Unit-1.docx

**Unit-1** **Modulation** Modulation is the process of superimposing information (baseband signal) onto a high-frequency carrier wave for efficient transmission. This process is essential in communication systems, as it enables the transmission of signals over long distances. Modulation is the pro...

**Unit-1** **Modulation** Modulation is the process of superimposing information (baseband signal) onto a high-frequency carrier wave for efficient transmission. This process is essential in communication systems, as it enables the transmission of signals over long distances. Modulation is the process of converting the carrier signal into an electrical signal. Amplitude and phase remain the same in FM. **Analog Modulation Techniques** These techniques involve modulating an analog carrier signal with an analog message signal. **Amplitude Modulation (AM)** - **Principle:** The amplitude of the carrier wave is varied in proportion to the instantaneous amplitude of the message signal. - **Advantages:** Simple to implement, efficient for low power signals. - **Disadvantages:** Susceptible to noise, low bandwidth efficiency. **Frequency Modulation (FM)** - **Principle:** The frequency of the carrier wave is varied in proportion to the instantaneous amplitude of the message signal. - **Advantages:** Better noise immunity than AM, higher fidelity. - **Disadvantages:** Requires higher bandwidth, more complex circuitry.  **Phase Modulation (PM)** - **Principle:** The phase of the carrier wave is varied in proportion to the instantaneous amplitude of the message signal. - **Advantages:** Better noise immunity than AM, can be used for efficient digital modulation. - **Disadvantages:** More complex circuitry than AM or FM. three types of digital to analog modulation (Figure 4) ASK FSK PSK QAM Figure 4: Digital to analog modulation techniques **Amplitude Shift Keying (ASK)** - **Principle:** The amplitude of the carrier wave is varied to represent binary data (0s and 1s). - **Advantages:** Simple to implement, efficient for low data rates. - **Disadvantages:** Susceptible to noise, low bandwidth efficiency. **Frequency Shift Keying (FSK)** - **Principle:** The frequency of the carrier wave is varied to represent binary data (0s and 1s). - **Advantages:** Better noise immunity than ASK, can be used for frequency-hopping spread spectrum. - **Disadvantages:** Lower data rate compared to PSK. **Phase Shift Keying (PSK)** - **Principle:** The phase of the carrier wave is shifted to represent different data symbols. - **Advantages:** Higher data rate compared to ASK and FSK, better spectral efficiency. - **Disadvantages:** More complex circuitry, susceptible to phase ambiguity. - **Quadrature Phase Shift Keying (QPSK):** A special case of PSK that transmits two bits per symbol by using four different phase shifts. In essence, modulation is a fundamental technique that enables efficient, long-distance, and reliable communication. **Mobile Wireless Communication** Mobile wireless communication system has gone through several evolution stages in the past few decades after the introduction of the first-generation mobile network in the early 1980s. Due to huge demand for more connections worldwide, mobile communication standards advanced rapidly to support more users. Let's take a look at the evolution stages of wireless technologies for mobile communication. **History of wireless technology** Marconi, an Italian inventor, transmitted Morse code signals using radio waves wirelessly to a distance of 3.2 KMs in 1895. It was the first wireless transmission in the history of science. Since then, engineers and scientists have been working on efficiently communicating using RF waves. The telephone became popular during the mid of 19th century. Due to wired connection and restricted mobility, engineers started developing a device that doesn't require a wired connection and transmits voice using radio waves. **The invention of the first mobile phone -- The evolution begins** Martin Cooper, an engineer at Motorola during the 1970s working on a handheld device capable of two-way communication wirelessly, invented the first-generation mobile phone. It was initially developed to use in a car; the first prototype was tested in 1974. This invention is considered a turning point in wireless communication which led to an evolution of many technologies and standards in the future. **1G -- First-generation mobile communication system** The first generation of mobile networks was deployed in Japan by Nippon Telephone and Telegraph Company (NTT) in Tokyo in 1979. At the beginning of the 1980s, it gained popularity in the US, Finland, the UK, and Europe. This system used analog signals, and it had many disadvantages due to technology limitations. ------------------------------------------------------------- ----------------------------------------------------------- **Time Division-Synchronous Code Division Multiple Access** **Primarily developed by China** **WiMax 16.M** **Approved as 4G technology, but Lte is succeeded as 4G** ------------------------------------------------------------- ----------------------------------------------------------- **Most popular 1G system during the 1980s** - Advanced Mobile Phone System (AMPS) - Nordic Mobile Phone System (NMTS) - Total Access Communication System (TACS) - European Total Access Communication System (ETACS) **Key features (technology) of the 1G system** - Frequency 800 MHz and 900 MHz - Bandwidth: 10 MHz (666 duplex channels with a bandwidth of 30 KHz) - Technology: Analogue switching - Modulation: Frequency Modulation (FM) - Mode of service: voice only - Access technique: Frequency Division Multiple Access (FDMA) **Disadvantages of 1G system** - Poor voice quality due to interference - Poor battery life - Large-sized mobile phones (not convenient to carry) - Less security (calls could be decoded using an FM demodulator) - A limited number of users and cell coverage - Roaming was not possible between similar systems \-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-- **2G -- Second generation communication system GSM**  The 2G GSM (Global System for Mobile Communications) technology is one of the major second-generation mobile network technologies. It brought significant improvements over the previous technology (AMPS), including digital modulation, circuit switching, and time division multiplexing. GSM allowed data transmission rates of up to 9.6 Kbps and introduced security features such as encryption to protect communication. GSM is a European 2G standard. Its commercial development started in 1991, becoming popular worldwide. The first system to be used had an operating frequency of 900MHz, with future variants in 1800MHz, 1900MHz, and 450MHz. **1 -Mobile Station (MS)**: The mobile station is the device used by the user, such as a mobile phone. It consists of a mobile terminal (MT) and a Subscriber Identity Module (SIM) card. The MT is the hardware of the mobile phone, while the SIM card contains subscriber identification information. 