2382 results about "Spectral efficiency" patented technology

The evolution of high rate data services within future wireless networks will call for new RF access technologies to enable substantial increases in overall system spectral efficiency at an acceptably low cost to the user. Space-Time Coding (STC) is an antenna array processing technology currently simulating considerable Interest across the wireless industry. The invention provides a space-time coding apparatus having an input, a trellis encoder, a modulator, a demultiplexer, and a set of signal outputs wherein the input is operable to receive a stream of data. This allows de-multiplexing to take place after coding and modulation has been performed. The trellis encoder comprises a convolutional encoder operable to sequentially group data to provide coded bits to provide QPSK symbols. By the selection of convolutional encoder rates and/or modulation alphabets STCs of any desired dimensionality may be produced including multi-dimensional codes.

A method and system are disclosed that can be applied to achieve high-throughput in a WLAN. Central to the present invention is the use of an SDMA compatible multi-beam antenna system by a WLAN access point. A system based on two types of antennas-dynamic beam forming and fixed beam antennas—is described. A mechanism and protocol are described that implement simultaneous transmissions with respect to an SDMA compatible access point and thereby improve spectral efficiency, and by extension achieve higher throughput. Based on the recognition that current WLAN MAC has major limitations in throughput, certain MAC extensions (that can be applied independently of SDMA) are described. Also disclosed are power-saving and power control techniques that improve battery performance and contribute to a reduction in station size, and a means of reducing channel interference. The present invention also deals with the problem of backward compatibility with conventional devices that implement the protocol that is a subset covered by the present invention.

A communication system optimizes cell edge performance and spectral efficiency by a first step of measuring, by the Node B, at least one system performance metric. A next step includes sending, by the Node B, an indicator for the at least one system performance metric measurement. A next step includes receiving the indicator for the at least one system performance metric measurement. A next step includes determining an adaptive power control parameter based on the at least one system performance metric measured by the Node B and system performance metrics measured by at the least one other neighboring Node B. A next step includes using the adaptive power control parameter to update an uplink transmit power level for at least one user equipment served by the Node B.

A method of transmission in a wireless communication system having a transmitter and a receiver. In the transmitter: signals are encoded using a space-domain precoder for spatial multiplexing, time-domain variable delay is introduced at each signal communication path for time diversity, and the signal are transmitted to the receiver. In the receiver the signal transmissions from the transmitter are decoded using a space-domain decoder, wherein time diversity and spatial multiplexing are combined, to increase communication robustness and spectral efficiency.

In one embodiment, a method for generating an adaptive air interface waveform includes generating a waveform that includes a variable carrier frequency and variable bandwidth signal. The variable bandwidth signal includes one or more subcarriers that are dynamically placeable over a range of frequencies, and each subcarrier is separately modulated according to a direct sequence (DS) spread spectrum (SS) technique. The waveform has an embedded pilot usable to optimize one or more spectrum efficiencies of the waveform. A modulation constellation, a code rate, and a code length of the generated waveform are adapted according to an available spectrum and one or more sub-carrier conditions.

The present invention provides for a communication system and method that overlays signals which are simultaneously mutually orthogonal in both the time and frequency domains, thereby enhancing spectral efficiency. Whereas commonly used sinusoids provide only two mutually orthogonal functions (sine and cosine), certain polynomials provide multiple orthogonal functions, which are also finite in both time and frequency. Using multiple orders of the orthogonal functions allows overlaying signals within a symbol to generate a modulated signal carrying more information than with traditional QAM. Correlating a received signal with locally generated replicas of the orthogonal functions allows demodulation of the signal. This modulation is applicable to twisted pair, cable, fiber, satellite, broadcast and all types of wireless access. The method and system are compatible with many current and future multiple access systems, including EV-DO, UMB, WiMax, WCDMA (with or without MBMS/MIMO), HSPA Evolution, and LTE.

The Long Term Evolution Advanced (LTE-A) network, is a heterogeneous network, where macro and pico base stations (BSs) coexist to improve spectral efficiency per unit area. Systems and methods described herein attempt to provide a solution to the interference coordination problem between macro BSs and pico user equipments (UEs). Specifically, the systems and methods conduct interference coordination based on the concept of almost blank subframe (ABS), which is supported by the LTE-A standard. The macro BSs choose their ABS configurations in a cooperative way such that the overall system throughput is optimized.

