Abstract:
A subchannel scheduling method in a multi-user MIMO-OFDM environment modifies proportional fairness scheduling specifications and maximizes a system throughput under conditions that a minimum data transmission rate required by a multimedia user be ensured. In a method for allocating subchannels in a wireless network, plural users are subscribed in the wireless network, a base station has NT transmission antennas, a user i has NR reception antennas, a network capacity determined by the NT transmission antennas and K subcarrier groups is divided into K transmission subchannel groups, and a network bandwidth determined by the NT transmission antennas is divided into the K subchannel groups. The base station sequentially allocates channels to the users on the basis of a proportional value of a data transmission rate supported to each user and an average throughput of each user in a predetermined time and a service quality required by each user.
Abstract:
A transmitter station and receiver station have common maximum number of transmission bits per symbol of each subcarrier and information of encoding types to be selected. The transmitter station selects the modulation type from the propagation path quality of each subcarrier, executes encoding with the encoding type corresponding to the number of bits for communication with the selected modulation type, distributes the maximum number of transmission bits per symbol of each subcarrier by dividing the code, and transmits the data through modulation of only the number of bits for communication with the selected modulation type among distributed bits in each subcarrier. The receiver station executes demodulation by selecting the modulation type used for demodulation from the propagation path quality, summarizes the demodulation result with addition of reception of the signal having a zero degree of likeliness for the number of wanted bits, and executes decoding to the result of demodulation.
Abstract:
Transmission power relative to a propagation path having a variation in gain is controlled to increase communication channel capacity, and a data rate is controlled in accordance with the variation of the increased communication channel capacity. In order to increase the communication channel capacity, the transmission power is determined so that the sum of noise power (=received noise power/propagation path gain) converted into one at a transmitter and the transmission power becomes constant. As a result, contrary to the background art, the transmission power is controlled to be reduced when the propagation path gain decreases and to be increased when the propagation path gain increases.
Abstract:
This invention provides a mobile communication system which expanded the operation limitation of the heretofore adopted mobile communication systems and improved the spectrum efficiency greatly. A data transmission method for use in the mobile communication system of the present invention includes means for channel pluralizing by which to expand the Shannon limit and means for interference reduction by which to expand the interference limit. More specifically, a transmitting module comprises M units of modulators and L units of transmitting antennas, generates L units of signals by multiplying M units of modulated signals by a complex matrix consisting of M×L units of elements, and transmits the L units of signals from the L units of transmitting antennas.
Abstract:
This invention provides a mobile communication system which expanded the operation limitation of the heretofore adopted mobile communication systems and improved the spectrum efficiency greatly. A data transmission method for use in the mobile communication system of the present invention includes means for channel pluralizing by which to expand the Shannon limit and means for interference reduction by which to expand the interference limit. More specifically, a transmitting module comprises M units of modulators and L units of transmitting antennas, generates L units of signals by multiplying M units of modulated signals by a complex matrix consisting of M×L units of elements, and transmits the L units of signals from the L units of transmitting antennas.
Abstract:
In a radio communication system, transmitter and receiver stations share information on a maximum number of bits communicated per symbol. The transmitter station encodes a signal with sufficient error correcting capabilities to create a codeword. The transmitter station allocates the bits from the codeword to each symbol, modulates the symbols using a modulation type which processes symbols each having a number of bits equal to or smaller than the maximum number of bits per symbol, and transmits the modulated symbols. The receiver station demodulates the symbols using a modulation type which processes a larger number of bits per symbol as the transmission path quality is higher from among modulation types which process symbols having a number of bits equal to or smaller than the maximum number of bits per symbol.
Abstract:
To provide a positioning system, a positioning method, and a positioning server, which are capable of improving accuracy in detection of a position. In a positioning system, three or more access points connected to a terminal station by wireless communication are connected to a positioning server through a network, the access points transmit, to the positioning server, information regarding times of having received a signal transmitted from any one of the access points or the terminal station, and the positioning server measures a position of the terminal station based on the information regarding the times, the information having been received from the access points. In the positioning system, the access points select a communication method for maximizing a strength of the signal received from the terminal station and receive the signal from the terminal station, and the positioning server measures the position of the terminal station based on the information regarding the times, the information having been received from the access points.
Abstract:
Transmission power relative to a propagation path having a variation in gain is controlled to increase communication channel capacity, and a data rate is controlled in accordance with the variation of the increased communication channel capacity. In order to increase the communication channel capacity, the transmission power is determined so that the sum of noise power (=received noise power/propagation path gain) converted into one at a transmitter and the transmission power becomes constant. As a result, contrary to the background art, the transmission power is controlled to be reduced when the propagation path gain decreases and to be increased when the propagation path gain increases.
Abstract:
In a radio communication system, transmitter and receiver stations share information on a maximum number of bits communicated per symbol. The transmitter station encodes a signal with sufficient error correcting capabilities to create a codeword. The transmitter station allocates the bits from the codeword to each symbol, modulates the symbols using a modulation type which processes symbols each having a number of bits equal to or smaller than the maximum number of bits per symbol, and transmits the modulated symbols. The receiver station demodulates the symbols using a modulation type which processes a larger number of bits per symbol as the transmission path quality is higher from among modulation types which process symbols having a number of bits equal to or smaller than the maximum number of bits per symbol.
Abstract:
In a radio-communication system and a radio station, one or more subcarriers are grouped, and the maximum bit number per symbol of the modulation method used for each subcarrier is determined for each group and shared between a transmitting station and a receiving station. The transmitting station divides and allocates a coded signal to subcarriers in accordance with the bit number per symbol, modulates each of the allocated signals by a predetermined modulation method, and transmits the modulated signals. The receiving station demodulates the received signal by the predetermined modulation method, adds a signal having zero likelihood when the bit number per symbol of a modulation method for demodulation is different from a maximum bit number, and decodes the demodulated signal by summarizing the demodulated results.