2- **Base Station (BS):** The base station is responsible for providing coverage and connectivity to mobile devices within its service area. It consists of an antenna and a radio transceiver that transmit and receive radio signals to the mobile station. 3- **Base Station Transceiver Station (BTS):** The base station transceiver station is responsible for radio communication with mobile devices. It controls voice and data communication in the service cell and manages the allocation of radio resources. 4- **Base Station Controller (BSC):** The base station controller is responsible for the management and control of base stations in a particular area. It handles functions such as radio channel allocation, handover management (smooth transfer) between cells, and power control. 5- **Mobile Switching Center (MSC):** The mobile switching center is the central element of the GSM network. It is responsible for call switching, subscriber authentication, roaming management, and other network services. The MSC is also connected to other networks, such as the fixed telephone network, for call routing. 6- **Home Location Register (HLR)**: The home location register is a centralized database that contains information about subscribers in the GSM network. It stores data such as phone numbers, subscriber authentication, enabled services, and location information. 7- **Visitor Location Register (VLR):** The visitor location register is a temporary database that contains information about subscribers who are currently roaming outside their home area. The VLR is responsible for managing visiting subscribers and their authentication. **8- Gateway Mobile Switching Center (GMSC):** The gateway mobile switching center is responsible for the interconnection between the GSM network and other networks, such as fixed networks or mobile networks of other operators. \[A **gateway** is a network device that acts as an entry and exit point between different networks, allowing communication between them\] 9- The **Um interface** is responsible for communication between the mobile device and the base station, while the **Abis interface** is responsible for communication between the base station and the base station controller. **Key features of the 2G system** - The digital system (switching) - SMS services are possible - Roaming is possible - Enhanced security - Encrypted voice transmission - First internet at a lower data rate - Disadvantages of the 2G system - Low data rate - Limited mobility - Less features on mobile devices - Limited number of users and hardware capability **2.5G and 2.75G system** In order to support higher data rates, General Packet Radio Service (GPRS) was introduced and successfully deployed. GPRS was capable of data rates up to 171kbps (maximum).\ EDGE -- Enhanced Data GSM Evolution was also developed to improve the data rate for GSM networks. EDGE was capable of supporting up to 473.6kbps (maximum).\ Another popular technology CDMA2000 was also introduced to support higher data rates for CDMA networks. This technology has the ability to provide up to 384 kbps data rate (maximum). \-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-- **3G -- Third-generation communication system** Third-generation mobile communication started with the introduction of UMTS -- Universal Mobile Terrestrial / Telecommunication Systems. UMTS has a data rate of 384kbps, and it supports video calling for the first time on mobile devices. After the introduction of the 3G mobile communication system, smartphones became popular across the globe. Specific applications were developed for smartphones that handle multimedia chat, email, video calling, games, social media, and healthcare. The Universal Mobile Telecommunications System (UMTS) is a third-generation (3G) mobile communications technology that evolved from the Global System for Mobile Communications (GSM). UMTS is one of the main technologies used for mobile communication, offering higher data rates and a more advanced architecture compared to its predecessor. Here is an overview of the UMTS network architecture: 1. **User Equipment (UE):** The UE refers to the mobile device used by the end-user, such as a smartphone, tablet, or data card. 2. **Utran (UMTS Terrestrial Radio Access Network):** 3. **Core Network (CN):** 4. **Interfaces:** Various interfaces connect the different network elements, enabling communication and control. For example, the Iu interface connects the RNC and the core network, while the Iub interface connects the RNC and the Node B. UMTS introduced several enhancements over GSM, including higher data rates, support for packet-switched data services, and improved multimedia capabilities. It served as a stepping stone to the later development of Long-Term Evolution (LTE) and other advanced mobile communication technologies. **Key features of the 3G system** - Higher data rate - Video calling - Enhanced security, more users, and coverage - Mobile app support - Multimedia message support - Location tracking and maps - Better web browsing - TV streaming - High-quality 3D games **3.5G to 3.75 Systems** In order to enhance the data rate in existing 3G networks, two technology improvements are introduced to the network. HSDPA -- High-Speed Downlink Packet Access and HSUPA -- High-Speed Uplink Packet Access, developed and deployed to the 3G networks. 