Abstract: The present invention provides a method which performs an estimation of a SIR as basis for transmit power control. The SIR estimation is performed for a radio signal (u) which is transmitted from a transmitter (35) to a receiver (43) over a radio channel (37). A channel estimate h and a combining weight w are first obtained (83). Then an estimated SIR value is generated (85) based at least in part on the channel estimate h and the combining weight w. The estimated SIR value is generated such that it equals a first estimated SIR value multiplied by a numerical factor. The numerical factor is dependent on the channel estimate h and the combining weight w in a manner such that it attains a minimum value whenever the channel estimate h and the combining weight w are linearly dependent. The invention also comprises devices for carrying out the method.

Abstract: A network node (28) communicates over a radio interface (32) with a wireless terminal (30). Both the network node (28) and the wireless terminal (30) have multiple-input multiple-output (MIMO) capabilities. A MIMO-related order (90) is generated for inclusion in control signaling on a high speed downlink shared channel from the network node (28) to the wireless terminal (30). The MIMO-related order (90) is configured to modify channel quality indication (CQI) communications between the wireless terminal (30) and the base station (28) in view of MIMO capabilities of the wireless terminal (30). The method further comprises providing a channel quality indication (CQI) report (92) the wireless terminal (30) to the base station (28) in accordance with the order.

Abstract: A radiographic imaging device has: a generating unit that generates image data expressing a radiographic image formed by irradiated radiation; a first communicating unit at which wireless communication is possible selectively in either of a direct communication mode or an indirect communication mode; a storing unit that stores a setting of a communication mode; and a control unit that, if a setting to carry out communication in the direct communication mode has been made, controls the first communicating unit to carry out wireless communication in the direct communication mode, and, if a setting to carry out communication in the indirect communication mode has been made, controls the first communicating unit to attempt wireless communication in the indirect communication mode with a control device that controls the radiographic imaging device, and, if communication is impossible, controls the first communicating unit to carry out wireless communication in the direct communication mode.

Abstract: Example embodiments disclosed herein relate to the determination of maximal independent sets (MISs) of mobile devices. Example embodiments include participating with other mobile devices of a plurality of mobile devices in concurrent distributed determinations of a plurality of MISs of the mobile devices and selecting one of the plurality of MISs.

Abstract: A method of communicating a chirp signal from a transmitter suitable for receipt at a proximal receiver and a distal receiver, the chirp signal including a plurality of packets, each packet including at least one symbol, each symbol including one or more identical chirps, the method including: generating the chirp signal by interleaving constituent packets of: (i) a first set of packets encoded with first data, each packet including one or more symbols having a first time period t1, and (ii) a second set of packets encoded with second data, each packet including one or more symbols having a second time period t2, where t1<t2; and transmitting the generated chirp signal.

Abstract: Devices and methods for determining transmission rates based on a virtual diversity receiver (VDR) scheme are disclosed. Performance is improved through determination of appropriate transmission rates, which are determined based on one or more signal to interference plus noise ratios (SINRs). The SINRs are calculated using virtual noise and channel coefficient values obtained as part of the VDR scheme. Utilizing an underlying pilot structure a user device may receive several sets of symbols. These symbols are then used to obtain both real and virtual channel noise power values and channel coefficients. These values and coefficients are then used to determine first and second SINR values indicative of one or more channels in the communication network. These SINR values may correlate to transmission rates (modulation order and/or coding rate). The SINRs may be sent to a base station, or the user device itself may determine one or more transmission rates.

Abstract: There are provided an apparatus and a method for super high-speed wireless communications. The apparatus includes a signal processor transmitting data to be transmitted through a predetermined super high-speed communications network when the super high-speed communications network is connected and transmitting data to be transmitted through a predetermined high-speed communications network when the super high-speed communications network is disconnected; a super high-speed wireless communications unit converting the data transmitted from the signal processor to a super high-speed wireless signal suitable for transmission through the super high-speed communications network; and a high-speed wireless communications unit converting the data transmitted from the signal processor to a high-speed wireless signal suitable for transmission through the high-speed communications network.

