Matsushita Electric Industrial Co., Ltd.

Ntt Mobile Communications Network, Inc.

Matsushita Communication Industrial Co., Ltd.

Roland Go

Kazuyuki Miya

Hiroyuki Kanaya

Akihiro Higashi

Taku Nagase

Tadashi Matsumoto

A synchronizing method and circuit accurately and stably operates a direct spread spectrum multiple access communication system. A signal transmitted by modulating the spreading code with data at the transmission side is sampled by a signal of n times (n: 1 or larger integer) the clock speed of the spread spectrum signal at the reception side, and the correlation is detected by a digital matched filter. Consequently, the detection output in every sample in the symbol period is compared with the envelope detection output determined in every sampling period, and the sample positions for a specific number of determined samples are stored in the descending order of the output. The number of times of storage of large sample positions in the stored detection output is counted in every symbol period, and the position of the largest number of storage times is detected as the peak position. From this peak position, capturing or holding the symbol period, and setting of the reception window position results.

Spread spectrum communication synchronizing method and its circuit

A synchronizing method and circuit accurately and stably operates a direct spread spectrum multiple access communication system. A signal transmitted by modulating the spreading code with data at the transmission side is sampled by a signal of n times (n: 1 or larger integer) the clock speed of the spread spectrum signal at the reception side, and the correlation is detected by a digital matched filter. Consequently, the detection output in every sample in the symbol period is compared with the envelope detection output determined in every sampling period, and the sample positions for a specific number of determined samples are stored in the descending order of the output. The number of times of storage of large sample positions in the stored detection output is counted in every symbol period, and the position of the largest number of storage times is detected as the peak position. From this peak position, capturing or holding the symbol period and setting of the reception window position results.

A base station of a CDMA communication system includes a transmission de-correlator for eliminating interferences between communication channels of a downlink. The transmission de-correlator has a memory storing a set of data representative of the products of transmission information bits for the respective channels, and the sums of the products of the spread code data sequences for the respective channels, and the elements of an inverse matrix with respect to a predetermined matrix of a cross-correlation between the spread code data sequences for the respective channels. The sums correspond to additions of the products along a direction of columns or to additions of the products along a direction of rows of the inverse matrix. A counting device is operative for causing the memory to sequentially output the data therefrom. An adder serves to calculate a sum of the data outputted from the memory.

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Yokohama, Japan

Roland Go