What is 5G RSMA | Advantages of RSMA | Disadvantages of RSMA

This page describes 5G RSMA (Resource Spread Multiple Access) basics and RSMA types. It mentions 5G RSMA advantages (Pros) and RSMA disadvantages (Cons). The links to advantages and disadvantages of LTE and other wireless standards are also mentioned.

5G technology uses various multiple access techniques such as CP-OFDM/OFDMA for downlink, SC-FDM/SC-FDMA for uplink and RSMA for Internet of Things (IoT). RSMA is used in use cases which requires asynchronous and grantless access.

RSMA Basics | RSMA Types

Following are the functions of RSMA.
• RSMA technique spreads the signal across time and/or frequency resources allocated.
• It uses lower rate channel coding in order to spread the signal to achieve low spectral efficiency.
• Signals of the respective users can be recovered at the same time even in presence of mutual interference.

RSMA is considered to be more robust due to following reasons.
• The coding gain provides Eb/No efficiency in comparison with orthogonal spreading or simple repetition method.
• Here more powerful codes can be used compare to simple repetition method. This is also combined with low rate convolution codes.

Following are the RSMA types.
• Single Carrier RSMA
• Multi-carrier RSMA or OFDM based RSMA

Refer difference between Single carrier and Multi-carrier >>. Now let us understand difference between single carrier RSMA and Multi-carrier RSMA i.e. OFDM based RSMA.

Single Carrier RSMA

Single Carrier RSMA

The figure-1 depicts single carrier RSMA. As shown it consists of coder, interleaver, spreader or scrambler and cyclic prefix (CP) addition modules in the transmitter. It consists of CP removal, despreader, deinterleaver and decoder in the receiver chain.

Single carrier RSMA delivers better power amplifier (PA) efficiency. Moreover it does not have any synchronization requirement.

Multi Carrier RSMA | OFDM based RSMA

Multi Carrier RSMA, OFDM RSMA

The figure-2 depicts multi carrier RSMA. As shown it consists of coder, interleaver, spreader, S/P (serial to parallel converter), IFFT, P/S (parallel to serial converter) and CP addition modules at the transmitter side. It consists of CP removal, S/P, FFT, P/S, despreader, deinterleaver, decoder modules at the receiver.

Multi carrier RSMA or OFDM based RSMA exploits wider BW (Bandwidth) in order to achieve low latency for less power constained applications such as M2M and IoT (Internet of Things).

RSMA Advantages

Single carrier RSMA advantages are as follows:
➨Allows asynchronous multiplexing
➨Grantless transmission with minimal signaling overhead
➨Link budget gain

OFDM based RSMA advantages are as follows:
➨Grantless transmission with minimal signaling overhead

RSMA Disadvantages

Single carrier RSMA disadvantages are as follows:
➨It is not suitable for higher spectral efficiency.

OFDM based RSMA disadvantages are as follows:
➨It requires synchronous multiplexing.

5G NR Numerology | 5G NR Terminology

5G NR Control channels | 5G NR Traffic Channels | 5G NR Reference Signals and sequences


This 5G tutorial also covers following sub topics on the 5G technology:
5G basic tutorial
5G Frequency Bands
5G millimeter wave tutorial
5G mm wave frame
5G millimeter wave channel sounding
Difference between 4G and 5G
5G testing and test equipments
5G network architecture
5G NR Physical layer
5G NR MAC layer
5G NR RLC layer
5G NR PDCP layer

Difference between OFDM, FBMC, OFDMA and FDM

Following links provide difference between OFDM and FBMC as well as difference between OFDM vs OFDMA and difference between OFDM vs FDM.
OFDM Frame Structure and comparison with OFDMA
Basics of OFDM and difference between FDM and OFDM

Advantages and Disadvantages of other wireless technologies

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RF and Wireless Terminologies