Why is Multiplexing Important in 5G Networks for Better Performance

Multiplexing is a crucial aspect of 5G networks, allowing multiple signals to be transmitted over a single communication channel. This significantly improves performance by increasing data transfer rates and reducing latency.

5G networks use a technique called orthogonal frequency-division multiplexing (OFDM) to enable multiplexing. OFDM divides data into multiple smaller streams, which are then transmitted over different frequencies. This allows for more efficient use of bandwidth and better resistance to interference.

The result is a more robust and efficient network that can handle a large number of devices and applications. For example, a 5G network with multiplexing can support up to 100 times more devices than a 4G network.

Multiplexing Techniques are a crucial aspect of 5G technology. They allow multiple channels or users to share the same system resource, increasing efficiency and transmission capacity.

There are several traditional multiplexing techniques, including Frequency Division Multiplexing (FDM), Time Division Multiplexing (TDM), Code Division Multiplexing (CDM), Wavelength Division Multiplexing (WDM), Space Division Multiplexing (SDM), and Polarization Division Multiplexing (PDM).

FDM divides the total channel bandwidth into multiple subbands, each assigned to a user or signal by modulating with a specific carrier frequency. TDM, on the other hand, assigns user data to periodically recurring timeslots, making it suitable for digital signal transmission. CDM uses specified orthogonal spread spectrum codes to allocate resources. WDM multiplexes several optical carrier signals onto a single optical fiber by using different wavelengths. SDM transmits separate data streams in parallel using the same time/frequency resources. PDM uses orthogonal polarizations to transfer signals, allowing for reuse of the same frequency band.

Here are the traditional multiplexing techniques listed:

Time Division Multiplexing (TDM) is a technique for the serial transmission of user data over a common medium such as a coaxial cable.

At a time, only one user's data are transmitted serially in a time slot. TDM allows each user to use the entire system bandwidth.

In addition to user data, signaling and frame alignment word (FAW) are inserted into the frame.

TDM is a suitable technique for digital signal transmission, commonly used in digital telephone systems.

A key feature of TDM is clock recovery and frame synchronization at the receiver to recover data for each channel.

Here are the traditional multiplexing techniques mentioned in the article:

In a MIMO system, data is encoded in both space and time domains and transmitted by multiple antennas through a MIMO propagation channel. This setup is shown in Figure 12.

A MIMO system typically consists of NT transmit antennas and NR receive antennas. This configuration allows for various multiplexing techniques to increase channel capacity.

The data transmission process involves encoding the data in both space and time domains, which enables the use of multiple antennas to transmit the same data. This approach helps to improve the system's capacity and reliability.

Here's a brief overview of the key components involved in a MIMO system:

By using multiple antennas, a MIMO system can take advantage of the spatial diversity of the propagation channel, which helps to improve the system's capacity and reliability.

5G NR supports both Frequency Division Duplex (FDD) and Time Division Duplex (TDD) schemes.

FDD is similar to FDM, using separate carrier frequencies for UL and DL.

TDD is similar to TDM, using only one carrier frequency and assigning transmission/reception in UL and DL by different time slots.

TDD is the main duplexing mode for higher frequencies.

FDD is used for lower frequencies as interference problems with large cells are reduced by having different frequencies in UL and DL.

Multiplexing is essential in 5G for efficient data transmission.

5G NR supports both Frequency Division Duplex (FDD) and Time Division Duplex (TDD) schemes.

FDD is used for lower frequencies, reducing interference problems with large cells by using separate carrier frequencies for UL and DL. Data are transmitted in both directions simultaneously.

TDD, on the other hand, is used for higher frequencies and assigns transmission/reception in UL and DL by different time slots.

In 5G NR, duplexing schemes play a crucial role in ensuring efficient data transmission. The technology supports both Frequency Division Duplex (FDD) and Time Division Duplex (TDD) schemes.

TDD is the main duplexing mode for higher frequencies, while FDD is used for lower frequencies to reduce interference problems with large cells.

