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Thursday, 29 September 2022

Four Ways 5G Can Improve the Battery Life of User Equipment (UE)

We have looked at different approaches in this blog and the 3G4G website on reducing the power consumption (see related posts below). In a blog post some months back, Huawei highlighted how 5G can improve the battery life of UE. The blog post mentioned four approaches, we have looked at three of them on various blogs. 

The following is from the blog post:

RRC_INACTIVE State

A UE can access network services only if it establishes a radio resource control (RRC) connection with the base station. In legacy RATs, a UE is either in the RRC_CONNECTED state (it has an RRC connection) or the RRC_IDLE state (it does not have an RRC connection). However, transitioning from the RRC_IDLE state to the RRC_CONNECTED state takes a long time, so it cannot meet the low latency requirement of some 5G services. But a UE cannot just stay in the RRC_CONNECTED state because this will consume much more UE power.

To solve this problem, 5G introduces the RRC_INACTIVE state, where the RRC connection is released but the UE context is retained (called RRC Release with Suspend), so an RRC connection can be quickly resumed when needed. This way, a UE in the RRC_INACTIVE state can access low-latency services whenever needed but consume the same amount of power as it does in the RRC_IDLE state.

DRX + WUS

Discontinuous reception (DRX) enables a UE in the RRC_CONNECTED state to periodically, instead of constantly, monitor the physical downlink control channel (PDCCH) to save power. To meet the requirements of different UE services, both short and long DRX cycles can be configured for a UE. However, when to wake up is determined by the predefined cycle, so the UE might wake up unnecessarily when there is no data scheduled.

Is there a way for a UE to wake up only when it needs to? Wake-up Signal (WUS) proposed in Release 16 is the answer. This signal can be sent before the next On Duration period (during which the UE monitors the PDCCH) so that the UE wakes up only when it receives this signal from the network. Because the length of a WUS is shorter than the On Duration Timer, using WUS to wake up a UE saves more power than using only DRX.

BWP Adaptation

In theory, working on a larger bandwidth consumes more UE power. 5G provides large bandwidths, but it is unnecessary for a UE to always work on large bandwidth. For example, if you play online mobile games on a UE, only 10 MHz of bandwidth is needed for 87% of the data transmission time. As such, Bandwidth Part (BWP) is proposed in 5G to enable UEs to work on narrower bandwidths without sacrificing user experience.

BWP adaptation enables the base station to dynamically switch between BWPs based on the UE’s traffic volume. When the traffic volume is large, a UE can work on a wide BWP, and when the traffic volume is small, the UE can work on a narrow one. BWP switching can be performed based on the downlink control information (DCI) and RRC reconfiguration messages. This ensures that a UE always works on a bandwidth that supports the traffic volume but does not consume too much power.

Maximum MIMO Layers Reduction

According to 3GPP specifications, the number of receive and transmit antennas used by a UE cannot be fewer than the maximum number of MIMO layers in the downlink and uplink, respectively. For example, when a maximum of four downlink MIMO layers are configured for a UE, the UE must enable at least four receive antennas to receive data. Therefore, if the maximum number of MIMO layers can be reduced, the UE does not have to activate as many antennas, reducing power consumption.

This can be achieved in 5G because the number of MIMO layers can be re-configured based on assistance information from UEs. After receiving a request to reduce the number of MIMO layers from a UE, the base station configures fewer MIMO layers for the UE through an RRC reconfiguration message. In this way, the UE can deactivate some antennas to save power.

Power consumption in the networks and the devices is a real challenge. While the battery capacity and charging speeds are increasing, it is also important to find ways to optimise the signalling parameters, etc. One such approach can be seen in the tweet above regarding regarding T-Mobile in The Netherlands, selectively switching off a carrier in the night and switching it back when the cell starts loading or in the morning.

We will see lot more innovations and optimisations to dynamically update the technologies, parameters, optimisations to ensure power savings wherever possible.

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Monday, 19 September 2022

Is there a compelling Business Case for 5G Network Slicing in Public Networks?

Since the industry realised how the 5G Network Architecture will look like, Network Slicing has been touted as the killer business case that will allow the mobile operators to generate revenue from new sources.

Last month ABI Research said in a press release:

According to global technology intelligence firm ABI Research, 5G slicing revenue is expected to grow from US$309 million in 2022 to approximately US$24 billion in 2028, at a Compound Annual Growth Rate (CAGR) of 106%. 

“5G slicing adoption falls into two main categories. One, there is no connectivity available. Two, there is connectivity, but there is not sufficient capacity, coverage, performance, or security. For the former, both private and public organizations are deploying private network slices on a permanent and ad hoc basis,” highlights Don Alusha, 5G Core and Edge Networks Senior Analyst at ABI Research. The second scenario is mostly catered by private networks today, a market that ABI Research expects to grow from US$3.6 billion to US$109 billion by 2023, at a CAGR of 45.8%. Alusha continues, “A sizable part of this market can be converted to 5G slicing. But first, the industry should address challenges associated with technology and commercial models. On the latter, consumers’ and enterprises’ appetite to pay premium connectivity prices for deterministic and tailored connectivity services remains to be determined. Furthermore, there are ongoing industry discussions on whether the value that comes from 5G slicing can exceed the cost required to put together the underlying slicing ecosystem.”

