1. Asked: May 17, 2023In:

    hardware virtualization and software virtualization

    admin

    Certainly! Software virtualization is a technology that enables you to create virtual environments, known as virtual machines (VMs), on top of an existing operating system. It allows you to run multiple operating systems and applications within a single host operating system. Here's a simple explanaRead more

    Certainly! Software virtualization is a technology that enables you to create virtual environments, known as virtual machines (VMs), on top of an existing operating system. It allows you to run multiple operating systems and applications within a single host operating system.

    Here’s a simple explanation with an example:

    Imagine you have a computer running a specific operating system, such as Windows or macOS. With software virtualization, you can install a virtualization software, like Oracle VirtualBox or VMware Workstation, on top of your existing operating system.

    Once you have the virtualization software installed, you can create virtual machines within it. Each virtual machine acts as a separate computer with its own operating system and applications. For example, you can create a virtual machine running Linux within your Windows computer.

    The virtualization software emulates the underlying hardware resources, such as the processor (CPU), memory (RAM), and storage, for each virtual machine. It creates a virtual environment that allows the guest operating systems (running within the virtual machines) to function as if they were running on real hardware.

    You can install different operating systems on each virtual machine and use them for various purposes. For instance, you can have one virtual machine with Windows for gaming, another with Linux for web development, and even a virtual machine with macOS for iOS app development.

    Software virtualization offers flexibility as it allows you to run different operating systems concurrently without needing dedicated hardware for each one. It’s a useful tool for testing software compatibility, running legacy applications, or creating isolated environments for experimentation.

    In summary, software virtualization lets you create virtual machines within an existing operating system, enabling you to run multiple operating systems and applications simultaneously. It provides a convenient way to use different operating systems without the need for separate physical computers.

    Examples of popular software virtualization solutions are Oracle VirtualBox, VMware Workstation, and Parallels Desktop.

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  2. Asked: May 17, 2023In:

    hardware virtualization and software virtualization

    admin

    Hardware virtualization is a technology that allows you to create multiple "virtual" computers, called virtual machines (VMs), on a single physical computer. Each virtual machine behaves like a real computer, with its own operating system and applications, even though it's actually sharing the resouRead more

    Hardware virtualization is a technology that allows you to create multiple “virtual” computers, called virtual machines (VMs), on a single physical computer. Each virtual machine behaves like a real computer, with its own operating system and applications, even though it’s actually sharing the resources of the physical computer.

    Here’s a simple explanation with an example:

    Imagine you have a powerful computer with a special feature called a hypervisor. The hypervisor is like a supervisor that manages the virtual machines. With hardware virtualization, you can use the hypervisor to create several virtual machines on your computer.

    Each virtual machine can run its own operating systems, like Windows, Linux, or macOS, and you can install different applications on each one. For example, on one virtual machine, you can run Windows and use it for gaming, while on another virtual machine, you can run Linux and use it for web development.

    The hypervisor ensures that each virtual machine has its fair share of the computer’s resources, such as the processor (CPU), memory (RAM), and storage. It also keeps the virtual machines isolated from each other, so if one virtual machine crashes or gets infected with malware, it won’t affect the others.

    Think of hardware virtualization as creating multiple mini-computers within a single powerful computer. It allows you to make the most out of your hardware resources by running multiple operating systems and applications simultaneously, each in its own virtual environment.

    Popular examples of hardware virtualization technologies are VMware ESXi, which is commonly used in enterprise environments, and Oracle VM VirtualBox, which is more commonly used on personal computers.

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  3. Asked: May 17, 2023In:

    hardware virtualization and software virtualization

    admin

    Hardware virtualization and software virtualization are two different approaches to implementing virtualization technologies. Hardware Virtualization: Hardware virtualization, also known as full virtualization or native virtualization, involves the use of special hardware support from the CPU (CentrRead more

    Hardware virtualization and software virtualization are two different approaches to implementing virtualization technologies.

