5G Architecture - Semafour Workshop

Icaro Da Silva @ SEMAFOUR Workshop 2015-08-25

5G a r c h it ec t u r e – Ch a l l en g es a n d o ppo r t u n it ies

Ericsson Internal | 2014-09-11 | Page 2

› Support of a diverse range of use cases: M-MTC, C-MTC and xMBB › High rates (up to 10Gbps), low latency (~1ms) drive a new RAT (NX) › RAN Integration of the new RAT (NX) and LTE (5G RAT family) › 5G RAN / CN (logical) functional split similar to EPC/LTE › Diversity of implementations e.g. co-sited RAN/CN › Diversity of deployments e.g. centralized / distributed › SDN / NFV to be explored for the CN design › Support of network slicing

t h e 5g a r c h it ec t u r e su m m a r y 1/2


t h e 5g a r c h it ec t u r e su m m a r y 2/2

Control plane

User plane


› Senior Researcher @ Ericsson AB (Wireless Access Networks) › Control Plane architecture coordinator in METIS-II (pre-standardization for the 5G RAN architecture + CN/RAN split)

› Co-author of a book chapter about 5G architecture › Previously worked with OSS-based SON, SON topics in RAN 3/2, data analytics on e2e protocol traces, network mgmt. prototyping

Few w o r d s a bo u t m e…


› Most people say that network architecture is about building a system by putting pieces of technology together (bottom up vision)

› According to network architects (top down vision)

–Investigation of system requirements / drivers –Split functionalities in network elements and define interfaces –Design of protocols for interfaces so NE’s can communicate

› Most people ignore that UE’s are NE’s and the air interface is an interface › It’s all about standards in order to enable a multi-vendor ecosystem

Fe w w o r d s a b o u t n e t w o r k a r c h it e c t u r e (R&D c o n t e x t )…


› #1: New 5G air interface (called here NX): flexible but simple › #2: 5G lean design: lean but with efficient access / mobility › #3: Integration of NX and LTE evolution: the 5G RAT couple › #4: Many use cases, single 5G system: end of “one-fits-all”?

5g a r c h it ec t u r e Ch a l l en g es a n d o ppo r t u n it ies


› Support higher frequency bands with wider bandwidth – New numerology compared to LTE is required

› Support lower latency

– Shorter (and more flexible) TTIs and a new channel structure

› Better support very dense and EE deployments and beamforming

– Enabled by for example removing legacy limitations e.g. Cell-specific RS

› Better support the diverse range of 5G use cases (M-MTC, C-MTC and xMBB)

#1: n ew 5G a ir in t er f a c e (NX) f l ex ib l e bu t s im pl e

Ericsson Research Blog, “Release 14, the Start of 5G standardization”

http://www.ericsson.com/research-blog/lte/release-14-the-start-of-5g-standardization/


#1: n ew 5G a ir in t er f a c e (NX) f l ex ib l e bu t s im pl e

› Flexibility: potential AI variants per spectrum range, many levels of integration

› Simplicity: one protocol stack, one new air interface, one set of specifications, common higher layers, common including CN, common network management


› Industry concensus about the importance of energy efficiency in 5G –Minimize ”always on” signals (not directly related to user-data delivery) –Sync signals (PSS/SSS), Cell specific-RS (C-RS), Sys info, etc. –Currently essential signals for sys access and mobility procedures (common)

#2: 5G l ea n d es ig n l ea n bu t ef f ic ien t sy s t em a c c ess

Ultra-lean

• No ”always-on” refeference signals • Minimum amount of ”always-broadcast ”system information • ...

Today

• Reference signals • Broadcast” system information • ...

Ericsson Research Blog, “Release 14, the Start of 5G standardization”, 2015

http://www.ericsson.com/research-blog/lte/release-14-the-start-of-5g-standardization/


› Challenging propagation in higher frequency drives the usage of massive beamforming

› Beamforming vs. broadcasting

› Beam-based system access: how the NW knows where the UE’s are? Which signals will the UE monitor?