Abstract: A spatial multiplexing scheduler in, for example, an eNB or other base station, determines rank n precoders for UEs. Each UE reports the preferred precoder from this set of rank n precoders. The preferred precoder results in imbalance in performance over m layers compared to the rest of (n?m) layers. The UEs also report channel quality to the eNB, from which the eNB determines which layer(s) is better for the UE. For example, when n=2 and m=1, the eNB may then select two UEs such that, for the same precoder used by the UEs, the first UE has much higher layer 1 performance than layer 2, and the second UE has much higher layer 2 performance than layer 1. These two UEs may then share the same frequency-time domain resources, with the first UE information sent/received on layer 1, while the second UE information is sent/received on layer 2.

Abstract: A method for transmitting, at a user equipment having N (N being an integer greater than 1) transmission antennas, an uplink signal to a base station and a method for receiving, at the base station, an uplink signal from the user equipment are disclosed. The base station transmits reception capability information of the base station to the user equipment. Reception capability information includes information indicating that the base station may receive a signal transmitted through a maximum of M (M being an integer greater than 1) transmission antennas. The user equipment transmits the uplink signal using N transmission antennas if N is not greater than M and transmits the uplink signal using M transmission antennas if N is greater than M.

Abstract: A method is provided for sending a communications signal in a communications network having a plurality of nodes assuming alternating sleeping and waking states and in which a sender node executes a step of sending an initial preamble, prior to sending data to a destination node. The method includes at least one operation of a neighbor node of the sender node relaying the initial preamble, where a relaying operation corresponds to sending a preamble formed from the preamble sent during the preceding relaying operation, the preamble sent during the first relaying operation being formed from the initial preamble, and the at least one relaying operation continuing until the destination node for the data detects the sent preamble.

Abstract: The method and apparatus disclosed herein improve throughput conditions limited by multiplicative noise by determining precoder weights for each data stream communicated between a MIMO transmitter node and a MIMO receiver node. The precoder weights are determined based on information derived from non-precoded reference symbols to decrease the energy allocated to the dominant signal path relative to the energy allocated to the non-dominant signal paths.

Abstract: An apparatus, a method and a computer program product for seamless transition between WiFi networks (including in particular WiFi Internet networks) includes within a mobile communication apparatus a mobility layer that is tunneled to a mobility server within a network infrastructure. The mobile communications apparatus includes a wireless network capability, a global positioning system capability, an internal network protocol address and a routing capability. The apparatus, the method and the computer program product also provide that the mobility layer is programmed to sequentially and automatically tunnel to the mobility server at an available geographically defined WiFi network access location predicated upon a global positioning system determined position of the mobile communication apparatus. Embodiments also provide seamless transitions between WiFi networks and cellular networks.

Abstract: Active packaging for supplying power, data, or both power and data to an electronic media device while the device is housed within the active packaging is provided. The active packaging may include one or more electrical traces in-molded or printed onto the packaging that couple to a suitable connector on the device. Power may also be provided via one or more wireless power techniques. Multiple active packages may be conductively stacked to transmit power, data, or both power and data to a row or stack or devices. POM sensors integrated with or attached to the device (or the active packaging itself) may detect various movement events. Coordinated and synchronized display effects may be presented while the devices are housed within the active packaging.

Abstract: A method and system for improved communication are disclosed herein. In at least one example embodiment, the present disclosure relates to a method of communication by a first device with second and third devices. The method includes engaging in first communications with the second device, with which the first device is in a first paired relationship, terminating the first paired relationship, and either receiving from the third device a request to enter into a second paired relationship or sending to the third device the request to enter into the second paired relationship. Additionally, the method includes either outputting an image for detection by the third device, or detecting the image when output by the third device. Further, the method includes communicating with the third device so as to establish the second paired relationship with the third device and, upon establishing that relationship, automatically reestablishing the first paired relationship.

Abstract: According to one embodiment, a wireless communication apparatus includes a first wireless communication unit, a second wireless communication unit, a reception power management unit, a frequency selection unit, and a frequency-hopping management unit. The second wireless communication unit performs wireless communication by means of a second wireless communication system different from the first communication system. The reception power management unit measures reception power. The frequency selection unit selects frequency-channel data enabling the second wireless communication unit to perform communication, on the basis of the reception power measured by the reception power management unit. The frequency-hopping management unit determines a frequency channel from the frequency-channel data selected by the frequency selection unit, if the second wireless communication unit performs communication by using a frequency hopping system.

Abstract: A method for updating a location in a wireless communication system is disclosed. The method includes transmitting a request message to enter idle mode, receiving a response message including an Identifier (ID) of a first paging group and an ID of a second paging group in response to the request message, activating a paging group location update timer, when the MS leaves an area of the first paging group, and updating a location according to the paging group location update timer.

