U.S. patent application number 11/030061 was filed with the patent office on 2005-06-02 for radio communication system and radio terminal device using faster and slower radio networks cooperatively.
This patent application is currently assigned to KABUSHIKI KAISHA TOSHIBA. Invention is credited to Takabatake, Yoshiaki, Tamada, Yuzo, Toshimitsu, Kiyoshi.
Application Number | 20050118985 11/030061 |
Document ID | / |
Family ID | 14103843 |
Filed Date | 2005-06-02 |
United States Patent
Application |
20050118985 |
Kind Code |
A1 |
Takabatake, Yoshiaki ; et
al. |
June 2, 2005 |
Radio communication system and radio terminal device using faster
and slower radio networks cooperatively
Abstract
A communication system including a first terminal device
connected to first and second networks, having only a reception
function with respect to the first network and transmission and
reception functions with respect to the second network, the first
network being a radio network according to IEEE 802.11 and the
second network being a radio network slower than the first network,
and a second terminal device connected to the first and second
networks, having at least a transmission function with respect to
the first network and transmission and reception functions with
respect to the second network is disclosed. In this communication
system, the first terminal device carries out a prescribed
procedure required in using the first terminal as a receiving side
in the first network, by carrying out communications with the
second terminal device through the second network, the second
terminal device transmits a prescribed information to the first
network on behalf of the first terminal device, the prescribed
information being an information required to be transmitted to the
first network in order for the first terminal device to receive
packets through the first network, and the first terminal device
receives the packets through the first network.
Inventors: |
Takabatake, Yoshiaki;
(Kanagawa, JP) ; Toshimitsu, Kiyoshi; (Kanagawa,
JP) ; Tamada, Yuzo; (Kanagawa, JP) |
Correspondence
Address: |
FOLEY AND LARDNER
SUITE 500
3000 K STREET NW
WASHINGTON
DC
20007
US
|
Assignee: |
KABUSHIKI KAISHA TOSHIBA
|
Family ID: |
14103843 |
Appl. No.: |
11/030061 |
Filed: |
January 7, 2005 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
11030061 |
Jan 7, 2005 |
|
|
|
09541889 |
Mar 31, 2000 |
|
|
|
6845090 |
|
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Current U.S.
Class: |
455/411 |
Current CPC
Class: |
H04W 88/04 20130101;
H04W 92/02 20130101; H04W 28/22 20130101; H04W 88/02 20130101; H04W
88/06 20130101; H04W 12/06 20130101; H04L 12/5692 20130101; H04W
84/12 20130101 |
Class at
Publication: |
455/411 |
International
Class: |
H04M 001/66 |
Foreign Application Data
Date |
Code |
Application Number |
Mar 31, 1999 |
JP |
11-094206 |
Claims
1. A communication system, comprising: a first terminal device
connected to first and second networks, having only a reception
function with respect to the first network and transmission and
reception functions with respect to the second network, the first
network being a radio network according to IEEE 802.11 and the
second network being a radio network slower than the first network;
and a second terminal device connected to the first and second
networks, having at least a transmission function with respect to
the first network and transmission and reception functions with
respect to the second network; wherein the first terminal device
carries out a prescribed authentication/admission procedure
required in using the first terminal as a receiving side in the
first network, by carrying out communications with the second
terminal device through the second network; the second terminal
device transmits a prescribed information to the first network on
behalf of the first terminal device, the prescribed information
being an information required to be transmitted to the first
network in order to complete the prescribed
authentication/admission procedure such that the first terminal
device becomes capable of receiving packets through the first
network; and the first terminal device receives the packets through
the first network.
2. The system of claim 1, wherein the packets are transmitted from
a source terminal to the second terminal device through the first
network, and then transmitted from the second terminal device to
the first terminal device through the first network using a
unidirectional downlink defined between the first terminal device
and the second terminal device in the first network.
3. The system of claim 1, wherein the packets are directly
transmitted from a source terminal to the first terminal device
through the first network.
4. The system of claim 1, wherein the first terminal device
notifies a source terminal having transmission and reception
functions with respect to the first network to the second terminal
device, and the second terminal device transmits an information
necessary for the source terminal to transmit the packets destined
to the first terminal device through the first network.
5. The system of claim 1, wherein the first terminal device
notifies a source terminal on a third network different from the
first and second networks to the second terminal device, the second
terminal device transmits a request for transmitting the packets to
the second terminal device to the source terminal through the third
network, the source terminal transmits the packets to the second
terminal device through the third network, and the second terminal
device transfers the packets received from the source terminal
through the third network to the first terminal device through the
first network.
6. The system of claim 1, wherein the first terminal device carries
out the prescribed procedure by transmitting a packet containing a
control information for the first network and attached with an
indication in a MAC layer indicating that the control information
is contained in the packet, to the second terminal device through
the second network, and the second terminal device identifies the
packet containing the control information by detecting the
indication by a processing in the MAC layer.
7. The system of claim 1, wherein the first terminal device carries
out the prescribed procedure by transmitting a packet containing a
control information for the first network and an indication
indicating that the control information is contained in the packet,
to the second terminal device through the second network, and the
second terminal device identifies the packet containing the control
information by detecting the indication by a processing in an upper
layer of a MAC layer.
8. A method of packet transfer in a communication system including
a first terminal device connected to first and second networks,
having only a reception function with respect to the first network
and transmission and reception functions with respect to the second
network, the first network being a radio network according to IEEE
802.11 and the second network being a radio network slower than the
first network, and a second terminal device connected to the first
and second networks, having at least a transmission function with
respect to the first network and transmission and reception
functions with respect to the second network, the method comprising
the steps of: carrying out a prescribed authentication/admission
procedure required in using the first terminal as a receiving side
in the first network, by carrying out communications between the
first terminal device and the second terminal device through the
second network; transmitting a prescribed information from the
second terminal device to the first network on behalf of the first
terminal device, the prescribed information being an information
required to be transmitted to the first network in order to
complete the prescribed authentication/admission procedure such
that the first terminal device becomes capable of receiving packets
through the first network; and receiving the packets at the first
terminal device through the first network.
Description
[0001] The present application is a divisional of U.S. application
Ser. No. 09/541,889, filed Mar. 31, 2000, the entire contents of
which are incorporated herein by reference.
BACKGROUND OF THE INVENTION
[0002] 1. Field of the Invention
[0003] The present invention relates to a radio terminal device
(which is also referred to as a wireless terminal device) having a
plurality of communication interfaces and a radio communication
system (which is also referred to as a wireless communication
system) including such radio terminal devices.
[0004] 2. Description of the Background Art
[0005] In recent years, the realization of home network is
attracting much attention, and in particular, the IEEE 1394 for
connecting between digital home electronic devices has been
attracting considerable attention. The IEEE 1394 bus is capable of
connecting a plurality of terminals in daisy chain or star
connection and transferring a wideband data in excess of 100 Mbps.
Also, it has a major feature that it is possible to transmit both
asynchronous data and isochronous data on the same cable. For this
reason, even though the IEEE 1394 bus was originally developed as a
next generation version of SCSI, there are increasing trends to use
the IEEE 1394 bus as a cable for connecting AV devices.
[0006] On the other hand, the realization of fast radio network
(radio LAN) is also attracting attention. In particular, since the
determination of the IEEE 802.11 specification in 1998, many radio
LAN products are appearing in the market and there has been a
remarkable decrease in the prices of these radio LAN products.
[0007] In conjunction with this trend for improved performance and
reduced cost of the radio technology, there is an active trend to
consider applications of the radio technology to the home
environment and this trend is expected to grow further in future as
can be anticipated by establishment of organizations such as HomeRF
and Bluetooth in the U.S.A. Also, from a viewpoint of the home
network, the radio system is an easily acceptable system as it does
not require any new cable construction. For this reason, the fast
radio LAN system is expected to play a central role in the future
home network.
[0008] However, there are some outstanding problems in the
application of a radio network to the home environment. One such
problem is the realization of a wideband data transfer using radio.
Data to be transferred in the home are expected to be mostly video
data such as those of TV broadcast or satellite broadcast, so that
the realization of a radio system capable of transferring such
wideband data is crucial for wider spread of radio systems in the
home environment.
[0009] To this end, a radio system using 5 GHz band is currently
proposed. This proposition is aimed at the realization of a radio
system capable of realizing the transmission rate of about 20 to 30
Mbps, by which several channels of MPEG2 video data can be
transferred. Also, the 5 GHz band radio frequencies are said to be
the last frequencies that can penetrate through many walls present
in the home environment, so that this is the most promising
candidate for the wideband radio system for home use.
[0010] But the 5 GHz band radio system also has its own problems.
Namely, it is currently impossible to realize LSI of the RF
function using CMOS. This is a severe drawback in view of a low
cost realization of the 5 GHz radio system, and its resolution is
imperative since it is expected that wider spread of radio systems
in the home environment critically depends on how cheaply this 5
GHz band radio system can be offered to the general users.
[0011] As described, a radio device for transferring wideband data
such as 5 GHz band radio system is expected to be rather expensive,
and for this reason it is expected that a cost of the radio
terminal itself will be very high in realizing the video data
delivery in the home environment. This is a very serious problem
for very cost sensitive products such as home electronic
devices.
SUMMARY OF THE INVENTION
[0012] It is therefore an object of the present invention to
provide a communication system and a terminal device using first
and second networks, where the terminal device can receive data
transfers as a receiving node in the first network, even when the
terminal device has a first network interface through which only
reception is possible and a second network interface through which
both transmission and reception are possible.
