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Space-time transmit diversity systems and methods for OFDM applications

A time and space technology, applied in the field of space-time transmit diversity systems, which can solve problems such as unfavorable code performance and complex decoders

Active Publication Date: 2007-05-09
APPLE INC
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

While trellis codes provide additional coding gain, they have the disadvantages of more complex decoders (since these codes operate on QAM symbols) and difficulty in combining trellis space-time codes with powerful soft-decoding FEC codes such as Turbo Concatenation of Convolutional Codes and Convolutional Codes
due to B 2 ≥0, so is always bad for code performance

Method used

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  • Space-time transmit diversity systems and methods for OFDM applications
  • Space-time transmit diversity systems and methods for OFDM applications
  • Space-time transmit diversity systems and methods for OFDM applications

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Embodiment Construction

[0052] According to the embodiment of the present invention, a method is provided for mapping users to multi-antenna transmission resources, enabling the network to utilize time-frequency diversity and multi-user diversity. In addition, mapping also allows flexible radio resource management / allocation and provides different QoS based services. Within the same framework, users with SISO, MISO, MIMO capabilities can be supported.

[0053] As an overview, each user may be mapped onto different OFDM resources, which may be subchannels such as AMC subchannels and / or diversity subchannels. For MIMO users, it is preferable to support multiple different space-time coding schemes, such as SM (Spatial Multiplexing) and STTD (Space-Time Transmit Diversity).

[0054] On a continuous basis, there is a stream of OFDM symbols associated with each transmit antenna. Each user may first be mapped to one or more OFDM symbols, and then each OFDM symbol may be mapped to its associated antenna. ...

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Abstract

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.

Description

[0001] related application [0002] This application claims U.S. Provisional Patent Application No. 60 / 558566, filed April 2, 2004, U.S. Provisional Patent Application No. 60 / 563,802, filed April 21, 2004, and U.S. Provisional Patent Application No. 60 / 563,802, filed April 28, 2004 Benefit of Application No. 60 / 566009. technical field [0003] The present invention relates to a space-time transmit diversity system and method for OFDM (Orthogonal Frequency Division Multiplexing) applications. Background technique [0004] For open-loop fading channels, diversity is often considered, and the only option is to mitigate fading effects and improve system reliability. While FEC (Forward Error Correction) coding provides important time diversity, for slow fading environments, space diversity / polarization proves to be more effective. The goal of so-called space-time codes is to maximize the diversity gain. [0005] There are basically two types of space-time codes: trellis codes ...

Claims

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Application Information

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IPC IPC(8): H04B7/06H04J11/00H03M13/05
CPCH04B7/0684
Inventor M·贾童文J·马P·朱D·－S·于
Owner APPLE INC