Matsushita Electric Industrial Co., Ltd.

Matsushita Electric Ind., Ltd.

Mikio Shimazu

Seiji Horii

Akinori Tatsumi

Mitsuhiro Suzuki

Takako Hirose

Hiroaki Iwamoto

Hisashi Inoue

Shiro Iwasaki

Masayuki Kumazawa

Shuichi Ojima

Takashi Katsura

Yuji Shimizu

Eiichi Hatae

Takuya Kobayashi

Masahide Morozumi

Takayuki Hamaki

Jun Yamaguchi

Akio Miyazaki

A packet transmission apparatus transfers arriving packets directly to a highest-priority queue under non-congestion conditions, and classifies the priority of a packet only on the existence of congestion. In one embodiment, non-congestion is determined when all queues are empty. In another embodiment, congestion or non-congestion is determined by upper and lower thresholds on the total number of packets in all queues. The ability to omit classifying incoming packets in the non-congestion condition improves processing speed, and eliminates the need for re-queuing or packet-replacing operations.

Apparatus and method for packet transmission

An apparatus for embedding information in a signal includes a band dividing device, a block divider, a quantization portion, a signal replacement portion, a mean difference addition portion, a mean calculation portion, and a band synthesis portion. The band dividing device divides the signal into transform coefficients over a plurality of frequency bands. The block divider divides one frequency band into a plurality of blocks in accordance with a previously determined block size. The quantization portion calculates for each block, a mean value M of the transform coefficients in the block, and subjects the mean value M to linear quantization, using a previously determined quantization step-size Q to calculate a quantization value. The signal replacement portion replaces the quantization value for each block, on the basis of the quantization value and the value of the information to be embedded. The mean difference addition portion subjects the replaced quantization value, for each block, to inverse linear quantization using the quantization step-size Q to calculate a mean value M&prime;, and adds a difference DM between the mean value M&prime; and the mean value M to all the transform coefficients in the block. The mean calculation portion calculates a mean value LM of the transform coefficients in the frequency band after the addition of the difference DM. The band synthesis portion reconstructs a signal in which the information has been embedded using the frequency band after the addition of the difference DM and the other frequency bands.

Apparatus for and method of embedding and extracting digital information and medium having program for carrying out the method recorded thereon

In a radio communication system for performing digital radio communications by using time-division multiplexed time slots, a first personal station receives its user's speech through the microphone, converts it into audio data, and transmits them on time slots to a second personal station. On the other hand, the first personal station receives non-audio data from the data processor connected with the second personal station and stores. When the audio data amount inputted to the first personal station in a unit time period is lower than a threshold and the communications between the first personal station and the second personal station are put in a silence condition, the first personal station transmits non-audio data on times slots to the second personal station. When the communications return to a sound condition, audio data transmission is restored. Whether each time slot carries audio data or non-audio data is designated by an identifier which is written in a predetermined field of each time slot.

Digital radio communication system with efficient audio and non-audio

The caller personal station of the present invention includes the following units: a channel search unit for scanning the plurality of communication channels to search for an unoccupied channel and regarding the unoccupied channel as a multicast channel; and a simultaneous call unit for repeatedly transmitting a simultaneous call frame on the multicast channel for a first predetermined time period, the simultaneous call frame indicating a simultaneous call to the other personal stations; a multicast unit for transmitting multicast frames on the multicast channel when a second predetermined time period has passed, the multicast frames containing data to be multicast. On receiving the simultaneous call frame by sequentially sensing the plurality of communication channels, the other personal stations enter a receiving state of multicast frames on the multicast channel. The simultaneous call unit includes the following units: a simultaneous call frame generation unit for generating the simultaneous call frame; a transmission timer for counting the first predetermined time period and generating a time-out; and a simultaneous call frame transmission unit for repeatedly transmitting the simultaneous call frame on the multicast channel from a start of counting the predetermined time period until the time-out is generated.

Caller personal station equipped with simultaneous call function and

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Iizuka, Japan

Mikio Shimazu