[0013] More specifically, it is an object of the present invention
to provide a radio communication system and a radio terminal device
using 2.4 GHz band radio network and 5 GHz band radio network, for
example, where the radio terminal device only has a reception
function for the 5 GHz band radio network but is still capable of
carrying out the authentication/admission processing in the 5 GHz
band radio network and/or the AV control protocol processing with
respect to a node on the IEEE 1394 bus by utilizing the 2.4 GHz
band radio network, while carrying out the actual data transfer
using the 5 GHz band radio network.
[0014] According to one aspect of the present invention there is
provided a communication system, comprising: a first terminal
device connected to first and second networks, having only a
reception function with respect to the first network and
transmission and reception functions with respect to the second
network, the first network being a radio network according to IEEE
802.11 and the second network being a radio network slower than the
first network; and a second terminal device connected to the first
and second networks, having at least a transmission function with
respect to the first network and transmission and reception
functions with respect to the second network; wherein the first
terminal device carries out a prescribed procedure required in
using the first terminal as a receiving side in the first network,
by carrying out communications with the second terminal device
through the second network; the second terminal device transmits a
prescribed information to the first network on behalf of the first
terminal device, the prescribed information being an information
required to be transmitted to the first network in order for the
first terminal device to receive packets through the first network;
and the first terminal device receives the packets through the
first network.
[0015] According to another aspect of the present invention there
is provided a terminal device, comprising: a first interface
configured to carry out at least a packet transmission with respect
to a first network which is a radio network according to IEEE
802.11; a second interface configured to carry out packet
transmission and reception with respect to a second network which
is a radio network slower than the first network; and a control
unit configured to carry out communications with another terminal
through the second interface so as to carry out a prescribed
procedure required in using the another terminal as a receiving
side in the first network, and transmit a prescribed information to
the first network on behalf of the another terminal, the prescribed
information being an information required to be transmitted to the
first network in order for the another terminal to receive packets
through the first network, such that the another terminal can
receive the packets through the first network.
[0016] According to another aspect of the present invention there
is provided a terminal device, comprising: a first interface
configured to carry out at least a packet reception with respect to
a first network which is a radio network according to IEEE 802.11;
a second interface configured to carry out packet transmission and
reception with respect to a second network which is a radio network
slower than the first network; and a control unit configured to
carry out communications with another terminal through the second
interface so as to carry out a prescribed procedure required in
using own terminal as a receiving side in the first network, such
that the another terminal transmits a prescribed information to the
first network on behalf of the own terminal, the prescribed
information being an information required to be transmitted to the
first network in order for the own terminal to receive packets
through the first network, and receive the packets through the
first network.
[0017] According to another aspect of the present invention there
is provided a communication system, comprising: a first terminal
device connected to first and second networks, having only a
reception function with respect to the first network and
transmission and reception functions with respect to the second
network, the first network being a radio network according to IEEE
802.11 and the second network being a radio network slower than the
first network; a second terminal device connected to the first
network and a third network different from the first and second
networks, having at least a transmission function with respect to
the first network and transmission and reception functions with
respect to the third network; a third terminal device connected to
the second and third networks, having transmission and reception
functions with respect to the second and third networks; and a
fourth device provided on the third network, having transmission
and reception functions with respect to the third networks; wherein
the first terminal device carries out a prescribed procedure
required in using the first terminal as a receiving side in the
first network, by carrying out communications with the third
terminal device through the second network; the third terminal
device carries out the prescribed procedure by carrying out
communications with the second terminal device through the third
network; the third terminal device carries out another prescribed
procedure required in relaying packets transferred from the fourth
device towards the first terminal device at the second terminal
device, by transferring a control information received from the
first terminal device through the first network, to the second
terminal device through the third network; the first terminal
device transmits a packet transmission request with respect to the
fourth device, to the third terminal device through the second
network; the third terminal device transfers the packet
transmission request received from the first terminal device, to
the fourth device through the third network; the fourth device
transmits packets in response to the packet transmission request
received from the third terminal device, to the second terminal
device through the third network; and the second terminal device
transfers the packets received from the fourth device, to the first
terminal device through the first network.
[0018] According to another aspect of the present invention there
is provided a terminal device for carrying out a data transfer with
respect to a first terminal through a first network, under a
control of a second terminal, the first terminal having only a
reception function with respect to the first network and
transmission and reception functions with respect to a second
network, the first network being a radio network according to IEEE
802.11 and the second network being a radio network slower than the
first network, the second terminal being connected to the second
network and a third network different from the first and second
networks and having transmission and reception functions with
respect to the second and third networks, the terminal device
comprising: a first interface configured to carry out at least a
packet transmission with respect to the first network; a second
interface configured to carry out packet transmission and reception
with respect to the third network; and a control unit configured to
receive a control information transferred from the second terminal
through the third network, and transfer packets received from a
third device provided on the third network, to the first terminal
through the first network according to the control information.
[0019] According to another aspect of the present invention there
is provided a terminal device for controlling a data transfer with
respect to a first terminal through a first network from a second
terminal, the first terminal having only a reception function with
respect to the first network and transmission and reception
functions with respect to a second network, the first network being
a radio network according to IEEE 802.11 and the second network
being a radio network slower than the first network, the second
terminal being connected to the first network and a third network
different from the first and second networks and having at least a
transmission function with respect to the first network and
transmission and reception functions with respect to the third
network, the terminal device comprising: a first interface
configured to carry out packet transmission and reception with
respect to the second network; a second interface configured to
carry out packet transmission and reception with respect to the
third network; and a control unit configured to carry out
communications with the first terminal through the first interface
and communications with the second terminal through the second
interface, so as to carry out a prescribed procedure required in
using the first terminal as a receiving side in the first network,
carry out another prescribed procedure required in relaying packets
transferred from a third device provided on the third network
towards the first terminal at the second terminal by transferring a
control information received from the first terminal through the
first network to the second terminal through the third network, and
transfer the packet transmission request received from the first
terminal through the second network to the third device through the
third network.
[0020] According to another aspect of the present invention there
is provided a terminal device for receiving a data transfer through
a first network from a first terminal by utilizing a second
terminal through a second network, the first network being a radio
network according to IEEE 802.11 and the second network being a
radio network slower than the first network, the first terminal
being connected to the first network and a third network different
from the first and second networks and having at least a
transmission function with respect to the first network and
transmission and reception functions with respect to the third
network, and the second terminal being connected to the second
network and the third network and having transmission and reception
functions with respect to the second and third networks, the
terminal device comprising: a first interface configured to carry
out at least a packet reception with respect to a first network
which is a radio network according to IEEE 802.11; a second
interface configured to carry out packet transmission and reception
with respect to a second network which is a radio network slower
than the first network; and a control unit configured to carry out
communications with the second terminal through the second
interface so as to carry out a prescribed procedure required in
using own terminal as a receiving side in the first network,
transmit a packet transmission request with respect to a third
device provided on the third network to the second terminal through
the second network, and receive packets transmitted from the third
device in response to the packet transmission request and relayed
by the first terminal through the first network.
[0021] According to another aspect of the present invention there
is provided a method of packet transfer in a communication system
including a first terminal device connected to first and second
networks, having only a reception function with respect to the
first network and transmission and reception functions with respect
to the second network, the first network being a radio network
according to IEEE. 802.11 and the second network being a radio
network slower than the first network, and a second terminal device
connected to the first and second networks, having at least a
transmission function with respect to the first network and
transmission and reception functions with respect to the second
network, the method comprising the steps of: carrying out a
prescribed procedure required in using the first terminal as a
receiving side in the first network, by carrying out communications
between the first terminal device and the second terminal device
through the second network; transmitting a prescribed information
from the second terminal device to the first network on behalf of
the first terminal device, the prescribed information being an
information required to be transmitted to the first network in
order for the first terminal device to receive packets through the
first network; and receiving the packets at the first terminal
device through the first network.
[0022] According to another aspect of the present invention there
is provided a method of packet transfer in a communication system
including a first terminal device connected to first and second
networks, having only a reception function with respect to the
first network and transmission and reception functions with respect
to the second network, the first network being a radio network
according to IEEE 802.11 and the second network being a radio
network slower than the first network, a second terminal device
connected to the first network and a third network different from
the first and second networks, having at least a transmission
function with respect to the first network and transmission and
reception functions with respect to the third network, a third
terminal device connected to the second and third networks, having
transmission and reception functions with respect to the second and
third networks, and a fourth device provided on the third network.,
having transmission and reception functions with respect to the
third networks, the method comprising the steps of: carrying out a
prescribed procedure required in using the first terminal as a
receiving side in the first network, by carrying out communications
between the first terminal device and the third terminal device
through the second network; carrying out the prescribed procedure
by carrying out communications between the third terminal device
and the second terminal device through the third network; carrying
out another prescribed procedure required in relaying packets
transferred from the fourth device towards the first terminal
device at the second terminal device, by transferring a control
information received from the first terminal device through the
first network, from the third terminal device to the second
terminal device through the third network; transmitting a packet
transmission request with respect to the fourth device, from the
first terminal device to the third terminal device through the
second network; transferring the packet transmission request
received from the first terminal device, from the third terminal
device to the fourth device through the third network; transmitting
packets in response to the packet transmission request received
from the third terminal device, from the fourth device to the
second terminal device through the third network; and transferring
the packets received from the fourth device, from the second
terminal device to the first terminal device through the first
network.
[0023] Other features and advantages of the present invention will
become apparent from the following description taken in conjunction
with the accompanying drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
[0024] FIG. 1 is a schematic diagram showing a configuration of a
network system according to the first embodiment of the present
invention.
[0025] FIG. 2 is a diagram showing a protocol stack for a control
packet transfer protocol used in the network system of FIG. 1.
