208 results about "Backward channel" patented technology

A method for controlling errors in a wireless link layer using a simultaneous multiple copy scheme and an adaptive forward error correction (FEC) scheme in a wideband wireless communication is provided. The method for controlling errors in a link layer in wideband wireless communication using an automatic repeat request (ARQ) scheme, in which a wideband wireless channel is used for communication between a first node and a second node, includes the steps of (a) estimating the error ratio of a forward (a direction in which a cell is transmitted from the first node to the second node) channel using the state of a backward (a direction in which a cell is transmitted from the second node to the first node) channel, and transmitting a cell, in which a forward error correction (FEC) code having an encoding ratio that varies depending on the estimated error ratio is included in a protocol data unit (PDU) of a wireless link layer, through the forward channel and (b) re-transmitting the copy of a cell transmitted in the step (a), when feedback information that indicates that an error exists in the cell transmitted in the step (a) is received through the backward channel. It is possible to reduce the number of times of re-transmission by improving the probability of correcting forward errors using more error controlling bits as the state of the channel is worse and to minimize the waste of resources using less error controlling bits as the state of the channel is better, to thus obtain the optimal performance and guarantee the minimum delay time.

Various embodiments are described to coordinate a wireless network over a power line network or other wired back channel.

A proxy mobile station for retransmitting reverse channel signals from a mobile station to a base station of a wireless network. The proxy mobile station comprises: 1) a controller for receiving reverse channel data to be transmitted to the base station and transmitting the reverse channel data using an assigned mobile station identifier associated with the mobile station; and 2) a radio frequency transceiver for up-converting the encoded reverse channel data for transmission to the base station. The assigned mobile station is modifiable and may be modified by an external control device.

A precoder and a precoding method in a multiuser multi-antenna system are provided. The precoder includes a channel checker for determining a DownLink (DL) channel condition of terminals in a service coverage area, a pre-compensator for pre-compensating, for channel distortion, signals to be sent to the terminals when a nonlinear algorithm is selected based on the channel condition of the terminals, and an interference remover for canceling interference in a channel by multiplying the pre-compensated signals by inverse channels of the terminals, and for canceling interference between the terminals. Accordingly, the pre-equalization can be carried out without global channel state information, and an increase of the transmit power can be prevented in the permutation.

An apparatus and method for transmitting Walsh information over a packet data control channel in a base station of a mobile communication system that transmits packet data and has the packet data control channel for transmitting control information related to transmission of packet data. Receivers decode reverse ACK channel (R-ACKCH) signals received from corresponding mobile stations, and count the number of NAKs from the decoded information. A Walsh mask broadcasting controller receives the number of NAKs from the receivers, and outputs a Walsh mask information broadcasting enable signal if the number of NAKs is larger than a predetermined threshold. A transmitter generates and broadcasts Walsh mask information of the base station upon receiving the Walsh mask information broadcasting enable signal.

The present embodiments provide methods and systems for use in controlling and/or optimizing resource usage of reverse channel (142) wireless communications. Some embodiments determine a starting time (1014) of an access channel slot (628) of a reverse channel. Prior to the starting time of the slot, resource usage is reduced (1024) for reverse channel resources by at least one of a plurality of communications over the reverse channel. Upon detecting an absence (1030) of an access channel communication the resource usage of at least one of the plurality of communications over the reverse channel are increased (1034). Some methods provide for the transmitting of non-access channel communications over a reverse channel and determine an offset threshold (1222) defined by a time duration (632, 648) prior to a starting time of an access channel slot. Upon detecting an occurrence of the offset threshold, transmission resource usage of the non-access channel communication is reduced (1228).

Techniques are disclosed for passing Extended Display Identification Data (EDID) or Enhanced-EDID (E-EDID) in an uncompressed multimedia communication system including a video sink side communicatively coupled to a video source side. An EDID AVAILABLE packet is communicated via a serial backward channel from the video sink side. A REQUEST is communicated to the video sink side via a serial forward channel to indicate the video sink side can send the EDID data. The EDID data is then communicated to the video sink side via the serial backward channel.

A disclosed radio relay apparatus receives signals from a transmitter via multiple receive antennas and transmits relay signals derived from the received signals to a receiver via multiple transmit antennas. The apparatus includes a channel estimation unit configured to estimate a forward channel matrix H₁ representing radio channel characteristics between the transmitter and the radio relay apparatus and a loop channel matrix G representing interference occurring in the relay signals due to concurrently transmitting and receiving signals at the radio relay apparatus, a weight optimization unit configured to derive a canceling matrix C through iterative operations using the forward channel matrix H₁, the loop channel matrix G and a backward channel matrix H₂ representing radio channel characteristics between the radio relay apparatus and the receiver, and a feedback compensation unit configured to subtract a signal weighted in accordance with the canceling matrix C in a feedback path from a relay signal in a main signal path to adjust the relay signal.