    1. Hardware Virtualization: Hardware virtualization, also known as full virtualization or native virtualization, involves the use of special hardware support from the CPU (Central Processing Unit) to create and manage virtual machines (VMs). It enables the simultaneous execution of multiple operating systems on a single physical machine, each running in its own isolated virtual environment.

    Key characteristics of hardware virtualization include:

    • Hypervisor: Hardware virtualization relies on a hypervisor or virtual machine monitor (VMM) that runs directly on the physical hardware. The hypervisor manages the allocation of physical resources, such as CPU, memory, and I/O devices, to the virtual machines.
    • Isolation: Each virtual machine operates as an independent entity, isolated from other VMs and the underlying physical hardware. This isolation ensures that activities within one VM do not affect the others.
    • Guest OS: In hardware virtualization, guest operating systems are typically unaware that they are running on virtualized hardware. They interact with the virtual hardware provided by the hypervisor, which translates their requests to the underlying physical hardware.

    Examples of hardware virtualization technologies include VMware ESXi, Microsoft Hyper-V, and KVM (Kernel-based Virtual Machine).

    1. Software Virtualization: Software virtualization, also known as emulation or hosted virtualization, does not rely on specialized hardware features. Instead, it uses software to create and manage virtual environments. In software virtualization, an application called a virtual machine monitor (VMM) or a virtualization layer runs on top of a host operating system, and guest operating systems run within the virtual environment created by the VMM.

    Key characteristics of software virtualization include:

    • Host OS: The host operating system provides a platform for running the virtualization layer or VMM. The VMM then allows multiple guest operating systems to run on top of the host OS.
    • Emulation: In software virtualization, the VMM emulates the underlying hardware resources, such as CPU, memory, and I/O devices, to provide a virtual environment for the guest operating systems. This emulation introduces some performance overhead compared to hardware virtualization.
    • Guest OS: Guest operating systems run as applications within the virtual environment created by the VMM. They are aware that they are running on virtualized hardware and interact with the virtual hardware interfaces provided by the VMM.

    Examples of software virtualization technologies include Oracle VirtualBox and VMware Workstation.

    In summary, hardware virtualization relies on specialized hardware support from the CPU to create and manage virtual machines, while software virtualization uses software-based techniques to emulate the underlying hardware resources and create virtual environments. Hardware virtualization generally offers better performance and isolation, while software virtualization is often more flexible and easier to set up on existing systems.

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  4. Asked: May 1, 2023In:

    Explanation of 5G SSBurst

    admin

    These points should give you a good understanding of SSburst in the context of 5G networks. SSburst stands for Synchronization Signal Burst, which is a specific type of signal used in 5G networks for initial device synchronization and cell detection. It is an essential part of the 5G NR (New Radio)Read more

    These points should give you a good understanding of SSburst in the context of 5G networks.

    1. SSburst stands for Synchronization Signal Burst, which is a specific type of signal used in 5G networks for initial device synchronization and cell detection.
    2. It is an essential part of the 5G NR (New Radio) air interface, responsible for transmitting the primary synchronization signal (PSS) and secondary synchronization signal (SSS) in the downlink.
    3. The PSS and SSS are used by user devices (UEs) to identify and synchronize with the 5G base station (gNB) during initial network access.
    4. SSburst operates within the synchronization channel (SSCH) and is transmitted in the time domain using Orthogonal Frequency Division Multiplexing (OFDM) symbols.
    5. The SSburst contains specific patterns and reference signals that help the UE in detecting and synchronizing to the gNB’s frame structure and timing.
    6. The PSS provides coarse synchronization, allowing the UE to identify the center frequency of the gNB.
    7. The SSS provides fine synchronization, enabling the UE to determine the cell identity and frame timing.
    8. SSbursts are transmitted periodically by the gNB, allowing UEs to continuously synchronize with the network and maintain a connection.
    9. The SSburst is part of the initial access procedure in 5G, which involves cell search, synchronization, and random access.
    10. Once a UE successfully synchronizes with the gNB using the SSburst, it can proceed with higher-layer procedures, such as random access and data communication.

