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STiMi/ CMMB
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STiMi, the Satellite & Terrestrial Interactive Multimedia Infrastructure, is the physical layer transmission technology for mobile multimedia broadcasting system. It is designed for reliable transmission of mobile multimedia service in China, which is characterized by large area and complex wireless environment. STiMi employs the state of art technologies such as High-structured LDPC Coding, OFDM Modulation, Channel Estimation & Equalization and Fast Synchronization to provide the video, audio and data service to handheld receivers. It works at the frequency ranging from 30MHz ¡« 3000MHz and supports both 8MHz and 2MHz bandwidth.
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STiMi has been approved by SARFT (the State Administration of Radio Film and Television) as GY/T220.1-2006 ¡°Mobile Multimedia Broadcasting Part 1: Framing Structure, Channel Coding and Modulation for Broadcasting Channel¡±, the industry standard for CMMB physical layer, and will be broadly used in mobile multimedia broadcasting in China.
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Advantage of STiMi
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Satellite & Terrestrial SFN
STiMi supports hybrid satellite and terrestrial SFN (Signal Frequency Network). The S-band satellite network provides excellent coverage of the whole Chinese territory. 95% of Chinese territory, including rural areas, deserts, mountains and the ocean can be covered by satellite network, thus the terminals within these areas can receive the signal directly from the satellite. In urban areas consisting of 5% of Chinese territory, the complementary terrestrial network fills the gaps of satellite coverage. This hybrid satellite and terrestrial network not only enables the fast and secure deployment of national wide mobile multimedia broadcasting service, but also meets the requirements of operation of regional programs.
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Mobility
Taking advantage of state of the art technologies such as OFDM modulation, LDPC coding and Interleaving, STiMi enables the high performance of signal reception in the mobile environment. For example, the high-structured LDPC encoding and decoding scheme not only enhance the receiving performance, but also simplify the implementation of encoder and decoder, which make IC design much easier.
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Power Saving
STiMi employs innovative time slotting technology to minimize the power consumption of handheld devices such as mobile phone, PMP and notebook. STiMi enables the handheld devices to stay active only in a fraction of the time and work in power saving mode in an off period, by which, the power consumption of handheld devices is greatly reduced and the longer viewing time per battery charge is achieved
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STiMi applies many innovative technologies such as Channel Estimation and Equalization in time and frequency domain. These technologies enable the users to receive real-time high quality audio and video programs even in complex wireless environment. By using the beacon in time domain, STiMi speeds up program channel acquisition, which greatly improves the user experience.
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Flexibility
STiMi uses logical channels to optimize the transmission of mobile multimedia service. There are one Control Logical Channel (CLCH) and 1~39 Service Logical Channels (SLCH).The capacity of each Logical Channel is respectively configurable on channel coding rate, constellation and time slots allocation.
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