Abstract: A method for allowing terminals to exchange discovery or synchronization signals to determine their presences among each other within a service area of a base station is provided. The method includes collecting multicast identifiers of another terminal for use in multicast communication, receiving a multicast control channel for Device-to-Device (D2D) multicast communication, performing Cyclic Redundancy Check (CRC) on the received multicast control channel using the collected multicast identifiers, and receiving, when the CRC is successful, the D2D multicast according to the multicast control channel.

Abstract: Methods and systems for providing a service are provided. A request is received to provide the service to a device. A location of the device, or a network interface through which the device is coupled, is determined. Finally, the delivery of the service is authorized based on the determined location of the device, or the determined network interface.

Abstract: Enhanced reception in a communication system is achieved by applying a time domain generated time-reversed channel response to signals transmitted from a group of transmitter to a group of receivers. The time-reversed channel response is generated from a radio frequency channel response derived from signals previously received from the group of receivers, but reversed in the time domain. The time-reversed channel response is convolved with an information signal that when transmitted in a coordinated fashion from the group of transmitters, the signals arrive at each receiver in the group of distant receiving communication devices at approximately the same time where the signals coherently combine, thereby increasing signal power at the receivers. This permits detection at a greater range or with a lower bit error rate. In addition, the many-to-many configuration enables signal power from each transmitter to be focused temporarily and spatially on each receiver.

Abstract: Systems, methods, and devices enable spectrum management by identifying, classifying, and cataloging signals of interest based on radio frequency measurements. In an embodiment, signals and the parameters of the signals may be identified and indications of available frequencies may be presented to a user. In another embodiment, the protocols of signals may also be identified. In a further embodiment, the modulation of signals, data types carried by the signals, and estimated signal origins may be identified.

Abstract: A mobile device may be configured with multiple access point names (APNs) including a roaming APN and a non-roaming APN. After a mobile device determines whether it is roaming, it may transmit a service request with the corresponding APN. The network may then select a profile based on the APN that may include quality of service parameters and other parameters for servicing the mobile device. The profile may be obtained from a local home location register or a remote home location register.

Abstract: A method and a system is provided for Coordinate Rotation Digital Computer (CORDIC) based matrix inversion of input digital signal streams from multiple antennas using an bi-directional ring-bus architecture. The bi-directional ring bus includes a first ring bus having signals flow in a clockwise direction, and a second ring bus having signals flow in a counter-clockwise direction. An I/O controller is coupled to the first and the second ring bus, respectively. A plurality of processing elements (PEs), where each of the plurality of PEs is coupled to the first and the second ring bus, respectively, wherein each of the plurality of PEs includes at least one CORDIC core for performing CORDIC iterations on the plurality of input digital stream signals to produce inversed matrix signals.

Abstract: Network node for a distributed cooperative multi-antenna communication, including at least two sending and receiving units, wherein the network node is adapted to receive an indication of a protocol descriptor from a mobile communication device and wherein the network node is communicatively couplable with at least one further network node. Furthermore, the network node may be adapted to provide and/or receive an indication of a protocol descriptor and/or a channel access method to/from the at least one further network node.

Abstract: A method and a system of setting up a reference signal in a radio communication system. The radio communication system includes a serving cell and a neighboring cell, and a mobile terminal of the serving cell uses the same temporal frequency resource so as to receive a serving resource block from the serving cell and receive an interference resource block from the neighboring cell. The method according to the present disclosure includes a step of setting up a user-specific reference signal in the interference resource block and a step in which puncturing is performed at same temporal frequency position as the temporal frequency position at which the user-specific reference signal is set up on the interference resource block of the serving resource block so as to prevent any signal from being transmitted at the punctured temporal frequency position.

Abstract: A radio communication system (1) has: a radio terminal (UE); a radio base station (BS1) which transmits radio signals (RS1) to the radio terminal (UE) corresponding to the feedback from the radio terminal (UE); and a radio base station (BS2) which transmits, corresponding to the feedback from the radio terminal (UE), radio signals (RS2) to the radio terminal (UE) at the frequency and time identical to the frequency and time at which the radio signals (RS1) are transmitted. The time interval at which the radio terminal (UE) performs the feedback to the radio base station (BS1) is longer than the time interval at which the radio terminal (UE) performs the feedback to the radio base station (BS2).

