A/D conversion of the other way around, a baseband
signal processing unit 22 which performs signal processing of the
digital signal, a control unit 23 which controls the RF unit 21,
the baseband signal processing unit 22 and the like, a memory 24,
and a display unit 25.
[0062] A database is provided in the memory 24, and the database
stores the information signal of the propagation situation and the
terminal capability of the respective terminals existing in the
same distributed wireless network.
[0063] FIG. 5 indicates one example of the database in the memory
24, which stores data such as bit rates, propagation environments,
processing state and request information signal of the respective
wireless terminals. For example, if it is assumed that the
information signal shown in FIG. 5 is held by the control terminal
12, the control terminal 12 assigns the largest partial charge of
the received information signal to the wireless terminal 6 having a
good propagation environment and a high-speed bit rate, and assigns
the partial charge lower than that of the wireless terminal 6, to
the wireless terminals 1, 3 and 5 having medium bit rates and
propagation environments. The propagation environment of the
wireless terminal 4 is the same level as that of the wireless
terminal 3, but the corresponding bit rate is low. Because of this,
any partial charge is not assigned to the wireless terminal 4 in
this embodiment.
[0064] In this embodiment, there is shown a case in which
assignment is determined by the bit rate and the propagation
environment, but the assignment may be performed based on the
processing state of the respective wireless terminals, or an item
other than those shown in FIG. 5 may be added in the database in
the memory 24, and assignment may be performed based on the added
item.
[0065] FIG. 6 is a flowchart indicating the processing procedure in
the second embodiment of the distributed wireless network system.
At first, the wireless terminal 1 transmits the individual terminal
information signal for identifying its own terminal, a cooperative
reception request signal for requesting cooperative reception to
other wireless terminals, and received signal information signal
relating to the cooperation-requested received information signal
to the control terminal 12 (step S1). The control terminal 12
having received this signal transmits a cooperation request signal
& the received signal information signal to other wireless
terminals (step S2). The other wireless terminals having received
this signal transmit a response (Ack or Nack) indicating whether to
cooperate for the reception to the control terminal 12 (step
S3).
[0066] The control terminal 12 then checks up the database shown in
FIG. 5 in the memory 24, to determine the assignment to the
respective wireless terminals (step S4), and transmits the
assignment information signal to the respective wireless terminals
(step S5).
[0067] The respective wireless terminals having received the
assignment information signal respectively transmit a reception
request signal for the assigned part to the base station 11 or the
like (step S6). The base station 11 transmits the requested
information signal to the respective wireless terminals (step
S7).
[0068] The wireless terminals other than the wireless terminal 1
transmit the assignment information signal having received by its
own terminal to the wireless terminal 1 (step S8).
[0069] As described above, in the second embodiment, when a certain
wireless terminal requests cooperative reception to the control
terminal 12, the control terminal 12 determines the reception
assignment for the respective wireless terminals, taking into
consideration the transmission rate and the propagation environment
of the respective wireless terminals. Therefore, a plurality of
wireless terminals can receive the desired information signal most
efficiently by cooperatively receiving the information signal. The
information signal received by the assigned respective wireless
terminals can be reliably delivered to the wireless terminal which
has made the request, since the information signal is transmitted
between the respective wireless terminals.
Third Embodiment
[0070] In the third embodiment, the control terminal 12 relays
transmission of the deficiency information signal.
[0071] FIG. 7 is a diagram showing a network configuration
according to the third embodiment of the distributed wireless
network system. Hereafter, points different from the first
embodiment will be mainly explained. FIG. 7 indicates an example in
which the propagation environment of the wireless terminal 3 is the
best. In this case, the control terminal 12 transmits a supplement
signal (4) instructing supplement of information signal to the
wireless terminal 3.
[0072] The wireless terminal 3 having received the supplement
signal (4) receives the information signal (1) for supplement from
the base station 11, and transmits the received information signal
(1) for supplement to the control terminal 12. The control terminal
12 transmits the deficiency information signal (5) to the
respective wireless terminals, based on the evaluation signal
indicating the part deficient in the received information signal,
the propagation situation and the terminal capability of the
respective wireless terminals. At this time, the control terminal
12 transmits the whole information signal to the wireless terminal
4, which has not received any information signal 1 from the base
station 11.