Beamforming techniques to limit radiated power where there is the potential for interference with macro-cellular coverage or with adjacent mobile stations. Smart antenna beamforming techniques (including the use of angle of arrival information) are combined with access probe information to determine the direction for radiated power and the level of the needed transmitted power as well for the small office or home (SOHO) environment. The placement of RF power in the SOHO specific to where it is needed, minimizes radiating power in directions where it will cause interference with macrocell coverage. In addition, the beamforming techniques provide a base transceiver station with an economical method to quickly solve coverage issues internal to a SOHO, without introducing interference external to this coverage environment. In addition, there specific placement of the RF power where it is needed provides an increase in spectral efficiency of a deployed network.

A multiple-input multiple-output (MIMO) wireless communication system. A transmitter that includes a plurality of transmit antennas selects one of a spatial multiplexing scheme and a spatial diversity scheme, processes a signal in the selected transmission scheme, and transmits the signal through the plurality of transmit antennas. A receiver that includes a plurality of receive antennas processes a signal in a reception scheme mapped to a transmission scheme of the transmitter. The transmission schemes include a transmission scheme for maximizing diversity gain and a transmission scheme for maximizing spectral efficiency. The MIMO communication system using an adaptive transmission mode switching technique performs switching between MIMO transmission modes using spatial selectivity of a channel, thereby obtaining maximum gain in a signal to noise ratio (SNR) and spectral efficiency according to channel state.

Bandwidth allocation configuration and fully decentralized adaptive medium access control (AMAC) systems and methods with support for time critical applications, spectrum efficiency, scalability enhancements, and fair allocation of bandwidth among nodes sharing a common channel. The methods fully integrate TDMA and CSMA/CA channel access approaches and incorporate adaptive congestion and collisions avoidance scheme to reduce bandwidth wastage and diminish adverse cross layers interactions. AMAC improves support for multi-media traffic while allowing higher transmission incidents from large number of transmitting devices sharing a common channel, with fair distribution of the available bandwidth, to enable improved multi-level-security connectivity over a common multi-hop wireless network, provide end-to-end performance enhancement for constant bit rate traffic, variable bit rate traffic, and distribute bandwidth fairly amongst competing TCP traffic flows that traverse varying length paths in multi-hop ad-hoc wireless networks.

A system for redistributing a multiple input audio/video and data signals having a redistributing device equipped to receive signals in a multiple formats and redistribute a selected signal to a user's premises over conductors, preferably existing twisted-pair telephone wire. The redistributing device is in interactive communication with a communications interface located in the user's premises which receives user-input control signals and contains switching circuitry which routes the selected signal to the user's premises where it is received by the receiving unit such as a television receiver. A single redistributing device services an entire multi-user network from a common distribution point, and services multiple users independently. The system of the invention does not interfere with normal use of the telephone network, so users can interactively access services provided by the system and use the telephone at the same time. In one preferred embodiment the system of the invention dynamically allocates frequencies and modulation techniques to various output signals, to maximize spectral efficiency and minimize interference and cross-talk.

A method and apparatus for transmitting beacon signals in a wireless communications network. For a given cell site, a single frequency may be used for the beacon signal by assigning different beacon signal time slots to different sectors of the cell site. During one time slot, the beacon signal is transmitted to one of the sectors, and during another one of the time slots, the beacon signal is transmitted to a different one of the sectors. Because a single frequency can be used for all of the sectors of a cell site, more frequencies are available for other purposes, such as for user traffic, for example. The invention improves spectral efficiency, reduces adjacent channel interference and co-channel interference and allows power consumption to be controlled.

A communication system optimizes cell edge performance and spectral efficiency by determining an adaptive power control parameter based on system performance metrics measured by a serving Node B and further measured by, and reported to the serving Node B by, neighboring Node B's. The adaptive power control parameter is then used to determine an uplink transmit power of a user equipment (UE) served by the serving Node B. The uplink transmit power may be determined by the Node B and then conveyed to the UE, or the Node B may broadcast the adaptive power control parameter to the UE and the UE may self-determine the uplink transmit power. In addition, as a frequency reuse factor of one has been proposed for such communication systems, interference levels may be even further improved by employment of an intra-site interference cancellation scheme in the sectors serviced by the Node B.

To address the need for a resource allocation scheme that results in a better tradeoff between the cell-edge performance and the overall spectral efficiency, a communication system is provided that allocates uplink transmit power to user equipment (UEs) based on a fractional power control scheme. In another embodiment, since the cell-edge users are also likely to be power limited, the communication system may implement a minimized uplink transmission bandwidth resource allocation scheme that may work with the fractional power control scheme to achieve a level of performance desired for uplink transmissions in 3GPP (Third Generation Partnership Project) and 3GPP2 Evolution communication systems.