     

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  5. Asked: May 1, 2023In:

    Fundamentals of 5G Waveform, Numerology, and Frame Structure

    admin

    The choice of radio waveform is the core physical layer decision for any wireless access technology. After assessments of all the waveform proposals, 3GPP agreed to adopt orthogonal frequency division multiplexing (OFDM) with a cyclic prefix (CP) for both DL and UL transmissions. CPOFDM can enable lRead more

    The choice of radio waveform is the core physical layer decision for any wireless access technology. After assessments of all the waveform proposals, 3GPP agreed to adopt orthogonal frequency division multiplexing (OFDM) with a cyclic prefix (CP) for both DL and UL transmissions.

    CPOFDM can enable low implementation complexity and low cost for wide bandwidth operations and multiple-input multiple-output (MIMO) technologies. NR also supports the use of discrete Fourier transform (DFT) spread OFDM (DFTS-OFDM) in the uplink to improve coverage.

    NR supports operation in the spectrum ranging from sub-1 GHz to millimeter wave bands. Two frequency ranges (FR) are defined in Release 15:
    • FR1:450 MHz – 6 GHz, commonly referred to as sub-6 GHz.
    • FR2: 24.25 GHz – 52.6 GHz, commonly referred to as millimeter wave.

    Scalable numerologies are key to support NR deployment in such a wide range of spectrum. NR adopts flexible subcarrier spacing of 2^𝜇 ⋅ 15 kHz (𝜇 = 0, 1, … , 4) scaled from the basic 15 kHz subcarrier spacing in LTE. Accordingly, the CP is
    scaled down by a factor of 2^−𝜇 from the LTE CP length of 4.7 μs. This scalable design allows support for a wide range of deployment scenarios and carrier frequencies.

    At lower frequencies, below 6 GHz, cells can be larger and subcarrier spacings of 15 kHz and 30 kHz are suitable. At higher carrier frequencies, phase noise becomes more problematic, and in FR2, NR supports 60 kHz and 120 kHz for data channels and 120 kHz and 240 kHz for the SS/PBCH block (SSB) used for initial access. At higher frequencies, cells and delay spread are typically smaller and the CP lengths provided by the 60 and 120 kHz numerologies are sufficient.

    A frame has a duration of 10 ms and consists of 10 subframes. This is the same as in LTE, facilitating NR and LTE coexistence. Each subframe consists of 2^𝜇 slots of 14 OFDM symbols each.

    Although a slot is a typical unit for transmission upon which scheduling operates, NR enables transmission to start at any OFDM symbol and last only as many symbols as needed for the communication. This type of “mini-slot” transmission can thus facilitate very low latency for critical data as well as minimize interference to other links per the lean carrier design principle that aims at minimizing transmissions.

    Latency optimization has been an important consideration in NR. Many other tools besides “mini-slot” transmission have been introduced in NR to reduce latency.

     

     

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  6. Asked: April 12, 2023In:

    Hardware Virtualization

    admin

    Sure, I can explain hardware virtualization in simple terms! Hardware virtualization is a technique that allows multiple "virtual" computers to run on a single physical computer. This is achieved by creating a layer of software, called a "virtual machine monitor" or "hypervisor," that sits between tRead more

    Sure, I can explain hardware virtualization in simple terms!

    Hardware virtualization is a technique that allows multiple “virtual” computers to run on a single physical computer. This is achieved by creating a layer of software, called a “virtual machine monitor” or “hypervisor,” that sits between the physical computer’s hardware and the virtual computers’ operating systems.

    The hypervisor allocates the physical computer’s resources, such as CPU, memory, and disk space, among the virtual computers. Each virtual computer sees a complete and isolated set of hardware, including its own CPU, memory, and storage.

