Abstract: Embodiments herein relate to a method performed by a relay node for relaying user data from/to one or more communication devices to/from a radio access node in a wireless communication network. The relay node receives a first user data stream in a first time slot and/or a second user data stream in a second time slot from a first communication device and a second communication device respectively, or from the radio access node. The relay node independently applies a network coding on the received first and/or second user data streams. The relay node forwards the network coded first user data stream in a third time slot to the radio access node or the first communication device, and/or the second user data stream in another time slot to the radio access node or the second communication device.

Abstract: Embodiments herein relate to a method performed by a relay node (13,14) for relaying user data from/to one or more communication devices (10,11) to/from a radio access node (12) in a wireless communication network (1). The relay node receives a first user data stream and/or a second user data stream from a first communication device (10) and a second communication device (11) respectively, or from the radio access node, which first user data stream is comprised in a first time slot and/or the second user data stream is comprised in a second time slot. The relay node applies a network coding on the received first user data stream independently of the second user data stream and/or the received second user data stream independently of the first user data stream.

Abstract: A data communication involves selecting a group (15) of M multiple source nodes (12, 16) among N multiple source nodes (10, 12, 14, 16) present in a communication system (1) and having data destined for a destination node (30), where 2?M<N. A relay node (20) network codes data from the selected group (15) of M nodes (12, 16) to form combined, network coded data. This resulting data is sent to towards the destination node (30). The purposeful selection of source nodes (10, 12, 14, 16) in connection with network coding substantially increases the throughput of the communication system (1).

Abstract: A method and arrangement for retransmission control. A method in a sending system entity for controlling retransmissions of data to a sending system entity is provided. Initial data encoded with a first forward error correction code is sent 200 to the receiving system entity. When transmitted initial data is determined to be affected by errors at the receiving system entity, the sending system entity receives 202 a request to retransmit the initial data combined 204 by new data encoded with a second forward error correction code in a combined data stream which is encoded 206 with a third forward error correction code before being sent 208 to the receiving system entity. By combining initial data and encoded new data in a combined data stream when resending, an effective and flexible procedure for retransmissions is achieved, which doesn't introduce any substantial delay of the data.

Abstract: A communication unit for use in a wireless communication system in which a transmitting unit is arranged for wireless communication with at least one receiving unit, said network further comprising at least a first and a second relay node arranged to receive a signal from the transmitting unit and forward it to the receiving unit, said node being characterized in that it comprises a processor arranged to perform the following steps: identifying at least a first and a second communication path between the transmitting unit and the receiving unit, at least one of said paths involving the first or the second relay node, calculating a first and a second capacity of at least one hop in the first and second communication path, respectively communicating information related to the first and second capacity to at least one other communication node in the wireless network.

Abstract: A base station in a wireless network receives link quality data from multiple relay nodes that relay data from the user terminals to the base station and/or from user terminals. The base station applies one or more cost functions to the link quality data and selects a relay node from the multiple relay nodes for network coding of data from a group of the user terminals based on results of the one or more cost functions. The base station notifies the selected relay node to network code data from the group of user terminals.

Abstract: A first radio frequency, RF, signal is directly received from a first source radio node in a radio destination node. The first RF signal includes a coded first source information signal. A second RF signal is directly received from a second source radio node that includes a coded second source information signal. A third RF signal is received from an intermediate network node that includes a network coded signal which is a combined coded information signal generated at the intermediate node after demodulating the coded first source information signal and the coded second source information signal received from the first and second source radio nodes.

Abstract: A base station serves multiple user terminals via a relay node in a cell of a wireless network. The base station includes a time division scheme selection unit that selects a time division scheme from multiple time division schemes that optimizes a parameter associated with network coding of data transmitted between the multiple user terminals and the base station via the relay node. The base station further includes a transmission allocation unit that allocates uplink and/or downlink transmission intervals and interval lengths, based on the selected time division scheme, to each of the multiple user terminals and to the relay node. The base station also includes a notification message unit that notifies the multiple user terminals and the relay node of their respective transmission interval and interval length allocation.

Abstract: A method and arrangement for retransmission control. A method in a sending system entity for controlling retransmissions of data to a sending system entity is provided. Initial data encoded with a first forward error correction code is sent 200 to the receiving system entity. When transmitted initial data is determined to be affected by errors at the receiving system entity, the sending system entity receives 202 a request to retransmit the initial data combined 204 by new data encoded with a second forward error correction code in a combined data stream which is encoded 206 with a third forward error correction code before being sent 208 to the receiving system entity. By combining initial data and encoded new data in a combined data stream when resending, an effective and flexible procedure for retransmissions is achieved, which doesn't introduce any substantial delay of the data.

Abstract: A radio channel estimation technique is described for use in a OFDM-based radio communications system. A block of OFDM symbols is transmitted from multiple antennas over multiple sub-carrier frequencies. The block of OFDM symbols includes known pilot symbols as well as data symbols to be determined by a receiver. The pilot symbols are transmitted in a predetermined pattern at periodic times on periodic sub-carriers. A pilot channel estimate is determined for each pilot symbol in the received block of OFDM symbols. An N×M matrix of points corresponding to the received OFDM symbol block is formed. N is the number of sub-carriers and M is the number of OFDM symbols in the OFDM symbol block. The matrix is formed by inserting pilot channel estimates at predetermined positions in the N×M matrix according to the predetermined pilot pattern and inserting zeros in remaining positions in the N×M matrix.