The invention relates to a method is shown for improving the spectral efficiency of a communication system (100) that comprises at least one Super Base Station SBS (1) and at least one terminal (3-1), wherein at least one Relay Base Station RBS (2-1s used to relay asymmetric up- and downlink data between said at least one Super Base Station SBS (1) and said at least one terminal (3-1) and wherein said asymmetry of said up- and downlink data is considered when dynamically allocating transmission resources to said relay link (5-1, 6-1) between said at least one SBS (1) and said at least one RBS (2-1) and to said link (7-1, 8-1) between said at least one RBS (2-1) and said at least one terminal (3-1).

Downlink and uplink frequencies in a wireless access system are time-shared by adjacent sectors, but remain dedicated to downlink or uplink transmission and may utilize FDD-only bandwidth within the MMDS spectrum. TDD wireless access equipment need only be modified by introducing a frequency change at the normal TDD guard point, with respective downlink or uplink periods for adjacent sectors offset to form overlapping frames. Cyclo-stationary processing, block equalization, and burst timing coordination allow the boundary between downlink and uplink portions of both frames to be set dynamically, improving spectral efficiency. Fast frequency switching within an allotted physical slot enables synchronization of time-sharing the dedicated frequencies to be maintained among sectors and cells. Duplex spacing between downlink and uplink frequencies for a given sector and adjacent sectors, combined with in-depth filtering of received signals, prevents spurious out-of-band transmission signal strength from reaching an interference level.

The present invention provides reduced power dissipation and other benefits at the optical transport network layer by utilizing a digital subcarrier optical network comprising multiple digital subcarrier cross-connect switches. This offers several advantages for optical networks, including spectral efficiency and robustness against signal corruption and consumption of less energy than traditional TDM-based electric switches (OTN/SONET/SDH).

The invention provides a reconfigurable intelligent surface assisted multi-user MIMO uplink transmission method. According to the transmission method, a signal sent by a user side is reflected to a base station through an RIS, and the RIS can change the phase of the signal incident on the RIS. Aiming at a bottleneck problem of channel information acquisition of an RIS-assisted multi-user MIMO transmission system, only partial channel state information is utilized, including instantaneous channel state information from the RIS to a base station channel and statistical channel state informationfrom a user to the RIS channel; through an alternate optimization method, a deterministic equivalence principle, a block coordinate descent method, an MM method and the like, a sending covariance matrix and an RIS phase shift matrix of a user are jointly designed to maximize the global energy efficiency of the system or traverse the spectral efficiency; when the channel state information is changed, the user side dynamically implements transmission power distribution with maximum energy or spectral efficiency, and the RIS dynamically adjusts the phase shift matrix. According to the invention,the implementation complexity is low, and the performance of multi-user MIMO uplink transmission can be effectively improved.

The technical scheme provided by the invention is applied to a honeycomb network of mobile communication. A device to device (D2D) technology is applied to the honeycomb network, so that D2D user pairs are allowed to multiplex the resources of honeycomb network users for communicating. The invention provides a user position list-based method for selectively multiplexing multiple honeycomb user resources for the D2D user pairs, which is used for selecting a plurality of honeycomb users farthest from the D2D user pairs for each pair of D2D users for resource multiplexing. By using the scheme provided by the invention, the complexity of an algorithm is lowered when a base station end selects a plurality of honeycomb users for resource multiplexing, and the interference between the resource multiplexing D2D user pairs and the honeycomb users is reduced to the maximum extent, so that the spectrum efficiency of an entire system is improved. Moreover, the method has high practical operability, is easy to implement in practice, and is applied more flexibly.

A method and system for generating and transmitting optical signals with only one sideband. Single-sideband optical signal transmission reduces the signal impairment effects associated with dispersion. Such transmission also increases the spectral efficiency of optical transmission systems. Single-sideband modulation also makes possible electrical compensation for optical link dispersion during transmission. Single-sideband modulation is generated using the modulating data signal and its Hilbert transform, which is approximated by a tapped-delay time filter. Line coding is used to remove the low-frequency content in the modulating data signal, avoiding the inefficiencies of tapped-delay-line filter approximated Hilbert transformers at low frequencies. Line coding can also help optical single side band signal generation and transmission using a simple optical filter instead of Hilbert transformers.