In this video, we dive deep into how 5G achieves ultra-low latency, making it a game-changer for real-time applications like autonomous vehicles, industrial IoT, and mission-critical communications. The introduction of mini-slots, preemptive scheduling, and self-contained slots brings unparalleled flexibility to 5G networks.
We’ll explore:
* Mini-Slots: A shortened version of traditional slots that reduces wait times, allowing data transmission without waiting for slot boundaries. Mini-slots can start at any symbol boundary, making data scheduling more dynamic.
* Preemptive Scheduling: Learn how 5G schedules high-priority traffic (like URLLC) by "stealing" resources from ongoing lower-priority traffic. This ensures that latency-sensitive data gets through without delay.
* Self-Contained Slots: Understand how self-contained slots in 5G allow complete downlink transmission, acknowledgment, and uplink response within a single slot, reducing latency to as low as 500 microseconds.
* Subcarrier Spacing: Discover how the flexible subcarrier spacing in 5G allows different slot durations depending on the use case, helping optimize for both latency and throughput.
* Trade-Offs: We’ll also discuss the trade-off between latency and power efficiency. With 5G’s mini-slots and preemptive scheduling, low-latency devices often need to stay active, consuming more power.
Whether you're working in telecom or simply interested in how 5G technology supports low-latency applications, this video is for you. Understand how these advanced features pave the way for future technologies like smart cities, remote surgery, industrial automation, and real-time communication.
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We’ll explore:
* Mini-Slots: A shortened version of traditional slots that reduces wait times, allowing data transmission without waiting for slot boundaries. Mini-slots can start at any symbol boundary, making data scheduling more dynamic.
* Preemptive Scheduling: Learn how 5G schedules high-priority traffic (like URLLC) by "stealing" resources from ongoing lower-priority traffic. This ensures that latency-sensitive data gets through without delay.
* Self-Contained Slots: Understand how self-contained slots in 5G allow complete downlink transmission, acknowledgment, and uplink response within a single slot, reducing latency to as low as 500 microseconds.
* Subcarrier Spacing: Discover how the flexible subcarrier spacing in 5G allows different slot durations depending on the use case, helping optimize for both latency and throughput.
* Trade-Offs: We’ll also discuss the trade-off between latency and power efficiency. With 5G’s mini-slots and preemptive scheduling, low-latency devices often need to stay active, consuming more power.
Whether you're working in telecom or simply interested in how 5G technology supports low-latency applications, this video is for you. Understand how these advanced features pave the way for future technologies like smart cities, remote surgery, industrial automation, and real-time communication.
Subscribe to "Learn And Grow Community"
YouTube : https://www.youtube.com/@LearnAndGrowCommunity
LinkedIn Group : https://linkedin.com/company/LearnAndGrowCommunity
Follow #learnandgrowcommunity
#5g #5gsa #5gnsa #5gran #5gcore #5gnr #5gnetwork #5gnetworks #newradio #telecommunications #telecom #oran #openran #4gvs5g #5gvs4g #5gtechnology #MiniSlots #PreemptiveScheduling #lowlatency #WirelessInnovation #telecominsights #urllc #mobilebroadband #RealTime5G #smartcities #autonomousdriving #telecominsights
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LearningTranscript
00:00Hi, in the last session, we learned
00:02that how the flexible subcarrier spacing in 5G
00:05can lead to different slot lengths
00:07and how it can improve the network latency, which
00:10is crucial for time-sensitive applications.
00:13We learned that how the higher subcarrier spacings
00:15reduce the slot durations.
00:18We also learned that why we actually
00:20needed flexible numerology in 5G to cater millimeter bands.
00:25Now, in this session, we will explore two additional features
00:28in 5G NR that further contribute
00:30to achieving lower latencies.
00:33In LTE, the transmission time interval, or TTIE,
00:37is the duration of a transmission slot,
00:39and it is fixed at 1 millisecond.
00:42As shown in picture, the shortest delay
00:45in the LTE between a downlink data transmission
00:47and the corresponding ACK or NACK notification in the uplink
00:51is 4 milliseconds.