› Beam-based mobility: which signals will the UE measure if C-RSs are minimized? How to achieve reliability?

#2: 5G l ea n d es ig n l ea n bu t ef f ic ien t m o b il it y

(Less of an issue for small cells)

** lower diffraction and higher outdoor/indoor penetration losses, which means that signals will have less ability to propagate around corners and penetrate walls

Ericsson Research Blog, “Massive Beamforming in 5G Radio Access”, 2015 Barati et al. “Directional Cell Search for Millimeter Wave Cellular Systems”, 2014

http://www.ericsson.com/research-blog/5g/massive-beamforming-in-5g-radio-access/


#3: In t eg r a t io n o f NX a n d LTE 5G Ra t “c o u pl e”, w h y ?

Athley et al, “Providing Extreme Mobile Broadband using higher frequency bands, beamforming and Carrier Aggregation” @ PIMRC’2015

› Higher-frequency spectrum needed to satisfy future traffic demands › Joint low-frequency/high-frequence operation needed for full-area coverage

(1) (2)

(3) (4)


RRC

RLC

MAC

PHY

PDCP

RLC

MAC

PHY

5G CN

5G RAN LTE New AI

Common PDCP/RRC

RLC

MAC

PHY

RLC

MAC

PHY

5G CN

5G RAN LTE New AI

PDCP PDCP

RRC RRC

Common Core Network

5G CN

5G RAN

RRC

PHY

PDCP

PHY

RLC

MAC

LTE New AI

• Tight coordination gains from cross-carrier scheduling

• Limited to co-located scenarios or ideal backhaul

• Coordination gains from a common CP: mobility, multi-connectivity, traffic steer.

• Suitable for any type of backhaul in non-collocated scenarios.

• Reduced delays on hard HO compared to current interworking

• Only air interface selection

Common MAC

#3: In t eg r a t io n o f NX a n d LTE o pt io n s f o r t h e pr o t o c o l in t eg r a t io n

Da Silva et al, “Tight integration of new 5G air interface and LTE to fulfill 5G requirements” @ VTC Spring’2015


› Reduction of signaling overhead – IDLE CONNECTED is signaling heavy – Smartphone connections are very short – Between bursts UE moves to IDLE – MTC solutions would also benefit from this

› NX should support an efficient sleep mode › RAN context is kept (in UE and network)

to allow fast and low-overhead transitions

# 3: In t e g r a t io n o f NX a n d LTE n x s l e e p in g s t a t e

No RAN context

RAN context kept

Sleep Active

Da Silva et al., “Towards an efficient sleeping for 5G devices” submitted to Globecom’2015


#3: In t eg r a t io n o f NX a n d LTE n x s l eepin g s t a t e a n d c o m m o n s t a t e m a c h in e

Da Silva et al., “Towards an efficient sleeping for 5G devices” submitted to Globecom’2015


#4: M a n y u se c a ses , s in g l e 5G sy s t em en d o f “o n e-f it s -a l l ”?

› Simplicity was one of the key successes in LTE › Future-proofness is a very important requirement for early 5G releases

› Flexibility: potential variants per service within the same RAN – The RAN should support the concept of network slicing (management isolation) – Efficient usage of operator’s assets such as equipment and spectrum


› New aspects of the 5G architecture drive new self-configuration and self-optimization challenges

› Few examples of potential problems for self-configuration/optimization functions – Integration of AI variants per carrier frequency – Integration of NX and LTE at the RAN level – Energy efficiency tuning tradeoff of EE vs. agile system access and mobility – CN trends such as NFV/SDN flexibility means headaches to network management – Network slicing and QoS observability

Wh a t a b o u t SON in 5G?


›Network management understanding is extremely important to bring sanity to the research community working with future network architecture

Req u es t t o t h e n et w o r k m a n a g em en t c o m m u n it y


Documents

5G Architecture - Semafour Workshop