摘要:
A method and system for wireless data communication using a first wireless communication technology and a second wireless communication technology. The second wireless communication technology being different from the first wireless communication technology. A transmitter is arranged to transmit data using frame structures based on the first wireless communication technology and the second wireless communication technology in which the frame structure based on the second wireless communication technology has a timing structure, MAC and pilot that are also used with the frame structure of the first wireless communication technology. The transmitter is arranged to selectively change transmission on a frame by frame basis between the first wireless communication technology and the second wireless communication technology.
摘要:
A method and apparatus are provided for measuring channel quality over which has been transmitted a sequence of symbols produced by encoding and constellation mapping a source data element sequence. The method includes receiving a sequence of received symbols over the channel whose quality is to be measured. The sequence of received symbols is de-mapped based on a first channel quality indicator previously transmitted to a transmitter of the sequence of symbols. The method also includes decoding the de-mapped symbols to produce a decoded output sequence. In some embodiments, the decoding may be based on the first channel quality indicator. The method also includes re-encoding the decoded output sequence to produce a re-encoded output sequence. The method also includes correlating the de-mapped symbols with the re-encoded output sequence to produce a second channel quality indicator. The second channel quality indicator is transmitted to the transmitter to adaptively select a type of mapping based on the second channel quality indicator. In some embodiments, the transmitter may adaptively select a type of encoding based on the second channel quality indicator.
摘要:
The present invention provides an effective way to create a virtual MIMO transmission system using mobile terminals that have only one transmit path and antenna. This is accomplished by assigning mobile terminals to a group and assigning certain shared resources and user-specific resources to those mobile terminals in the group. In a synchronized fashion, the mobile terminals will provide uplink transmission in concert, as if they were a single entity having multiple transmission paths and antennas. Preferably, the shared resources bear on how the data is transmitted, and the user-specific resources relate to pilot signals. The data transmitted may be encoded in any number of ways, and in one embodiment, the mobile terminals may relay their information to each other, such that uplink transmissions can incorporate STTD decoding or other space-time codes. The invention is applicable to virtually any multiple access technology, including OFDM, TDMA, and CDMA, preferably synchronous CDMA.
摘要:
The present invention relates to decoding space time coded (STC) signals transmitted from a number of transmit antennas. First, a separate detection technique is used to determine initial decoding solutions corresponding to the symbols transmitted from each of a number of transmit antennas at a given time. For each initial solution, a limited area about the initial solution is defined. Each of the limited areas will correspond to regions including constellation points proximate the initial solution. The initial solutions are used to define a limited, multi-dimensional space. Accordingly, the initial solutions are used to reduce the search complexity associated with joint decoding by defining a limited space about the initial solutions. Finally, a joint decoding technique is implemented within the limited space to find a final solution.
摘要:
Embodiments of the invention provide orthogonal Frequency Division Multiplexing-Space-time Block Codes (OFDMSTBC) mappings for code rate 1, 2 and 4 codes for 4 Transmit Antennas. To overcome the innate weakness of known codes, a new class of STBC codes is provided which is particularly suited for OFDM applications, although other applications are also contemplated. Codes for STBC mappings in the time direction, the frequency direction and a combined time frequency mapping for multiple antennas are provided. In OFDM applications, these codes exploit the properties of OFDM and FEC codes to substantially maintain the advantages of Alamouti codes. Furthermore, while the detailed examples given herein focus on four antenna applications, they can be easily extended to systems with more than four antennas.
摘要:
A method and apparatus for improving channel estimation within an OFDM communication system. Channel estimation in OFDM is usually performed with the aid of pilot symbols. The pilot symbols are typically spaced in time and frequency. The set of frequencies and times at which pilot symbols are inserted is referred to as a pilot pattern. In some cases, the pilot pattern is a diagonal-shaped lattice, either regular or irregular. The method first interpolates in the direction of larger coherence (time or frequency). Using these measurements, the density of pilot symbols in the direction of faster change will be increased thereby improving channel estimation without increasing overhead. As such, the results of the first interpolating step can then be used to assist the interpolation in the dimension of smaller coherence (time or frequency).
摘要:
Methods and devices are provided for MIMO OFDM transmitter and receivers having odd and/even numbers of transmit antennas. Various methods for pre-coding information bits before space time coding (STC) are described for enabling transmission of information bits over all antennas. Methods of decoding received signals that have been pre-coded and STC coded are also provided by embodiments of the invention. Pilot patterns for downlink and uplink transmission between a base station and one or more wireless terminals for three transmit antenna transmitters are also provided. Variable rate codes are provided that combine various fixed rate codes in a manner that results in codes whose rates are dependent on all the various fixed rate codes that are combined.
摘要:
A method and system for wireless data communication using a first wireless communication technology and a second wireless communication technology. The second wireless communication technology being different from the first wireless communication technology. A transmitter is arranged to transmit data using frame structures based on the first wireless communication technology and the second wireless communication technology in which the frame structure based on the second wireless communication technology has a timing structure, MAC and pilot that are also used with the frame structure of the first wireless communication technology. The transmitter is arranged to selectively change transmission on a frame by frame basis between the first wireless communication technology and the second wireless communication technology.
摘要:
The present invention relates to soft handoffs in an OFDM system. Each mobile terminal measures pilot signal strengths of transmissions from adjacent base stations. If the pilot signal strength for a base station exceeds the defined threshold, that base station is added to an active set list. Each mobile terminal notifies the base stations of their active set lists. By providing the set list to the base station controller and the servicing base station, the mobile terminal identifies the sole servicing base station or triggers a soft handoff mode when multiple base stations appear on the active set list. The soft handoff mode uses a combination of scheduling and space-time coding to affect efficient and reliable handoffs.
摘要:
Systems and methods for closed loop MIMO (multiple input and multiple output) wireless communication are provided. Various transmit formats including spatial multiplexing and STTD are defined in which vector or matrix weighting is employed using information fed back from receivers. The feedback information may include channel matrix or SVD-based feedback.