摘要:
A multi-radio device system includes a set of sending radio devices and a set of receiving radio devices. Among the sending radio devices is a load-balancing radio device that receives data packets from an originating network. The load-balancing radio device labels data packets with sequence numbers and distributes the labeled data packets among the sending radio devices based on the relative capacities and statuses of those sending radio devices. The sending radio devices transmit the labeled data packets to the receiving radio devices. The receiving radio devices send the labeled data packets to an aggregating radio device within the set of receiving radio devices. The aggregating radio device uses the sequence numbers to ensure that the data packets are forwarded to a destination network in the correct order, extracting original data packets from the labeled data packets before forwarding the original data packets on toward the destination network.
摘要:
A multi-radio device system includes a set of sending radio devices and a set of receiving radio devices. Among the sending radio devices is a load-balancing radio device that receives data packets from an originating network. The load-balancing radio device labels data packets with sequence numbers and distributes the labeled data packets among the sending radio devices based on the relative capacities and statuses of those sending radio devices. The sending radio devices transmit the labeled data packets to the receiving radio devices. The receiving radio devices send the labeled data packets to an aggregating radio device within the set of receiving radio devices. The aggregating radio device uses the sequence numbers to ensure that the data packets are forwarded to a destination network in the correct order, extracting original data packets from the labeled data packets before forwarding the original data packets on toward the destination network.
摘要:
Radios synchronize their timing mechanisms using a timing signal that those radios propagate from one radio to another. Radios that are close to each other transmit only during times that none of the other nearby radios is trying to receive. In one scheme, a “master” radio initiates communication while another “slave” radio responds in a pre-determined manner. The master generates and propagates an inverted timing signal to the slave, which propagates approximately the same inverted timing signal to other radios in the slave's cluster. Each radio can be in one of three different modes: “source,” “auto,” and “recipient” modes. A “source” radio generates a timing signal independently. A “recipient” radio uses a received timing signal and forwards it to other radios. An “auto” radio behaves as a “recipient” radio while a timing signal is detectable, but behaves as a “source” radio if the timing signal is lost.
摘要:
A method and apparatus for decoding a baseband signal of a radio signal removes, from the baseband signal, low-frequency and long-term noise that increases the possibility of decoding errors. The removal of low-frequency and long-term noise is performed by accumulating differences between the actual signal levels of the baseband signal and the expected signal levels for the baseband signal and subtracting the accumulated difference from the baseband signal before decoding. In one scheme, the baseband signal contains a predetermined training sequence of signal levels, where the differences between the actual signal levels of the baseband signal and the expected signal levels for the predetermined training sequence are accumulated. At the end of the training sequence, the accumulated training sequence difference is used as the accumulated difference and subtracted from the baseband signal, thereby providing stable operation for decoding signal levels that follow the training sequence.
摘要:
A method and apparatus are provided that performs timing acquisition for multiple radio terminals. According to one aspect of the present invention the invention includes receiving a sequence of symbols modulated onto a carrier frequency over a channel and demodulating the symbols using a clock frequency. The invention further includes determining a frequency offset of the received symbols with respect to the clock frequency and applying the determined frequency offset to adjust the clock frequency.
摘要:
An image data compression technique is described which utilizes calculating means and a selected series of bit calculating stages having delays, to estimate one or more quantization parameters for such data. The estimation process preferably is iterated a number of times, with the values found through each estimation being used as the trial values for subsequent estimations. In addition, an initial trial value is selected by a data look ahead technique, which assures that its value is within range of the final quantization parameter used to quantize the data. The final quantization parameter insures that the compressed data fits within a predetermined number of encoded data bits to be transmitted or recorded, for example, in a recording medium.
摘要:
The present invention provides methods and systems for allowing a receiver in a (wireless) communication system to synchronize its timing and frequency subsystems in accordance with a received signal. In accordance with one aspect, a method is provided in which a relative time of arrival of sync values provided in a received signal are determined and used to align the receiver's reference signal(s) accordingly. Other aspects of the invention will become apparent from the detailed description of exemplary embodiments that follows.
摘要:
In a data compression process such as employed to compress video or other data, it is preferable not to compress the image data representative of the video image in a sequential format, or to take the data from the same area of the image. To equalize the information content of the data prior to compression, the present shuffling/deshuffling technique divides the video image into a multitude of image representing blocks, and selects a predetermined number of the image blocks from different spatial locations in the image, to form a succession of data sets representative of the video image information. That is, the selection of the image representing blocks is such that the information content (complexity) in each data set is similar to the information content in each other data set and further similar to the average information content of the entire video image. Thus, the subsequent quantizing factor used in the compression process will tend to be similar for successive data sets, thereby reducing any distortion introduced by the compression process. The image representing blocks may be formed of sequentially scanned blocks of the video image, or of transform coefficients representing similar blocks of the video image. The shuffled data is deshuffled by the inverse process.
摘要:
Editing of information recovered from a relatively high speed communications medium such as a communications channel or magnetic tape often times allows only a portion of the information to be recovered. Storing information in complete segments from which portions of an image, called "snatches," may be recovered helps. An image signal is compressed in such a way that a snatch can be used during decompression to reconstruct a recognizable image from less than all the information that defines the image-thereby giving rise to the notion of a partially reconstructed image. The image information comprises several pixel data blocks with each block including sufficient pixel image data to reconstruct a portion of the image. The pixel data blocks are discrete cosine transformed ("dct") to generate a set of dct coefficient blocks. The dct coefficients for a group of dct coefficient blocks are rank ordered from highest visibility coefficient (corresponding to lowest dct frequency coefficient) to lowest visibility coefficient (corresponding to highest dct frequency coefficient), and then are quantized, entropy encoded, and formatted together with synchronization information and parity checks from the error correction encoding before being transmitted on a channel or recorded on magnetic tape. A decompression and reconstruction arrangement functions essentially as the inverse of the compression arrangement. It is during the decompression that snatches are retrieved and used to reconstruct a partial (video) image by using some but not necessarily all the dct coefficients that define the image.
摘要:
When a signal-to-noise ratio affecting radio communication becomes sufficiently low, then the data transmission rate is responsively decreased in compensation. The signal-to-noise ratio of the communication link is thereby increased. Data for multiple different services is transmitted in data packets between two radios. By allocating one part, or time slot, of the data packet's payload to one service, and allocating another part, or time slot, of the data packet's payload to another service, communications sessions for multiple services can be maintained concurrently. Services are prioritized relative to each other. In case the signal-to-noise ratio becomes too low, data packet portions that are related to lower-priority services can be omitted from some data packets before those data packets are transmitted. Data remaining in the packet can be sent at a reduced data transmission rate without causing the quality of service for the remaining packets to fall below the minimum required level.