Abstract: Techniques are provided for third-party assisted peer-to-peer (P2P) communication. For example, there is provided a method, operable by a network entity, that may involve receiving first information from a first mobile entity, the first information comprising a first message for a second mobile entity. The method may involve receiving second information from the second mobile entity, the second information comprising a second message for the first mobile entity. The method may further involve coding third information based at least in part on the first information and the second information, and sending the third information to the first and second mobile entities. The method may also involve transmitting a control signal that includes processing information for decoding the coded third information to extract the first message or the second message.

Abstract: An autonomous vehicle detects a tailgating vehicle and uses various response mechanisms. For example, a vehicle is identified as a tailgater based on whether its characteristics meet a variable threshold. When the autonomous vehicle is traveling at slower speeds, the threshold is defined in distance. When the autonomous vehicle is traveling at faster speeds, the threshold is defined in time. The autonomous vehicle may respond to the tailgater by modifying its driving behavior. In one example, the autonomous vehicle adjusts a headway buffer (defined in time) from another vehicle in front of the autonomous vehicle. For example, if the tailgater is T seconds too close to the autonomous vehicle, the autonomous vehicle increases the headway buffer to the vehicle in front of it by some amount relative to T.

Abstract: An autonomous vehicle detects a tailgating vehicle and uses various response mechanisms. For example, a vehicle is identified as a tailgater based on whether its characteristics meet a variable threshold. For example, when the autonomous vehicle is traveling at slower speeds, the threshold is defined in distance. When the autonomous vehicle is traveling at faster speeds, the threshold is defined in time. The autonomous vehicle may respond to the tailgater by modifying its driving behavior. In one example, the autonomous vehicle adjusts a headway buffer (defined in time) from another vehicle in front of the autonomous vehicle. For example, if the tailgater is T seconds too close to the autonomous vehicle, the autonomous vehicle increases the headway buffer to the vehicle in front of it by some amount relative to T.

Abstract: Systems, methods, and apparatus are described that employ a partial interference alignment scheme in conjunction with an interference detection scheme to mitigate interference in quasi-static multiple input multiple output (MIMO) channels. In an aspect, sets of transmitter and receiver pairs are determined based on feasibility of alignment of the transmitters at the receivers of the sets in accordance with an interference alignment scheme and path loss associated with signal transmissions between the transmitter and receiver pairs, wherein the sets include different alignment assignments of the respective transmitters at the respective receivers of the sets. The alignment assignments can include different numbers of the transmitters aligned at the receivers of the sets. A set is then selected from the sets that contributes to an interference profile at the receivers that facilitates interference detection at the receivers.

Abstract: A wireless relay module for networked communications between a series of medical devices and a remote monitoring device. An interface circuit coupled to each medical device communicates with the wireless relay module via a wireless relay network. The relay module communicates with the remote monitoring device over an internet-accessible wireless communication network. The controller determines a status of the networks. When the status indicates that the internet-accessible wireless communications network is available, a transmitter transmits medical device data over this network. When the internet-accessible wireless communications network is not accessible, another transmitter transmits the data to another wireless relay module. In addition, the controller obtains status information the two networks, and either transmits this information to one of the medical devices or prepares the information for display on a display of the wireless relay module.

Abstract: The disclosure is directed to providing device interaction recommendations based on past interactions between devices in networks with similar network configurations. An aspect receives first network configuration information and device interaction history information associated with a first device network, the first device network comprising a first plurality of devices, wherein the first network configuration information comprises capability information of each of the first plurality of devices, and wherein the interaction history information comprises a history of interactions among the first plurality of devices, generates a set of interaction recommendations based on the first network configuration information and the device interaction history information, identifies a second device network comprising a second plurality of devices and having second network configuration information, and sends the set of interaction recommendations to the second device network.

Abstract: This disclosure pertains to a method in a network node, a method in user equipment, a network node and user equipment in a wireless communications network. More particularly, there is provided methods and platforms for network based control of report messages comprising logged measurements in a wireless communications network. In accordance with some example embodiments, a UE (30) that has stored logged data i.e. logged measurements that are bigger than a single transmission packet, i.e. report message, segments the logged measurements and sends only a portion of the logged measurements that fits into a single report message. The UE (30) also indicates to a network node (28) that additional logged measurements exist at the UE buffer (44).