[0026] FIG. 3 is a diagram showing a protocol stack for a data
packet transfer protocol used in the network system of FIG. 1.
[0027] FIG. 4 is a block diagram for explaining one exemplary
processing for packet transfer among radio terminals in the network
system of FIG. 1.
[0028] FIG. 5 is a block diagram for explaining another exemplary
processing for packet transfer among radio terminals in the network
system of FIG. 1.
[0029] FIG. 6 is a diagram showing a processing sequence for
communications among radio terminals in the network system of FIG.
1.
[0030] FIG. 7 is a diagram showing a MAC address correspondence
table that can be used in the network system of FIG. 1.
[0031] FIG. 8 is a schematic diagram showing a configuration of a
network system according to the second embodiment of the present
invention.
[0032] FIG. 9 is a diagram showing a processing sequence for
communications among radio terminals in the network system of FIG.
8, in the case of direct packet transfer.
[0033] FIG. 10 is a diagram showing a processing sequence for
communications among radio terminals in the network system of FIG.
8, in the case of packet transfer relaying.
[0034] FIG. 11 is a schematic diagram showing a configuration of a
network system according to the third embodiment of the present
invention.
[0035] FIG. 12 is a diagram showing a protocol stack for a AV/C
protocol execution used in the network system of FIG. 11.
[0036] FIG. 13 is a diagram showing a protocol stack for a MPEG2
data transfer protocol used in the network system of FIG. 11.
[0037] FIG. 14 is a diagram showing a network configuration as
recognized by a radio terminal and a node on IEEE 1394 bus, and
exemplary communication resources reserved in the network system of
FIG. 11.
[0038] FIG. 15 is a diagram showing a processing sequence for
communications among radio terminals in the network system of FIG.
11.
[0039] FIG. 16 is a schematic diagram showing a configuration of a
network system according to the fourth embodiment of the present
invention.
[0040] FIG. 17 is a diagram showing a first half of a processing
sequence for communications among radio terminals in the network
system of FIG. 16.
[0041] FIG. 18 is a diagram showing a second half of a processing
sequence for communications among radio terminals in the network
system of FIG. 16.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0042] In the following, the preferred embodiments of the present
invention will be described with references to the drawings. In the
first to fourth embodiments described below, an exemplary case of a
radio system in a home network of a home will be described, where
this radio system can use a faster (assumed to be 5 GHz band) radio
LAN as a first network and a slower (assumed to be 2.4 GHz band)
radio LAN, and define a unidirectional downlink on the faster radio
LAN. Among these, the third and fourth embodiments are specifically
directed to the case where the IEEE 1394 bus can be used as a third
network in addition.
[0043] Referring now to FIG. 1 to FIG. 7, the first embodiment of a
radio communication system and a radio terminal device according to
the present invention will be described in detail.
[0044] This first embodiment is directed to a scheme by which a
radio terminal having only a reception function with respect to the
5 GHz band radio LAN (or capable of utilizing only a reception
function with respect to the 5 GHz band radio LAN) carries out a
processing (such as authentication/admission processing, for
example) with respect to the 5 GHz band radio LAN, via the 2.4 GHz
band radio LAN.
[0045] FIG. 1 shows an exemplary configuration of a network system
in which the 5 GHz band radio LAN and the 2.4 GHz band radio LAN
are used cooperatively. These radio LANs are both operated
according to the IEEE 802.11 protocol, but uses different radio
frequencies so that there is no interference between them.
[0046] The network system of FIG. 1 includes a radio terminal 101
which provides a P.C. (Point Coordinator) function in the 5 GHz
band radio LAN 121, a radio terminal 103 which has transmission and
reception functions with respect to the 5 GHz band radio LAN, and a
radio terminal 102 which has only a reception function with respect
to the 5 GHz band radio LAN. In addition, the radio terminal 101
and the radio terminal 102 have transmission and reception
functions with respect to the 2.4 GHz band radio LAN by which they
can communicate with each other.
[0047] Note that the following description is directed to an
exemplary case in which each of the radio terminal 101 and the
radio terminal 102 has a MAC address on the 2.4 GHz band radio LAN
and a MAC address on the 5 GHz band radio LAN separately, but it is
also possible to use the same MAC address for the MAC address on
the 2.4 GHz band radio LAN and the MAC address on the 5 GHz band
radio LAN. In the following, it is assumed that the radio terminal
101 has an address "X1" on the 2.4 GHz band radio LAN and an
address "X2" on the 5 GHz band radio LAN, the radio terminal 102
has an address "Y1" on the 2.4 GHz band radio LAN and an address
"Y2" on the 5 GHz band radio LAN, and the radio terminal 103 has an
address "Z" on the 5 GHz band radio LAN.
[0048] According to the IEEE 802.11 protocol, when one radio
terminal carries out a communication with a desired correspondent
radio terminal, a radio terminal authentication processing should
be carried out between these radio terminal prior to the
communication. Also, when one radio terminal makes a connection to
a desired radio LAN, a radio LAN admission processing should be
carried out between the radio terminal and the P.C. (the radio
terminal 101 in the case of FIG. 1) as a processing for making the
connection. In the configuration of FIG. 1, the radio terminal 102
has only a reception function with respect to the 5 GHz band radio
LAN, so that this radio terminal 102 cannot directly carry out the
authentication/admission processing using the 5 GHz band radio
frequencies at a time of carrying out a communication with another
radio terminal (the radio terminal 101 or the radio terminal 103,
for example).
[0049] In this embodiment, the radio terminal 102 having only a
reception function with respect to the 5 GHz band radio LAN carries
out the authentication/admission processing with respect to the 5
GHz band radio LAN, via the 2.4 GHz band radio LAN.
[0050] In order to carry out the authentication processing
according to the IEEE 802.11, it is necessary for both terminals to
notify each other an authentication algorithm that is executable on
the own terminal as well as the MAC address of the own terminal.
For this reason, in order for the radio terminal 102 that has only
a reception function with respect to the 5 GHz band radio LAN to
carry out the authentication processing with another radio terminal
in the 5 GHz band radio LAN, there is a need to notify the
information necessary for the authentication processing (the
executable authentication algorithm and the MAC address) using a
different route. In FIG. 1, the 2.4 GHz band radio LAN is utilized
for this purpose. Similarly, in the case where the radio terminal
102 makes a connection to the radio terminal 101 which is the P.C.
of the 5 GHz band radio LAN, there is a need for the radio terminal
102 to notify the MAC address of the own terminal to the radio
terminal 101, and in FIG. 1, the 2.4 GHz band radio LAN is also
utilized for this purpose.
[0051] FIG. 2 shows a protocol stack indicating how the
authentication/admission processing is carried out between the
radio terminal 101 and the radio terminal 103 in this case. In FIG.
2, the authentication/admission processing with respect to the 5
GHz band radio LAN is abbreviated as "5G control", and the
authentication/admission processing with respect to the 2.4 GHz
band radio LAN is abbreviated as "2.4G control". As can be seen
from FIG. 2, in this embodiment, the authentication/admission
processing of the radio terminal 102 with respect to the 5 GHz band
radio LAN is carried out at the radio terminal 101 which is the
P.C. of the 5 GHz band radio LAN, via the 2.4 GHz band radio LAN.
On the other hand, between the radio terminal 101 and the radio
terminal 103 which has both transmission and reception functions
with respect to the 5 GHz band radio LAN, the
authentication/admission processing with respect to the 5 GHz band
radio LAN is carried out via the 5 GHz band radio LAN.
[0052] FIG. 3 shows a protocol stack indicating how the actual data
transfer is carried out between the radio terminal 101 and the
radio terminal 102, as well as between the radio terminal 101 and
the radio terminal 103. As can be seen from FIG. 3, the actual data
are transferred via the 5 GHz band radio LAN, but only data
transmitted from the radio terminal 101 towards the radio terminal
102 will be transferred to the radio terminal 102.
[0053] In the case of carrying out the authentication/admission
processing on the 5 GHz band radio LAN via the 2.4 GHz band radio
LAN and transferring the actual data via the 5 GHz band radio LAN,
a packet identification method on the 2.4 GHz band radio LAN must
be devised. Namely, it is necessary to specify which layer should
be used by the radio terminal 101 in order to identify a packet on
which the control information for the 5 GHz band radio LAN is
loaded among the packets received at an interface with respect to
the 2.4 GHz band radio LAN.
[0054] Two examples for this packet identification processing and
the actual data transfer processing will now be described with
references to FIG. 4 and FIG. 5.
[0055] FIG. 4 and FIG. 5 show various drivers operating on each MAC
layer, in addition to the physical and MAC layers of the 2.4 GHz
band radio LAN and the 5 GHz band radio LAN (denoted in the figures
as 2.4G-PHY, 2.4G-MAC, 5G-PHY, and 5G-MAC respectively). Here,
control drivers for handling the authentication/admission, the data
transfer request, etc., and data drivers for handling the actual
data transfer are distinguished.
[0056] FIG. 4 and FIG. 5 also show various applications to be
executed using these drivers, including an ordinary application to
be executed on the 2.4 GHz band radio LAN (abbreviated as 2.4G
application in the figures), an ordinary application to be executed
on the 5 GHz band radio LAN (abbreviated as 5G application in the
figures), and an AWL (Asymmetric Wireless Link) application in
which the control information is exchanged via the 2.4 GHz band
radio LAN and the actual data are transferred on the 5 GHz band
radio LAN.