3.5G network can support up to 2mbps data rate. 3.75 system is an improved version of the 3G network with HSPA+ High-Speed Packet Access Plus. Later this system will evolve into a more powerful 3.9G system known as [[LTE]](https://www.3gpp.org/technologies/keywords-acronyms/97-lte-advanced) (Long Term Evolution). **Disadvantages of 3G systems** - Expensive spectrum licenses - Costly infrastructure, equipment, and implementation - Higher bandwidth requirements to support a higher data rate - Costly mobile devices - Compatibility with older generation 2G systems and frequency bands \-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-- **4G -- Fourth-generation communication system** 4G systems are enhanced version of 3G networks developed by IEEE, offers higher data rate, and are capable of handling more advanced multimedia services. LTE and LTE advanced wireless technology used in 4th generation systems. Furthermore, it has compatibility with the previous versions; thus, easier deployment and upgrade of LTE and LTE advanced networks are possible. Simultaneous transmission of voice and data is possible with an LTE system, which significantly improves the data rate. All services, including voice services, can be transmitted over IP packets. Complex modulation schemes and carrier aggregation are used to multiply uplink/downlink capacity. Wireless transmission technologies like WiMax are introduced in 4G systems to enhance data rate and network performance.  The 4G (fourth generation) system architecture is designed to provide faster and more efficient wireless communication compared to its predecessor, 3G (third generation). The key features of 4G architecture include high data rates, improved spectral efficiency, and seamless connectivity. Here are the main components of a typical 4G system architecture: 1. **User Equipment (UE):** UE refers to the mobile device used by the end-user, such as smartphones, tablets, or other devices with 4G capability. 2. **Evolved NodeB (eNodeB):** eNodeB is the base station in 4G networks. It is responsible for radio communication with the UE and manages the radio resources. Unlike 3G, where there are separate entities for NodeB (radio access network) and RNC (Radio Network Controller), 4G combines these functions into a single eNodeB. 3. **Evolved Packet Core (EPC):** EPC is the core network of the LTE (Long-Term Evolution) system. It includes several key components: - **Mobility Management Entity (MME):** MME is responsible for managing the UE\'s mobility, including tracking and paging. It handles tasks related to session management and signaling. - **Serving Gateway (SGW):** SGW is responsible for routing and forwarding user data packets. It acts as an anchor point for mobility-related functions and is involved in the handover procedure. - **Packet Data Network Gateway (PGW):** PGW is responsible for connecting the LTE network to external packet data networks (e.g., the internet). It also manages IP address allocation and performs policy enforcement. - **Home Subscriber Server (HSS):** HSS stores subscriber information and manages user authentication, authorization, and mobility-related information. - **Policy and Charging Rules Function (PCRF):** PCRF is responsible for policy control and flow-based charging in the LTE network. It helps in defining and enforcing policies related to quality of service (QoS) and charging. 4. **Interworking Function (IWF):** IWF facilitates communication between LTE and non-LTE networks, ensuring interoperability. 5. **Public Data Network (PDN):** PDN represents external networks such as the internet or corporate networks to which the UE may connect. 6. **Backhaul Network:** The backhaul network connects the eNodeB to the core network, providing the necessary transport for user data and signaling between the base station and the EPC. 7. **X2 Interface:** The X2 interface facilitates communication between neighboring eNodeBs, enabling handovers between cells served by different eNodeBs. Overall, the 4G system architecture is designed to provide high-speed, low-latency wireless communication with efficient use of spectrum and improved network capacity. It forms the foundation for more advanced technologies like 5G, which build upon the principles of 4G architecture. \[When a mobile device initiates a data session (e.g., browsing the internet), the data packets from the device first reach the **S-GW**. The S-GW forwards these packets to the **P-GW**, which then routes them to the appropriate external network (e.g., the internet). For incoming data, the process is reversed: data packets from the external network reach the P-GW, which forwards them to the S-GW, and then to the mobile device via the LTE network. S5 interface: Connects an SGW to a PGW within the same mobile network operator (MNO). S8 interface: Connects an SGW in a visited network (VPLMN) to a PGW in the home network (HPLMN) when a user is roaming.\] **Key features of the 4G system** - Much higher data rate up to 1Gbps - Enhanced security and mobility - Reduced latency for mission-critical applications - High-definition video streaming and gaming - Voice over LTE network VoLTE (use IP packets for voice) **Disadvantages of the 4G system** - Expensive hardware and infrastructure - Costly spectrum (in most countries, frequency bands are too expensive) - High-end mobile devices compatible with 4G technology are required, which is costly - Wide deployment and upgrade are time-consuming \-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-- **5G -- Fifth-generation communication system** 5G network is using advanced technologies to deliver ultra-fast internet and multimedia experience for customers. Existing LTE advanced networks will transform into supercharged 5G networks in the future. In earlier deployments, 5G network will function in non-standalone mode and standalone mode. In non-standalone mode, both LTE spectrum and 5G-NR spectrum will be used together. Control signaling will be connected to the LTE core network in non-standalone mode. There will be a dedicated 5G core network higher bandwidth 5G -- NR spectrum for standalone mode.  