# 無線多媒體網路期末

### **Dynamic Reuse of Unlicensed Spectrum ?**

* Dynamic Reuse of Unlicensed Spectrum (DRUS) is a technique for improving the utilization of unlicensed radio frequency (RF) spectrum, which is spectrum that is not reserved for specific users or applications and can be used by anyone for a variety of purposes, such as wireless networking, telecommunication, and broadcasting.

* DRUS involves the use of algorithms and other techniques to dynamically assign and reassign unlicensed spectrum to different users and applications based on the demand for the spectrum and the available bandwidth. This allows for more efficient use of the spectrum, as it can be shared among multiple users rather than being reserved for a single user or application.

* DRUS can be used in a variety of settings, including wireless networks, telecommunication systems, and broadcasting systems. It is particularly useful in environments where there is high demand for unlicensed spectrum, as it allows for more efficient use of the available spectrum resources.

* There are several different approaches to implementing DRUS, and the specific approach used will depend on the specific requirements and constraints of the application or system in which it is being used. Some of the key factors that can impact the effectiveness of DRUS include the level of interference present in the environment, the level of coordination among users, and the availability of spectrum sensing and measurement tools.

#### **LTE-Unlicensed Program and Standardization**
##### **Motivation:**
* The motivation for the LTE-Unlicensed (LTE-U) program and standardization was to address the increasing demand for mobile data services, which was leading to congestion on traditional licensed mobile networks. One approach to addressing this congestion was to offload some of the traffic to the unlicensed band, which is available for use by anyone without the need for a license.

* One approach to using the unlicensed band for mobile data services is Carrier WiFi, in which operators deploy WiFi access points (APs) as part of their network infrastructure. The advantage of this approach is that it can help reduce congestion and improve Internet access for customers. However, there are also disadvantages to this approach. One disadvantage is that Carrier WiFi uses different access and management mechanisms from the LTE network, which can lead to inefficiency in network management and spectrum usage.

#### **LTE Unlicensed (LTE U)**

* LTE Unlicensed (LTE U) is a technology that allows mobile carriers to use unlicensed spectrum (frequencies that are not assigned to a specific operator and can be used by anyone) to provide LTE mobile services. It was developed by the LTE-U Forum, a group of companies including Verizon, Alcatel Lucent, Ericsson, Qualcomm, and Samsung. The goal of LTE U is to adapt the existing features of 3GPP LTE (a mobile communication standard) to unlicensed operation, while also taking into consideration the requirements of other users of the unlicensed spectrum, such as Wi-Fi.

* LTE U uses mechanisms such as carrier selection, on-off switching, and carrier-sensing adaptive transmission (CSAT) to coexist with Wi-Fi and other systems that use the same unlicensed spectrum. Carrier selection involves selecting a channel that is free of interference, while on-off switching allows the LTE U cell to stop transmitting when traffic demand is low. CSAT allows the LTE U cell to share the spectrum with other systems in a time-division multiplex (TDM) manner, adjusting its duty cycle based on the activity of the channel and the presence of Wi-Fi signals.

* LTE U has been implemented in some areas in the United States, but its deployment and adoption have been somewhat limited due to concerns about its impact on the performance of Wi-Fi networks. Recent studies have shown that the throughput of Wi-Fi tends to decrease when sharing the same channel with LTE U or other technologies that use unlicensed spectrum.

#### **Licensed Assisted Access (LAA)**
* Licensed Assisted Access (LAA) is a technology that allows mobile carriers to use unlicensed spectrum to boost their downlink throughput through carrier aggregation and the use of supplemental downlink. It was approved by the 3GPP in Release 13 in 2015, and an enhanced version called eLAA was approved in Release 14 to allow for uplink transmission in the 5 GHz band. LAA uses control and signaling information on a licensed carrier (PCell) and additional carriers from unlicensed bands (SCells) to increase data throughput.

* LAA operates in bands 46 and 47, which are in the 5,150-5,925 MHz range. Band 47 is a subset of band 46 and has a bandwidth of 10 MHz or 20 MHz. LAA uses listen before talk (LBT) to ensure that it coexists with other systems using the same unlicensed spectrum. LBT requires devices to first sense the channel to determine if it is clear before transmitting. If the channel is busy, the device waits a certain period of time before trying again. LAA also uses frame structure type 3 and discovery reference signals (DRS) to allow for efficient use of radio resources.

