Ofdm is a frequency division multiplexing fdm scheme used as a digital multi carrier modulation method. Ofdmasc fdma in 4g lte part 2 streams of data, in the form of bits, reaches network gateway from various sources. Orthogonal frequency division multiplexing and related. It is a digital multicarrier scheme that uses a large number of closelyspaced subcarriers to carry data and control information. Construct an ofdm modulator that has two symbols and insert a dc null. The lte ofdm subcarrier spacing equals 15 khz for both downlink and uplink. The proposed bit mapping scheme can enhance the robustness of the index modulation in dm ofdm im. Subcarrier mapping based on slice visibility for video. The present invention relates to the mapping of data and pilot symbols in an ofdm system. Ofdm transmitters low cost is the ability to implement the mapping of bits to unique carriers via.
A new bit mapping scheme for dm ofdm im is proposed. Pdf performance analysis of dualhop ofdm relay systems. In the distributed subcarrier mapping mode, dft outputs of the input data are allocated over the entire bandwidth with zeros occupying the unused subcarriers, whereas con. Orthogonal frequency division multiplexing ofdm modulation a mapping of the information on changes in the carrier phase, frequency or amplitude or combination. A subcarrier is a sideband of a radio frequency carrier wave, which is modulated to send additional information. Symbol error performance analysis of ofdm relaying system. The subcarrier indices are numbered from 1 to cin fft, where n fft is the number of fft points. Using a large number of parallel narrow band sub carriers instead of a single wideband carrier to transport information. Index modulation aided subcarrier mapping for dualhop ofdm relaying miaowen wen, senior member, ieee, xuan chen, qiang li, ertugrul basar, senior member, ieee, yikchung wu, senior member, ieee, and wensong zhang abstractthere is a recent surge of research interest in the study of performanceenhancing techniques for orthogonal. Pdf index modulation aided subcarrier mapping for dualhop. This paper presents the outage probability and outage capacity analysis of cooperative orthogonal frequency division multiplexing ofdm system with subcarrier mapping scm in rayleigh fading. Each individual subcarrier is modulated at a low symbol rate with a conventional modulation format.
An introduction to orthogonal frequency division multiplex. Lte is designed to meet carrier needs for highspeed data and media transport as well as highcapacity voice support well into the next decade. Ofdma is a method that assigns different group of subcarriers in frequency to different users. Ergodic capacity of ofdm af fixed gain relay system with subcarrier mapping.
Our asymptotic sep analysis reveals that the traditional scm which can maximize the capacity can not improve the average sep for uncoded ofdm system, however the average sep can be decreased significantly by dropping several worst links. Outage analysis of a dualhop ofdm amplifyandforward relay. Rather than transmit a highrate stream of data with a single subcarrier, ofdm makes use of a large number of closely spaced. New constellation design and bit mapping for dual mode ofdmim. The spacing is such that the subcarriers are orthogonal, so they wont interfere with one another despite the lack of guard bands between them. However, no study has examined its exact or approximate closeform analysis under nakagamim fading. Orthogonal frequency division multiplexing ofdm is a digital multicarrier modulation scheme that extends the concept of single subcarrier modulation by using multiple subcarriers within the same single channel. Multicarrier transmission over mobile radio channels. Modulation a mapping of the information on changes in the carrier phase, frequency or amplitude or. Index modulation aided subcarrier mapping for dualhop ofdm relaying article pdf available in ieee transactions on communications pp99 june 2019 with 340 reads how we measure reads.
Ber performance of the dpsk differentially phase shift keying modulated dualhop ofdm based df decode and forward relay system, implementing subcarrier mapping scm at the relay r station, is examined. The novel approach of simofdm tries to exploit an additional new dimension in the ofdm frame coming from the state of each. The ofdm modulator enables you to specify the subcarrier indices for the pilot signals. Subcarrier mapping scm is considered to be crucial for capacitymaximization in an orthogonal frequency division multiplexing ofdm relaying network. This seems reasonable since ofdm with long enough cyclic prefix is a powerful mean to mitigate multipath. Scm also known as scma, subcarrier multiple access is used in passive optical network pon access infrastructures as a variant of wavelength division multiplexing wdm. Ofdm has developed into a popular scheme for wideband digital communication. With dsp techniques fft and ifft, subcarrier spacing can be reduced to.