Data transmission in FDD is simultaneous, using separate carrier frequencies for uplink (UL) and downlink (DL).

In single user MIMO, the user equipment (UE) plays a crucial role in transmitting sounding reference signals through each of its antenna ports.

The UE's limited size and power mean it's difficult to add more RF chains, so SRS resources are transmitted on antenna ports one by one using transmit antenna switching (TAS).

The gNB estimates the channel based on the received sounding reference signals, which it uses to calculate the downlink precoding weights.

The gNB then transmits the PDSCH using the calculated precoder.

This procedure is a straightforward but effective way for the gNB to estimate the channel and transmit data to the UE.

Uplink transmission modes are an essential part of 5G NR technology. 5G NR supports uplink PUSCH precoding up to 4 layers.

In the case of DFT-based transform precoding, only single-layer transmission is supported. This means that the transmitted symbols are layer mapped and then precoded at the UEs.

The gNB instructs the UE on PDCCH regarding the choice of precoding matrix selected from a codebook, which is known as codebook based. This is illustrated in Figure 19a.

If the gNB doesn't instruct the UE on PDCCH, the UE measures the DL CS-RS signal to determine precoding weights, which is known as non-codebook based. This approach is shown in Figure 19b.

In Multi-User MIMO schemes, gNB communicates with multiple UEs at the same time using the same time/frequency resources. This allows for more efficient use of network resources.

MU-MIMO schemes support up to 2 layers per UE, which is smaller than SU-MIMO's maximum of 8 layers. However, the maximum number of layers per cell is higher, enabling multiple UEs to use 2x2 MIMO simultaneously.

The DL MU-MO Type II codebook allocates a set of beams to each UE, which is a weighted combination of beams with relative amplitudes and co-phasing phase shifts.

Beamformed CSI-RS relies on gNB having advanced information to allow beamforming of the CSI Reference Signal transmissions.

Multiplexing is a crucial aspect of 5G technology, allowing multiple users to share the same time and frequency resources. This is achieved through various multiplexing schemes, including spatial multiplexing and MIMO schemes.

In a CDMA system, each user is assigned a specific spreading code, enabling multiple users to send information simultaneously over a single communication channel. This principle is based on the spread spectrum method.

Some common multiplexing schemes include:

Service-Based Multiplexing is a key concept in 5G NR technology. It allows for efficient use of radio resources by enabling multiple services to share the same frequency band.

One of the key benefits of Service-Based Multiplexing is its ability to support a wide range of services, from low-latency applications to high-bandwidth services. This is made possible by the use of advanced duplexing schemes, such as spatial multiplexing.

Spatial multiplexing is a technique that allows multiple data streams to be transmitted simultaneously over the same frequency band. This is achieved through the use of Multiple-Input Multiple-Output (MIMO) schemes, which enable multiple antennas to be used to transmit and receive data.

Here's a breakdown of the different types of duplexing schemes:

The CSI framework plays a crucial role in Service-Based Multiplexing, as it enables the base station to estimate the channel state information and allocate resources accordingly. This results in improved spectral efficiency and better service quality.

Code Division Multiple Access (CDMA) is a multiple access method that allows multiple users to share the same time and frequency resources.

CDMA is based on the spread spectrum principle, where each transmitter uses a pseudo-random code to modulate the data, and the receiver decodes the modulated signal using its own pseudo-random code.

The principle of CDMA is illustrated in Figure 7, but I'll try to simplify it: imagine multiple users sending information simultaneously over a single communication channel, each with their own unique code.

There are traditional multiplexing techniques, including Frequency Division Multiplexing (FDM), Time Division Multiplexing (TDM), Code Division Multiplexing (CDM), Wavelength Division Multiplexing (WDM), Space Division Multiplexing (SDM), and Polarization Division Multiplexing (PDM).

Here's a brief summary of each:

These multiplexing techniques help increase the efficiency of using system resources and the transmission capacity of the system.