* There are two transmission modes defined for LAA in Release 13: one for transmissions on the physical downlink shared channel (PDSCH) and one for transmitting DRS without PDSCH. LAA has been implemented in some areas, but its deployment and adoption have been limited due to concerns about its impact on the performance of Wi-Fi networks.
#### **LBT Variation**

* In LBT with VCW, exponential backoff is used on top of the FCW. In this case, the contention window doubles each time the transmission of the device is collided. The device continues to retransmit until it reaches the maximum number of retransmissions per packet (KL), after which the contention window is reset to WL. The device also resets the contention window to WL after a collision-free transmission. In both variations of LBT, the contention window size (WL) is chosen based on the specific technology and the requirements of the unlicensed spectrum being used.

* It is important to note that LBT is used to improve coexistence between systems using the same unlicensed spectrum, but it may not completely eliminate interference or impact on performance. Studies have shown that the throughput of Wi-Fi networks can be affected when sharing the same channel with technologies like LAA that use LBT.

#### **LTE-WLAN Aggregation (LWA)**

* LTE-WLAN Aggregation (LWA) is a technology that allows mobile carriers to use both LTE and Wi-Fi networks to provide broadband services to users. LWA supports link aggregation at the packet data control protocol (PDCP) layer, which allows the LTE eNB to independently route PDCP packet data units (PDUs) of the same IP flow through both the LTE and Wi-Fi links.

* In LWA, the Xw interface is used to route PDCP PDUs to Wi-Fi access points (APs). The Xw interface is terminated at the WLAN termination, a 3GPP logical node that may control one or more Wi-Fi APs and provides seamless mobility among them. A new Ether-type is defined to identify PDCP PDUs routed over Wi-Fi, which allows the Wi-Fi APs to differentiate LWA traffic from other Wi-Fi traffic. However, software or firmware upgrades may be needed for legacy Wi-Fi APs to recognize this new Ether-type and enable LWA operation.

* LWA has been implemented in some areas and has the potential to provide improved coverage and capacity for mobile broadband services by leveraging the strengths of both LTE and Wi-Fi networks. However, its deployment and adoption have been limited in some cases due to the complexity of integrating the two technologies and the need for software or firmware upgrades of Wi-Fi APs.

#### **LTE WLAN radio level integration with IPsec tunnel (LWIP)**

* LTE WLAN radio level integration with IPsec tunnel (LWIP) is a technology that allows for the integration of Long-Term Evolution (LTE) and wireless local area network (WLAN) networks at the radio level. It enables the transparent transmission of Internet Protocol (IP) data over legacy WiFi access points (APs) from an LTE evolved Node B (eNB) to a user equipment (UE) using an LWIP security gateway (SeGW) as a relay.

* The SeGW is introduced between the LTE eNB and the UE and acts as a security gateway that encrypts the IP data using IPsec (Internet Protocol Security) before it is transmitted over the WiFi APs. This process creates an IPsec tunnel between the SeGW and the UE, allowing the transmission of IP packets over either the LTE or WiFi link, but not both. This is because the Transmission Control Protocol (TCP) cannot handle the out-of-order delivery of packets transmitted over two different radio interfaces.

* LWIP provides a more universal solution for accessing the unlicensed band and supports the switching of IP flows at the IP layer. It does not require the use of a new Ether type and can be implemented using legacy WiFi APs. Overall, LTE WLAN radio level integration with IPsec tunnel (LWIP) allows for the seamless transmission of IP data over both LTE and WiFi networks, improving the overall performance and connectivity of wireless communication systems.

#### **WiFi 7 Multi Link Operation**

* WiFi 7 Multi Link Operation is a feature of modern WiFi access points (APs) that allows for the use of multiple independent links to connect to multiple stations (STAs). This is typically achieved through the use of dual or tri-band operations, where the WiFi media access control (MAC) and physical (PHY) layers of different bands operate almost independently.

* There are two main modes of multi-link operation: restricted mode and dynamic link switch. In restricted mode, data and acknowledgement (ACK) packets are transmitted over one link, while management information is transmitted over another link. In dynamic link switch mode, multiple links can be used for the transmission of the same flow, with management information and negotiation sent over another link. This allows for load balancing across multiple links and improved performance.

* There are also two main types of multi-link operation: asynchronous and synchronous. In asynchronous multi-link operation, each link operates independently, with no coordination between them. In synchronous multi-link operation, the links are coordinated to ensure that they operate in a synchronized manner.

* Finally, multi-link operation can be performed in either duplicate mode or joint mode. In duplicate mode, each link transmits the same data, while in joint mode, each link transmits different data. The choice between these modes depends on the specific requirements and constraints of the network.