[0073] If there is no wireless terminal which has not received any
information signal 1, and all the wireless terminals have received
the same information signal 1 from the base station 11 or the like
beforehand, and only the deficient part is respectively requested,
the control terminal 12 receives only the deficiency information
signal (5) of the respective wireless terminals from the wireless
terminal 3.
[0074] In this manner, since the control terminal 12 adjusts the
received information signal of the respective wireless terminals,
even if the respective wireless terminals cannot receive the whole
information signal by themselves, or even if there is a failure in
reception, the whole information signal can be finally received
accurately. Moreover, by efficiently transmitting only the
information signal relating to the deficient part, congestion in
the distributed wireless network can be reduced.
[0075] FIG. 8 is a diagram showing the network configuration when
the control terminal 12 requests transmission of information signal
relating to a deficient part in a wireless terminal, to all
wireless terminals receiving the same information signal. In this
case, the control terminal 12 transmits the supplement signal (4)
to all wireless terminals 1, 2 and 4 receiving the same information
signal.
[0076] The respective wireless terminals transmit supplement
information signal (1') indicated by the supplement signal (4) to
the base station 11, and receive deficiency information signal (5)
in its own terminal from the base station 11.
[0077] Since the control terminal 12 transmits the supplement
information signal (1') and the deficiency information signal (5)
between the respective wireless terminals and the control terminal
12, the throughput of the control terminal 12 itself increases than
that shown in FIG. 7, but since the information signal of the
respective wireless terminals can be effectively used, an advantage
similar to that of the diversity reception can be obtained.
[0078] Particularly, in FIG. 7, when the propagation situation and
the terminal performance or the like of the wireless terminal 3 are
substantially equal to those of other wireless terminals, or when
the propagation situation of the wireless terminals 1 and 2 is not
so bad, the method shown in FIG. 8 is effective. Therefore, it can
be considered to use the methods shown in FIG. 7 and FIG. 8
selectively according to the processing capacity of the control
terminal 12 itself and the propagation situation of other wireless
terminals.
[0079] FIG. 9 is a diagram showing another network configuration
according to the third embodiment of the distributed wireless
network system. In FIG. 9, there is shown an example in which when
a plurality of wireless terminals cooperate with each other to
receive information signal according to an assignment instruction
from the control terminal 12 as shown in FIG. 2, the control
terminal 12 relays the transmission of the supplement signal.
[0080] Points different from the method shown in FIG. 3 will be
mainly explained below. In the method shown in FIG. 9, the
respective wireless terminals receive an assignment instruction as
shown in FIG. 3 from the control terminal 12, and individually
receives an assignment signal (9) from the base station 11.
Thereafter, in the method shown in FIG. 3, the respective wireless
terminals transmit the received signal for the assigned part to
other wireless terminals. But in the method shown in FIG. 9, the
respective wireless terminals transmit the received signal (a) for
the assigned part to the control terminal 12. The control terminal
12 then transmits a signal (b) for a part other than the assigned
part to the respective terminals.
[0081] It may be determined by the control terminal 12 itself
whether to relay the transmission of the supplement signal (4), or
it may be determined by a wireless terminal which requests
cooperation. In the latter case, the wireless terminal which
requests cooperation transmits a cooperative reception request
signal to the control terminal 12, and may transmit a signal
indicating the presence of relay to the control terminal 12. As a
result, for example, when a known user is nearby, the first or the
second embodiment in which the information signal is transmitted
without using the control terminal 12 can be selected, and the
third embodiment in which transmit between users is not performed
can be selected, according to the situation where there is no other
user in the same network nearby.
[0082] As described above, in the third embodiment, since the
deficiency information signal at the time of reception by the
respective wireless terminals is received via the control terminal
12, it is not necessary to transmit the deficiency information
signal between the respective wireless terminals, and hence
security is improved.
Fourth Embodiment
[0083] In the fourth embodiment, the control terminal 12 itself
transmits information signal between the base station 11 and the
control terminal 12.
