1, Introduction Marconi from 1897 at a fixed station with a tug to complete the wireless communication between the trial began, wireless Communications technology Has been rapid development. Communications industry is currently hot technologies third generation mobile communication ( 3G ) Has a higher radio frequency utilization efficiency, can provide fast, convenient wireless applications, high-speed data transmission and broadband multimedia services (transmission speed minimum 384k, up to 2M). Although the 3G system than the old 2G system many times faster transmission speed, but still can not meet future demand for multimedia communications. Future Communications market Mainstream services need to provide customers with convenient access to information worldwide consulting capacity, so the future of communications services must have broadband (Broadband), global (Globalization), instant (Immediacy) and mobility (Mobility). To achieve this goal, we must be unlimited broadband Internet access and broadband integrated communications network, but to achieve the broadband wireless communication networks and the integration of the core backbone network, including 3G, including the use of current mobile communication networks are not, and the development of 4G wireless communication technology to support wireless Internet access has become essential. Not yet developed the international unity of 4G communications standards, developed countries have hope in the future 4G standards to gain a place, Europe and the United States and Japan, have long invested heavily in research, and China also in 2002 launched a research and development of 4G Basically, the international synchronization.
According to the forecast, 4G systems will use a lot of new generation of advanced communications technologies such as OFDM, SDR, MIMO and smart Antenna , Space-time coding, providing peak rates up to 100Mb / s, to meet future high-bandwidth real-time multimedia services to business needs. However, with this series of wide application of the latest technology, the new generation system, the algorithm complexity and the overall transmission performance than the previous generation system has an order of magnitude increase, how many of the processing system, the control unit to provide an efficient, high- bandwidth, flexible interconnect architecture, a 4G wireless communications system design challenging problems.
2,4 G system platform architecture structures the problems faced by
(1) digital baseband processor of the increased complexity of the algorithm
4G mobile communication system was introduced in MIMO wireless communication technology. That is, distributed access methods, the transmission signal by multiple antennas to send and receive at the same time, the sender and the receiver between the radio channel from the traditional single input single output (SISO) system into (MIMO) system. MIMO channel can be viewed as a set of parallel subchannels, the total channel capacity for the independence of the channel capacity of quantum channel and, in theory, with the number of antennas increase, significantly increased channel capacity, to improve the wireless network information throughput, expand coverage and improve the quality of transmission offers great potential. However, under multi-antenna MIMO wireless communication system problem caused by the baseband signal processing complexity of geometric growth. Programmable logic device according to the existing logic of scale, it is difficult in the conditions of single or veneer to achieve all of the base-band logic algorithm, a necessary requirement for the base station platform for complex interconnect structure.
(2) huge amount of real time data transfer requirements
4G system, the physical layer baseband processing required to deal with the transmission of data between nodes with high real time. If using the traditional shared bus type (such as: PCI, CompactPCI, etc.), with the baseband processor nodes increases, the amount of data between nodes increases rapidly interactive, real-time transmission between devices is bound to affect performance. Therefore, the traditional share-based architecture with the bus system is difficult to achieve these requirements. Necessary to design a new platform architecture to ensure scalability in a good premise, to achieve connectivity between devices on the bus for data transfer latency when a small bus.
(3) high scalability and flexibility requirements
Current international standards for 4G systems has not been determined, using the baseband processing algorithms and link layer protocols are still ongoing verification and perfection.