The sub-6-GHz spectrum of FR1 ranges are used in the initial deployments of 5G networks. In order to achieve a higher data rate, [[5G technology]](https://www.rfpage.com/how-5g-technology-works/) will use millimeter waves and unlicensed spectrums for data transmission. **Key features of 5G technology** - Ultra-fast mobile internet up to 10Gbps - Low latency in milliseconds (significant for mission-critical applications) - Total cost deduction for data - Higher security and reliable network - Uses technologies like small cells and beamforming to improve efficiency - Forward compatibility network offers further enhancements in future - Cloud-based infrastructure offers power efficiency, easy maintenance, and upgrade of hardware **Comparison of 1G to 5G technology** 1G-to-5G-Comparison  **ITU** - International Telecommunication Union (ITU), specialized agency of the [United Nations](https://www.britannica.com/topic/United-Nations) that was created to encourage international cooperation in all forms of [telecommunication](https://www.britannica.com/technology/telecommunication). - Its activities include maintaining order in the allocation of [radio](https://www.britannica.com/topic/radio) frequencies, setting standards on technical and operational matters, and assisting countries in developing their own telecommunication systems. - The origin of the ITU can be traced to 1865, when the [International Telegraph Union](https://www.britannica.com/topic/International-Telegraph-Union) was established by a [convention](https://www.britannica.com/dictionary/convention) signed in Paris. **IMT (International Mobile Telecommunications) 2020** IMT for 2020 and beyond is envisaged to expand and support diverse usage scenarios and applications that will continue beyond the current IMT. Furthermore, a broad variety of capabilities would be tightly coupled with these intended different usage scenarios and applications for IMT for 2020 and beyond. IMT standards, particularly in the context of 5G (IMT-2020), focus on three key usage scenarios that are central to how modern networks are designed and utilized. These scenarios are **eMBB (enhanced Mobile Broadband)**, **URLLC (Ultra-Reliable Low-Latency Communication)**, and **mMTC (massive Machine Type Communication)**. Here\'s how each one applies: **1. eMBB (enhanced Mobile Broadband)** - **Description**: eMBB is designed to provide significantly faster data speeds and higher capacity for mobile broadband services. It enhances the user experience by supporting applications that require large amounts of data and high-definition content. - **Usage Scenarios**: - **High-Definition Streaming**: Watching 4K or even 8K video content on mobile devices without buffering. - **Virtual Reality (VR) and Augmented Reality (AR)**: Enabling immersive experiences with smooth, high-quality graphics and real-time interactions. - **Smartphones and Tablets**: Improved download and upload speeds for everyday internet use, from browsing to social media and gaming. - **Crowded Areas**: Providing reliable high-speed internet in dense environments like stadiums, concerts, or city centers. **2. URLLC (Ultra-Reliable Low-Latency Communication)** - **Description**: URLLC focuses on delivering extremely low latency (delay) and high reliability for mission-critical applications. This is crucial for services where even a slight delay can have significant consequences. - **Usage Scenarios**: - **Autonomous Vehicles**: Supporting Vehicle-to-Everything (V2X) communication, allowing vehicles to interact with each other and with infrastructure in real-time for safe and efficient driving. - **Remote Surgery**: Enabling surgeons to perform operations remotely with precise control and minimal delay, which is critical for patient safety. - **Industrial Automation**: Real-time control of machinery and robots in manufacturing, where even a millisecond delay can disrupt operations. - **Public Safety**: Ensuring reliable communication for first responders and emergency services during critical situations. **3. mMTC (massive Machine Type Communication)** - **Description**: mMTC is designed to support a massive number of devices that require sporadic, low-power communication. It is ideal for the Internet of Things (IoT), where many devices are connected to the network but require minimal data transfer. - **Usage Scenarios**: - **Smart Cities**: Connecting thousands of sensors and devices like smart meters, environmental monitors, and traffic lights to improve city management. - **Agriculture**: Enabling IoT devices to monitor soil conditions, weather, and crop health across large agricultural areas, allowing for precision farming. - **Healthcare**: Supporting wearable health monitors that track vital signs and communicate data to healthcare providers, especially in remote areas. - **Logistics and Supply Chain**: Tracking packages and shipments globally with IoT devices that communicate their status, location, and environmental conditions.  **IMT-2020 Requirements:** To achieve this vision, the ITU has specified several key performance requirements that 5G networks must meet: 1. **Peak Data Rate:** - - - 2. **User Experienced Data Rate:** - - - 3. **Latency:** - - 4. **Mobility:** - - 5. **Connection Density:** - - 6. **Energy Efficiency:** - 7. **Spectrum Efficiency:** - 8. **Area Traffic Capacity:** - - **Radio Spectrum** The radio spectrum is the part of the electromagnetic spectrum with frequencies from 3 Hz to 3,000 GHz (3 THz). Electromagnetic waves in this frequency range, called radio waves, are widely used in modern technology, particularly in telecommunication. To prevent interference between different users, the generation and transmission of radio waves is strictly regulated by national laws, coordinated by an international body, the International Telecommunication Union (ITU). It encompasses a wide array of frequencies, each serving different communication purposes, from broadcasting television and radio to enabling mobile phone services, Wi-Fi, and satellite