### **MIMO and Beamforming**

* Multiple-Input Multiple-Output (MIMO) is a wireless communication technology that uses multiple antennas at both the transmitter and receiver to improve communication performance. MIMO systems can transmit and receive multiple data streams simultaneously over the same frequency band, which can improve the capacity and reliability of wireless networks.

* Beamforming is a technique that is often used in conjunction with MIMO systems to improve the range and performance of wireless communication. It involves the use of multiple antennas at the transmitter or receiver to create a focused beam of energy that is directed at the intended receiver or transmitter. This can help to improve the signal-to-noise ratio (SNR) and reduce interference, which can result in improved communication performance.

* There are several different types of beamforming, including digital beamforming, analog beamforming, and hybrid beamforming. The specific type of beamforming used will depend on the requirements and constraints of the application or system in which it is being used.

* MIMO and beamforming are widely used in a variety of wireless communication systems, including cellular networks, wireless LANs, and satellite systems, to improve the capacity, range, and reliability of the communication link.

#### **Benefits of Multiple Antenna Transmission**

* There are several benefits of using multiple antennas in wireless communication systems:

1. Increased capacity: Using multiple antennas at both the transmitter and receiver can increase the capacity of a wireless communication system, as it allows multiple data streams to be transmitted and received simultaneously over the same frequency band. This can be particularly useful in environments where there is a high demand for wireless capacity.

2. Improved range: Multiple antennas can be used to create a focused beam of energy that is directed at the intended receiver or transmitter, which can help to improve the range of the communication link. This can be particularly useful in environments where the transmitter and receiver are located far apart, or where there are obstacles that can interfere with the signal.

3. Increased reliability: Multiple antennas can be used to improve the reliability of a wireless communication link by reducing the effects of interference and fading. This can be particularly useful in environments where there are many sources of interference or where the signal quality may vary.

4. Improved energy efficiency: Multiple antennas can be used to improve the energy efficiency of a wireless communication system by allowing the transmitter to focus its energy on the intended receiver and reduce the amount of energy that is transmitted in other directions. This can help to extend the battery life of wireless devices and reduce the overall energy consumption of the system.

5. Enhanced security: Multiple antennas can be used to improve the security of a wireless communication system by using beamforming and other techniques to create multiple secure communication channels that are resistant to interception and jamming. This can be particularly useful in environments where the security of the communication link is a critical concern.

#### **Supplementary: Forward Error Correction**

* Forward Error Correction (FEC) is a technique used in communication systems to improve the reliability of data transmission over noisy or error-prone channels. It involves adding redundant data to the original message, which can be used by the receiver to detect and correct errors that may occur during transmission.

* There are several different types of FEC schemes, including block codes and convolutional codes. Block codes work by dividing the original message into blocks of a fixed size and adding a fixed number of redundant bits to each block. Convolutional codes work by adding redundant bits to the original message in a continuous stream, using a predetermined set of rules.

* FEC schemes can be used in a variety of communication systems, including wireless communication systems, satellite systems, and digital communication systems. They are particularly useful in environments where the communication channel is prone to errors or interference, as they can help to improve the reliability of the transmission.

* FEC is often used in conjunction with other error correction and detection techniques, such as Automatic Repeat reQuest (ARQ) and Cyclic Redundancy Check (CRC), to provide a comprehensive approach to error correction and detection.

#### **Supplementary: Linear Block Codes**

* Linear block codes are a type of error-correcting code that is used in communication systems to detect and correct errors that may occur during the transmission of data. They are called "linear" codes because the redundant bits that are added to the original message are generated using a linear combination of the original message bits.

* Linear block codes work by dividing the original message into blocks of a fixed size, called "code words," and adding a fixed number of redundant bits to each code word. These redundant bits are generated using a predetermined set of rules, and they can be used by the receiver to detect and correct errors that may have occurred during transmission.

* Linear block codes have several important properties that make them useful for error correction. They are easy to implement and decode, and they have a low overhead, which means that they do not require a large number of redundant bits to be added to the original message. They also have a good error-correction performance, which means that they are able to correct a relatively large number of errors for a given block size.

* Linear block codes are widely used in a variety of communication systems, including wireless communication systems, satellite systems, and digital communication systems. They are particularly useful in environments where the communication channel is prone to errors or interference, as they can help to improve the reliability of the transmission.

#### **Supplementary: Convolutional Codes**

* Convolutional codes are a type of error-correcting code that is used in communication systems to detect and correct errors that may occur during the transmission of data. They are called "convolutional" codes because they work by adding redundant bits to the original message in a continuous stream, using a predetermined set of rules.