Pdf on the optimal subcarrier mapping scheme in ofdm. Orthogonal frequency division multiplexing ofdm is a method of encoding digital data on multiple carrier frequencies. Figures 25 from 3 present the results of that paper. Examples include the provision of colour in a black and white television system or the provision of stereo in a monophonic radio broadcast. Pdf on the optimal subcarrier mapping scheme in ofdm decode. Index modulation aided subcarrier mapping for dualhop. There is no physical difference between a carrier and a subcarrier. Subcarrier multiplexing scm is a method for combining multiplexing many different communications signals so that they can be transmitted along a single optical fiber. A transmitter includes a baseband modulator, subcarrier mapping, inverse fourier transform, cyclic prefix addi. Subcarrier mapping scm is considered to be crucial for capacitymaximization in orthogonal frequency division multiplexing ofdm relaying networks and has been investigated extensively.
When there is more than one transmit antenna, ensure that the pilot indices for each symbol differ between antennas. Pdf a new modulation technique, named as orthogonal frequency division multiplexing ofdm with. The subcarrier indices are numbered from 1 to n fft. In ofdm a number of different frequency carriers are modulated with a signal from a scheme such as quadrature amplitude modulation qam. The result of the subcarrier mapping is the set l 0, 1, 2, m1 of complex subcarrier amplitudes, where n of the amplitudes are nonzero. In multiuser channel spread mimo ofdm provides more capacity than the other schemes. Mapping of information on changes in the carrier phase, frequency or amplitude or. Index modulation aided subcarrier mapping for dualhop ofdm.
Mapping incoming bits to the subcarrier indices is one of the flexible properties of ofdmim. This paper considers the ordered subcarrier pairing schemes, i. Pilot symbols are necessary for a channel estimation such as to effect coherent detection of e. Overview of the 3gpp long term evolution physical layer 1 1 introduction the 3gpp long term evolution lte represents a major advance in cellular technology. Performance of ofdm af relaying system with subcarrier. Subcarrier spreading for ici mitigation in ofdmofdma systems. Overview of the 3gpp long term evolution physical layer. Performance analysis of dualhop ofdm relay system with. Pdf index modulation aided subcarrier mapping for dual. The indices can be specified for each symbol and transmit antenna. Spectrum of a single modulated ofdm subcarrier truncated.
The capacitymaximization scm scheme is analyzed and closedform expressions are derived for the outage probability and outage capacity of the. Orthogonal frequency division multiplexing and related technologies fall 2007 mohamed essam khedr modulation mapping in ofdm. Subcarrier mapping based on slice visibility for video transmission over ofdm channels laura toni, dawei wang, pamela c. Using a large number of parallel narrowband sub carriers instead of a single wideband carrier to transport information. The selection of the subcarrier spacing in an ofdm based system needs to carefully balance overhead from the cyclic prefix against sensitivity to doppler spreadshift and other types of frequency errors and inaccuracies. Whereas ofdm assigns one block in time to one user. Pdf ofdm with subcarrier number modulation researchgate. Mapping bit stream to baseband pulseshaping filter. As in ofdma, an mpoint idft transforms the subcarrier amplitudes to a complex time domain signal. Implications to ofdm zero tones on edge of band time domain windowing smoothes adjacent symbols ieee 802.
The inverse discrete fourier transform idft equation is represented as 12. A mapping function, p, maps input data symbols in a to a size n vector, s s1, s2, s n. In multihop ofdm relay systems the endtoend average capacity can be increased by incorporating subcarrier mapping scm at the relay nodes. Jun 01, 2015 ofdm divides a given channel into many narrower subcarriers. Concepts of orthogonal frequency division multiplexing ofdm.
Performance of ofdm af relay system with subcarrier mapping. On the optimal subcarrier mapping scheme in ofdm decodeandforward relay systems conference paper pdf available. Outage probability and outage capacity analysis of. Ofdm is a combination of modulation and multiplexing. This comes about by having the subcarrier spacing equal to the reciprocal of symbol time. Although scm in an ofdm system has been investigated extensively, nevertheless, the outage probability and outage capacity analysis of the system is not yet available in the literature. Show the subcarrier mapping of the ofdm symbols created by. The orthogonal frequency division multiplexing ofdm and singlecarrier frequencydivision multiple access scfdma, also called fftspread ofdm technologies have been widely adopted in modern wireless communication systems, such as 3gpp long term evolution lte, ieee 802.
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