Nippon Telegraph and Telephone Corporation

Ntt Corporation

Kazuo Osaka

Toshifumi Miyagi

Hayato Fukuzono

Keita Kuriyama

Yu Ono

Fumiaki Nagase

Hitoshi Hasegawa

Masafumi Yoshioka

Hiroyuki Furuya

Takafumi Hayashi

A wireless communication method according to one embodiment includes:

Wireless communication system, wireless communication method, and transmitter

A wireless quality degradation factor detection method according to an embodiment includes a spectrum generation step of generating a spectrum based on a received radio wave, a determination step of determining whether or not information based on the generated spectrum contains a factor that prevents maintenance of the quality of the received radio wave based on a determination criterion specified in advance, an identification step of identifying the factor that prevents maintenance of the quality of the received radio waves based on the result of the determination and the determination criterion, and an output step of outputting information representing the identified factor.

Method and apparatus for detecting deterioration factor of wireless quality

A wireless communication method according to an embodiment includes converting n+1 signals into n predetermined power signals obtained by setting a C/N to a predetermined value and into n divided signals obtained by setting the C/N to 1/n of a predetermined value and performing division into n, superimposing the n predetermined power signals and the n divided signals that have been converted, non-orthogonally so as to be n multiplexed signals for the n frequency channels, transmitting the n multiplexed signals, receiving n multiplexed signals, demodulating n predetermined power signals from the n multiplexed signals that have been received, creating replica signals of each of the n predetermined power signals, subtracting each of the n replica signals that have been created from each of the n multiplexed signals, and combining the n subtracted signals.

Wireless communication system, wireless communication method, transmitter, and receiver

A congestion control method in an IP telephone system includes acquiring a number of simultaneous calls in one line shared by a plurality of IP telephones, acquiring a call time order corresponding to length of a call time for each call, and controlling a packet discard rate of each call on the basis of the number of simultaneous calls and the call time order. The packet discard rate of each call is set to a predetermined first upper limit value or less. In addition, the packet discard rate is set higher as the call time is longer, and the packet discard rate is set lower as the call time is shorter. Further, the packet discard rate of the latest call having the shortest call time is set to be equal to or less than a predetermined second upper limit value lower than the predetermined first upper limit value.

Congestion control method, congestion control device, and congestion control program

To avoid uniform deterioration of the voice quality of all the calls sharing an IP phone line at a time of congestion. The congestion control method in an IP phone system includes a call state acquisition process of acquiring the number of simultaneous call sessions in one line shared by a plurality of IP phones. A congestion control method further includes a packet loss control process of setting a priority ranking to each call session and dynamically controlling packet loss rates of the call sessions in accordance with the number of the simultaneous call sessions and the priority ranking. In the packet loss control process, the packet loss rate is set lower for call sessions ranked higher in priority, and higher for call sessions ranked lower in priority.

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Musashino, Japan

Kazuo Osaka