[0084] FIG. 10 is a diagram showing a network configuration
according to the fourth embodiment of the distributed wireless
network system. The control terminal 12 in FIG. 10 can transmit
information signal between the base station 11 and the respective
wireless terminals. For example, in a vehicle such as a train or a
bus or the like, the propagation environments of the respective
wireless terminals held by passengers are not so good, whereas
there are many cases in which the propagation environment of the
control terminal 12 fitted on the ceiling or the like of the
vehicle is good. In such a case, information signal from the base
station 11 can be received more reliably and at a higher speed by
the control terminal 12 than by the respective wireless
terminals.
[0085] Therefore, in the fourth embodiment, the respective wireless
terminals transmit a reception request signal to the control
terminal 12, and the control terminal 12 receives desired
information signal from the base station 11, based on the reception
request signal, and transmits the received information signal to
the respective wireless terminals.
[0086] FIG. 11 is a flowchart showing the processing procedure
according to the fourth embodiment. At first, the respective
wireless terminals in the distributed wireless network transmit the
individual terminal information signal (2) for identifying
themselves, and a desired received signal (6) indicating the type
of information signal which the wireless terminals request
reception, to the control terminal 12 (step S11).
[0087] The control terminal 12 stores the number of wireless
terminals having transmitted the desired received signal (6) in the
memory 24, and determines whether the value is larger than a
specified number (step S12). When the value is larger than the
specified number, the control terminal 12 requests reception of
information signal 1 corresponding to the desired received signal
(6) to the base station 11 (step S13), and receives the information
signal (1) (step S14).
[0088] Upon completion of reception, the control terminal 12
performs accounting processing, and transmits the received
information signal 4 to the wireless terminal having transmitted
the desired received signal (6) (step S15).
[0089] On the other hand, when it is determined that the value is
not larger than the specified number, it is determined whether to
perform reception even if the number of the wireless terminals has
not yet reached the specified number (step S16). If the
determination is NO, control returns to step S11, and if YES,
processing at step S13 is performed.
[0090] The specified number may be determined by the control
terminal 12, or by the wireless terminal. For example, when it is
determined by the control terminal 12, control is simple, but the
degree of freedom according to the user's situation is low. On the
other hand, when it is determined by the wireless terminal, the
specified number can be changed according to the situation of the
number of users, but processing such as transmitting the
information signal relating to the situation of the number of users
or the like to the wireless terminal becomes necessary.
[0091] At step S15, it is desirable to change a charged fare
according to the number of wireless terminals which request
reception. In other words, as the number of wireless terminals
increases, the charged amount per one terminal is decreased.
[0092] As described above, in the fourth embodiment, the
information signal, of which reception is requested by the
respective wireless terminals, is received representatively by the
control terminal 12, and distributed to the respective wireless
terminals. Because of this, stable transmission becomes possible at
all times, without relying on the propagation environments of the
respective wireless terminals. Therefore, this embodiment is
particularly effective, when the propagation environments from the
base station 11 or the like of the respective wireless terminals
are bad.
[0093] FIG. 12 and FIG. 13 are respectively illustrations showing a
network configuration in modified examples of the fourth
embodiment. As shown in FIG. 12, the wireless terminals 1 to 5
transmit information signal to each other, receive the same
information signal 1 by cooperating with each other, and share the
received information signal. The control terminal 12 may determine
assignment for each wireless terminal and transmit an assignment
signal (9) to the respective wireless terminals, or the assignment
for each wireless terminal may be determined only by the
information signal exchange between wireless terminals.
[0094] Even if the information signal is received by a plurality of
wireless terminals by cooperating with each other, when there is
still deficiency information signal, the processing shown in FIG.
11 is carried out. In this case, at least one wireless terminal
transmits the evaluation signal (3) to the control terminal 12. For
example, in FIG. 13, the wireless terminal 5 representatively
transmits the individual terminal information signal (2) (here,
information signal of the wireless terminals 1 to 5), and the
evaluation signal (3).
[0095] The control terminal 12 receives the information signal for
the relevant part from the base station 11 and the like, and
distributes the information signal to the desired wireless
terminals. As a result, the user receives only the necessity
minimum deficiency information signal from the control terminal 12,
thereby enabling reduction of the amount charged by the control
terminal 12, while reliably receiving the whole necessary
information signal. In FIGS. 10, 12 and 13, there is shown an
example in which the control terminal 12 has a plurality of
antennas, but the plurality of antennas are not always necessary,
and the similar processing can be performed with only one
antenna.
