35results about How to "Efficient retransmission" patented technology

The present invention provides a data transmitting method with hybrid automatic repeat request in multi-carrier system. In this method, the signal-to-noise ratios of respective sub-carriers are compared with a threshold, the data on the sub-carriers having the signal-to-noise ratios lower than the threshold are selectively retransmitted by mapping these data onto the sub-carriers having the good channel conditions, and then the retransmitted data are combined hybrid-automatically in the receiver of the opposite terminal. By using the method the system throughput can be enhanced effectively without impairing the bit error rate of the system.

A method for an Automatic Repeat reQuest (ARQ) at a receiver in a Multiple Input Multiple Output (MIMO) system wherein when a received packet is erroneous and the erroneous packet is received from the weakest antenna in a Space Multiplexing (SM) mode, a first smallest number of retransmissions is computed to acquire a Signal to Noise Ratio (SNR) within or above an Adaptive Modulation and Coding (AMC) level. When the first number of the retransmissions is greater than a threshold, the sender is requested to retransmit the packets from the strongest antenna in the SM mode and when the first number of the retransmissions is smaller than the threshold, the sender is requested to retransmit the packets from the weakest antenna in the SM mode.

The invention discloses a video frame structure and D2D (Device-to-Device) communication based video multicast method. The video frame structure and D2D communication based video multicast method comprises steps that a base station announces a video multicast service, and all the interested users in a cell join in the service to form a multicast cluster; the base station carries out video stream multicast for the users in the cluster by regarding the transmission time of one basic unit GOP (Group of Pictures) in a video code as a cycle; the users check received information and report sequence numbers of frames having packet loss in the GOP to the base station after the multicast sub time slot is ended; the base station after receiving feedback information of the users establishes a sequence list based on the priorities of to-be-restored frames and establishes a CQI matrix of a D2D link between target frames ACK-devices and NACK-devices; relay selection and grouping are performed based on the CQI matrix and the time Tm required for transmission of the target frame m is calculated; and after the transmission is finished, the sequence number of the current target frame in the sequence list is deleted. The video frame structure and D2D communication based video multicast method efficiently overcomes the problem that the multicast rate in the multimedia multicast is always affected by the worst fading channel in the cluster, and greatly improves the video quality within limited spectrum resources from the perspective of the user.

A data transmitter transmitting a data packet containing identifier information including a kind of data, a sequence of data, and / or a packet generating sequence. A receiver extracting a packet number and the identifier information for an error-receipt occurring data packet based upon the identifier information recorded in a header of the packet, generating retransmission control information, such as retransmission times and priority, based on the extracted packet number and the identifier information and transmitting the retransmission control information to the transmitter of the packet. The retransmitting the error-occurring data packet according to the received retransmission control information. The number of retransmissions and the retransmission priority can be varied according to characteristics of the transmitted data, so that retransmissions is suitable for the characteristics of the data and to more stably receive the data that is more influential to the restoration of the data.

A retransmission method and apparatus in a multi-hop broadband wireless communication system are provided, in which if there is a failed data block among data blocks received from a source node, a Relay Station (RS) transmits a feedback message requesting retransmission of the failed data block to the source node, transmits a successfully received data block to a destination node, receives a retransmitted data block for the failed data block from the source node, transmits the received retransmitted data block to the destination node, receives from the destination node a feedback message about data blocks transmitted to the destination node, and transmits the feedback message to the source node.

A retransmission control method is provided. In the method, all base stations perform error judgment for a signal sent from a mobile station 1. Then, first and second base stations send results of error judgment to a third base station which is a communication partner of the mobile station 1. The third base station sends NACK for requesting retransmission to the mobile station 1 only when every result of error judgment of the first and second base stations indicates that there is an error.

A data transmitter transmitting a data packet containing identifier information including a kind of data, a sequence of data, and / or a packet generating sequence. A receiver extracting a packet number and the identifier information for an error-receipt occurring data packet based upon the identifier information recorded in a header of the packet, generating retransmission control information, such as retransmission times and priority, based on the extracted packet number and the identifier information and transmitting the retransmission control information to the transmitter of the packet. The retransmitting the error-occurring data packet according to the received retransmission control information. The number of retransmissions and the retransmission priority can be varied according to characteristics of the transmitted data, so that retransmissions is suitable for the characteristics of the data and to more stably receive the data that is more influential to the restoration of the data.