[0057] In FIG. 4 and FIG. 5, a dotted line indicates a packet
transfer route in the case of executing the ordinary application on
the 2.4 GHz band radio LAN, a dashed line indicates a packet
transfer route in the case of executing the ordinary application on
the 5 GHz band radio LAN, and a solid line indicates a packet
transfer route in the case of executing the AWL application. In
both FIG. 4 and FIG. 5, the radio terminal 103 is an ordinary
terminal on the 5 GHz band radio LAN so that the processing
according to the ordinary (IEEE 802.11) protocol of the 5 GHz band
radio LAN is carried out between the radio terminal 101 and the
radio terminal 103.
[0058] Now a concrete processing for the control packet transfer
and the data packet transfer in the case of executing the AWL
application between the radio terminal 101 and the radio terminal
102 will be described.
[0059] First, the case of using the exemplary configuration of FIG.
4 will be described.
[0060] After receiving a packet at a physical layer processing unit
(2.4G-PHY in FIG. 4) for the 2.4 GHz band radio LAN, the radio
terminal 101 carries out the "packet distributing" processing for
identifying whether the received packet is a packet corresponding
to the application on the 2.4 GHz band radio LAN or a packet
corresponding to the AWL application at a MAC layer processing unit
(2.4G-MAC in FIG. 4) which is an upper layer processing unit of the
physical layer processing unit. A "packet distributing" processing
unit is provided in the MAC layer processing unit for this
purpose.
[0061] In order to identify a packet on the MAC layer in this way,
there is a need to define a flag indicating that the information
corresponding to the AWL application is loaded in that packet,
within a MPDU (MAC Protocol Data Unit) that is defined as a packet
for the MAC layer processing in the IEEE 802.11. By checking
presence/absence of such a flag, the MAC layer processing unit for
that 2.4 GHz band radio LAN judges whether the received packet
should be transferred to the control driver of the AWL application
or to the control driver of the ordinary 2.4 GHz application.
[0062] Also, data to be transmitted from the AWL application on the
radio terminal 101 towards the radio terminal 102 are transferred
to the "packet distributing" processing unit within the MAC layer
processing unit (5G-MAC in FIG. 4) for the 5 GHz band radio LAN via
its data driver. Here, the fact that this data packet is
transmitted from the AWL application is indicated by a flag on the
MPDU, and then the packet transmission processing is carried out
according to a packet transmission algorithm using a unidirectional
downlink from the radio terminal 101 to the radio terminal 102. If
it is possible to carry out the unidirectional packet transfer
processing from the radio terminal 101 to the radio terminal 102
without changing the ordinary MAC algorithm on the 5 GHz band radio
LAN, the "packet distributing" processing unit within the MAC layer
processing unit for the 5 GHz band radio LAN will be
unnecessary.
[0063] Next, the processing in the case of executing the AWL
application at the radio terminal 102 will be described.
[0064] In the case where the radio terminal 102 executes the AWL
application on the own terminal, the control processing necessary
for it is carried out on the 2.4 GHz band radio LAN. For this
reason, a packet carrying the control information that is
transmitted from the AWL application is transferred to the "packet
distributing" processing unit within the MAC layer processing unit
(2.4G-MAC in FIG. 4) for the 2.4 GHz band radio LAN via the control
driver of the AWL application. Here, the fact that this packet is a
control packet for executing the AWL application is indicated by a
flag on the MPDU, and then this packet is transferred to the radio
terminal 101 via the MAC/physical layer processing units for the
2.4 GHz band radio LAN.
[0065] Also, the radio terminal 102 has only a reception function
(5G-PHY(R), 5G-MAC(R) in FIG. 4) with respect to the 5 GHz band
radio LAN, and is capable of executing only the AWL application
using this function. The radio terminal 102 receives only data
packets of the AWL application from the 5 GHz band radio LAN. Thus
packets received at an interface with respect to the 5 GHz band
radio LAN of the radio terminal 102 are all to be transferred to
the AWL application, so that all the packets from the MAC layer
processing unit for the 5 GHz band radio LAN will be transferred to
the data driver of the AWL application, and the "packet
distributing" processing as used in the radio terminal 101 is
unnecessary in the radio terminal 102.
[0066] As described here, the radio terminal 102 executes only the
packet reception processing with respect to the 5 GHz band radio
LAN so that the execution of the AWL application between the radio
terminal 101 and the radio terminal 102 is possible even when the
same MAC address is used as the MAC address on the 2.4 GHz band
radio LAN and the MAC address on the 5 GHz band radio LAN of the
radio terminal 102. In such a case, it is necessary for the "packet
distributing" processing unit of the radio terminal 101 to
recognize in advance that the MAC address on the 2.4 GHz band radio
LAN and the MAC address on the 5 GHz band radio LAN of the radio
terminal 102 are the same.
[0067] Next, the case of using the exemplary configuration of FIG.
5 will be described.
[0068] First, the processing in the case of executing the AWL
application at the radio terminal 101 will be described.
[0069] In FIG. 5, unlike FIG. 4, no new function is added to the
MAC layer processing for each radio LAN in the radio terminal 101
and the radio terminal 102, and whether the received packet is a
packet for the application on the 2.4 GHz band or 5 GHz band radio
LAN or a packet for the AWL application is identified at an upper
level driver of the MAC layer.
[0070] First, the radio terminal 101 transfers a packet received by
the physical layer processing unit (2.4G-PHY in FIG. 5) and the MAC
layer processing unit (2.4G-MAC in FIG. 5) for the 2.4 GHz band
radio LAN, to the corresponding control driver. Then, the MPDU
header is removed from the packet received from the MAC layer
processing unit, and the information on internal data is checked.
Here, a field for identifying that the information corresponding to
the AWL application is loaded on this packet is defined as one of
the information on internal data, and whether the received packet
is a packet corresponding to the AWL application or not is judged
according to this field. This packet identification processing is
carried out by the AWL driver defined as an upper level driver of
the control and data drivers in FIG. 5.
[0071] Also, data transmitted from the AWL application on the radio
terminal 101 towards the radio terminal 102 are transferred as
follows. Namely, a packet on which this data is loaded is
transferred to the AWL driver at which the information indicating
that this is a packet corresponding to the AWL application is
attached to this packet, and this packet is transferred to the
lower level data driver. Then, this packet with the above
information attached is transferred to the radio terminal 102 via
the MAC/physical layer processing units for the 5 GHz band radio
LAN through the unidirectional downlink. Here, in FIG. 5, it is
assumed that the unidirectional packet transfer processing from the
radio terminal 101 to the radio terminal 102 can be executed
without modifying the ordinary MAC algorithm on the 5 GHz band
radio LAN, but if some processing for the purpose of carrying out
the unidirectional packet transfer processing is required, a
function for executing that processing will be provided in the MAC
layer processing unit for the 5 GHz band radio LAN.
[0072] Next, the processing in the case of executing the AWL
application at the radio terminal 102 will be described.
[0073] In the case of executing the AWL application on the own
terminal, the radio terminal 102 executes the control processing
necessary for that purpose on the 2.4 GHz band radio LAN. For this
reason, the control packet transmitted from the AWL application is
attached with an indication that this packet is a packet
corresponding to the AWL application at the AWL driver, and then
transferred to the radio terminal 101 via its control driver and
the MAC/physical layer processing units for the 2.4 GHz band radio
LAN.
[0074] Also, the radio terminal 102 has only a reception function
(5G-PHY(R), 5G-MAC(R) in FIG. 5) with respect to the 5 GHz band
radio LAN, and is capable of executing only the AWL application
using this function. The radio terminal 102 receives only data
packets of the AWL application from the 5 GHz band radio LAN. Thus
packets received at an interface with respect to the 5 GHz band
radio LAN of the radio terminal 102 are all to be transferred to
the AWL application, so that all the packets from the MAC layer
processing unit for the 5 GHz band radio LAN will be transferred to
the data driver of the AWL application.
[0075] The execution of the AWL application between the radio
terminal 101 and the radio terminal 102 can be realized using this
scheme.
[0076] FIG. 6 shows an exemplary processing sequence at a time of
actually transferring data from the radio terminal 101 to the radio
terminal 102 in the radio network operated in this scheme. Here, it
is assumed that the data transfer processing is carried out by the
Contention Mode of the IEEE 802.11 as the transfer protocol on the
radio LANs, and the carrier sense processing is carried out prior
to a series of data transfer processing from each radio terminal.
This processing sequence proceeds as follows.
[0077] (0) The radio terminal 102 carries out the authentication
processing with the radio terminal 101, and becomes a state in
which communications using the 2.4 GHz band radio LAN are
possible.
[0078] (1) The radio terminal 103 carries out the authentication
processing with the radio terminal 101, and then makes a connection
to the 5 GHz band radio LAN for which the radio terminal 101 is the
P.C., via the 5 GHz band radio LAN.
[0079] (2) The radio terminal 102 carries out the authentication
processing for the 5 GHz band radio LAN with the radio terminal
101, via the 2.4 GHz band radio LAN, and then makes a connection to
the 5 GHz band radio LAN for which the radio terminal 101 is the
P.C.
[0080] Here, the radio terminal 102 notifies its own MAC address
(=Y2) on the 5 GHz band radio LAN to the radio terminal 101 via the
2.4 GHz band radio LAN. As a result, the radio terminal 101
memorizes that the MAC address (=Y1) on the 2.4 GHz band radio LAN
corresponds to the MAC address (=Y2) on the 5 GHz band radio
LAN.
[0081] (3) The radio terminal 102 transmits a request indicating
the data transfer from the radio terminal 101 to the radio terminal
102 via the 5 GHz band radio LAN, to the radio terminal 101 via the
2.4 GHz band radio LAN.
[0082] Here, the radio terminal 102 may issue an RTS request for
the 5 GHz band radio LAN by using an RTS (Request to Send) packet
on the 2.4 GHz band radio LAN, or define a packet for transferring
control information for the 5 GHz band radio LAN on the 2.4 GHz
band radio LAN and issue the RTS request by using this packet.
