Receiving and dispatching method and system based on orthogonal frequency division multiplexing

Abstract

The present invention belongs to the mobile communication field, and discloses a receiving and dispatching method and a system based on the orthogonal frequency division multiplexing, to make the receiving and dispatching system have a stronger anti-jamming capacity. In the present invention, error correcting coding and grouping are performed to the signals of predetermined lengths at the transmitting end, making the length of each group be less than the predetermined length, the encoded signal of each group is respectively mapped to an orthogonal code, and each orthogonal code which is obtained after being mapped is transmitted through the OFDM system. The OFDM signal corresponding with each orthogonal code is transmitted on the continuous time frequency block. The transmitting end differentiates the transmission signals of a plurality of channels by the way of scrambling from the channel scrambling code, and differentiates the transmission signals of different cells by the way of scrambling from the scrambling codes of cells. In addition, a coherent demodulation can be realized by using pilot frequency.

Description

technical field [0001] The present invention relates to the field of mobile communication, in particular to a signal transmission technology based on Orthogonal Frequency Division Multiplexing ("OFDM" for short). Background technique [0002] Cellular technology is a wireless mobile communication technology that divides a geographical area into several small cells, called "cellular" (cell). Cell phones (or mobile phones) use this technology and are therefore often referred to as cellular phones. [0003] Dividing a large geographical area into multiple "cells" is to make full use of the limited wireless transmission frequencies. Each set of connections (and in the case of wireless telephony, each set of conversations) requires a dedicated frequency. In order to allow more conversations to take place simultaneously, cellular systems assign a certain amount of frequency to each "cell" (ie, each small area). Non-adjacent cells can use the same frequency, so that limited radi...

AI Technical Summary

Problems solved by technology

[0012] In practical applications, the above scheme has the following problems: when transmitting signals through the OFDM system, it cannot be guaranteed that the spread spectrum signals received by the receiving end are still orthogonal, and the reliability of transmission cannot be guaranteed

[0013] The main reason for this situation is that due to the inherent frequency selective fading in the OFDM system and the inherent time selective fading in mobile communications, different subcarriers will have different magnitudes of attenuation at different times, which in turn makes the control channel The transmitted 1024-bit long WALSH orthogonal code is no longer orthogonal at the receiving end, so that the receiving performance of the receiver for the control channel is greatly reduced

In addition, because the 10-bit information of the control channel is not protected by error correction codes, and the receiver uses non-coherent demodulation, the transmission reliability is reduced

Therefore, when the user equipment is in a high-speed mobile state, the transmitted signal will have a large error rate, which cannot meet the requirements of the system

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