    Hardware virtualization is useful for a variety of reasons, including:

    • Running multiple operating systems on a single computer: With hardware virtualization, you can run multiple operating systems, such as Windows and Linux, on a single physical computer. This is useful for testing software or running applications that are only available on a specific operating system.
    • Consolidating servers: Instead of running multiple physical servers, each dedicated to a single application or task, hardware virtualization allows you to run multiple virtual servers on a single physical server. This can save on hardware costs and simplify management.
    • Isolating applications: By running applications in their own virtual machines, you can isolate them from other applications and improve security.

    I hope that helps! Let me know if you have any further questions.

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  7. Asked: April 8, 2023In:

    Dual connectivity in 5G and Pros and Cons

    admin

    Dual connectivity is a feature in 5G networks that allows a device to simultaneously connect to two base stations (known as gNBs or gNodeBs) at the same time. This means that the device can use the resources of both base stations to increase data speeds and improve overall network performance. In duRead more

    Dual connectivity is a feature in 5G networks that allows a device to simultaneously connect to two base stations (known as gNBs or gNodeBs) at the same time. This means that the device can use the resources of both base stations to increase data speeds and improve overall network performance.

    In dual connectivity, one base station serves as the primary connection (known as the Master gNB) and the other as a secondary connection (known as the Secondary gNB). The device communicates with both base stations simultaneously, but all the control signaling and most of the user data are transmitted through the Master gNB.

    Dual connectivity can provide several benefits for 5G networks, including increased coverage and capacity, improved reliability, and reduced latency. It is particularly useful in dense urban areas and locations with high network traffic, where multiple base stations can provide better coverage and more bandwidth to users.

    There are several pros and cons of dual connectivity in 5G networks. Here are some of the most significant advantages and disadvantages:

    Pros:

    1. Increased data speeds: By connecting to two base stations at the same time, a device can utilize the resources of both to increase data speeds and improve overall network performance.
    2. Improved coverage: Dual connectivity allows for better coverage, especially in areas with weak signals or obstacles that block signals from a single base station.
    3. Reduced latency: Dual connectivity can reduce latency by enabling the device to communicate with the closest base station, which can help to reduce delays in transmitting and receiving data.
    4. Increased capacity: Dual connectivity can increase the network capacity by allowing multiple devices to connect to multiple base stations simultaneously, thereby reducing congestion and improving performance.

    Cons:

    1. Increased complexity: Dual connectivity involves more complex network architecture and signaling, which can make it more challenging to manage and troubleshoot network issues.
    2. Higher power consumption: Dual connectivity requires the device to maintain two connections simultaneously, which can consume more battery power and reduce battery life.
    3. Increased network overhead: Dual connectivity can increase the amount of control signaling and management required to maintain two connections simultaneously, which can increase network overhead and reduce efficiency.
    4. Higher costs: Dual connectivity requires additional infrastructure, such as multiple base stations, which can increase the cost of deploying and maintaining the network.
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  8. Asked: April 7, 2023In:

    5G Numerology

    admin

    Numerology in 5G refers to the different frequencies, bandwidths, and subcarrier spacings used in 5G wireless networks. As of Release 17, there are 7 types of numerology (SCS 15, 30, 60, 120, 240, 480, 960 kHz). In particular, 5G networks use a range of frequencies, including both sub-6 GHz and mmWaRead more

    Numerology in 5G refers to the different frequencies, bandwidths, and subcarrier spacings used in 5G wireless networks. As of Release 17, there are 7 types of numerology (SCS 15, 30, 60, 120, 240, 480, 960 kHz).

    In particular, 5G networks use a range of frequencies, including both sub-6 GHz and mmWave (millimeter-wave) frequencies, to provide higher data rates, lower latency, and more reliable connectivity compared to previous generations of wireless networks.

    The term “numerology” specifically refers to the way that different frequencies and subcarrier spacings are organized and combined in 5G networks. This includes the use of different channel bandwidths (ranging from 5 MHz to 400 MHz), and subcarrier spacing (ranging from 15 kHz to 960 kHz).