communication. Electromagnetic Spectrum and Radio Spectrum Diagram **Key Concepts of the Radio Spectrum:** 1. **Frequency Bands:** - - - - - 2. **Wavelength and Frequency Relationship:** - 3. **Spectrum Allocation:** - - - - - - - - - - - - - - - - - - - - - - - - - - 4. **Spectrum Licensing:** - - 5. **Unlicensed Spectrum:** - 6. **Spectrum Management:** - **mmWave Characteristics** - Millimeter wave also referred as mmwave. Millimeter wave is extremely high range frequency wave. Therefore it is also called EHF. - As implied by the name, millimeter waves are electromagnetic waves with a wavelength (λ) that is approximately 1 mm (1 to 10 mm, to be more precise). Converting that wavelength into frequency using the equation *f = c*/λ, where *c* is the speed of light (3 x 10^8^ m/s), gives a frequency range of 30-300 GHz - Because of it's high frequency and propagation characteristics, it is very useful for many applications like cellular communications, radar etc.. - propagation characteristic means the way it changes and interact with the atmosphere. **Mmwave 5G range:** It ranges from 30GHz to 300GHz. **mmwave wavelength:** It's wavelength ranges from 10mm t0 1 mm. So it is longer than infrared or x-ray but shorter than radio wave. **Higher frequencies** have several advantages, including: - **Greater bandwidth:** More data can be transmitted over a given channel. - **Shorter wavelengths:** Millimeter waves can be focused into narrower beams, which can improve signal quality and reduce interference. - **Higher capacity:** More devices can be connected to a single millimeter wave cell. However, higher frequencies also have some disadvantages, such as: - **Shorter range:** Millimeter waves are more easily absorbed by objects and the atmosphere, limiting their range. - **Susceptibility to interference:** Millimeter waves are more susceptible to interference from other sources, such as rain and foliage **How far mmwave can travel?** Because of it's high frequency, it will not travel or propagate over long distances. Oxygen molecules interact with these waves at higher frequencies. And absorb it's energy. Because of it's high frequencies, it can not travel long distances. If you take an example of 28GHz mmwave, it can travel up to 300 meters. **Millimeter Wave Characteristics** 1. High range frequency. 2. Mmwave doesn't bend around corners. 3. It can be easily blocked. 4. It behaves as light. So you can direct them using antennas. 5. It can transmit large amounts of data. 6. It can travel shorter distance compared to low frequencies. 7. Higher frequencies means it will take very less time to reach users. 8. Interacts with oxygen molecules. 9. Distance Coverage in **indoor**: 2mtr. and **outdoor**: 300mtr **5G mmWave: Facts and fiction** **mmWave doesn't penetrate walls** -- High frequency 5G signals cannot travel far, and the transition from indoors to outdoors doesn't work very well. However, large-scale MIMO and beamforming do not require a strict line of sight to take advantage of millimeter waves. Millimeter-wave signals may not penetrate deep into the building but bounce around the building to ensure a proper signal. **5G won't work in rains** -- When it rains, the millimeter-wave signal strength drops slightly, first at a slightly slower speed, and then connection problems can occur. How bad it gets depends on how hard it rains and other factors, such as the distance from the cell tower. Rain causes most problems when connecting at the edge of a millimeter-wave base station range. **Use cases for 5G mmWave** - Fixed wireless internet access: 5G mmWave gigabit data rates can completely replace a variety of Internet access technologies with hybrid fiber and wireless networks that connect subscribers. - Outdoor small cell for urban/suburban environment: A promising deployment scenario for 5G mmWaves is to increase capacity in demanding public spaces and venues. - Mission-critical control application: Self-driving cars, vehicle-to-vehicle communications, and drone communications provide similar deployment scenarios for 5G mmWave with less than 1-millisecond predictive network delays. - Indoor hotspot cells: Offices, shopping malls, and other indoor areas require high-density 5G mmWave microcells. These small cells can support download speeds up to 20 Gbps, providing seamless access to cloud data and the ability to support multiple applications and various forms of entertainment and multimedia. - Internet of Things: Potentially, it covers smart home applications, security, energy management, logistics and tracking, healthcare, etc. **5G NR** - 5G New Radio (NR) is the global standard for a unified, more capable 5G wireless air interface. It is delivering significantly faster and more responsive mobile experiences. - 5G NR, is a set of standards that replace the fourth-generation wireless ([4G](https://www.techtarget.com/searchmobilecomputing/definition/4G)) LTE network communications standard. - 5G NR is the specification for fifth-generation wireless (5G) networks, describing how 5G products like smartphones transmit data with 5G NR network infrastructure like a 5G-enabled [base station](https://www.techtarget.com/whatis/definition/base-station). - Data transmissions using 5G NR are faster and have less latency when compared to previous 4G standards. - An important **goal** of 5G NR is to support the growth of wireless communication by enhancing the amount of data transmitted over a given spectrum (the electromagnetic radiation spectrum efficiency) for mobile broadband. - 5G NR is designed to support **fiber-equivalent bandwidth** transmissions required for data-intensive applications like streaming video, as well as for low-bandwidth transmissions used in machine-to-machine communications at a massive scale. - 5G NR works using the same radio access technology as 4G Long-Term Evolution (LTE) networks use \-- orthogonal frequency-division multiple access (OFDM). 