Accton Technology Corporation

Guu-Chang Yang

Pei-Hsuan Lin

Chia-Ming Yang

Jie-Hau Huang

Hong-Chin Lin

Hsuan-Ching Chao

Cheng-Yuan Chang

Yung-Hsien Chang

In a multi-carrier and multi-rate CDMA system, a base station transmits an index tag to a number of mobile stations. The index tag has a length indicating a transmission rate and all index tags are nodes in a code tree. In the code tree, mother nodes and their child nodes block each other and are not assigned to the mobile stations at the same time. At the same time, index tags of nodes in the same level of the code tree map are orthogonal to each other. The mobile station constructs an index tag matrix according to the index tag. Then, the index tag matrix is multiplied with a generating matrix that is stored in every mobile station to generate a spreading factor matrix whose rows respectively correspond to different carriers.

Multicarrier and multirate CDMA system

A multicarrier direct-sequence code-division multiple-access (MC-DS/CDMA) communications system is provided. A code tree of two-dimensional orthogonal variable spreading factor (2D-OVSF) codes is then generated for the system. To generate the code tree, a set of existing M&#xd7;N2D-OVSF matrices, in the form of Afor i={1, 2, . . . , K} is selected as seed matrices. Mrepresents the number of available frequency carriers in the MC-DS/CDMA system, and Nrepresents a spreading factor code length. Another set of existing M&#xd7;N2D-OVSF matrices, in the form of Bfor i={1, 2, . . . , K} is then selected as mapping matrices. The mapping matrices are used to generate corresponding children matrices. These second layer child matrices are MM&#xd7;NNmatrices with cardinality KK, which are defined by reiterating the relationship: where &#x2295; indicates a Kronecker product, and i=1, 2, 3, 4, . . . , K.

Method for generating 2D OVSF codes in multicarrier DS-CDMA systems

A code tree of two-dimensional orthogonal variable spreading factor (2D-OVSF) code matrices for a multicarrier direct-sequence code-division multiple-access (MC-DS/CDMA) communications system is generated by providing two sets of 2&#xd7;2 orthogonal matrices {AA} and {BB}. The first set of 2&#xd7;2 matrices is used to generate a pair of sibling nodes in the code tree that respectively represent matrices Aand Aby iterating the relationship:

The present invention relates to both of a bi-stage correlation calculation demodulation system, and a fast walsh block demodulation device at a receiver, wherein the bi-stage correlation calculation demodulation system has a characteristic of bi-stage correlation calculation in which the subsequent second-stage correlation calculations are dependent on the first-stage correlation calculation results by utilizing an incomplete orthogonal property within CCK codewords to arrange the CCK codewords operated in the first-stage correlation calculations and second-stage correlation calculations properly and respectively. The fast walsh block demodulation device comprises: a plurality of adders (operators) constructed to be a first-level correlation calculation circuit and a second-level correlation calculation circuit, and a plurality of process modules constructed to be a third-level correlation calculation circuit, the process modules having the functions of picking one maximum value from four values and performing third-level correlation calculation of conventional basic fast walsh block demodulation device.

Complementary code keying demodulation system

In this invention, a new tree-structured generation method for obtaining orthogonal variable spreading factor (OVSF) codes that preserve orthogonality between different rates and spreading factors (SF) based on Gray code labels in a CDMA system is presented. Each OVSF code is uniquely associated with a Gray code label. An efficient method for deciding if the code is a mother code or children code of the other code without searching an entire code tree is proposed. Furthermore, by taking advantage of the Gray code labeling, each OVSF code can be generated directly from a generating matrix instead of being generated recursively using a tree structure. An OVSF code reassignment method with Gray code labeling is also given.

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Taichung, Taiwan

Guu-Chang Yang