[0083] (4) The radio terminal 101 transmits the RTS packet on the 5
GHz band radio LAN on behalf of the radio terminal 102 according to
the request of (3), so as to reserve media.
[0084] Here, the radio terminal 101 may reserve media by
transmitting a CTS (Clear to Send) packet corresponding to this RTS
packet, on the 5 GHz band radio LAN.
[0085] (5) The radio terminal 101 transmits a packet towards the
radio terminal 102.
[0086] (6) The radio terminal 101 transmits an Ack packet
corresponding to the packet transmitted by the processing of (5),
on the 5 GHz band radio LAN on behalf of the radio terminal
102.
[0087] Here, a packet transmission interval in the series of packet
transmissions from (4) to (6) is the SIFS interval which is the
minimum packet transmission interval specified in the IEEE
802.11.
[0088] (7) The radio terminal 103 transmits the RTS packet on the 5
GHz band radio LAN, so as to reserve media for the data transfer
from the radio terminal 103 to the radio terminal 101 (the carrier
sense processing is carried out prior to this RTS packet
transmission).
[0089] (8) The radio terminal 101 transmits the CTS packet
corresponding to the RTS packet of (7) on the 5 GHz band radio LAN,
so as to reserve media.
[0090] (9) The radio terminal 103 transmits a packet towards the
radio terminal 101.
[0091] (10) The radio terminal 101 transmits an Ack packet
corresponding to the packet transmitted by the processing of (9),
to the radio terminal 103.
[0092] Here, a packet transmission interval in the series of packet
transmissions from (7) to (10) is also the SIFS interval which is
the minimum packet transmission interval specified in the IEEE
802.11.
[0093] (11) While the processing from (7) to (10) is carried out,
the radio terminal 102 transmits another request indicating the
data transfer from the radio terminal 101 to the radio terminal 102
via the 5 GHz band radio LAN, to the radio terminal 101 via the 2.4
GHz band radio LAN (the processing as (3)).
[0094] (12) The radio terminal 101 transmits the RTS packet on the
5 GHz band radio LAN on behalf of the radio terminal 102 according
to the request of (11), so as to reserve media.
[0095] Here, the radio terminal 101 may reserve media by
transmitting a CTS (Clear to Send) packet corresponding to this RTS
packet, on the 5 GHz band radio LAN.
[0096] (13) The radio terminal 101 transmits a packet towards the
radio terminal 102.
[0097] (14) The radio terminal 101 transmits an Ack packet
corresponding to the packet transmitted by the processing of (13),
on the 5 GHz band radio LAN on behalf of the radio terminal
102.
[0098] Here, a packet transmission interval in the series of packet
transmissions from (12) to (14) is also the SIFS interval which is
the minimum packet transmission interval specified in the IEEE
802.11.
[0099] By this series of processing, even the radio terminal 102
which has only a reception function with respect to the 5 GHz band
radio LAN can receive data from the 5 GHz band radio LAN without
affecting the radio terminal 103 that is operated by the ordinary
radio LAN protocol, so that it becomes possible to provide a
unidirectional data downloading service on the radio LAN operated
by the protocol such as the IEEE 802.11.
[0100] Note that, the above example is directed to the case where
the radio terminal 102 uses different addresses for the MAC address
on the 2.4 GHz band radio LAN and the MAC address on the 5 GHz band
radio LAN, but as already mentioned above, these MAC addresses are
not necessarily different and it is also possible to use the same
MAC address for the MAC address on the 2.4 GHz band radio LAN and
the MAC address on the 5 GHz band radio LAN.
[0101] Note also that, in the above processing (2), the radio
terminal 101 can store the MAC address correspondence in a
correspondence table shown in FIG. 7. In the correspondence table
of FIG. 7, the MAC address of each interface of the radio terminal
with which the radio terminal 101 can communicate is registered.
Using such a correspondence table, it is possible to carry out
communications using the 2.4 GHz band radio LAN and the
unidirectional downlink on the 5 GHz band radio LAN as described
above.
[0102] Referring now to FIG. 8 to FIG. 10, the second embodiment of
a radio communication system and a radio terminal device according
to the present invention will be described in detail.
[0103] In the first embodiment, the data transfer from the radio
terminal 101 which is the P.C. to the radio terminal 102 has been
described. In this second embodiment, the data transfer from the
radio terminal 103 to the radio terminal 102 (in a configuration
basically similar to that of the first embodiment) will be
described. Also, in this second embodiment, the case of the data
transfer from the radio terminal 103 to the radio terminal 102
using the ordinary MAC processing (by the radio terminal 103) and
the case of the data transfer from the radio terminal 103 to the
radio terminal 102 relayed by the radio terminal 101 which is the
P.C. will be described.
[0104] FIG. 8 shows a configuration similar to that of the first
embodiment, in which the data transfer from the radio terminal 103
to the radio terminal 102 is realized. In this example, it is
assumed that the radio terminal 102 can ascertain the MAC address
of a terminal existing on the 5 GHz band radio LAN from the
framework of the IEEE 802.11, and requests a packet transfer from
the radio terminal 103 by ascertaining its MAC address
accordingly.
[0105] Here, the radio terminal is operated according to the IEEE
802.11 protocol used in the 5 GHz band radio LAN, but the radio
terminal 102 is a terminal in which only a reception function with
respect to the 5 GHz band radio LAN is provided. Consequently, in
this embodiment, there are two cases including the case where the
data transfer from the radio terminal 103 to the radio terminal 102
can be realized directly through the 5 GHz band radio LAN and the
case where data are transferred from the radio terminal 103 via the
radio terminal 101 which has a function for transferring data to
the radio terminal 102.
[0106] Normally, in the MAC protocol of the IEEE 802.11, if the Ack
packet is not returned from a terminal to which a packet is
transmitted, a terminal that transmitted the packet will judge that
a packet transfer has failed and re-transmit the packet. Therefore,
in the case of transferring a packet to a terminal like the radio
terminal 102 which only has a packet reception function, the same
packet would be transmitted many times repeatedly unless some
measure to prevent this from happening is provided. As a measure to
prevent this from happening, it is possible to provide a processing
for ignoring presence/absence of the Ack packet reception at a
terminal that transmitted a packet depending on the destination of
the packet, or a processing to transmit the Ack packet from a
terminal other than the destination terminal of the packet (a
source terminal, for example) on behalf of the destination
terminal. In the following, it is assumed that a terminal that
transmits a packet is a terminal in accordance with the IEEE 802.11
such as the radio terminal 103, so that the former method to ignore
the Ack packet cannot be adopted. Consequently, this example is
directed to the case of realizing a direct packet transfer from the
radio terminal 103 to the radio terminal 102 in which the Ack
packet corresponding to a packet transmission from the radio
terminal 103 to the radio terminal 102 is transmitted from the
radio terminal 101 on behalf of the radio terminal 102.
[0107] FIG. 9 shows an exemplary processing sequence in the case of
realizing the direct packet transfer from the radio terminal 103 to
the radio terminal 102 using this scheme for transmitting the Ack
packet from the radio terminal 101. Here, it is assumed that the
data transfer processing is carried out by the Contention Mode of
the IEEE 802.11 as the transfer protocol on the 5 GHz band radio
LAN. It is also assumed that the radio terminal 102 makes a
connection to the 5 GHz band radio LAN using a procedure as
described in the first embodiment. This processing sequence
proceeds as follows.
[0108] (0) The radio terminal 102 carries out the authentication
processing with the radio terminal 101, and becomes a state in
which communications using the 2.4 GHz band radio LAN are
possible.
[0109] (1) The radio terminal 103 carries out the authentication
processing with the radio terminal 101, and then makes a connection
to the 5 GHz band radio LAN for which the radio terminal 101 is the
P.C., via the 5 GHz band radio LAN.
[0110] (2) The radio terminal 102 carries out the authentication
processing for the 5 GHz band radio LAN with the radio terminal
101, via the 2.4 GHz band radio LAN, and then makes a connection to
the 5 GHz band radio LAN for which the radio terminal 101 is the
P.C.
[0111] (3) The radio terminal 101 notifies information on the MAC
addresses of the radio terminals existing in the 5 GHz band radio
LAN according to the IEEE 802.11 protocol.
[0112] (4) The radio terminal 102 transmits a request indicating
the data transfer from the radio terminal 103 to the radio terminal
102 via the 5 GHz band radio LAN, to the radio terminal 101 via the
2.4 GHz band radio LAN.
[0113] (5) The radio terminal 101 transmits the RTS packet on the 5
GHz band radio LAN on behalf of the radio terminal 102 according to
the request of (4), so as to reserve media. At this point, the
source terminal of the requested packet is set as the radio
terminal 103 and the destination terminal of the requested packet
is set as the radio terminal 102.
[0114] (6) The radio terminal 103 transmits the CTS packet
corresponding to the RTS packet of (5) on the 5 GHz band radio LAN,
so as to reserve media.
[0115] (7) The radio terminal 103 transmits a packet towards the
radio terminal 102.
[0116] (8) The radio terminal 101 transmits an Ack packet
corresponding to the packet transmitted by the processing of (7),
on the 5 GHz band radio LAN on behalf of the radio terminal
102.
[0117] Here, a packet transmission interval in the series of packet
transmissions from (5) to (8) is the SIFS interval which is the
minimum packet transmission interval specified in the IEEE
802.11.