00:54Although this 4 millisecond delay
00:55is acceptable for the mobile broadband applications,
00:59but it is too long for the ultra-reliable low latency
01:02communication, or URLLC use cases.
01:06In 5G NR, this delay can be significantly
01:09reduced, which make it more suitable for low latency
01:12applications.
01:14So 5G NR introduced the concept of self-contained slots.
01:19This self-contained slot allows more efficient data
01:22transmission, especially in TDD systems or time division
01:26duplex systems.
01:28This means that within a TDD band,
01:30the downlink data, guard period, and the corresponding ACK
01:34or NACK notification can all be accommodated
01:37within a 500 millisecond slot.
01:39Now, depending on the numerology,
01:41this entire process can be completed
01:43within a single slot.
01:45Apart of the self-contained slot and flexible subcarrier
01:48spacing, 5G NR also introduced another concept
01:52of mini-slot, which provides even more flexibility
01:55in the data transmission.
01:57A mini-slot is just a shortened version of a regular slot.
02:01This is introduced to further reduce the latency
02:04by allowing quicker data transmissions.
02:07In NR, a mini-slot can start at any symbol boundary.
02:11So there is no need to wait for the next slot boundary
02:14to schedule any data.
02:16That is why it reduces the delay.
02:18Additionally, a mini-slot is not fixed in length.
02:22It can contain either two or four or seven symbols.
02:25However, a standard slot is fixed at 14 symbols.
02:30So mini-slots can offer flexibility in slot duration
02:34based on the specific needs of the transmission.
02:37And this is especially beneficial for the low latency
02:40applications.
02:41This flexibility in the duration and start time
02:45allows low latency devices to transmit data
02:48without waiting for the next slot boundary
02:50or being constrained by a long slot.
02:52And this has effectively minimized the latency.
02:56Now let's talk about preemptive scheduling
02:59and understand how it works in practice.
03:02So in this scenario, the Mac scheduler
03:05initially allocates some resources
03:07to a mobile broadband UE, which you can see here
03:09with the gray color.
03:11But then we steal some resources from this pre-scheduled mobile
03:14broadband transmissions and reallocate that resource
03:17to transmit URLLC data, which is in red color.
03:22This happens to ensure that the URLLC low latency
03:26data gets the priority.
03:28This approach is known as preemptive scheduling,
03:31where URLLC data can override the pre-scheduled transmissions
03:36to meet its strict latency requirement.
03:39Now, if you are doing this, then we
03:41need to inform the UE as well that some of the scheduled
03:44slots are now used for other services.
03:46And for this purpose, a preemption indicator is sent.
03:50And you will get notified that some of its resources
03:53have been reallocated for URLLC data transmissions.
03:57These different levels of flexibility
03:59are helping 5G NR to achieve lower latency,
04:02as URLLC data can be scheduled with a lot of flexibility
04:07in slot duration and slot time.
04:09Typically, the UE monitors the downlink control information
04:13channel, or DCI channel, to know when it needs to receive data.
04:19The UE monitors the channel at the beginning of each slot
04:22and then goes into the sleep mode
04:24for the rest of the slot duration
04:26to save the battery power.
04:28However, for the low latency devices that uses many slots
04:32and the data can be scheduled at any time and at any slot,
04:36so we have a trade-off here.
04:38Because low latency devices has to constantly monitor
04:41the DCI channel.
04:42And hence, they cannot sleep between the slot boundaries.
04:46And this increases the power consumption.
04:49Therefore, it's essential to understand
04:52the trade-off between achieving a low latency
04:54and maintaining the power efficiency.
04:57In summary, many slots and preemptive scheduling
05:00are the important design innovations in 5G NR
05:04to serve the ultra-reliable and low latency use cases.
05:07And they significantly contribute
05:09in achieving these low latency requirements
05:11for the next generation applications.
05:14So that's it for today.
05:15In the next session, we'll be talking
05:16about scheduling in 5G NR.
05:19So stay tuned for the updates.
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