* Convolutional codes work by encoding the original message using a "trellis" diagram, which is a graphical representation of the code. The trellis diagram consists of a series of nodes that represent the possible states of the code, and edges that represent the transitions between states. The redundant bits are generated by following the transitions between the nodes of the trellis diagram.

* Convolutional codes have several important properties that make them useful for error correction. They are able to correct a large number of errors for a given code rate (the ratio of the number of redundant bits to the number of original message bits), and they are able to adapt to changing channel conditions. They also have a good error-correction performance, which means that they are able to correct a relatively large number of errors for a given block size.

* Convolutional codes are widely used in a variety of communication systems, including wireless communication systems, satellite systems, and digital communication systems. They are particularly useful in environments where the communication channel is prone to errors or interference, as they can help to improve the reliability of the transmission.

#### **MIMO Categories**

* There are several categories of MIMO (Multiple-Input Multiple-Output) systems, which are classified based on the number of antennas used at the transmitter and receiver:

1. Single-Input Single-Output (SISO) systems: These systems use a single antenna at both the transmitter and receiver. SISO systems are the simplest form of MIMO systems and are commonly used in a variety of wireless communication systems.

2. Single-Input Multiple-Output (SIMO) systems: These systems use a single antenna at the transmitter and multiple antennas at the receiver. SIMO systems can be used to improve the capacity and reliability of wireless communication systems by allowing multiple data streams to be received simultaneously.

3. Multiple-Input Single-Output (MISO) systems: These systems use multiple antennas at the transmitter and a single antenna at the receiver. MISO systems can be used to improve the range and performance of wireless communication systems by creating a focused beam of energy that is directed at the intended receiver.

4. Multiple-Input Multiple-Output (MIMO) systems: These systems use multiple antennas at both the transmitter and receiver. MIMO systems can be used to improve the capacity, range, and reliability of wireless communication systems by allowing multiple data streams to be transmitted and received simultaneously over the same frequency band.

* There are several factors that can impact the performance of MIMO systems, including the number of antennas used, the type of antenna arrays used, the separation between the antennas, and the type of modulation and coding scheme used. The specific configuration of a MIMO system will depend on the requirements and constraints of the application or system in which it is being used.

#### **Diversity**

* In wireless communication systems, diversity refers to the use of multiple communication channels or paths to transmit and receive signals. In a multiple-input multiple-output (MIMO) system, diversity can be achieved by using multiple antennas at both the transmitter and the receiver.

* There are several types of diversity that can be used in MIMO systems:

1. Spatial diversity: This refers to the use of multiple antennas at both the transmitter and the receiver to create multiple, independent communication paths. This can improve the reliability of the communication link by reducing the impact of fading and interference.

2. Frequency diversity: This refers to the use of different frequency bands for different antennas. This can improve the reliability of the communication link by reducing the impact of frequency-selective fading.

3. Time diversity: This refers to the use of different time slots or frames for different antennas. This can improve the reliability of the communication link by reducing the impact of temporal fading.

* In general, diversity techniques can help to improve the performance of MIMO systems by providing redundant communication paths and reducing the impact of fading and interference.

#### **Spatial Diversity and Spatial Multiplexing**

* Spatial diversity and spatial multiplexing are two techniques that can be used in multiple-input multiple-output (MIMO) systems to improve communication performance.

* Spatial diversity refers to the use of multiple antennas at both the transmitter and the receiver to create multiple, independent communication paths. This can improve the reliability of the communication link by reducing the impact of fading and interference. Spatial diversity can be achieved through a variety of techniques, such as antenna separation, polarization diversity, and beamforming.

* Spatial multiplexing refers to the use of multiple antennas at both the transmitter and the receiver to transmit and receive multiple independent data streams simultaneously. This can increase the capacity of the communication link by allowing more data to be transmitted in the same amount of time. To use spatial multiplexing effectively, the transmitter and receiver must be able to distinguish between the different data streams, which can be achieved through the use of advanced signal processing techniques such as precoding and equalization.

* In general, spatial diversity and spatial multiplexing can both be used to improve the performance of MIMO systems, but they are distinct techniques that achieve different goals. Spatial diversity is focused on improving the reliability of the communication link, while spatial multiplexing is focused on increasing the capacity of the communication link.

#### **Spatial Diversity of a SISO System**

* Spatial diversity refers to the use of multiple antennas at both the transmitter and the receiver to create multiple, independent communication paths. In a single-input single-output (SISO) system, which uses a single antenna at both the transmitter and the receiver, it is not possible to achieve spatial diversity.