[0118] Next, the processing in the case where the direct packet
transfer from the radio terminal 103 to the radio terminal 102 is
impossible will be described. Here, it is assumed that, in the
configuration of FIG. 8, the radio terminal 103 is capable of
communicating only with the radio terminal 101, and the radio
terminal 102 is capable of receiving packets only from the radio
terminal 101. Therefore, in the case of transferring a packet from
the radio terminal 103 to the radio terminal 102, it is necessary
to relay the packet at the radio terminal 101. This example is
directed to the case where the radio terminal 101 that received "a
request for packet transfer from the radio terminal 103 to the
radio terminal 102" from the radio terminal 102 via the 2.4 GHz
band radio LAN will activate two packet transfers including a
packet transfer from the radio terminal 103 to the own terminal
(radio terminal 101) and a packet transfer from the own terminal
(radio terminal 101) to the radio terminal 102.
[0119] FIG. 10 shows an exemplary processing sequence in the case
of realizing the packet transfer from the radio terminal 103 to the
radio terminal 102 using this scheme. Here, it is also assumed that
the data transfer processing is carried out by the Contention Mode
of the IEEE 802.11 as the transfer protocol on the 5 GHz band radio
LAN. It is also assumed that the radio terminal 102 makes a
connection to the 5 GHz band radio LAN using a procedure as
described in the first embodiment. This processing sequence
proceeds as follows.
[0120] (0) The radio terminal 102 carries out the authentication
processing with the radio terminal 101, and becomes a state in
which communications using the 2.4 GHz band radio LAN are
possible.
[0121] (1) The radio terminal 103 carries out the authentication
processing with the radio terminal 101, and then makes a connection
to the 5 GHz band radio LAN for which the radio terminal 101 is the
P.C., via the 5 GHz band radio LAN.
[0122] (2) The radio terminal 102 carries out the authentication
processing for the 5 GHz band radio LAN with the radio terminal
101, via the 2.4 GHz band radio LAN, and then makes a connection to
the 5 GHz band radio LAN for which the radio terminal 101 is the
P.C.
[0123] (3) The radio terminal 101 notifies information on the MAC
addresses of the radio terminals existing in the 5 GHz band radio
LAN according to the IEEE 802.11 protocol.
[0124] (4) The radio terminal 102 transmits a request indicating
the data transfer from the radio terminal 103 to the radio terminal
102 via the 5 GHz band radio LAN, to the radio terminal 101 via the
2.4 GHz band radio LAN.
[0125] (5) The radio terminal 101 transmits the RTS packet on the 5
GHz band radio LAN on behalf of the radio terminal 102 according to
the request of (4), so as to reserve media. At this point, the
source terminal of the requested packet is set as the radio
terminal 103 and the destination terminal of the requested packet
is set as the radio terminal 101.
[0126] (6) The radio terminal 103 transmits the CTS packet
corresponding to the RTS packet of (5) on the 5 GHz band radio LAN,
so as to reserve media.
[0127] (7) The radio terminal 103 transmits a packet towards the
radio terminal 101.
[0128] (8) The radio terminal 101 transmits an Ack packet
corresponding to the packet transmitted by the processing of (7),
on the 5 GHz band radio LAN.
[0129] Here, a packet transmission interval in the series of packet
transmissions from (5) to (8) is the SIFS interval which is the
minimum packet transmission interval specified in the IEEE
802.11.
[0130] (9) After a certain period of time (the DIFS interval, for
example) has elapsed, the radio terminal 101 transmits the RTS
packet on the 5 GHz band radio LAN on behalf of the radio terminal
102 according to the request of (4) again, so as to reserve media.
At this point, the source terminal of the requested packet is set
as the radio terminal 101 and the destination terminal of the
requested packet is set as the radio terminal 102.
[0131] Here, the radio terminal 101 may reserve media by
transmitting a CTS packet corresponding to this RTS packet, on the
5 GHz band radio LAN.
[0132] (10) The radio terminal 101 transmits the packet received by
the processing of (7), towards the radio terminal 101.
[0133] (11) The radio terminal 101 transmits an Ack packet L
corresponding to the packet transmitted by the processing of (10),
on the 5 GHz band radio LAN.
[0134] Here, a packet transmission interval in the series of packet
transmissions from (9) to (11) is the SIFS interval which is the
minimum packet transmission interval specified in the IEEE
802.11.
[0135] Using this scheme, it becomes possible to realize the packet
transfer between the radio terminal in accordance with the
specification of the 5 GHz band radio LAN (radio terminal 103) and
the radio terminal which has only a reception function with respect
to the 5 GHz band radio LAN (radio terminal 102).
[0136] Referring now to FIG. 11 to FIG. 15, the third embodiment of
a radio communication system and a radio terminal device according
to the present invention will be described in detail.
[0137] This third embodiment is directed to the case of operating
the radio network (using the 2.4 GHz band radio LAN and the 5 GHz
band radio LAN) together with the IEEE 1394 bus.
[0138] In this embodiment, a radio terminal having a P.C. function
which is capable of carrying out communications by both the 2.4 GHz
band radio LAN and the 5 GHz band radio LAN is provided on the IEEE
1394 bus, and this radio terminal relays the data transfer to the
radio terminal which has (or which is capable of utilizing) only a
reception function with respect to the 5 GHz band radio LAN from a
device on the IEEE 1394 bus such as a DVD.
[0139] The example described here is directed to the case where the
radio terminal on the radio network downloads image information
from a DVD existing on the IEEE 1394 bus, and in particular the AV
control protocol is executed between this radio terminal and the
DVD via the 2.4 GHz band radio LAN, and the actual image data are
received via the 5 GHz band radio LAN.
[0140] FIG. 11 shows an exemplary configuration of a network system
in this case. It is assumed that the radio LANs are operated
according to the IEEE 802.11 protocol similarly as in the first and
second embodiments. The network system of FIG. 11 includes a radio
terminal 601 which provides a P.C. function in the 5 GHz band radio
LAN 621, a radio terminal 603 which has transmission and reception
functions with respect to the 5 GHz band radio LAN, and a radio
terminal 602 which has only a reception function with respect to
the 5 GHz band radio LAN. In addition, the radio terminal 601 and
the radio terminal 602 have transmission and reception functions
with respect to the 2.4 GHz band radio LAN by which they can
communicate with each other. Moreover, the radio terminal 601 has
an interface with respect to the IEEE 1394 bus 623, and is
connected to a TV 604 and a DVD 605 via the IEEE 1394 bus.
[0141] This embodiment is directed to the case where the AV control
protocol (AV/C protocol) to be executed between the radio terminal
602 and the DVD 605 is executed via the 2.4 GHz band radio LAN and
the IEEE 1394 bus, and as a result the MPEG2 data transmitted from
the DVD 605 are transferred to the radio terminal 602 via the IEEE
1394 bus and the 5 GHz band radio LAN.
[0142] Here, in the AV/C protocol, 1394 nodes having 1394
interfaces are recognized in units called Unit, and constituent
elements (such as a cassette table section or a CD section in an
audio component system, for example) within the 1394 terminal are
recognized in units called SubUnit. In this embodiment, it is
assumed that the AV/C protocol is to be executed between the DVD
605 on the IEEE 1394 bus and the radio terminal 602 by recognizing
each other at a level of their constituent elements (SubUnits of
the AV/C protocol), rather than directly recognizing each other.
More specifically, in the case of FIG. 11, the constituent element
(SubUnit) in the DVD 605 is recognized from a viewpoint of the
radio terminal 602 as if it is existing in the radio terminal 601,
while the constituent element (SubUnit) in the radio terminal 602
is recognized from a viewpoint of the DVD 605 on the IEEE 1394 bus
as if it is existing in the radio terminal 601.
[0143] In the following, the case of transferring the MPEG2 data in
the DVD 605 to the radio terminal 602 will be described, assuming
that the AV/C protocol is executed between the radio terminal 602
and the DVD 605 based on such a recognition.
[0144] FIG. 12 shows a protocol stack indicating how the AV/C
protocol is executed in this embodiment, and FIG. 13 shows a
protocol stack indicating how the actual MPEG2 data transfer is
carried out in this embodiment. As can be seen from FIG. 12 and
FIG. 13, the radio terminal 601 provides a function for terminating
the IEEE 1394 bus protocol and connecting the IEEE 1394 bus with
the 2.4 GHz band radio LAN or the 5 GHz band radio LAN at a level
of an upper layer protocol (such as FCP layer in the AV/C protocol
or CIP layer in the MPEG2 data transfer, for example).
[0145] In the radio network operated in this way, the processing
for actually transferring the MPEG2 data on the DVD 605 to the
radio terminal 602 according to a request from the radio terminal
602 is carried out as follows. This example is directed to the case
where a VTR SubUnit exists in the DVD 605 on the IEEE 1394 bus, a
Display SubUnit exists in the radio terminal 602, and the MPEG2
data transfer is carried out between these SubUnits.
[0146] FIG. 14 shows how the DVD 605 and the radio terminal 602 are
recognizing each other and what communication resources are
reserved in executing the MPEG2 data transfer. In FIG. 14, from a
viewpoint of the DVD 605, the Display SubUnit in the radio terminal
602 appears as if it is existing in the radio terminal 601, and
this Display SubUnit and the VTR SubUnit is connected through an
internal connection B inside the DVD 605, an isochronous channel X
on the IEEE 1394 bus, and an internal connection A inside the radio
terminal 601. On the other hand, from a viewpoint of the radio
terminal 602, the VTR SubUnit in the DVD 605 appears as if it is
existing in the radio terminal 601, and this VTR SubUnit and the
Display SubUnit is connected through an internal connection D
inside the radio terminal 602, a channel Y on the 5 GHz band radio
LAN, and an internal connection C inside the radio terminal
601.
