Modulation device and modulation realization method suitable for EDGE system

Abstract

The invention discloses a modulation device and a modulation realization method suitable for EDGE systems. The device includes a baseband digital modulation part, a digital up-conversion quadrature modulator and a high-speed digital-to-analog converter. The baseband digital modulation part includes a switching control signal generation module, a modulation output switching switch, two modulation input switching switches, a GMSK baseband modulation module and an 8PSK baseband modulation module, the switching control signal generation module generates one output switching control signal and two input switching control signals, and the two input switching control signals are mutually For inversion, the output switching control signal and one input switching control signal are only delayed by one time slot cycle, and the modulation input switching switch is respectively connected to the data to be modulated and the fixed bit "1"; the digital up-conversion quadrature modulator includes a CIC filter and a low-pass FIR filter. The invention can ensure the smooth switching of the modulation mode, make the output signal more complete and correct, so that the base station system can achieve better wireless indicators such as modulation spectrum and switching spectrum.

Description

technical field [0001] The present invention relates to the field of mobile communication, in particular to a modulation device and modulation implementation method suitable for EDGE (Enhanced Data Rates For GSM Evolution, enhanced data rate GSM evolution scheme) system. Background technique [0002] GSM (Global System for Mobile Communications), as a second-generation digital mobile cellular communication system mainly based on voice services, has been widely used all over the world. However, with the development of mobile communication technology and the diversification of services, people's demand for mobile data services continues to increase. In order to meet people's demand for mobile data, the GSM system that mainly supports voice services has proposed two high-speed data service models in its Phase2 and Phase2+ specifications (the second-stage specification), namely, based on high-speed data bit rate and circuit switching HSCSD (High Speed ​​Circuit Switched Data) a...

AI Technical Summary

Problems solved by technology

[0005] However, when the existing scheme was realized, the following problems could not be effectively solved: firstly, the integrated digital up-conversion quadrature modulator simply adopts cascaded CIC filters (integrating comb filters) 21 and 22 to Interpolation filtering is realized, so a better modulation spectrum cannot be obtained; secondly, in the EDGE system, regardless of GMSK modulation or 8PSK modulation, a BURST (burst pulse) time slot needs to be fixedly transmitted. 156.25Symbol (symbol), the usual processing method It is to discard the 0.25 Symbol or combine the data of 8 BURST time slots in one frame into 6 156Symbol time slots and 2 157Symbol time slots, but these two methods will cause the modulation phase between adjacent time slots to be discontinuous, thus affecting Wireless indicators such as modulation spectrum and switching spectrum; in addition, in the process of GMSK modulation and 8PSK modulation, there are steps of shaping filtering, which are generally realized by using a look-up table method or a filter with a general structure. However, these two methods require A large number of resources, the efficiency is not high; finally, due to the modulation of the EDGE system, it is necessary to smoothly switch between the GMSK modulation and the 8PSK modulation according to the time slot, but the existing devices generally simply use one modulation module to work with the clock to enable, while the other works Switching is performed by disabling the clock, which will cause incoherent data during switching, which will affect the switching spectrum indicators

Images