    Additionally, the 5G numerology includes the use of different channel bandwidths and subcarrier spacings to optimize data transmission for different types of devices and applications. This allows for more efficient use of the available spectrum, which is important for supporting the increasing demand for wireless data and the growing number of connected devices.

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  9. Asked: April 5, 2023In:

    EPS to 5G Hand-over with the N26 Interface

    admin
    This answer was edited.

    Here is the call flow of preparation in steps:   Call handover initiation starts from UE and E-UTRAN toward each other, proceeds from E-UTRAN to the S-GW, and then for roaming calls, call handover initiation proceeds from S-GW to the UPF+P-GW-U The E-UTRAN sends the Handover Call Request to theRead more

    Here is the call flow of preparation in steps:

     

    1. Call handover initiation starts from UE and E-UTRAN toward each other, proceeds from E-UTRAN to the S-GW, and then for roaming calls, call handover initiation proceeds from S-GW to the UPF+P-GW-U
    2. The E-UTRAN sends the Handover Call Request to the MME.
    3. The MME forwards the Relocation Request to the AMF.
    4. The AMF invokes the Nsmf_PDUSession_CreateSMContext service operation on SMF. The PGW-C+SMF address identifies this service operation. The service operations can be UE EPS PDN Connection, AMF ID, or Direct Forwarding Flag. The AMF then indicates the handover preparation to avoid switching the UP path. The SMF searches for the corresponding PDU session that is based on EPS Bearer Contexts. The AMF includes Direct Forwarding Flag to inform the SMF of the applicability of indirect data forwarding.
    5. If you have deployed the dynamic PCC, the SMF+ PGW-C initiates the SMF-initiated SM Policy Modification toward the PCF.
    6. The PGW-C+SMF sends the N4 Session Modification to PGW-U+UPF to establish the CN tunnel for a PDU Session. The PGW-U+UPF receives the uplink packets from NG-RAN. This step involves creating uplink PDRs and FARs for the 5G session along with the QFIs that are mapped from the existing 4G bearers.

    7. The PGW-C+SMF sends a Nsmf_PDUSession_CreateSMContext Response to the AMF. This response includes PDU Session ID, S-NSSAI, and N2 SM Information.

      The N2 SM Information includes PDU Session ID, S-NSSAI, QFIs, QoS Profiles, EPS Bearer Setup List, mapping between EBIs and QFIs, CN Tunnel information, and cause code details.

      The SMF includes mapping between EBIs and QFIs as the N2 SM Information container. If the P-GW-C+SMF determines that session continuity from EPS to 5GS is not supported for the PDU session, then the P-GW-C+SMF does not provide the Session Manager information for the corresponding PDU session. However, the P-GW-C+SMF includes the cause code details for rejecting the PDU session transfer in the N2 SM information.

    8. The V-SMF and V-UPF establish an N4 session with each other.
    9. The AMF sends the Handover Request to NG-RAN.
    10. The NG-RAN sends the Handoff Request Acknowledgment for the received Handover Request to the AMF.

    11. The AMF sends a Nsmf_PDUSession_UpdateSMContext Request, T-RAN SM N3 forwarding information list message to the SMF for updating the N3 tunnel information.

      The Nsmf_PDUSession_UpdateSMContext request includes a PDU Session ID, S-NSSAI, and N2 SM Information. The tunnel information exists in the NGAP IE DL Forwarding UP TNL Information of the Handoff Request Acknowledgment that is received from NG-RAN.