Abstract: A receiver includes an antenna array that generates received signals from a first remote transmitter and a second remote transmitter, the antenna array having a beam pattern that is controllable based a control signal. A plurality of receiver sections process the received signals to generate down-converted signals. A receiver processing module, generates the control signal to control the beam pattern to a first pattern during a first time period for reception from the first remote transmitter, generates a first reception estimate based on the down-converted signals during the first time period, generates the control signal to control the beam pattern to a second pattern during a second time period for reception from the second remote transmitter, generates a second reception estimate based on the down-converted signals during the second time period, and generates inbound data based on the first reception estimate and the second reception estimate.

Abstract: The present disclosure provides a method of generating codebook in a wireless communication system with multiple antenna arrays, as well as a wireless communication system, base station and terminal using the codebook for communication. The method comprises steps of: providing a basic codebook which contains multiple pre-coding matrices; and assigning phase offsets to certain pre-coding matrices in the basic codebook to form a codebook with phase offset. The feedback overhead from a client to a base station side is reduced and a good precision of feedback for multi-antenna array is kept by applying the method of generating codebook and using the generated codebook in the wireless communication system, base station and terminal.

Abstract: A Bluetooth adapter is shared among guest operating systems of different virtual machines running on a common host computer system using a Bluetooth virtualization stack. The Bluetooth virtualization stack is exposed as a Bluetooth adapter to a guest operating system and as a Bluetooth application to a host operating system. The Bluetooth virtualization stack parses individual socket streams associated with an asynchronous connectionless link (ACL) originating from the guest operating system and couples the socket streams to an application interface associated within the host operating system. Plural instances of the guest operating system and corresponding Bluetooth virtualization stack collectively present a set of socket connections to the host operating system. A Bluetooth driver within the host operating system multiplexes the set of socket streams, advantageously sharing the Bluetooth adapter among different instances of the guest operating system.

Abstract: Provided are a method and device for performing a position update in machine to machine (M2M) communication. An M2M apparatus in an idle mode receives a paging message from a base station. The paging message comprises an action code and a network access type, the action code being an indication for the M2M apparatus to implement position update. When the network access type indicates the allocation of resources for a ranging request, the M2M apparatus transmits the ranging request to the base station by means of an allocated uplink.

Abstract: The present invention is a safety and tracking system that includes a master or master control unit with visual and audible signal intensity indicators, a numerical indicator, a plurality of manual control buttons that provide input data to the master control unit, a plurality of indicator lights with audible sounder, a controlled gain antenna array that exchanges, sends and receives the input data, a transceiver that provides a communications link between the master control unit and a locator tag and a microprocessor. There are also one or more corresponding target or locator tags that include a panic button, an indicator lights with a sounder, an antenna that exchanges, sends and receives the input data, a transceiver and a microprocessor to coordinate the input data to the master control unit.

Abstract: A timing method and communication apparatus therefor. The timing method, performed by a mobile communication device, includes: activating a first communication module; receiving updated information when the first communication module is active; determining and setting an expiry time for an adaptive timer based on the updated information; activating the adaptive timer to count to the determined expiry time; and activating a second communication module when the adaptive timer expires.

Abstract: An apparatus and method for power control are provided. In a receiver in a mobile communication system, a Receive (Rx) signal received through a plurality of antennas is estimated. A power ratio between a traffic channel of the Rx signal and a pilot channel of the Rx signal is determined. A Log Likelihood Ratio (LLR) value is determined using the power ratio between the traffic channel and the pilot channel, a symbol of the traffic channel, and an Rx signal estimation value to which precoding is applied.

Abstract: Techniques for explicit feedback delay measurement are described. An apparatus may comprise a processor to generate a steering matrix for transmit spatial processing over a channel, determine a delay time associated with explicit feedback information for the channel, and determine whether to modify the steering matrix with the explicit feedback information based on the delay time. Other embodiments are described and claimed.

Abstract: A system including an input module, a first gain module, a second gain module, and a preamble estimation module. The input module is configured to receive an input signal from a station. The input signal includes (i) a first preamble sequence, and (ii) subcarriers. The first gain module is configured to, based on the input signal, generate first channel gain values. Each of the first channel gain values is for a respective one of the subcarriers. A second gain module is configured to, based on the first channel gain values, generate second channel gain values. A preamble estimation module is configured to estimate the first preamble sequence based on (i) the first channel gain values, and (ii) the second channel gain values.

