Detailed Description Of The Invention About Pdu

Besides data field, pdu 210 at least further includes fields such as a sequence number 212, a data length reset bit 214, and a length field 216. The sequence number 212 is used to record the sequence for transmitting each pdu 210 between the transmitting terminal 110 and the receiving terminal 120. The data length reset bit 214 is a field of 1-bit divided from the currently existed HE field (not shown in FIG. 2A), and the field 214 is also referred to as an R field.

When the data length reset bit is set as 0, it indicates that the pdu length does not need to be changed, and the original length of pdu 210 is taken as a predetermined pdu 210 length for receiving; otherwise, it indicates that the receiving terminal 120 needs to change the predetermined pdu length for receiving. When the receiving terminal 120 found that the data length reset bit of pdu 210 is 1, the records of the length field 216 of the pdu 210 is further looked up, so as to obtain the updated length of pdu 210.

The fields of pdu 220 at least include a sequence number 222, a data message receiving state field 224, and a super field (SUFI) 226. The sequence number 222 is used to determine the sequence for transmitting the pdu 220. The data message receiving state field 224 is used to record that the transmitting state of the pdu 210 is successful or failure, and whether it requires retransmitting pdu 210 or not. It shall be noted that, after receiving the pdu 210, the receiving terminal 120 detects whether an error occurs to the pdu 210 or not, and calculates a bit error rate (ber) and a Block Error Rate (BER) of the pdu 210. The receiving terminal 120 may record the ber or the BER in the SUFI field 226 of the pdu 220. The BER is obtained through an equation, e.g., BER=(1-(1-ber)pdu length), which is not limited in this embodiment.

Furthermore, the transmitting terminal 110 may also actively send a request for changing the pdu length. After receiving the retransmission request from the receiving terminal 120, the transmitting terminal 110 not only sends out the retransmitted pdu, but also calculates and measures a retransmission rate, and if the rate is changed, the transmitting terminal 110 calculates an appropriate pdu length according to the ber or the BER fed back by the receiving terminal 120. For example, the transmitting terminal 110 records the number of the retransmitted first data message pdu within 1 minute, and supposing 10 first data message pdus need to be retransmitted within 1 minute, a retransmission rate is calculated as 0.67 pdu/Sec; now supposing the number of the first data message pdus for being retransmitted within 1 minute is dramatically increased to 100, the retransmission rate is about 6.7 pdu/Sec, and the transmitting terminal 110 is triggered to the adjust the pdu length after knowing that the retransmission rate is dramatically changed.

The data acknowledgement message pdu fed back from the receiving terminal 120 is attached with the information such as the ber or the BER of the previous data message pdu, and the transmitting terminal 110 calculates an appropriate pdu length according to the error message information included in the data acknowledgement message. Supposing the calculated reasonable pdu length should be one tenth of the original pdu length, the transmitting terminal 110 defines one tenth of the original pdu length as a new third data message pdu for transmitting data. Similarly, the transmitting terminal 110 further sets the data length reset bit in the third data message pdu as 1 while transmitting data with the third data message pdu, and marks the package length of the third data message pdu in the changed pdu length field 232, so as to inform the receiving terminal 120 to take the third data message pdu length as the predetermined pdu length for receiving.

By: alina9911

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Cixi Jinchi Plastic & Rubber Electric Appliances Factory is specializing in the production of pdu socket, floor socket and mobile power outlet.