5G NR, however, uses newer techniques such as QAM, beamforming, and other new features that increase the efficiency of a network and lower latency. - The frequency of the electromagnetic waves used in 5G NR varies along the wireless spectrum in defined sub-6 and millimeter wave (mmWave) frequency bands. **Benefits of 5G NR** The benefits of 5G New Radio over even the best LTE networks include the following: - Larger network capacity. - Increased energy savings per device. - Shorter time between updates \-- reducing average service creation time cycle. - Improved technology for maintaining the quality of a connection over a broad geographical area. - Enhanced speed and data rates, meaning more bits are processed over a unit of time. - Improved efficiency in data sharing. - Improved latency over 4G. The three main **5G NR deployment** modes are the following: For standalone mode, the full 5G technical paradigm is deployed. No residual 4G technical underpinnings are involved. And, if the clients can take advantage of the deployment, then all 5G benefits are realized. In nonstandalone mode, a site is essentially a hybrid. Some 4G network infrastructure stays in place. While the radio frequency side of 5G NR presents benefits, what it uplinks into means a lesser overall experience, compared with standalone mode. This model permits carriers to phase in full 5G architecture at sites, enabling them to tout their 5G progress. In the third deployment mode, dynamic spectrum sharing, the same frequency can do time-sliced duty in both 4G and 5G modes, using advanced antenna and transceiver processing. This means no single spectrum band has to be dedicated to just 4G or 5G. **FDD and TDD** - FDD (Frequency Division Duplex) is a technique in mobile networks that uses separate frequency bands for uplink and downlink communication; TDD (Time Division Duplex) is a technique that uses the same frequency band for uplink and downlink but only communicates in one direction at a time. - Frequency Division Duplex or Duplexing (FDD) is a communication technique where uplink (phone to network) and downlink (network to phone) communications are sent on separate frequency bands. A guard band separates uplink and downlink frequency bands to avoid interference. - Time Division Duplex or Duplexing (TDD) is a communication technique where uplink (phone to network) and downlink (network to phone) communications are sent on the same frequency band at different time slots. Uplink and downlink communication are separated by guard times (period) to avoid overlaps. - Frequency Division Duplex (FDD) is ideal for communication systems where the uplink and downlink requirements are symmetric. Since FDD offers a continuous flow of data in both uplink and downlink directions, it has a higher overall capacity to deliver higher data throughput. - Time Division Duplex (TDD) is ideal for communication systems where the uplink and downlink requirements are asymmetric, i.e. requirements change. With TDD, a mobile operator can dynamically adjust the uplink and downlink capacity depending on the customer demand for upload vs download. **Feature** **FDD** **TDD** ----------------------------------------- ------------------------------------------------------------------------------------------------ -------------------------------------------------------------------------------------------------------------------- Spectrum utilisation Less efficient because separate bands used for uplink and downlink More efficient because it uses the same frequency band for uplink and downlink Cellular coverage More extended range because guard time (period) is not an issue in FDD Shorter range because guard time (period) is proportional to the range Network investment Fewer base stations are required because of broader coverage More base stations are needed due to smaller coverage Phone hardware -- duplexers A duplexer is required to use the same antenna for uplink and downlink signals simultaneously. Uplink and downlink are at different time slots Uplink and downlink needs Symmetric Asymmetric Uplink and downlink capacity allocation Uplink and Downlink bands are reserved and cannot be changed on the fly Since the same band is used for uplink and downlink, the capacity for uplink/downlink can be dynamically adjusted Guard bands/period Requires guard bands between uplink and downlink Requires guard times for uplink and downlink separation Time synchronisation Time synchronisation is not an issue with FDD TDD systems require time synchronisation between the serving cell and the neighbouring cells to avoid interference System latency FDD may have slightly lower latency due to simultaneous transmit and receive operations Latency in TDD can be influenced by time slot duration Interference management Less prone to self interference due to separate frequencies Requires careful coordination to avoid interference between devices sharing same band **Cellular Concept** The cellular concept divides the mobile network into the small areas called cells. Each cell has a base station that communicates with mobile devices within that cell. The same radio frequencies can be reused in different cells far apart. As you move, your device automatically switches to the new cell's base station in a process called handoff. This allows efficient use of limited frequencies to provide wide coverage and better service. **What is a Cellular Concept?** The cellular concept refers to the way mobile communication networks are designed and organized. Instead of having the big powerful transmitter covering the large area the network is divided into the smaller areas called cells. Each cell has its own small transmitter called a cell site or the base station. This base station can communicate with mobile devices like phones or tablets within that cell. The idea behind this cellular setup is to allow the same radio frequencies to be reused in different cells that are far apart. This way more people can use the network without the interference. When you move from one cell to the another while on the call or using internet your mobile device automatically switches to the new cells base station. This process is called the [handoff](https://www.geeksforgeeks.org/handoff-in-cellular-telecommunications/) or handover and it happens seamlessly without you noticing. The cellular concept allows