Wireless communication apparatus and wireless communication method

• US 9,136,976 B2
• Filed: 08/30/2010
• Issued: 09/15/2015
• Est. Priority Date: 09/04/2009
• Status: Expired due to Fees

• Current Assignee: Sony Corporation (Sony Group Corp.)
• Original Assignee: Sony Corporation (Sony Group Corp.)
• Inventors: Nakamura, Hitoshi, Shigei, Hiroyuki, Yata, Haruhiko, Itagaki, Takeshi, Yamaura, Tomoya, Honma, Katsunori, Kawai, Nobuaki, Kamimura, Hidekazu
• Primary Examiner(s): Patel, Parth
• Application Number:
  US13/392,755
• Publication Number:
  US 20120155518A1
• Time in Patent Office: 1,842 Days
• Field of Search: 375/219, 375/295, 375/227, 375/296, 375/224
• US Class Current: 1/1
• CPC Class Codes: H04L 1/0007 by modifying the frame length
• CPC Class Codes: H04L 27/2602 Signal structure
• CPC Class Codes: H04L 27/26035 Maintenance of orthogonality, e.g. for signals exchanged between cells or users, or by using covering codes or sequences using different training sequence per antenna H04B7/0684; code allocation H04J13/16
• CPC Class Codes: H04L 27/2626 Arrangements specific to the transmitter only
• CPC Class Codes: H04L 27/2647 Arrangements specific to the receiver only equalisation H04L27/01
• CPC Class Codes: H04L 47/36 by determining packet size, e.g. maximum transfer unit [MTU]
• CPC Class Codes: H04W 24/00 Supervisory, monitoring or testing arrangements
• CPC Class Codes: H04W 28/0231 based on communication conditions dynamic wireless traffic scheduling definition based on channel quality criteria H04W72/54
• CPC Class Codes: H04W 28/0284 detecting congestion or overload during communication monitoring arrangements H04L43/00
• CPC Class Codes: H04W 28/04 Error control
• CPC Class Codes: H04W 28/06 Optimizing the usage of the radio link, e.g. header compression, information sizing , discarding information system modifying transmission characteristic according to link quality by modifying frame length H04L1/0007; dynamic adaptation of the packet size for flow control or congestion control H04L47/365
• CPC Class Codes: H04W 28/18 Negotiating wireless communication parameters
• CPC Class Codes: H04W 8/04 Registration at HLR or HSS [Home Subscriber Server]
• CPC Class Codes: H04W 84/12 WLAN [Wireless Local Area Networks]

Abstract

[Object] To prevent or reduce the degradation in transmission characteristics caused by fast fading (fluorescent lamp interference) to achieve optimized throughput.

[Solution] A process for detecting fast fading (fluorescent lamp interference) is performed (ST2). Fast fading is detected by, for example, detecting a variable light source whose frequency is twice the frequency of an alternating current power supply. When fast fading is detected, a frame length update process is performed (ST3, ST4). In the case of “subject transmission” in which the subject apparatus is the transmitter of a data frame, the setting of the maximum number of aggregations in frame aggregation (A-MPDU, A-MSDU) is changed to “the recommended maximum number of aggregations”. “The recommended maximum number of aggregations” is set in advance so that the UDP throughput can be maximized under the conditions where fast fading has occurred. In the case of “subject reception” in which the subject apparatus is the receiver of a data frame, the subject apparatus sends a request message for limiting the maximum transmission length to the communication counterpart apparatus.

Claims

1. A wireless communication apparatus comprising:

a data transmitter that wirelessly transmits a data frame to a communication counterpart apparatus, the data frame being configured by combining a plurality of packets in accordance with A-MPDU (Aggregate MAC Protocol Data Unit) type of packet aggregation or A-MSDU (Aggregate MAC Service Data Unit) type of packet aggregation; and

a data frame limiter that

(i) detects whether fast fading is present, wherein the fast fading is detected based on measured maximum throughput with respect to maximum transmission length receivable at the communication counterpart apparatus, the measured maximum throughput being obtained by transmitting a test data frame and sequentially increasing a maximum number of aggregations until the maximum transmission length receivable at the communication counterpart apparatus is determined, and wherein detecting whether fast fading is present occurs when a subsequent measured throughput is less than the measured maximum throughput, and

(ii) in the event a detection result thereof indicates that the fast fading is present, performs a frame length update process in which a maximum number of packets of the data frame transmitted by the data transmitter is changed to a recommended maximum number, and in the event the detection result thereof indicates that the fast fading is not present, does not perform the frame length update process.

2. The wireless communication apparatus according to claim 1, wherein the fast fading is fading caused by a fluorescent lamp that discharges with a frequency of occurrence that is twice a frequency of an alternating current power supply.

3. The wireless communication apparatus according to claim 2, wherein the fast fading is detected by detecting a variable light source having a frequency that is twice the frequency of the alternating current power supply using an optical demodulator that uses a photoelectric conversion element.

4. The wireless communication apparatus according to claim 1, wherein the fast fading is detected using a measured signal-to-noise ratio, in accordance with a result of comparison between a packet error rate estimated using a relationship between a signal-to-noise ratio and a packet error rate under conditions of no fast fading and a measured packet error rate.

5. The wireless communication apparatus according to claim 1, wherein the fast fading is detected based on a measured packet error rate of a packet at an individual position in the data frame.

6. The wireless communication apparatus according to claim 1, wherein the data transmitter transmits the data frame using a multi-carrier method, and the fast fading is detected based on a change in a pilot signal which is monitored over the entirety of a received data frame.

7. The wireless communication apparatus according to claim 1, wherein data included in the packets has been convolutionally encoded, and the fast fading is detected based on a path metric obtained in Viterbi decoding of each packet in a received data frame.

8. The wireless communication apparatus according to claim 1, wherein the fast fading is detected based on a measured bit error rate of each of a plurality of blocks into which a received data frame is divided.

9. The wireless communication apparatus according to claim 1, wherein the data frame limiter enables the recommended maximum number of packets of the data frame to be changed by a user operation.

10. A wireless communication method comprising:

a data transmitting step of wirelessly transmitting a data frame to a communication counterpart apparatus, the data frame being configured by combining a plurality of packets in accordance with A-MP DU (Aggregate MAC Protocol Data Unit) type of packet aggregation or A-MSDU (Aggregate MAC Service Data Unit) type of packet aggregation; and

a data frame limiting step of detecting whether fast fading is present, wherein detecting the fast fading is based on measured maximum throughput with respect to maximum transmission length receivable at the communication counterpart apparatus, the measured maximum throughput obtained by transmitting a test data frame and sequentially increasing a maximum number of aggregations until the maximum transmission length receivable at the communication counterpart apparatus is determined, and wherein fast fading is detected when a subsequent measured throughput is less than the measured maximum throughput,

in the event a detection result thereof indicates that the fast fading is present, performing a frame length update process in which a maximum number of packets of the data frame transmitted by the data transmitter is changed to a recommended maximum number, and

in the event the detection result thereof indicates that the fast fading is not present, not performing the frame length update process.