[0147] Here, O_Plug and I_Plug provided in the DVD 605 and the
radio terminals 601 and 602 are interfaces for carrying out data
transmission and reception with respect to the isochronous channel
on the IEEE 1394 bus, which are defined by the ISO-IEC 61883
protocol. Also, the internal connections A, B, C and D provided in
the DVD 605 and the radio terminals 601 and 602 are connections for
connecting between SubUnits or between SubUnit and Plug in the 1394
nodes or the radio terminals, which are set up or released by the
AV/C protocol. Thus, in order to transfer the MPEG2 data from the
DVD 605 to the radio terminal 602, the transfer of the MPEG2 data
will be commanded after setting up such a communication route using
the ISO-IEC 61883 protocol and the AV/C protocol in the
configuration of FIG. 11. The transfer command will be executed by
the AV/C protocol.
[0148] FIG. 15 shows an exemplary processing sequence for
transferring the MPEG2 data from the DVD 605 to the radio terminal
602 after reserving communication resources as shown in FIG. 14.
Here, it is assumed that the ISO-IEC 61883 protocol is executable
even on the 5 GHz band radio LAN, so that the MPEG2 data
communication on the 5 GHz band radio LAN is transferred through
some communication channel (channel Y in FIG. 14) on the 5 GHz band
radio LAN. It is also assumed that the data transfer processing is
carried out by the Contention Mode of the IEEE 802.11 as the
transfer protocol on the 2.4 GHz band radio LAN and the 5 GHz band
radio LAN. It is also assumed that the radio terminal 602 makes a
connection to the 5 GHz band radio LAN using a procedure as
described in the first embodiment. This processing sequence
proceeds as follows.
[0149] (0) The radio terminal 602 carries out the authentication
processing with the radio terminal 601, and becomes a state in
which communications using the 2.4 GHz band radio LAN are
possible.
[0150] (1) The radio terminal 602 notifies information on SubUnits
in the own terminal to the radio terminal 601, and the DVD 605
notifies information on SubUnits in the own node to the radio
terminal 601.
[0151] (2) The radio terminal 602 requests the radio terminal 601
to disclose information on the SubUnits in the radio terminal
601.
[0152] (3) The radio terminal 601 discloses the VTR SubUnit
actually existing in the DVD 605 as information on the SubUnits in
the own terminal.
[0153] (4) The radio terminal 602 carries out the authentication
processing for the 5 GHz band radio LAN with the radio terminal
601, via the 2.4 GHz band radio LAN, and then makes a connection to
the 5 GHz band radio LAN for which the radio terminal 601 is the
P.C. Here, the MAC address (=Y) used in the 2.4 GHz band radio LAN
is also used as the MAC address in the 5 GHz band radio LAN.
[0154] (5) The radio terminal 602 executes a request for channel
acquisition on the 5 GHz band radio LAN, via the 2.4 GHz band radio
LAN (and the radio terminal 601 acquires the channel Y).
[0155] (6) The radio terminal 602 sets up a data transmission to
the radio channel Y from the O_Plug in the radio terminal 601 and a
data reception from the radio channel Y using the I_Plug in the own
terminal, according to the ISO-IEC 61883 protocol.
[0156] (7) The radio terminal 602 transmits an AV/C command
(Connect command) for connecting between the VTR SubUnit and the
O_Plug that are recognized as existing in the radio terminal 601 by
the internal connection C. At the same time, the Display SubUnit
and the I_Plug in the own terminal are connected by the internal
connection D.
[0157] (8) The radio terminal 601 acquires the isochronous channel
X on the IEEE 1394 bus in response to the Connect command from the
radio terminal 602.
[0158] (9) The radio terminal 601 sets up a data transmission to
the isochronous channel X from the O_Plug in the DVD 605 and a data
reception from the isochronous channel X using the I_Plug in the
own terminal, according to the ISO-IEC 61883 protocol.
[0159] (10) The radio terminal 601 transmits an AV/C command
(Connect command) for connecting between the VTR SubUnit and the
O_Plug existing in the DVD 605 by the internal connection B. At the
same time, the Display SubUnit and the I_Plug in the own terminal
are connected by the internal connection A.
[0160] (11) Upon receiving the AV/C response for the Connect
command, the radio terminal 602 transmits an AV/C command (Play
command) to the VTR SubUnit according to the AV/C protocol.
[0161] (12) The radio terminal 601 transfers the AV/C command (Play
command) transmitted with respect to the VTR SubUnit, to the DVD
605.
[0162] (13) The desired MPEG2 data are transferred from the DVD 605
to the Display SubUnit in the radio terminal 601.
[0163] (14) The radio terminal 601 transfers the transferred MPEG2
data towards the Display SubUnit of the radio terminal 602 which is
the actual data transfer destination, via the 5 GHz band radio
LAN.
[0164] By this series of processing, it becomes possible for the
radio terminal 602 which has only a reception function with respect
to the 5 GHz band radio LAN to receive the video data on the IEEE
1394 bus connected to the 5 GHz band radio LAN. In particular, it
is possible to execute the communication resource processing for
the purpose of transferring wideband data such as MPEG2 data and
the AV control protocol necessary for the MPEG2 data transfer.
[0165] Referring now to FIG. 16 to FIG. 18, the fourth embodiment
of a radio communication system and a radio terminal device
according to the present invention will be described in detail.
[0166] This fourth embodiment is directed to the case of the radio
network in which the 2.4 GHz band radio LAN and the 5 GHz band
radio LAN are operated independently, where both the radio terminal
providing the P.C. function on the 2.4 GHz band radio LAN and the
radio terminal providing the P.C. function on the 5 GHz band radio
LAN are existing on the same IEEE 1394 bus. The example described
here is also directed to the case where the radio terminal on the
radio network downloads image information from a DVD existing on
the IEEE 1394 bus, and in particular the AV control protocol is
executed between this radio terminal and the DVD via the 2.4 GHz
band radio LAN, and the actual image data are received via the 5
GHz band radio LAN.
[0167] The difference between this fourth embodiment and the third
embodiment is that a terminal for carrying out communications on
the 2.4 GHz band radio LAN and a terminal for carrying out
communications on the 5 GHz band radio LAN are different in this
fourth embodiment, and that a protocol for notifying control
information on the 5 GHz band radio LAN that is transmitted via the
2.4 GHz band radio LAN is executed between these terminals.
[0168] In other words, the processing (4) of FIG. 15 for making a
connection to the 5 GHz band radio LAN and the processing (6) of
FIG. 15 for reflecting the request for plug control processing on
the 5 GHz band radio LAN according to the ISO-IEC 61883 protocol
into the 5 GHz band radio LAN side that were carried out by the
radio terminal 601 of FIG. 11 via the 2.4 GHz band radio LAN in the
third embodiment will be executed as a communication protocol
between different radio terminals. It is assumed that the control
message transfer protocol for this purpose is defined in
advance.
[0169] FIG. 16 shows an exemplary configuration of a network system
in this case. It is assumed that the radio LANs are operated
according to the IEEE 802.11 protocol similarly as in the third
embodiment. The network system of FIG. 16 includes a radio terminal
1101 which provides a P.C. function in the 5 GHz band radio LAN
1201, a radio terminal 1103 which has transmission and reception
functions with respect to the 5 GHz band radio LAN, and a radio
terminal 1102 which has only a reception function with respect to
the 5 GHz band radio LAN. In addition, the radio terminal 1102 has
transmission and reception functions with respect to the 2.4 GHz
band radio LAN by which it can communicate with a radio terminal
1106. Moreover, the radio terminal 1101 and the radio terminal 1106
have interfaces with respect to the same IEEE 1394 bus 1203 and are
connected to a TV 1104 and a DVD 1105 via the IEEE 1394 bus.
[0170] This embodiment is also directed to the case where the AV/C
protocol to be executed between the radio terminal and the node on
the IEEE 1394 bus is executed via the 2.4 GHz band radio LAN, and
the MPEG2 data are actually transferred via the IEEE 1394 bus and
the 5 GHz band radio LAN.
[0171] In the following, the case of transferring the MPEG2 data in
the DVD 1105 to the radio terminal 1102 will be described, assuming
that the AV/C protocol is executed between the radio terminal 1102
and the DVD 1105 based on the recognition of the network as shown
in FIG. 14, similarly as in the third embodiment.
[0172] FIG. 17 and FIG. 18 show an exemplary processing sequence
for transferring the MPEG2 data from the DVD 1105 to the radio
terminal 1102 in this case. Here, it is also assumed that the
ISO-IEC 61883 protocol is executable even on the 5 GHz band radio
LAN. It is also assumed that the radio terminal 1102 makes a
connection to the 5 GHz band radio LAN using a procedure as
described in the first embodiment. This processing sequence
proceeds as follows.
[0173] (0) The radio terminal 1102 carries out the authentication
processing with the radio terminal 1106, and becomes a state in
which communications using the 2.4 GHz band radio LAN are
possible.
[0174] (1) The radio terminal 1101 notifies the 1394 interface
address (=A) of the own terminal to the radio terminal 1102. Here,
it is also possible for the radio terminal 1101 to broadcast the
1394 interface address of the own terminal on the 5 GHz band radio
LAN.
[0175] (2) The radio terminal 1102 notifies the 1394 address (=A)
of the radio terminal 1101 notified by the processing (1), to the
radio terminal 1106.
[0176] (3) The radio terminal 1106 confirms that the received 1394
address (=A) exists on the IEEE 1394 bus, and makes an initial
setting indicating that the control messages regarding the 5 GHz
band radio LAN that will be transmitted to the own device (radio
terminal 1106) thereafter are to be transferred to the radio
terminal 1101.