Abstract: Wireless sensing and communication system including sensors located in the roadway or in the vicinity of the roadway and which provide information which is transmitted to one or more interrogators in the vehicle by a wireless radio frequency mechanism. Power to operate a particular sensor is supplied by the interrogator or the sensor is independently connected to either a battery, generator, vehicle power source or some source of power external to the vehicle. The sensors can provide information about the exterior environment, about the roadway, ambient atmosphere, travel conditions and/or external objects. The sensors arranged on the roadway or ancillary structures include pressure sensors, temperature sensors, moisture content or humidity sensors, and friction sensors.

Abstract: A system and method is described herein for compensating for artifacts introduced by nodes in a wireless network. The method may include transmitting, by a first node, first characteristic information indicating the frequency response of the first node to a mobile station in the wireless network and receiving, by the first node from the mobile station, second characteristic information indicating the frequency response of a second node in the wireless network. By broadcasting the frequency response of each node in the network to each other node, the method may produce a compensated channel estimation that eliminates or reduces artifacts introduced by the nodes to wireless signals.

Abstract: A method of operation of a communication system includes: utilizing an estimation module estimating a log-likelihood ratio for a transmission; and utilizing a slicing module, coupled to the estimation module, slicing a constellation by: reading the log-likelihood ratio from the estimation module, defining a threshold within the constellation, and adjusting the threshold based on the log-likelihood ratio for determining a symbol.

Abstract: In a wireless sensor network, a local wireless network serves a plurality of sensor nodes. The local wireless network is reconfigurable for accepting a mobile computing device. The mobile computing device comprises a wireless network interface, such as a dongle, and is configured for selecting a set of sensor nodes for communications. The sensor network, a gateway, or a remote computing device may select the set of sensor nodes for communicating with the mobile computing device. A dongle may be provided for coupling the mobile computing device to the local wireless network. The dongle comprises a configuration unit for interfacing the mobile computing device with the local wireless network, an identification unit for storing user data used for user authentication, and a protection module for providing secure network access.

Abstract: System and method for calculating a transmitter beamforming vector related to a channel vector h under per-antenna power constraints combined with total power constraint, under per-antenna power constraints combined with overall line of site (LOS) effective isotropic radiated power (EIRP) and under all three constraints. Calculating a transmitter beamforming vector may be done in the transmitter, in the receiver and feedback to the transmitter or in both. The method may be adapted to perform with a multi-antenna receiver and with multi-carrier systems.

Abstract: Method, apparatus, and data packet format to implement transmit diversity in a multicarrier environment is disclosed. For diversity transmission operations, space frequency encoding techniques are employed creating distinguishable first and second time domain signals from a multicarrier frequency domain symbol bearing data of interest, which are then broadcast in parallel over first and second transmission units respectively. For diversity reception operations, complementary space frequency decoding is used to recover a corrected multicarrier frequency domain symbol from a time domain signal containing either this symbol, a space frequency modified symbol based on the multicarrier symbol, or a possible partial/complete combination of both. The data packet format includes portions defining a transmission diversity semaphore, a preamble enabling training of a receiver receiving the data packet, and a payload.

Abstract: A wireless communication device is configured for performing uplink transmission power control. The wireless communication device includes a processor and instructions stored in memory. The wireless communication device performs uplink transmission power control for multiple regulated frequency bands or component carriers. The wireless communication device determines a total transmission power for at least one component carrier and allocates transmission power to at least one antenna.

Abstract: Concepts and technologies are disclosed herein for collecting and analyzing data in a distributed sensor network. The distributed sensor network can include a number of distributed sensor systems having data sources such as sensors, communication equipment, and/or other systems and components. The distributed sensor systems also can include lighting systems, if desired. The distributed sensor systems can collect data from the data sources and provide the data to a local or remote entity such as a data analysis engine. The data analysis engine can request data from the distributed sensor systems, receive the data, and analyze the data for various purposes.

Abstract: A wireless communication system which performs data transmission from a first terminal including N antennas to a second terminal including M antennas using spatially multiplexed streams (N and M are integers larger than or equal to 2 and N<M) is disclosed. The system includes training request means, training means, channel matrix preparing means, transmission weight matrix computation means, and beamforming means.