Earlier this year, Daryl Schoolar - Research Director at IDC tackled this topic in his blog post:

5G network slicing, part of the 3GPP standards developed for 5G, allows for the creation of multiple virtual networks across a single network infrastructure, allowing enterprises to connect with guaranteed low latency. Using principles behind software-defined network and network virtualization, slicing allows the mobile operator to provide differentiated network experience for different sets of end users. For example, one network slice could be configured to support low latency, while another slice is configured for high download speeds. Both slices would run across the same underlying network infrastructure, including base stations, transport network, and core network.

Network slicing differs from private mobile networks, in that network slicing runs on the public wide area network. Private mobile networks, even when offered by the mobile operator, use infrastructure and spectrum dedicated to the end user to isolate the customer’s traffic from other users.

5G network slicing is a perfect candidate for future business connectivity needs. Slicing provides a differentiated network experience that can better match the customers performance requirements than traditional mobile broadband. Until now, there has been limited mobile network performance customization outside of speeds. 5G network slicing is a good example of telco service offerings that meet future of connectivity requirements. However, 5G network slicing also highlights the challenges mobile operators face with transformation in their pursuit of remaining relevant.

For 5G slicing to have broad commercial availability, and to provide a variety of performance options, several things need to happen first.

  • Operators need to deploy 5G Standalone (SA) using the new 5G mobile core network. Currently most operators use the 5G non-standalone (NSA) architecture that relies on the LTE mobile core. It might be the end of 2023 before the majority of commercial 5G networks are using the SA mode.
  • Spectrum is another hurdle that must be overcome. Operators still make most of their revenue from consumers, and do not want to compromise the consumer experience when they start offering network slicing. This means operators need more spectrum. In the U.S., among the three major mobile operators, only T-Mobile currently has a nationwide 5G mid-band spectrum deployment. AT&T and Verizon are currently deploying in mid-band, but that will not be completed until 2023.
  • 5G slicing also requires changes to the operator’s business and operational support systems (BSS/OSS). Current BSS/OSS solutions were not designed to support the increased parameters those systems were designed to support.
  • And finally, mobile operators still need to create the business propositions around commercial slicing services. Mobile operators need to educate businesses on the benefits of slicing and how slicing supports their different connectivity requirements. This could involve mobile operators developing industry specific partnerships to reach different business segments. All these things take time to be put into place.

Because of the enormity of the tasks needed to make 5G network slicing a commercial success, IDC currently has a very conservative outlook for this service through 2026. IDC believes it will be 2023 until there is general commercial availability of 5G network slicing. The exception is China, which is expected to have some commercial offerings in 2022 as it has the most mature 5G market. Even then, it will take until 2025 before global revenues from slicing exceeds a billion U.S. dollars. In 2026 IDC forecasts slicing revenues will be approximately $3.2 billion. However, over 80% of those revenues will come out of China.

The 'Outspoken Industry Analyst' Dean Bubley believes that Network Slicing is one of the worst strategic errors made by the mobile industry, since the catastrophic choice of IMS for communications applications. In a LinkedIn post he explains:

At best, slicing is an internal toolset that might allow telco operations or product teams (or their vendors) to manage their network resources. For instance, it could be used to separate part of a cell's capacity for FWA, and dynamically adjust that according to demand. It might be used as an "ingredient" to create a higher class of service for enterprise customers, for instance for trucks on a highway, or as part of an "IoT service" sold by MNOs. Public safety users might have an expensive, artisanal "hand-carved" slice which is almost a separate network. Maybe next-gen MVNOs.

(I'm talking proper 3GPP slicing here - not rebranded QoS QCI classes, private APNs, or something that looks like a VLAN, which will probably get marketed as "slices")

But the idea that slicing is itself a *product*, or that application developers or enterprises will "buy a slice" is delusional.

Firstly, slices will be dependent on [good] coverage and network control. A URLLC slice likely won't work reliably indoors, underground, in remote areas, on a train, on a neutral-host network, or while roaming. This has been a basic failure of every differentiated-QoS monetisation concept for many years, and 5G's often-higher frequencies make it worse, not better.

Secondly, there is no mature machinery for buying, selling, testing, supporting. price, monitoring slices. No, the 5G Network Exposure Function won't do it all. I haven't met a Slice salesperson yet, or a Slice-procurement team.

Thirdly, a "local slice" of a national 5G network will run headlong into a battle with the desire for separate private/dedicated local 5G networks, which may well be cheaper and easier. It also won't work well with the enterprise's IT/OT/IP domains, out of the box.

Also there's many challenges getting multi-operator slices, device OS links to slice APIs, slice "boundary controllers" between operators, aligning RAN and core slices, regulatory questionmarks and much more.

There are lots of discussion in the comments section that may be of interest to you, here.

