Multiplex communications – Communication over free space – Repeater
Reexamination Certificate
1999-02-17
2003-03-11
Trost, William (Department: 2683)
Multiplex communications
Communication over free space
Repeater
C455S012100
Reexamination Certificate
active
06532219
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a mobile satellite communication system, and more particularly to a transmission reservation in a mobile satellite communication system which uses a randomly access system and a reserving system.
2. Description of the Related Art
A communication system which utilizes a randomly access control system and a reserving system described below is well known as a communication system in a mobile satellite communication system for performing a communication between a mobile station and a base station apparatus
1
through a satellite.
At first, a mobile station trying to perform a communication transmits a short burst transmission having a long guard bit pattern to a base station apparatus
1
through an upward control channel. Usually, a plurality of mobile stations are assigned to the upward control channel. Thus, there may be a possibility that competition relation for the use of the upward control channel occurs between the respective mobile stations. For the purpose of arbitration the competition relation, a collision control bit pattern is transmitted from the base station apparatus
1
to each mobile station through a downward control channel. The collision control bit pattern includes an I/B (Idle/Busy) flag indicating whether or not the transmission can be performed by use of the upward control channel. Each mobile station always monitors the collision control bit pattern transmitted through this downward control channel. Only when the I/B flag of the collision control bit pattern is set in an “I” state of transmission permission, the short burst transmission is transmitted, and further a clocking operation of a timer is started.
Upon reception of this short burst transmission, the base station apparatus
1
sends a partial echo signal (hereafter, to be referred to as a PE signal) back to the mobile station. The transmission of the short burst transmission from the mobile station to the base station apparatus
1
is ended in this way. If the transmission data from the mobile station to the base station apparatus
1
can be accommodated in the short burst transmission, the transmission from the mobile station to the base station apparatus
1
is ended at this time.
When the I/B flag of the collision control bit pattern is set to the “I” state of transmission permission, the short burst transmission may be often transmitted by a plurality of mobile stations at the same time. In this case, the receiving operation is performed in the base station apparatus
1
, in a condition that the short burst transmissions from the plurality of mobile stations collide with each other. As a result, an error is detected in a CRC check operation to the received short burst transmissions. For this reason, the base station apparatus
1
treats the short burst transmissions from the respective mobile stations as non-reception.
On the other hand, the mobile station carries out the clocking operation of the timer and after the short burst transmission. The mobile station determines that the short burst transmission fails, when the timer is set to the state of time-out without any reception of the PE signal from the base station apparatus
1
after the short burst transmission. Then, the mobile station again tries the short burst transmission.
The above-mentioned description gives the communication between the mobile station and the base station apparatus
1
when the data transmitted by the mobile station can be accommodated in the single short burst transmission.
On the contrary, there may be a case in which the transmission data from the mobile station to the base station apparatus
1
is long so that the transmission data cannot be accommodated in the single short burst transmission. In this case, the base station apparatus
1
makes a reservation for use of the upward control channel by the mobile station having transmitted the short burst transmission for transmission of subsequent data. Then, the base station apparatus
1
transmits a collision control bit pattern including the PE signal indicative of the specification data identifying the above mobile station to the mobile station through the downward control channel. Upon reception of this PE signal, the mobile station transmits a long burst transmission including the subsequent data through the upward control channel.
The above-mentioned description gives the communication from the mobile station to the base station apparatus
1
by use of the reserving system.
FIGS. 1A-1
and
1
A-
2
, to
1
G-
1
to
1
G-
2
are time charts showing an actual example of a procedure of reserving the upward control channel in the mobile satellite communication system as mentioned above. In this mobile satellite communication system, the communication between the base station apparatus
1
and the mobile station is performed in accordance with a time divisional process. Each mobile station can carry out the transmission to the base station apparatus
1
through the upward control channel, by use of units obtained by dividing a time axis into predetermined time lengths. Moreover, the base station apparatus
1
can use each unit to thereby carry out the transmission through the downward control channel to each mobile station.
In the example shown in
FIGS. 1A-1
and
1
A-
2
, to
1
G-
1
to
1
G-
2
, reservations of the upward control channel are made between the base station apparatus
1
and mobile stations A and B. In this example, it is supposed that a transmission delay between each mobile station and the base station apparatus
1
is four frames (one frame is a time length corresponding to one unit).
In
FIGS. 1A-1
and
1
A-
2
, to
1
G-
1
to
1
G-
2
, when receiving the collision control bit pattern through the downward control channel at a unit No.
0
, the mobile station A requesting the transmission to the base station apparatus
1
determines whether or not an I/B flag of this collision control bit pattern indicates “I” or “B”. In this example, the I/B flag is set to the “I” state of transmission permission. Accordingly, the mobile station A transmits a short burst transmission
1
/
6
A at a unit NO.
2
. After this short burst transmission, the mobile station A starts a clocking operation of a radio channel connection failure timer.
The base station apparatus
1
receives this short burst transmission
1
/
6
A from the mobile station A at a unit NO.
6
delayed from the unit NO.
2
by the four frames. The base station apparatus
1
detects existence of long burst transmissions following the short burst transmission from the data of this received short burst transmission
1
/
6
A. At this time, the base station apparatus
1
transmits PE signals PEA
1
, to PEA
5
in which the number thereof corresponds to this subsequent long burst transmissions. Further, the base station apparatus
1
carries out transmission reservation management of the long burst transmissions from the mobile station A.
On the other hand, the mobile station A carries out the clocking operation of the radio channel connection failure timer, after the short burst transmission, as mentioned above. If the mobile station A does not receive any PE signal designating the mobile station A until the time-out of this radio channel connection failure timer, the mobile station A recognizes it as “radio channel connection failure”. Then, the mobile station A voluntarily ends a reception waiting process of the PE signal, and then carries out a retransmission process of again transmitting the short burst transmission.
However, in this example, the PE signals PEA
1
to PEA
5
are transmitted from the base station apparatus
1
to the mobile station A through the downward control channel. The first PE signal PEA
1
, is received by the mobile station A at a unit NO.
12
prior to the time-out of the timer. Accordingly, the mobile station A stops the radio channel connection failure timer, and then transmits a long burst transmission
2
/
6
A at a unit NO.
14
.
In this example, since continuously receiving th
Foley & Lardner
NEC Corporation
Rampuria Sharad
Trost William
LandOfFree
Transmission reservation in mobile satellite communication... does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Transmission reservation in mobile satellite communication..., we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Transmission reservation in mobile satellite communication... will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-3011512