Dual carrier modulation precoding

#The invention relates generally to orthogonal frequency division multiplexing (OFDM) communication systems and, more particularly, to precoding techniques performed by such systems.

#The WiMedia standard defines the specifications of a media access control (MAC) layer and a physical (PHY) layer based on orthogonal frequency division multiplexing (OFDM) transmissions. The current WiMedia standard enables short-range multimedia file transfers at rates of up to 480 Mbps with low power consumption. The standard operates in a frequency band between 3.1 GHz and 10.6 GHz in the ultra-wideband (UWB) spectrum. However, the highest data rate of the WiMedia standard rate cannot meet future wireless multimedia applications, such as high definition TV (HDTV) wireless connectivity. An effort is being made to increase the data rates to 1 Gbps and above.

#To this end, weak (or non-channel) channel coding and higher order modulation techniques have been envisioned to be used in future high data rate wireless systems. For example, the WiMedia PHY transfer rate can be increased to 960 Mbps if a ¾ convolutional code together with 16QAM modulation scheme are used. However, precoding of the transmitted OFDM symbols is required to ensure good performance.

#The subject matter that is regarded as the invention is particularly pointed out and distinctly claimed in the claims at the conclusion of the specification. The foregoing and other features and advantages of the invention will be apparent from the following detailed description taken in conjunction with the accompanying drawings.

#FIG. 1 is a block diagram of a transmitter adapted to perform the precoding technique realized in accordance with an embodiment of the invention;

#FIG. 2 is a graph showing simulation results of the precoding technique realized in accordance with the invention; and

#It is important to note that the embodiments disclosed by the invention are only examples of the many advantageous uses of the innovative teachings herein. In general, statements made in the specification of the present application do not necessarily limit any of the various claimed inventions. Moreover, some statements may apply to some inventive features but not to others. In general, unless otherwise indicated, singular elements may be in plural and vice versa with no loss of generality. In the drawings, like numerals refer to like parts through several views.

#FIG. 1 shows a non-limiting and exemplary block diagram of an OFDM based transmitter 100 adapted to implement an improved DCM precoding technique realized in accordance with an embodiment of the invention. The transmitter 100 can transmit data at a rate of 960 Mbps and above while ensuring a frequency diversity of at least order of 2.

#The transmitter 100 includes an encoder 110, a puncturer 120, a bit interleaver 130, a constellation mapping unit 140, a symbol interleaver 150, and an OFDM modulator 160. In accordance with the principles of the invention, input information bits are encoded by the encoder 110. Then, using the puncturer 120, the encoded bits are punctured and divided into data blocks, each data block including ‘m’ bits. Each data block is further divided into ‘p’ (where ‘p’ is an integer equal to greater than 2) sub-blocks, each including m/p bits.