the mobile networks to provide the coverage over a wide area while using the limited radio frequencies efficiently. It also helps to distribute the network load and provide better quality of service to the more users. **Frequency Scarcity Problem** If we use dedicated RF loop for every subscriber, we need a very large bandwidth to serve even a small number of subscribers in a single city. **Example** A single RF loop requires 50 kHz bandwidth. So for the one hundred thousand (100,000) subscribers we would need 100,000 x 50 kHz = 5 GHz bandwidth. To avoid needing such a huge bandwidth, subscribers have to share the RF channels instead of having dedicated loops for each. This sharing can be done using multiple access methods like [FDMA](https://www.geeksforgeeks.org/frequency-division-multiple-access-fdma-techniques/), TDMA, or [CDMA](https://www.geeksforgeeks.org/importance-of-cdma-in-todays-cellular-world/). Even with sharing, the number of RF channels needed to serve many subscribers becomes very high. **Example** Consider an area with 30 subscribers per square kilometer. Assume a 1% chance of not getting a channel (grade of service), and each subscriber using the service for 30 minutes on average (traffic offered). Then the number of RF channels required would be the following. **Radius (km)** **Area (sq km)** **Subscribers** **RF Channels** ----------------- ------------------ ----------------- ----------------- 1 3.14 100 8 3 28.03 900 38 10 314 10,000 360 For 10,000 subscribers, to allocate 360 radio channels, we would need a bandwidth of 360 x 50 KHz = 18 MHz. Having this much bandwidth is not possible. Therefore to avoid needing extremely large bandwidths, subscribers have to share channels instead of dedicated channels for each. The cellular concept allows the efficient use and reuse of the channels to provide the service with the limited bandwidth. **Cellular Approach** With limited radio frequency resources, the cellular principle can serve many subscribers at an affordable cost. In a cellular network, the total area is divided into smaller areas called "cells". Each of the cell can cover the limited number of mobile subscribers within its boundaries. Each cell can have the base station with the number of radio channels. Frequencies used in one cell area will be reused at the same time in a different cell that is far away. For example The typical seven cell pattern can be used. !(media/image15.png) The total available frequency resources are divided into seven parts, with each part having a number of radio channels. One part is allocated to the each cell site. In the group of 7 cells the available frequency spectrum is fully used. The same seven sets of the frequency can be reused after the certain distance. The group of cells where the available frequency spectrum is totally used up is called a cluster of cells. Two cells with the same number in adjacent clusters use the same set of radio channels. These are called "[co-channel cells](https://www.geeksforgeeks.org/co-channel-and-adjacent-channel-interference-in-mobile-computing/)". The distance between the cells using the same frequency should be enough to keep the interference between them at an acceptable level. Cellular systems are limited by this co-channel interference. **The cellular principle enables the following :** 1. More efficient use of limited radio frequency resources. 1. Manufacturing of all subscriber devices in a region with the same set of channels, so any mobile can be used anywhere within that region. **Frequency Reuse and Interference Control:** One of the key innovations in the cellular concept is **frequency reuse**. This involves using the same frequency in different cells that are separated by a sufficient distance to minimize interference. The separation distance is typically determined by the **reuse factor**, which specifies how many cells must be between cells using the same frequency. To further control interference, **power control** techniques are employed. Base stations can adjust their transmit power to minimize interference with neighboring cells and optimize coverage. **Handoff Mechanisms: Handoff** or **handover** is a critical aspect of cellular networks. It ensures that a call remains active as a user moves from one cell to another. There are two main types of handoff: - **Hard Handoff:** The call is completely transferred from one base station to another before the user\'s device connects to the new cell. - **Soft Handoff:** The call is maintained by both the original and new base stations during the transition, ensuring a seamless experience. **Cell Sectoring:** To improve coverage and capacity, cells can be divided into **sectors**. Each sector is served by a directional antenna, which focuses the signal in a specific direction. This helps to reduce interference and improve the signal-to-noise ratio. **Cell Splitting:** As traffic increases in a cell, it can be divided into smaller cells. This process is known as **cell splitting**. Cell splitting improves coverage, reduces interference, and increases capacity. **Benefits of the Cellular Concept:** - **Increased Capacity:** By dividing the coverage area into smaller cells, the system can handle more users simultaneously. - **Efficient Spectrum Utilization:** Frequency reuse allows the same spectrum to be used in multiple cells, maximizing its efficiency. - **Improved Coverage:** The overlapping nature of cells helps to minimize dead zones and ensure consistent coverage. - **Flexibility:** The cellular concept is adaptable to various environments and traffic patterns **MIMO** In wireless communications, when multiple antennas are used both at the transmitting end as well as the receiving end, the configuration is said to be multiple input, multiple output or MIMO to exploit **multipath propagation**. MIMO helps in sending and receiving multiple data signals simultaneously over the same radio channel. MIMO is a smart antenna technology, the other popular technology being multiple input, single output (MISO) and single input, multiple output (SIMO). The following diagram shows MIMO configuration − MIMO can be sub-divided into three main categories: [precoding](https://en.wikipedia.org/wiki/Precoding), [spatial multiplexing](https://en.wikipedia.org/wiki/Spatial_multiplexing) (SM), and [diversity coding](https://en.wikipedia.org/wiki/Diversity_Coding). **Key Benefits of MIMO:** - **Increased Data Rates:** By exploiting spatial diversity, MIMO can significantly increase the data throughput of a wireless link. - **Improved Reliability:** MIMO can enhance the reliability of a communication system by providing multiple paths for data transmission. - **Enhanced Coverage:** MIMO can improve coverage in areas with obstacles or weak signal strength. - **Reduced Interference:** MIMO can help reduce interference from other wireless devices. **How MIMO Works:** 1. **Multiple Antennas:** Both the transmitter and receiver have multiple antennas. 