Techniques that provide cost effective optical fiber communication links for HDCP transmission systems and the like are provided. A single fiber for bidirectional communication is enabled, without wavelength selective unit to achieve the HDCP transmission. One embodiment of the present invention has a forward channel using a light source (e.g., VCSEL at about 850 nm) in the GHz modulation level (e.g., 1 GHz or greater), and a corresponding photodetector. The backward channel has a light source (e.g., LED at 630 nm) in the MHz modulation level (e.g., 10 MHz or less), and a corresponding photodetector. One application is for realizing a home entertainment system (e.g., DVD player and high definition television) that employs an HDCP-enabled communication link to transmit copy restricted digital content.

Disclosed is a ring type wavelength division multiplexing (WDM) passive optical network (PON) system using the same wavelength for forward and backward channels while inexpensively implementing a redundancy function, and a switching media converter usable in the ring type WDM PON system. The WDM PON system provided a redundancy function to each node, so that the central office of the system can have a simplified architecture. Accordingly, there is an advantage in that the construction costs of the central office can be reduced. And, the network construction costs can be minimized because it is possible to provide a desired redundancy to a part of the nodes, taking into consideration the significance of each node.

The invention discloses a interference detecting method, resource distributing method and device in frequency division multiple access system. The interference detecting method in the invention includes following steps: said system includes several geography areas, useful frequency band of reversed channel in the area are divided into at least two sub-bands; detecting the interference of said sub-bands; Sending the interference detecting result information of said sub band. With the invention, AT can obtain more accurate reversed channel interference information. So, AT decides the emitting power based on every sub band, the character of frequency selecting can be used to improve performance; considering the resource interfered little is distributed to AT, the sub band with big interference is avoided to improve the performance of AT, and the interference between the sector/area is decreased.

In accordance with the present invention, a radio frequency identification (RFID) tag for use with an RFID system which includes one or more RFID tag readers, includes a tag communication device adapted to communicate with each of the one or more tag readers, a one-way hash function stored on the RFID tag, and a memory having stored therein a metaID. The tags may be locked and unlocked. The system includes a reader and a database. The system communicates with the tags via a forward channel and a backward channel. The present invention can singulate one tag from several responding tags and acquire the ID for the singulated tag.

A system and method for pausing communications from a transmitting radio for a certain period of time in order to allow transmission of other messages. When a first radio determines that a message needs to be transmitted either to a second radio or the transmitting radio, the first radio determines whether there are any available forward channels to transmit the call. If no forward channel is available, the first radio determines a period of time required to transmit the message and sends, on a reverse channel, a “request to pause” signal to the transmitting radio identifying that period of time. Upon receiving the “request to pause” signal, the transmitting radio ceases transmission on the forward channel for the specified period of time, during which time the first radio transmits the message.

Disclosed is a wireless communication system for providing a service in a time division duplexing (TDD) mode and a frequency division duplexing (FDD) mode according to a duplexing mode determination factor of a mobile station in a base station communicating with the mobile station. During call setup, the mobile station transmits the duplexing mode determination factor to the base station, sets a TDD mode or an FDD mode as a reverse mode set by the base station, and sets up a channel for the set reverse mode and a forward channel to perform communication. During call setup, the base station receives the duplexing mode determination factor from the mobile station, sets a reverse mode to the TDD mode or the FDD mode using the received duplexing mode determination factor, and sets up a reverse channel for the set mode and a TDD mode for forward transmission to communicate with the mobile station.

An interference relay channel (IRC) utilizes a single relay to assist communications between multiple source-destination links under the half-duplex (HD) constraint. It is assumed that each source has an independent message and its transmitted signal may cause interference at the other destinations. It is also assumed that each node only estimates its backward channels and has no knowledge of its forward channels as well as the other links. The role of the relay is to generate signals to cooperate with the intended signal and mitigate the interference at all destinations.

Disclosed is a method for controlling reverse transmission power in a cellular mobile communication system. A base station measures interference in a cell divided into a plurality of beamforming areas, determines an Interference Availability Bit (IAB) of a specific area where the measured interference is greater than or less than a threshold, and forms a beam so as to transmit the determined IAB to a beamforming area including the specific area. A terminal receiving the formed beam receives the IAB, and controls reverse transmission power according to the received IAB.