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In the field of wireless communication, ''macrodiversity''〔D. Gesbert, S. Hanly, H. Huang, S. Shamai, O. Simeone, W. Yu, (Multi-cell MIMO cooperative networks: A new look at interference ) IEEE Journal on Selected Areas in Communications, vol. 28, no. 9, pp. 1380-1408, Dec. 2010.〕〔D. A. Basnayaka, P. J. Smith and P. A. Martin, (Performance analysis of macrodiversity MIMO systems with MMSE and ZF receivers in flat Rayleigh fading ) IEEE Transactions on Wireless Communications, vol. 12, no. 5, pp. 2240-2251, May 2013.〕 is a kind of space diversity scheme using several receiver antennas and/or transmitter antennas for transferring the same signal. The distance between the transmitters is much longer than the wavelength, as opposed to microdiversity where the distance is in the order of or shorter than the wavelength. In a cellular network or a wireless LAN, macro-diversity implies that the antennas are typically situated in different base station sites or access points. Receiver macro-diversity is a form of antenna combining, and requires an infrastructure that mediates the signals from the local antennas or receivers to a central receiver or decoder. Transmitter macro-diversity may be a form of simulcasting, where the same signal is sent from several nodes. If the signals are sent over the same physical channel (e.g. the channel frequency and the spreading sequence), the transmitters are said to form a single frequency network - a term used especially in the broadcasting world. The aim is to combat fading and to increase the received signal strength and signal quality in exposed positions in between the base stations or access points. Macro diversity may also facilitate efficient broadcasting and multicasting services, where the same frequency channel can be used for all transmitters sending the same information. The diversity scheme may be based on transmitter (downlink) macro-diversity and/or receiver (uplink) macro-diversity. ==Examples== * CDMA soft handoff: * * UMTS softer handover. * OFDM and frequency-domain equalization (FDE) based Single Frequency Networks (SFN) are a form of ''transmitter macrodiversity'' used in broadcasting networks such as DVB-T and DAB * * Dynamic Single Frequency Networks (DSFN), where a scheduling scheme adapts the SFN formations dynamically to traffic conditions and/or receiver conditions * * 802.16e macro diversity handover (MDHO) * * 3GPP long term evolution (LTE) multicast-broadcast single frequency network (MBSFN), making it possible to efficiently send the same data to many mobiles in adjacent cells. * * Cooperative diversity, for example 3GPP long term evolution (LTE) ''coordinated multipoint transmission/reception'' (CoMP), making it possible to increase the data rate to a mobile situated in the overlap of several base station transmission ranges. 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Macrodiversity」の詳細全文を読む スポンサード リンク
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