TelecomStudy18

Sparse code multiple access (SCMA) is another waveform configuration of the flexible new air interface. This non-orthogonal waveform facilitates a new multiple access scheme in which sparse codewords of multiple layers of devices are overlaid in code and power domains and carried over shared time-frequency resources. Typically, the multiplexing of multiple devices may become overloaded if the number of overlaid layers is more than the length of the multiplexed codewords. However, with SCMA, overloading is tolerable with moderate complexity of detection thanks to the reduced size of the SCMA multi-dimensional constellation and the sparseness of SCMA codewords. In SCMA, coded bits are directly mapped to multi-dimensional sparse codewords selected from layer-specific SCMA codebooks. The complexity of detection is controlled through two major factors. One is the sparseness level of codewords, and the second is the use of multidimensional constellations with a low number of projecti...

The growing traffic demand necessitates increasing the amount of spectrum that may be utilised by the 5G systems. High frequency bands in the centimeter wave (cmWave) and millimeter wave (mmWave) range will be adopted due to their potential for supporting wider channel bandwidths and the consequent capability to deliver high data rates. The new spectrum below 6GHz is expected to be allocated for mobile communication at the World Radio Conference (WRC) 2015, and the band above 6GHz expected to be allocated at WRC 2019, as shown in Figure. 5G network is a heterogeneous network which enables the cooperation between lower-frequency wide-area coverage network and high-frequency network. The consensus is higher frequency bands are the complementary bands to 5G whereas low frequency bands (<6GHz) are still the primary bands of 5G spectrum. High frequency also enables unified access and backhaul since the same radio resources is shared. It is expected to ...

There are many different types of electromagnetic waves. These electromagnetic waves can be described by a sinusoidal function, which is characterized by wavelength. Wavelength (l) is the length of one complete oscillation and is measured in meters (m). Frequency and wavelength are related via the speed of propagation, which for radio waves is the speed of light (3 x10^8 m/s or meters per second). The wavelength of a frequency can be determined by using the following formula: Wavelength = Speed / Frequency Thus, for GSM 900 the wavelength is: Wavelength = 3×10^8 m/s / 900 MHz            Wavelength = 300,000,000 m/s  / 900,000,000 Wavelength = 0.33 m (or 33 cm) From this formula it can be determined that the higher the frequency, the shorter the wavelength. Lower frequencies, with longer wavelengths, are better suited to transmission over large distances, because they bounce on the surface of the e...