* However, there are other types of diversity that can be used in SISO systems to improve communication performance. For example, frequency diversity can be achieved by using different frequency bands for different transmission channels, and time diversity can be achieved by using different time slots or frames for different transmission channels.

* There are also techniques that can be used to improve the performance of a SISO system by exploiting the spatial characteristics of the communication channel. For example, beamforming can be used to direct the transmitted signal towards the receiver, and spatial filtering can be used at the receiver to reduce interference from other sources.

#### **Spatial Diversity of a SIMO System**

* In a single-input multiple-output (SIMO) system, which uses a single antenna at the transmitter and multiple antennas at the receiver, it is possible to achieve spatial diversity. This is because the multiple antennas at the receiver can create multiple, independent communication paths between the transmitter and the receiver.

* Spatial diversity can be achieved in a SIMO system through a variety of techniques, such as antenna separation, polarization diversity, and beamforming. By using these techniques, the SIMO system can improve the reliability of the communication link by reducing the impact of fading and interference.

* In general, the performance of a SIMO system can be improved by increasing the number of antennas at the receiver, as this increases the number of independent communication paths and provides more redundancy. However, the use of multiple antennas at the receiver also increases the complexity of the system and may require the use of advanced signal processing techniques to exploit the additional diversity.

#### **Spatial Diversity of a MIMO System**

* In a multiple-input multiple-output (MIMO) system, which uses multiple antennas at both the transmitter and the receiver, it is possible to achieve spatial diversity. This is because the multiple antennas at both the transmitter and the receiver can create multiple, independent communication paths between them.

* Spatial diversity can be achieved in a MIMO system through a variety of techniques, such as antenna separation, polarization diversity, and beamforming. By using these techniques, the MIMO system can improve the reliability of the communication link by reducing the impact of fading and interference.

* In general, the performance of a MIMO system can be improved by increasing the number of antennas at both the transmitter and the receiver, as this increases the number of independent communication paths and provides more redundancy. However, the use of multiple antennas at both the transmitter and the receiver also increases the complexity of the system and may require the use of advanced signal processing techniques to exploit the additional diversity.

#### **Spatial Multiplexing of a MIMO System**

* Spatial multiplexing refers to the use of multiple antennas at both the transmitter and the receiver to transmit and receive multiple independent data streams simultaneously. In a multiple-input multiple-output (MIMO) system, which uses multiple antennas at both the transmitter and the receiver, it is possible to use spatial multiplexing to increase the capacity of the communication link.

* To use spatial multiplexing effectively, the transmitter and receiver must be able to distinguish between the different data streams, which can be achieved through the use of advanced signal processing techniques such as precoding and equalization. The performance of spatial multiplexing in a MIMO system depends on the number of antennas at both the transmitter and the receiver, as well as the channel conditions.

* In general, the performance of a MIMO system can be improved by increasing the number of antennas at both the transmitter and the receiver, as this allows for the transmission of more independent data streams simultaneously. However, the use of multiple antennas also increases the complexity of the system and may require the use of advanced signal processing techniques to exploit the additional capacity.

#### **Beamforming Protocol in IEEE 802.11ad**

* IEEE 802.11ad is a wireless networking standard that uses beamforming technology to improve the performance of wireless communication in the 60 GHz frequency band. Beamforming is a technique that uses multiple antennas to transmit and receive signals, with the goal of focusing the signal energy in a particular direction. This can improve the range, capacity, and reliability of the wireless connection.

* In the IEEE 802.11ad standard, beamforming is used to improve the performance of point-to-point communication between devices. It allows devices to communicate over longer distances and at higher data rates than would be possible with traditional omnidirectional antennas.

* One of the key advantages of beamforming in IEEE 802.11ad is that it allows for highly directional communication, which can help to reduce interference and increase the capacity of the wireless network. This is especially useful in environments where there are many devices competing for bandwidth, such as in crowded office buildings or public spaces.

* Overall, beamforming is a key feature of the IEEE 802.11ad standard that allows for improved performance in wireless communication. It is an important technology for enabling high-speed, reliable communication in a variety of applications.

#### **IEEE 802.11ad**

* IEEE 802.11ad is a standard for wireless local area networks (WLANs) that operates in the 60 GHz frequency band. It is also known as WiGig and was developed as a high-speed alternative to the traditional WiFi standards that operate in the 2.4 GHz and 5 GHz frequency bands.