Abstract: A method for transmitting data flows between a network element and a number of receivers over a first channel. The method comprises the steps of: performing a link adaptation for the transmission of a data flow by said network element, and transmitting the data flow, transmitting an indication of a channel quality required for reception of the data flow on a second channel, receiving by said receivers said indication of channel quality, measuring a link quality by said receivers by monitoring a pilot channel, comparing said measured link quality with said received indication of the channel quality, and transmitting to said network element result of said comparison of said measured link quality with said received indication of the channel quality, if said result is lower than a predetermined value. The invention also relates to a network element and a user equipment.

Abstract: A radio channel estimation technique is described for use in a OFDM-based radio communications system. A block of OFDM symbols is transmitted from multiple antennas over multiple sub-carrier frequencies. The block of OFDM symbols includes known pilot symbols as well as data symbols to be determined by a receiver. The pilot symbols are transmitted in a predetermined pattern at periodic times on periodic sub-carriers. A pilot channel estimate is determined for each pilot symbol in the received block of OFDM symbols. An N×M matrix of points corresponding to the received OFDM symbol block is formed. N is the number of sub-carriers and M is the number of OFDM symbols in the OFDM symbol block. The matrix is formed by inserting pilot channel estimates at predetermined positions in the N×M matrix according to the predetermined pilot pattern and inserting zeros in remaining positions in the N×M matrix.

Abstract: A wireless communication system uses relaying to enhance performance. Artificial frequency selectivity and spatial diversity are provided by introducing delay diversity. A transformed OFDM chunk is subjected to a 2D cyclic prefix by pre-appending to a representation of the chunk the last column of the representation and by copying a number of the last rows of the pre-appended chunk to the top of the representation thereby forming an augmented OFDM chunk.

Abstract: A base station serves multiple user terminals via a relay node in a cell of a wireless network. The base station includes a time division scheme selection unit that selects a time division scheme from multiple time division schemes that optimizes a parameter associated with network coding of data transmitted between the multiple user terminals and the base station via the relay node. The base station further includes a transmission allocation unit that allocates uplink and/or downlink transmission intervals and interval lengths, based on the selected time division scheme, to each of the multiple user terminals and to the relay node. The base station also includes a notification message unit that notifies the multiple user terminals and the relay node of their respective transmission interval and interval length allocation.

Abstract: A base station in a wireless network receives link quality data from multiple relay nodes that relay data from the user terminals to the base station and/or from user terminals. The base station applies one or more cost functions to the link quality data and selects a relay node from the multiple relay nodes for network coding of data from a group of the user terminals based on results of the one or more cost functions. The base station notifies the selected relay node to network code data from the group of user terminals.

Abstract: A wireless communication system with relaying to enhance performance provides artificial frequency selectivity and spatial diversity by introducing delay diversity. A OFDM chunk is subjected to a 2D cyclic prefix by pre-appending to a representation of the chunk the last column of the representation. The last row of the pre-appended chunk is copied to the top of the augmented chunk forming an augmented chunk.

Abstract: A data communication involves selecting a group (15) of M multiple source nodes (12, 16) among N multiple source nodes (10, 12, 14, 16) present in a communication system (1) and having data destined for a destination node (30), where 2?M<N. A relay node (20) network codes data from the selected group (15) of M nodes (12, 16) to form combined, network coded data. This resulting data is sent to towards the destination node (30). The purposeful selection of source nodes (10, 12, 14, 16) in connection with network coding substantially increases the throughput of the communication system (1).

Abstract: A communication unit for use in a wireless communication system in which a transmitting unit is arranged for wireless communication with at least one receiving unit, said network further comprising at least a first and a second relay node arranged to receive a signal from the transmitting unit and forward it to the receiving unit, said node being characterized in that it comprises a processor arranged to perform the following steps: identifying at least a first and a second communication path between the transmitting unit and the receiving unit, at least one of said paths involving the first or the second relay node, calculating a first and a second capacity of at least one hop in the first and second communication path, respectively communicating information related to the first and second capacity to at least one other communication node in the wireless network.

Abstract: According to one embodiment, a wireless communication device estimates channel response based on a reduced-density common pilot signal comprising a plurality of regularly spaced common pilot symbols when the reduced-density common pilot signal is sufficient for estimating the channel response with a desired accuracy. The wireless communication device estimates the channel response based on the reduced-density common pilot signal and one or more additional pilot symbols adaptively allocated to the wireless communication device when the reduced-density common pilot signal is insufficient for estimating the channel response with the desired accuracy.

Abstract: A method for transmitting data flows between a network element and a number of receivers over a first channel. The method comprises the steps of: performing a link adaptation for the transmission of a data flow by said network element, and transmitting the data flow, transmitting an indication of a channel quality required for reception of the data flow on a second channel, receiving by said receivers said indication of channel quality, measuring a link quality by said receivers by monitoring a pilot channel, comparing said measured link quality with said received indication of the channel quality, and transmitting to said network element result of said comparison of said measured link quality with said received indication of the channel quality, if said result is lower than a predetermined value. The invention also relates to a network element and a user equipment.