2. **Spatial Diversity:** The multiple antennas at the transmitter can send the same data signal in different directions, creating multiple spatial paths. 3. **Beamforming:** The receiver can focus on the strongest signal path, improving signal quality and reducing interference. 4. **Spatial Multiplexing:** MIMO can also transmit multiple data streams simultaneously over the same frequency channel, further increasing data rates. **Beamforming** **Beamforming** is a technique used in wireless communication systems to focus the transmitted signal in a specific direction. This is achieved by controlling the phase and amplitude of the signals emitted from multiple antennas. By aligning the phases of the signals, the transmitter can create a beam of electromagnetic energy that is directed towards the desired receiver.   **Key Benefits of Beamforming:** - **Increased Signal Strength:** Beamforming can significantly increase the signal strength at the receiver, improving the quality of communication. - **Reduced Interference:** By focusing the signal in a specific direction, beamforming can minimize interference from other devices or sources. - **Improved Coverage:** Beamforming can help to extend the coverage area of a wireless system, especially in areas with obstacles or weak signal strength. - **Energy Efficiency:** By directing the signal towards the desired receiver, beamforming can reduce wasted energy. **How Beamforming Works:** 1. **Multiple Antennas:** The transmitter uses multiple antennas to transmit the signal. 2. **Phase Control:** The phase of the signal emitted from each antenna is carefully controlled. 3. **Beam Formation:** By adjusting the phases of the signals, the transmitter can create a beam of electromagnetic energy that is focused in a specific direction. 4. **Adaptive Beamforming:** In adaptive beamforming, the beam direction can be adjusted dynamically based on the channel conditions and the location of the receiver. **Applications of Beamforming:** - **Cellular Networks:** Beamforming is used in cellular networks to improve coverage, capacity, and energy efficiency. - **Wi-Fi:** Beamforming is used in Wi-Fi systems to enhance performance and range. - **Wireless Personal Area Networks (WPANs):** Beamforming can be used in technologies like Bluetooth and Zigbee to improve data rates and range. - **Radar Systems:** Beamforming is used in radar systems to focus the transmitted signal on a specific target. [What Is Beamforming? - MATLAB 3& Simulink (mathworks.com)](https://in.mathworks.com/discovery/beamforming.html) **OFDMA** (Orthogonal Frequency Division Multiple Access) is a multiple access technology used in wireless communication systems, such as 4G LTE and 5G. It\'s a more efficient way to share a radio spectrum among multiple users compared to traditional frequency division multiple access (FDMA). Orthogonal Frequency Division Multiplexing (OFDM) is an efficient modulation format used in modern wireless communication systems including 5G. OFDM combines the benefits of Quadrature Amplitude Modulation (QAM) and Frequency Division Multiplexing (FDM) to produce a high-data-rate communication system. QAM refers to a variety of specific modulation types: BPSK (Binary Phase Shift Keying), QPSK (Quadrature Phase Shift Keying), 16QAM (16-state QAM), 64QAM (64-state QAM), etc. The basic concept of OFDM was first proposed by R. W. Chang \[see Ref 3\], recognizing that bandlimited orthogonal signals can be combined with *significant overlap* while avoiding interchannel interference.  Using OFDM, we can create an array of subcarriers that all work together to transmit information over a range of frequencies.  **How does OFDMA work?** 1. **Frequency Division:** The available bandwidth is divided into many narrowband subcarriers. 2. **Orthogonality:** These subcarriers are designed to be orthogonal, meaning they don\'t interfere with each other. 3. **Resource Allocation:** Each user is assigned a subset of subcarriers based on their data rate requirements and channel conditions. 4. **Modulation:** Data is modulated onto the assigned subcarriers and transmitted. **Key benefits of OFDMA:** - **Improved spectral efficiency:** By dividing the spectrum into orthogonal subcarriers, OFDMA can accommodate more users and data traffic within a given bandwidth. - **Flexible resource allocation:** OFDMA allows for dynamic resource allocation based on user needs and channel conditions, ensuring efficient utilization of the spectrum. - **Robustness to interference:** The orthogonality of the subcarriers helps to minimize interference between users, improving overall system performance. - **Multi-user diversity:** OFDMA can exploit multi-user diversity by allocating resources to users with the best channel conditions, improving overall system throughput. **Applications of OFDMA:** - **4G LTE:** OFDMA is a core technology in 4G LTE networks, providing high-speed data transmission and supporting various applications. - **5G:** OFDMA is also used in 5G networks, offering even higher data rates, lower latency, and enhanced capabilities for various use cases, including IoT, autonomous vehicles, and virtual reality. - **Wi-Fi:** Some Wi-Fi standards, such as 802.11ac and 802.11ax, utilize OFDMA to improve performance and accommodate more devices on a single network.