    12. The SMF+PGW-C performs the N4 session modification toward UPF+PGW-U to create the indirect tunnel to forward the DL data from eNodeB to NG-RAN. This step includes creating UL PDRs for the redirected DL data and associating FARs with them to forward the FARs to NG-RAN. The mapping of these PDRs and FARs is based on QFI and the corresponding bearer ID.
    13. The PGW-C+SMF sends the Nsmf_PDUSession_UpdateSMContext Response to the AMF. This response includes PDU Session ID, EPS Bearer Setup List, and CN tunnel information for data forwarding. At this point, the indirect tunnels are established for DL data forwarding.
    14. The AMF sends the Forward Relocation Response to the MME.
    15. The MME sends the creation request for the indirect data forwarding tunnel to the S-GW. The S-GW sends the response for the indirect data forwarding tunnel to the MME.
    Here is the EPS to 5G Handover with N26 Interface Execution Call flow:

    1. Call handover initiation starts from the UE and E-UTRAN toward each other, proceeds from E-UTRAN to S-GW, and then for roaming calls, call handover initiation proceeds from S-GW to the UPF+P-GW-U.

      The MME sends the handover command to E-UTRAN.

    2. The E-UTRAN sends the handover command to the UE.
    3. The UE sends the confirmation message to NG-RAN for the received handover to 5G-RAN.
    4. The NG-RAN sends the Handover Notification message to the AMF.
    5. The AMF sends the Forward Relocation Complete Notification to the MME.
    6. The MME sends the Acknowledgment Response for the received Forward Relocation Complete Notification.
    7. The AMF sends Nsmf_PDUSession_UpdateSMContext Request to SMF +PGW-C. This request includes Handover Complete Indication for PDU Session ID details. For indirect forwarding, a timer in SMF+PGW-C starts to check when resources in UPF are to be released.
    8. The SMF performs N4 Modification Request with UPF+PGW-U to update the DL tunnel information for the FARs that are associated with DL PDRs of the 5G session. The DL data path is activated. At this point, the indirect tunnel also exists.
    9. The SMF informs PCF of the RAT type change.
    10. The SMF sends Nsmf_PDUSession_UpdateSMContext Response, with PDU Session ID, to SMF. The SMF confirms the reception of Handover Complete.
    11. After the timer that started in Step 7 expires, the SMF sends N4 Modification Request to UPF. This request is to remove the PDRs and FARs that are associated with the indirect data tunnel.
    12. The UE starts the EPS to 5GS mobility registration procedure and sends it to H-PCF.
    13. The E-UTRAN performs the resource cleanup in EPC by MME.
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  10. Asked: March 30, 2023In:

    5G USIM authentication process

    admin

    Authentication primarily happens in two places, one at each end of the network, the Home Subscriber Server, and in the USIM card. Let’s take a look at each of them. It is a mutual authentication process, which means: The network needs to authenticate our subscribers, in a way that can’t be spoofed/rRead more

    Authentication primarily happens in two places, one at each end of the network, the Home Subscriber Server, and in the USIM card. Let’s take a look at each of them. It is a mutual authentication process, which means:

    • The network needs to authenticate our subscribers, in a way that can’t be spoofed/replayed so we know who to bill & where to route traffic.
    • Subscribers need to authenticate the network so they know they can trust it to carry their traffic.

    So our USIM needs to authenticate the network, in the same way, the network authenticates the USIM.

    On the HSS and USIM, we have the K key (Secret key), OPc key (Operator key), for each IMSI on our network.

    A new key was also introduced for network authentication, called AUTN.

    The AUTN key is generated by the HSS by mixing the secret keys (K & OPc) and RAND values together.

    This AUTN key is sent to the USIM along with the RAND value. The USIM runs the same mixing on its private keys and RAND the HSS did to generate the AUTN, except this is the USIM generated – An Expected AUTN key (XAUTN). The USIM compares XAUTN and AUTN to make sure they match. If they do, the USIM then knows the network knows their secret keys.

    The USIM then does the same mixing it did in the previous option to generate the RES (result) key and send it back.

    The network has now authenticated the subscriber (HSS has authenticated the USIM via RES key) and the subscriber has authenticated the USIM (USIM authenticates HSS via AUTN key).

     

     

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