{{Unreferenced, date=January 2008 Dynamic Single Frequency Networks (DSFN) is a transmitter

macrodiversity In the field of wireless communication, ''macrodiversity''D. Gesbert, S. Hanly, H. Huang, S. Shamai, O. Simeone, W. YuMulti-cell MIMO cooperative networks: A new look at interferenceIEEE Journal on Selected Areas in Communications, vol. 28, no. 9, p ...

technique for

OFDM In telecommunications, orthogonal frequency-division multiplexing (OFDM) is a type of digital transmission and a method of encoding digital data on multiple carrier frequencies. OFDM has developed into a popular scheme for wideband digital commun ...

based cellular networks. DSFN is based on the idea of

single frequency network A single-frequency network or SFN is a broadcast network where several transmitters simultaneously send the same signal over the same frequency channel. Analog AM and FM radio broadcast networks as well as digital broadcast networks can operate ...

s (SFN), which is a group of radio transmitters that send the same signal simultaneously over the same frequency. The term originates from the broadcasting world, where a

broadcast network A terrestrial network (or broadcast network in the United States) is a group of radio stations, television stations, or other electronic media outlets, that form an agreement to air, or broadcast, content from a centralized source. For example, ...

is a group of transmitters that send the same TV or radio program. Digital wireless communication systems based on the

modulation scheme are well-suited to SFN operation, since OFDM in combination with some forward

error correction In information theory and coding theory with applications in computer science and telecommunication, error detection and correction (EDAC) or error control are techniques that enable reliable delivery of digital data over unreliable communica ...

scheme can eliminate

intersymbol interference In telecommunication, intersymbol interference (ISI) is a form of distortion of a signal in which one symbol interferes with subsequent symbols. This is an unwanted phenomenon as the previous symbols have a similar effect as noise, thus making ...

and

fading In wireless communications, fading is variation of the attenuation of a signal with various variables. These variables include time, geographical position, and radio frequency. Fading is often modeled as a random process. A fading channel is a ...

caused by

multipath propagation In radio communication, multipath is the propagation phenomenon that results in radio signals reaching the receiving antenna by two or more paths. Causes of multipath include atmospheric ducting, ionospheric reflection and refraction, and reflec ...

without the use of complex equalization. The concept of DSFN implies the SFN grouping is changed dynamically over time, from timeslot to timeslot. The aim is to achieve efficient spectrum utilization for downlink

unicast Unicast is data transmission from a single sender (red) to a single receiver (green). Other devices on the network (yellow) do not participate in the communication. In computer networking, unicast is a one-to-one transmission from one point in ...

multicast In computer networking, multicast is group communication where data transmission is addressed to a group of destination computers simultaneously. Multicast can be one-to-many or many-to-many distribution. Multicast should not be confused with ...

communication services in centrally controlled cellular systems based on for example the OFDM modulation scheme. A centralized scheduling

algorithm In mathematics and computer science, an algorithm () is a finite sequence of rigorous instructions, typically used to solve a class of specific Computational problem, problems or to perform a computation. Algorithms are used as specificat ...

assigns each data packet to a certain timeslot, frequency channel and group of base station transmitters. DSFN can be considered as a combination of packet scheduling, macro-diversity and

dynamic channel allocation In radio resource management for wireless and cellular networks, channel allocation schemes allocate bandwidth and communication channels to base stations, access points and terminal equipment. The objective is to achieve maximum system spectral e ...

(DCA). The scheduling algorithm can be further extended to dynamically assign other

radio resource management Radio resource management (RRM) is the system level management of co-channel interference, radio resources, and other radio transmission characteristics in wireless communication systems, for example cellular networks, wireless local area networks, ...

parameters to each timeslot and transmitter, such as modulation scheme and error correction scheme, in view to optimize the efficiency. DSFN makes it possible to increase the received signal strength to a mobile terminal in between several base station transmitters in comparison to non-macrodiversity communication schemes. Thus, DSFN can improve the coverage area and lessen the outage probability. Alternatively, DSFN may allow the same outage probability with a less robust but more efficient

modulation In electronics and telecommunications, modulation is the process of varying one or more properties of a periodic waveform, called the ''carrier signal'', with a separate signal called the ''modulation signal'' that typically contains informatio ...

and

error coding In information theory and coding theory with applications in computer science and telecommunication, error detection and correction (EDAC) or error control are techniques that enable reliable delivery of digital data over unreliable communic ...

scheme, and thus improve the

spectral efficiency Spectral efficiency, spectrum efficiency or bandwidth efficiency refers to the information rate that can be transmitted over a given bandwidth in a specific communication system. It is a measure of how efficiently a limited frequency spectrum is ut ...

in bit/s/Hz/base station transmitter in comparison to a non-macrodiversity communication scheme. DSFN resembles the

CDMA Code-division multiple access (CDMA) is a channel access method used by various radio communication technologies. CDMA is an example of multiple access, where several transmitters can send information simultaneously over a single communication ...

downlink

soft handover Soft handover or soft handoff refers to a feature used by the CDMA and W-CDMA standards, where a cell phone is simultaneously connected to two or more cells (or cell sectors) during a call. If the sectors are from the same physical cell site (a sec ...

. A difference is that in the CDMA case, co-channel interference from transmissions to other users are more efficiently avoided by giving the other users other spreading codes. A special form of DSFN is Continuous Transmission DSFN, where all base station transmitters always transmit at full power, without blocking of non-utilized transmitters, and without power control. This concept is very similar to so called

Virtual cellular network Virtual may refer to: * Virtual (horse), a thoroughbred racehorse * Virtual channel, a channel designation which differs from that of the actual radio channel (or range of frequencies) on which the signal travels * Virtual function, a programming ...

s (VCNs), where a virtual cell is a group of base stations sending using the same spreading code, or a group of OFDM transmitters form a Single Frequency Network. DSFN schemes can be described as a form of "virtual" power control.

See also