Abstract:
In a wireless communication system formed of a plurality of nodes, an arbitrary node receives messages broadcasted from neighbor nodes and calculates amounts of changes in receiving times that are differences between receiving times when the messages are currently received and receiving times when the messages are previously received with respect to the neighbor nodes. The node corrects reference time thereof based on the amounts of changes calculated with respect to the neighbor nodes.
Abstract:
In order to reduce interference that may be generated when a plurality of signals having different subcarrier intervals are received, a method of controlling a signal having a larger subcarrier interval to be suitable for a signal having a smaller subcarrier interval and a method of removing CFO interference are provided. Subcarrier intervals of a plurality of signals to be transmitted by wireless terminals are compared with each other, and signals are designed so that a signal having the largest subcarrier interval may be repeatedly transmitted. Therefore, interference that may be generated among different kinds of signals when the base station simultaneously receives the different kinds of signals to perform Fourier transform may be mitigated. In addition, interference caused by a CFO may be removed by previously compensating the CFO estimated in a time domain to perform Fourier transform.
Abstract:
In a wireless communication system, a transmitting node selects a simultaneously transmit-unavailable node of a 1-hop node of the transmitting node, and allocates a transmitting resource in transmissible resources, except for a transmission scheduled resource of a simultaneously transmit-unavailable node. Further, a receiving node selects a simultaneously receive-unavailable node of a 1-hop node, which is a transmission target of the receiving node selects a simultaneously transmit-unavailable node of a 1-hop node of the receiving node, and allocates a receiving resource in receivable resources, except for a transmission scheduled resource to a simultaneously transmit-unavailable node of a simultaneously receive-unavailable node of the 1-hop node, which is a transmission target of the receiving node.
Abstract:
A beamforming apparatus and method for expanding coverage of a control channel are provided, by which neighboring communication devices are classified according to the number of beams that they can receive, and therefore the frequency or period of beam transmission is adjusted to transmit a control channel by a beamforming method. Hence, an overhead reduction and an increase in transmission rate can be achieved, and coverage holes can be prevented.
Abstract:
An information exchange apparatus of each node for sharing information between a plurality of nodes receives request information from an adjacent node and determines an information transmitting node based on information that each node holds and request information from the adjacent node, and an information exchange apparatus of a node that is determined to be an information transmitting node generates candidate transmitting information by performing network coding of at least one information set of held information, determines one of candidate transmitting information sets as transmitting information, and transmits the candidate transmitting information set to the adjacent node.
Abstract:
A synchronization group management apparatus of a node recognizes a node belonging to a different group if groups having mobility are moved and located in the same area, and performs an operation of merging the different groups into one group by changing the frame start time and the synchronization reference time of the node.
Abstract:
A communication apparatus and a data transmission method of the communication apparatus are disclosed. The communication apparatus receives feedback messages corresponding to failed data from receivers, generates a feedback matrix in response to the feedback messages, selects transmission candidate data from the feedback matrix, performs network coding on the transmission candidate data, and transmits retransmission data generated by the network coding to the receivers. Transmission candidate data is selected from the feedback matrix, and network coding is performed on the transmission candidate data to retransmit data to the receivers.
Abstract:
A method and apparatus for synchronizing a carrier frequency of a node included in a distributed network are provided. The apparatus includes a frequency offset estimating unit, an offset average value calculating unit, and a frequency adjustment value calculating unit. The method includes receiving preambles from a plurality of nodes adjacent to the node, estimating offsets of the carrier frequencies from the received preambles for each of the plurality of neighbor nodes, calculating an average value of the estimated offsets, calculating an adjustment value of the carrier frequencies with respect to the entirety of the plurality of neighbor nodes by using the average value, and adjusting a carrier frequency of the node on the basis of the adjustment value.