* IEEE 802.11ad is designed to provide data rates of up to 7 Gbps over short ranges of up to a few meters. It uses a beamforming technique called "multi-gigabit beamforming" to focus the wireless signal and increase the range and reliability of the connection.

* IEEE 802.11ad is mainly used for applications that require high-speed data transfer, such as video streaming, file transfers, and gaming. It is typically used in conjunction with other WiFi standards to provide a seamless and high-speed wireless experience.

* However, the 60 GHz frequency band is highly susceptible to interference from walls and other objects, which limits the range and penetration of the wireless signal. As a result, IEEE 802.11ad is mainly used for short-range, high-bandwidth applications in controlled environments, such as in home networks or conference rooms.

#### **IEEE 802.11 AY**
* IEEE 802.11ay is a standard for wireless local area networks (WLANs) that operates in the 60 GHz frequency band. It is an extension of the IEEE 802.11ad standard, which was developed as a high-speed alternative to the traditional WiFi standards that operate in the 2.4 GHz and 5 GHz frequency bands.

* IEEE 802.11ay is designed to provide data rates of up to 20 Gbps over short ranges of up to a few meters. It uses a beamforming technique called "multi-gigabit beamforming" to focus the wireless signal and increase the range and reliability of the connection.

* IEEE 802.11ay is mainly used for applications that require ultra-high-speed data transfer, such as video streaming, file transfers, and gaming. It is typically used in conjunction with other WiFi standards to provide a seamless and high-speed wireless experience.

* However, the 60 GHz frequency band is highly susceptible to interference from walls and other objects, which limits the range and penetration of the wireless signal. As a result, IEEE 802.11ay is mainly used for short-range, ultra-high-bandwidth applications in controlled environments, such as in home networks or conference rooms.

### TSN

#### **TSN v.s . DetNet**
* TSN (Time-Sensitive Networking) is a set of IEEE 802 standards for deterministic networking, which aims to provide a common framework for real-time communication over Ethernet networks. TSN focuses on the lower layers of the OSI model, specifically layer 2 (the data link layer) and part of layer 1 (the physical layer). TSN aims to provide low-latency, high-bandwidth, and reliable communication for time-critical applications, such as industrial automation, vehicle-to-vehicle communication, and audio/video streaming.

* DetNet (Deterministic Networking) is a set of IETF (Internet Engineering Task Force) standards for deterministic networking, which extends the technologies developed in TSN to the network layer (layer 3) of the OSI model. DetNet aims to provide low-latency, high-reliability communication for time-critical applications over IP networks. DetNet can support both unicast and multicast traffic, and it can operate over various types of physical networks, such as Ethernet, MPLS, and IP.

* Both TSN and DetNet aim to significantly reduce latencies to the millisecond level, and they are designed to be highly reliable and robust. They are both suitable for use in time-critical applications that require low-latency, high-reliability communication. However, TSN is focused on the data link layer, while DetNet extends the technologies to the network layer, so they have different scope and focus.

### **5G Networks**

#### **NFV and VNF**

* Network Function Virtualization (NFV) is a technology that allows network functions, such as firewalls, load balancers, and routers, to be implemented in software and run on standard, off-the-shelf hardware. This is in contrast to traditional networking, where these functions are typically implemented in dedicated, proprietary hardware.

* Virtual Network Functions (VNFs) are software implementations of network functions that can be deployed on standard hardware using NFV. VNFs allow network operators to quickly and easily deploy new network functions, scale existing functions up or down as needed, and easily migrate functions between hardware platforms.

* The goal of NFV and VNFs is to improve the agility, scalability, and cost-efficiency of networking by decoupling the functions from the underlying hardware. This allows network operators to quickly and easily deploy new services and respond to changing traffic demands, without the need to purchase and install new hardware.

#### **Network slicing**

* Network slicing is a technique that allows a single physical network to be divided into multiple virtual networks, or "slices," each with its own set of resources and capabilities. Each slice is designed to support a specific type of traffic or application, such as voice, video, or IoT data.

* One of the main benefits of network slicing is that it allows network operators to tailor the resources and capabilities of each slice to the specific needs of the traffic or application it is supporting. This can help to improve the efficiency and performance of the network, as well as providing a better quality of service to end users.

* Network slicing can be implemented using a variety of technologies, including Network Function Virtualization (NFV) and Software-Defined Networking (SDN). It is particularly useful in 5G networks, where it can help to support a wide range of diverse use cases and applications with varying requirements for bandwidth, latency, and reliability.