Radio LAN data transmission system, radio LAN data transmission method, and computer product

• US 7,280,507 B2
• Filed: 02/19/2004
• Issued: 10/09/2007
• Est. Priority Date: 07/15/2003
• Status: Expired due to Fees

• Current Assignee: Fujitsu Limited
• Original Assignee: Fujitsu Limited
• Inventors: Nagano, Yuji, Ishii, Yuji, Ichiyanagi, Kazuhiro, Inomoto, Kazuyuki, Kusumoto, Akiko, Takeshita, Naoyuki, Miyajima, Shinichirou, Eguchi, Katsuhiro
• Primary Examiner(s): TAYLOR, BARRY W
• Application Number:
  US10/780,577
• Publication Number:
  US 20050013265A1
• Time in Patent Office: 1,328 Days
• Field of Search: 370/328, 370/338, 370/331, 370/389
• US Class Current: 370/331
• CPC Class Codes: H04W 36/02 Buffering or recovering information during reselection ; Modification of the traffic flow during hand-off

Abstract

If a radio LAN apparatus moves from a communication range of a first access point to a communication range of a second access point, and if communication link between the radio LAN apparatus and the first access point is broken, a memory control section stops transmitting data to the first access point. At this time, data to be transmitted to the first access point are not deleted from memory. After the radio LAN apparatus enters the communication range of the second access point, the memory control section resumes transmission of the data stored in the memory. Thereafter, the next data are transmitted. Thus, the data is transmitted in proper sequence.

Claims

1. A radio LAN data transmission system, comprising:

a host station, a relay station having a plurality of access points, and a mobile station having a radio LAN apparatus that transmits data to and receives data from the host station via the relay station, wherein the radio LAN apparatus includes

a memory unit that temporarily stores transmission data that is data to be transmitted to an access point; and

a memory control unit that provides a control to store the transmission data in the memory unit at the time of switching from one access point to another access point, and to transmit the transmission data to the another access point when the radio LAN apparatus establishes a communication link with the another access point;

wherein a desired one of the access points includes a storage unit that temporarily stores input data; and

a data smoothing unit that smoothes the input data to generate output data while the input data is being read from the storage unit and each access point includes;

a memory monitoring unit that outputs a completion signal to an access point other than the one access point, when reading of all the data stored in the storage unit has finished; and

a completion signal detecting unit that detects a completion signal output from a memory monitoring unit of an access point other than the one access point.

2. The radio LAN data transmission system according to claim 1, wherein the data smoothing unit outputs the output data at a transmission speed that is different from a transmission speed at which the input data is read.

3. The radio LAN data transmission system according to claim 2, wherein the data smoothing unit outputs the output data at a transmission speed that is lower than a transmission speed at which the input data is read.

4. The radio LAN data transmission system according to claim 1, wherein a desired one of the access point includes:

a packet number detecting unit that detects a first packet number that is a packet number of data transmitted from an access point other than the one access point and a second packet number that is a packet number of data transmitted from the radio LAN apparatus;

a packet number comparing unit that compares the first packet number and the second packet number, and generates a packet number result; and

a transmission data control unit that controls a sequence of transmitting the transmission data, based on the packet number result.

5. The radio LAN data transmission system according to claim 1, wherein a desired one of the access point includes:

a time stamp detecting unit that detects a first time stamp that is a time stamp of data transmitted from an access point other than the predetermined access point and a second time stamp that is a time stamp of data transmitted from the radio LAN apparatus;

a time stamp comparing unit that compares the first stamp and the second time stamp, and generates a time stamp result; and

a transmission data control unit that controls a sequence of transmitting the transmission data, based on the time stamp result.

6. A radio LAN data transmission system, comprising:

a host station, a relay station having a plurality of access points, and a mobile station having a radio LAN apparatus that transmits data to and receives data from the host station via the relay station, wherein the radio LAN apparatus includes

a memory unit that temporarily stores transmission data that is data to be transmitted to an access point; and

a memory control unit that provides a control to store the transmission data in the memory unit at the time of switching from one access point to another access point, and to transmit the transmission data to the another access point when the radio LAN apparatus establishes a communication link with the another access point;

wherein each access point includes;

a storage unit that temporarily stores input data;

a data smoothing unit that smoothes the input data to generate output data while the input data is being read from the storage unit;

a memory monitoring unit that outputs a completion signal to an access point other than the one access point, when reading of all the data stored in the storage unit has finished; and

a completion signal detecting unit that detects a completion signal output from a memory monitoring unit of an access point other than the one access point.

7. The radio LAN data transmission system according to claim 6, wherein the data smoothing unit outputs the output data at a transmission speed that is different from a transmission speed at which the input data is read.

8. The radio LAN data transmission system according to claim 7, wherein the data smoothing unit outputs the output data at a transmission speed that is lower than a transmission speed at which the input data is read.

9. The radio LAN data transmission system according to claim 6, wherein a desired one of the access point includes:

a packet number detecting unit that detects a first packet number that is a packet number of data transmitted from an access point other than the one access point and a second packet number that is a packet number of data transmitted from the radio LAN apparatus;

a packet number comparing unit that compares the first packet number and the second packet number, and generates a packet number result; and

a transmission data control unit that controls a sequence of transmitting the transmission data, based on the packet number result.

10. The radio LAN data transmission system according to claim 6, wherein a desired one of the access point includes:

a time stamp detecting unit that detects a first time stamp that is a time stamp of data transmitted from an access point other than the predetermined access point and a second time stamp that is a time stamp of data transmitted from the radio LAN apparatus;

a time stamp comparing unit that compares the first stamp and the second time stamp, and generates a time stamp result; and

a transmission data control unit that controls a sequence of transmitting the transmission data, based on the time stamp result.

11. A radio LAN data transmission method of transmitting data between a mobile station having a radio LAN apparatus and a host station, via a relay station having a plurality of access points, comprising:

temporarily storing transmission data in the radio LAN apparatus;

detecting whether a link between the radio LAN apparatus and any one of the access points is established;

reading the transmission data stored when it is detected at the detecting that a link between the radio LAN apparatus and any one of the access points has been established

temporarily storing data acquired by the access point in the access point; and

reading the data stored and then smoothing the data;

detecting an amount of data left unread in the access point;

generating a reading completion signal when it is detected at the detecting that the amount is zero; and

starting the transmission of the data, from the access point that receives the reading completion signal.

12. A computer-readable storage including a program for controlling a computer to executes data transmission between a mobile station having a radio LAN apparatus and a host station, via a relay station having a plurality of access points, the program making a computer execute:

temporarily storing transmission data in the radio LAN apparatus;

detecting whether a link between the radio LAN apparatus and any one of the access points is established;

reading the transmission data stored when it is detected at the detecting that a link between the radio LAN apparatus and any one of the access points has been established

temporarily storing data acquired by the access point in the access point; and

reading the data stored and then smoothing the data;

detecting an amount of data left unread in the access point;

generating a reading completion signal when it is detected at the detecting that the amount is zero; and

starting the transmission of the data, from the access point that receives the reading completion signal.