Title:
ASYMMETRICAL MODEM AND ASYMMETRICAL TRANSMISSION SYSTEM USING THE SAME, AND METHOD FOR LOOP-BACK TEST OF THE SYSTEM
Document Type and Number:
Japanese Patent JP3516666
Kind Code:
B2
Abstract:
PROBLEM TO BE SOLVED: To enable testing where the data is transmitted at the maximum speeds, both in the incoming and outgoing directions.
SOLUTION: A downstream cell is generated based on the test data by means of a cell generator 11 of an asymmetrical modem 10, and the generated downstream cell is transmitted to a second asymmetrical modem 20 via a transmission line 30. Each time the second asymmetrical modem receives the cell, it checks the data of the cell by means of a cell comparator 22, and counts the number of error cells among the downstream cells received during a transmission cycle of upstream cells. For the cell data generated by means of a cell generator 25, based on the same test data as used when generating the downstream cells, a bit on a bit position corresponding to the number of error cells is inverted and is returned as an upstream cell to the first asymmetrical modem. Each time the first asymmetrical modem receives the cell, it compares the data of the received cell with the test data, by means of a cell comparator 13. Based on the comparison result, the ratio of the number of error cells to the number of cells transmitted from the its own modem to the second asymmetrical modem is determined by a test control section 14.
Inventors:
Aotani, Yoshihisa
Application Number:
JP2001093158A
Publication Date:
April 05, 2004
Filing Date:
March 28, 2001
Export Citation:
Assignee:
NEC ACCESS TECHNICA LTD
International Classes:
H04L69/40; (IPC1-7): H04L29/14; H04L29/06
Attorney, Agent or Firm:
机 昌彦 （外２名）