[0177] (4) The radio terminal 1102 notifies information on SubUnits
in the own terminal to the radio terminal 1106, and the DVD 1105
notifies information on SubUnits in the own node to the radio
terminal 1106.
[0178] (5) The radio terminal 1102 requests the radio terminal 1106
to disclose information on the SubUnits in the radio terminal
1106.
[0179] (6) The radio terminal 1106 discloses the VTR SubUnit
actually existing in the DVD 1105 as information on the SubUnits in
the own terminal.
[0180] (7) When the radio terminal 1102 transmits a request for the
authentication processing for the 5 GHz band radio LAN or a request
for a connection (admission) to the 5 GHz band radio LAN for which
the radio terminal 1101 is the P.C., to the radio terminal 1106 via
the 2.4 GHz band radio LAN, the radio terminal 1106 transfers this
authentication request or connection request to the radio terminal
1101, and the authentication request or the connection request of
the radio terminal 1102 is processed at the radio terminal 1101.
Here, the MAC address (=Y1) used in the 2.4 GHz band radio LAN can
be also used as the MAC address in the 5 GHz band radio LAN.
[0181] (8) When the radio terminal 1102 transmits a request for
channel acquisition on the 5 GHz band radio LAN, via the 2.4 GHz
band radio LAN, the radio terminal 1106 transfers this channel
acquisition request to the radio terminal 1101, and the processing
for channel acquisition on the 5 GHz band radio LAN is carried out
at the radio terminal 1101 (and the radio terminal 1101 acquires
the channel Y).
[0182] (9) When the radio terminal 1102 transmits a request for
setting up a data transmission to the radio channel Y from the
O_Plug in the radio terminal 1101 according to the ISO-IEC 61883
protocol, via the 2.4 GHz band radio LAN, the radio terminal 1106
transfers this data transmission set up request to the radio
terminal 1101, and the data transmission set up processing is
carried out at the radio terminal 1101.
[0183] (10) The radio terminal 1102 transmits an AV/C command
(Connect command) for connecting between the VTR SubUnit and the
O_Plug that are recognized as existing in the radio terminal 1106
by the internal connection C, via the 2.4 GHz band radio LAN. At
the same time, the Display SubUnit and the I_Plug in the own
terminal are connected by the internal connection D.
[0184] (11) The radio terminal 1106 acquires the isochronous
channel X on the IEEE 1394 bus in response to the Connect command
from the radio terminal 1102.
[0185] (12) The radio terminal 1106 sets up a data transmission to
the isochronous channel X from the 0_Plug in the DVD 1105 and a
data reception from the isochronous channel X using the I_Plug in
the radio terminal 1101, according to the ISO-IEC 61883
protocol.
[0186] (13) The radio terminal 1106 transmits an AV/C command
(Connect command) for connecting between the VTR SubUnit and the
O_Plug existing in the DVD 1105 by the internal connection B. At
the same time, the Display SubUnit and the I_Plug in the own
terminal are connected by the internal connection A.
[0187] (14) The DVD 1105 carries out the processing corresponding
to the AV/C command transmitted by (13), and then returns an AV/C
response for notifying the processing result. This AV/C response is
transferred from the radio terminal 1106 to the radio terminal 1102
via the 2.4 GHz band radio LAN.
[0188] (15) The radio terminal 1106 transmits an AV/C command
(Connect command) for connecting between the O_Plug and the I_Plug
in the radio terminal 1101.
[0189] (16) The radio terminal 1101 carries out the processing
corresponding to the Av/C command transmitted by (15), and then
returns an AV/C response for notifying the processing result.
[0190] (17) Upon receiving the AV/C response for the Connect
command transmitted by (10), via the 2.4 GHz band radio LAN, the
radio terminal 1102 transmits an AV/C command (Play command) to the
VTR SubUnit that is recognized as existing in the radio terminal
1106.
[0191] (18) The radio terminal 1106 transfers the AV/C command
(Play command) transmitted with respect to the VTR SubUnit, to the
DVD 1105.
[0192] (19) The DVD 1105 carries out the processing corresponding
to the AV/C command transmitted by (18), and then returns an AV/C
response for notifying the processing result. This AV/C response is
transferred from the radio terminal 1106 to the radio terminal 1102
via the 2.4 GHz band radio LAN.
[0193] (20) The desired MPEG2 data are transmitted from the DVD
1105 onto the isochronous channel X.
[0194] (21) The radio terminal 1101 receives data on the
isochronous channel X and transfers this data to the channel Y on
the 5 GHz band radio LAN, such that the received MPEG2 data are
transmitted towards the Display SubUnit in the radio terminal 1102
which is the actual data transfer destination, via the 5 GHz band
radio LAN.
[0195] By this series of processing, it becomes possible for the
radio terminal 1102 which has only a reception function with
respect to the 5 GHz band radio LAN to receive the video data on
the IEEE 1394 bus connected to the 5 GHz band radio LAN. In
particular, even when the 2.4 GHz band radio communication function
and the 5 GHz band radio communication function are existing
independently on the IEEE 1394 bus, it is possible to carry out the
control and the set up of the 5 GHz band radio LAN via the 2.4 GHz
band radio LAN using the initial setting between the 2.4 GHz band
radio communication function and the 5 GHz band radio communication
function. Moreover, it is possible to execute the communication
resource processing for the purpose of transferring wideband data
such as MPEG2 data and the AV control protocol necessary for the
MPEG2 data transfer.
[0196] As described above, according to the present invention, in a
network in which at least a first network and a second network are
used (a home network in which the 2.4 GHz band radio LAN and the 5
GHz band radio LAN are used, for example), a terminal device (a
radio terminal, for example) which is capable of packet
transmission and reception in the second network but which is
capable only of packet reception in the first network can carry out
a procedure necessary in receiving data through the first network
by utilizing the second network, so that this terminal device can
be effectively utilized as a packet receiving node in the first
network without transmitting any packet to the first network from
this terminal device (that is, without requiring a packet
transmission function with respect to the first network in this
terminal device).
[0197] Thus according to the present invention, it becomes possible
to transfer information to a radio terminal having a transmission
and reception interface for the 2.4 GHz band radio LAN and a
reception interface for the 5 GHz band radio LAN from another radio
terminal on the 5 GHz band radio LAN, for example.
[0198] In addition, it is also possible to transmit various data
transferred on the other non-radio network such as the IEEE 1394
bus, for example, by relaying the data transfer at another radio
terminal having a transmission and reception Interface for the 5
GHz band radio LAN, so that it becomes possible to realize the data
communications as if it is connected to the IEEE 1394 bus through a
radio interface.
[0199] Namely, even when the radio terminal has only a reception
function with respect to the 5 GHz band radio LAN, the
authentication/admission processing in the 5 GHz band radio LAN or
the AV control protocol between the radio terminal and the node on
the IEEE 1394 bus can be carried out via the 2.4 GHz band radio
LAN, and the actual data transfer can be carried out via the 5 GHz
band radio LAN, so that the video data on the IEEE 1394 bus can be
received through the 5 GHz band radio interface.
[0200] Consequently, according to the present invention, it is
possible to reduce the cost of the radio terminal using expensive
components for the 5 GHz band radio communication, for example. In
particular, by providing only a reception function among the radio
communication function, and utilizing an inexpensive radio system
for the bidirectional communications, it is possible to reduce the
number of expensive radio components that are required in the
terminal, and thereby reduce the cost of the terminal.
[0201] Note that the video information utilization in the home is
mostly in a form of receiving/displaying video transmitted by a TV
or satellite broadcast for the purpose of watching broadcast
programs. This implies that the most users are likely to only
receive the video information and hardly transmit any video
information. In view of this fact, it is effective to provide only
a reception function in the terminal in order to realize wider
spread of the 5 GHz band radio function to many homes at low cost.
Thus, by providing only a reception function as an expensive radio
function such as the 5 GHz band radio function while also providing
a transmission function using another inexpensive radio function
such as the 2.4 GHz band radio function, it is possible to provide
radio terminals that can receive wideband image data and that can
be easily accepted in the home environment.
[0202] It is to be noted that the above embodiments have been
described for an exemplary case of using the IEEE 1394 bus as a
network other than the radio network, but the present invention is
equally applicable to the case of using a network other than the
IEEE 1394 bus in conjunction with the radio network.
[0203] It is also to be noted that the above embodiments have been
described for an exemplary case of the home network, but the
present invention is equally applicable to a network other than the
home network.
[0204] It is also to be noted that the above described embodiments
according to the present invention may be conveniently implemented
using a conventional general purpose digital computer programmed
according to the teachings of the present specification, as will be
apparent to those skilled in the computer art. Appropriate software
coding can readily be prepared by skilled programmers based on the
teachings of the present disclosure, as will be apparent to those
skilled in the software art.
[0205] In particular, each of the radio terminals of the above
described embodiments can be conveniently implemented in a form of
a software package.
[0206] Such a software package can be a computer program product
which employs a storage medium including stored computer code which
is used to program a computer to perform the disclosed function and
process of the present invention. The storage medium may include,
but is not limited to, any type of conventional floppy disks,
optical disks, CD-ROMs, magneto-optical disks, ROMs, RAMs, EPROMs,
EEPROMs, magnetic or optical cards, or any other suitable media for
storing electronic instructions.
[0207] It is also to be noted that, besides those already mentioned
above, many modifications and variations of the above embodiments
may be made without departing from the novel and advantageous
features of the present invention. Accordingly, all such
modifications and variations are intended to be included within the
scope of the appended claims.
* * * * *