Fifth Embodiment
[0096] In the first to the fourth embodiments described above,
there is shown an example in which one vehicle forms the
distributed wireless network, but a plurality of vehicles may form
the distributed wireless network.
[0097] FIG. 14 is a diagram showing a network configuration in the
fifth embodiment of the distributed wireless network system. FIG.
14 illustrates an example in which there are only a few wireless
terminals in a vehicle. In this case, for efficient use of the
system, it can be considered that one control terminal 12 controls
wireless terminals in another vehicle.
[0098] In FIG. 14, there is shown a case in which the control
terminal 12 is provided for each vehicle, but one control terminal
12 may be provided for a plurality of vehicles.
[0099] FIG. 15 illustrates a case in which the number of the
wireless terminals existing in the vehicle is large. For example,
when there are only a few wireless terminals in the vehicle, as
shown in FIG. 14, one control terminal 12 controls the wireless
terminals in a plurality of vehicles, and as the number of wireless
terminals increases, as shown in FIG. 15, separate control
terminals 12a and 12b may control the wireless terminals in the
respective vehicles for each vehicle.
[0100] In the case of FIG. 15, the respective control terminals 12a
and 12b may transmit a control signal or the like to each other.
Moreover, the service content (=received information signal) may be
different for each of the control terminals 12a and 12b, or may be
the same.
[0101] Particularly, the wireless terminal existing in the vicinity
of the boundary of the wireless propagation range of the respective
control terminals 12a and 12b may select the desired information
signal, if the information signal is different for each of the
control terminals 12a and 12b. Moreover, when the information
signal received by the plurality of control terminals 12a and 12b
is the same, it can be considered to select one having better
wireless situation, or to combine the information signal from the
both control terminals 12a and 12b.
[0102] As described above, in the fifth embodiment, since one
control terminal 12 can control the wireless terminals in a
plurality of vehicles, the number of the control terminals 12 can
be reduced. Moreover, since the plurality of control terminals 12a
and 12b can transmit a control signal or the like to each other, a
larger scale distributed wireless network system can be
constructed.
Other Embodiments
[0103] In the above respective embodiments, it is desired that the
respective wireless terminals can access the distributed wireless
network arbitrarily.
[0104] It is necessary to add information signal relating to the
distributed wireless network with respect to a wireless terminal,
which newly joins the distributed wireless network.
[0105] FIGS. 16 and 17 respectively illustrate an example in which
the wireless terminal coming into the area of the distributed
wireless network obtains the information signal relating to the
distributed wireless network. FIG. 16 illustrates an example in
which information signal transmitted from the control terminal 12
to the wireless terminals for each fixed time or as required, and
basic information signal such as the number of users and an average
bit rate (hereinafter, referred as distributed wireless network
information signal (c)) are distributed to all wireless terminals
located in the network.
[0106] FIG. 17 illustrates an example in which when the control
terminal 12 has a display unit 25, the distributed wireless network
information signal, for example, "a distributed wireless network is
now being formed, and information signal x is now cooperatively
receiving" is displayed on a display panel.
[0107] In the example shown in FIG. 16, the wireless terminal 4
which has newly moved into the distributed wireless network replies
a distributed wireless network joining request signal (d) to the
distributed wireless network information signal (c) provided from
the control terminal 12, thereby joining the distributed wireless
network. Likewise, even in the example shown in FIG. 17, the
wireless terminal 4 transmits the same signal (d) to the control
terminal 12, thereby joining the distributed wireless network.
[0108] In the above description, a train or a bus or the like has
been described as an example, but the similar system can be
constructed even in other places. Moreover, in the above
description, the control terminal 12 is assumed to be a dedicated
terminal, but the control terminal 12 is not necessarily the
dedicated terminal. For example, the control terminal 12 may be
selected from wireless terminals belonging to the distributed
wireless network. As the selection method, for example, it is
arranged such that the base station 11 or the like outside the
distributed wireless network transmits the same signal to the
respective wireless terminals in the distributed wireless network
at the same time, and the respective wireless terminals reply Ack
upon reception of the signal. The base station 11 or the like
selects a terminal suitable as the control terminal 12, based on
the information signal such as the reception time of Ack and the
intensity of the received signal from the respective terminals.
* * * * *