My belief is that we will see lots of interesting use cases with slicing in public networks but it will be difficult to monetise. The best networks will manage to do it to create some plans with guaranteed rates and low latency. It would remain to be see whether they can successfully monetise it well enough. 

For technical people and newbies, there are lots of Network Slicing resources on this blog (see related posts 👇). Here is another recent video from Mpirical:

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Saturday, 10 September 2022

CUPS for Flexible U-Plane Processing Based on Traffic Characteristics

I looked at Control and User Plane Separation (CUPS) in a tutorial, nearly five years back here. Since then most focus has been on 5G, not just on my blogs but also from the industry. 

Earlier this year, NTT Docomo's Technical Journal looked at CUPS for Flexible U-Plane Processing Based on Traffic Characteristics. The following is an extract from the article:

At the initial deployment phase of 5th Generation mobile communication systems (5G), the 5G Non-Stand-Alone (NSA) architecture was widely adopted to realize 5G services by connecting 5G base stations to the existing Evolved Packet Core (EPC). As applications based on 5G become more widespread, the need for EPC to achieve higher speed and capacity communications, lower latency communications and simultaneous connection of many terminals than ever has become urgent. Specifically, it is necessary to increase the number of high-capacity gateway devices capable of processing hundreds of Gbps to several Tbps to achieve high-speed, high-capacity communications, to distribute gateway devices near base station facilities to achieve even lower latency communications, and to improve session processing performance for connecting massive numbers of terminals simultaneously.

Conventional single gateway devices have both Control Plane (C-Plane) functions to manage communication sessions and control communications, and User Plane (U-Plane) functions to handle communications traffic. Therefore, if the previously assumed balance between the number of sessions and communications capacity is disrupted, either the C-Plane or the U-Plane will have excess processing capacity. In high-speed, high-capacity communications, the C-Plane has excess processing power, and in multiple terminal simultaneous connections, the U-Plane has excess processing power because the volume of communications is small compared to the number of sessions. If the C-Plane and U-Plane can be scaled independently, these issues can be resolved, and efficient facility design can be expected. In addition, low-latency communications require distributed deployment of the U-Plane function near the base station facilities to reduce propagation delay. However, in the distributed deployment of conventional devices with integrated C-Plane and U-Plane functions, the number of sessions and communication volume are unevenly distributed among the gateway devices, resulting in a decrease in the efficiency of facility utilization. Since there is no need for distributed deployment of C-Plane functions, if the C-Plane and U-Plane functions can be separated and the way they are deployed changed according to their characteristics, the loss of facility utilization efficiency related to C-Plane processing capacity could be greatly reduced.

CUPS is an architecture defined in 3GPP TS 23.214 that separates the Serving GateWay (SGW)/Packet data network GateWay (PGW) configuration of the EPC into the C-Plane and U-Plane. The CUPS architecture is designed so that there is no difference in the interface between the existing architecture and the CUPS architecture - even with CUPS architecture deployed in SGW/PGW, opposing devices such as a Mobility Management Entity (MME), Policy and Charging Rules Function (PCRF), evolved NodeB (eNB)/ next generation NodeB (gNB), and SGWs/PGWs of other networks such as Mobile Virtual Network Operator (MVNO) and roaming are not affected. For C-Plane, SGW Control plane function (SGW-C)/PGW Control plane function (PGW-C), and for U-Plane, SGW User plane function (SGW- U)/PGW User plane function (PGW-U) are equipped with call processing functions. By introducing CUPS, C-Plane/U-Plane capacities can be expanded individually as needed. Combined SGW-C/PGW-C and Combined SGW-U/PGW-U can handle the functions of SGW and PGW in common devices. In the standard specification, in addition to SGW/PGW, the Traffic Detection Function (TDF) can also be separated into TDF-C and TDF-U, but the details are omitted in this article.

From above background, NTT DOCOMO has been planning to deploy Control and User Plane Separation (CUPS) architecture to realize the separation of C-Plane and U-Plane functions as specified in 3rd Generation Partnership Project Technical Specification (3GPP TS) 23.214. Separating the C-Plane and U-Plane functions of gateway devices with CUPS architecture makes it possible to scale the C-Plane and U-Plane independently and balance the centralized deployment of C-Plane functions with the distributed deployment of U- Plane functions, thereby enabling the deployment and development of a flexible and efficient core network. In addition to solving the aforementioned issues, CUPS will also enable independent equipment upgrades for C-Plane and U-Plane functions, and the adoption of U-Plane devices specialized for specific traffic characteristics.

In the user perspective, the introduction of CUPS can be expected to dramatically improve the user experience through the operation of facilities specializing in various requirements, and enable further increases in facilities and lower charges to pursue user benefits by improving the efficiency of core network facilities.

Regarding the CUPS architecture, a source of value for both operators and users, this article includes an overview of the architecture, additional control protocols, U-Plane control schemes based on traffic characteristics, and future developments toward a 5G Stand-Alone (5G SA) architecture.

The article is available here.

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