On the Role of Experimental Research in the Evolution of Mobile Networks

Transcription

1 On the Role of Experimental Research in the Evolution of Mobile Networks Mahesh K. Marina Joint work with Mohamed Kassem, Navid Nikaein, Saravana Manickam, Alex Dawson, Xenofon Foukas and Cengis Hassan

2 Why Experiment? Some common (but non-exhaustive) list of reasons Comparative evaluation against state of the art approaches Determine sensitivity to various system parameter settings Assess system scalability Identify (un)desirable interactions with other system components Controlled testing of prototype implementations Real world validation prior to actual deployment Field experimentation to benchmark performance in typical usage scenarios Understand behavior of operational networks Measure end-user experience of network service they subscribed to Characterization of external influencing factors (traffic, channel, ) For hands-on learning and teaching

3 Different Generations of Mobile Networks 1G (e.g., AMPS) 2G (e.g., GSM, cdmaone) 2.5G (e.g., GPRS, EDGE) 3G (e.g., UMTS, cdma2000) 3.5G (e.g., HSPA) 4G (LTE, LTE- Advanced)

4 Different Generations of Mobile Networks 1G (e.g., AMPS) 2G (e.g., GSM, cdmaone) 2.5G (e.g., GPRS, EDGE) 3G (e.g., UMTS, cdma2000) 3.5G (e.g., HSPA) 4G (LTE, LTE- Advanced) Peak Data Rate (Kbps) GSM GPRS EDGE UMTS HSDPA HSPA LTE Rel-8 LTE-A Rel-10

5 Role of Experimental Research in the Evolution of Mobile Technologies Source: NSF Workshop on Network Research Testbeds: Workshop Report, November Phase 1 Research Community (academia/industry) Public-domain research CS experimental research (standardsagnostic, clean-slate) on wireless PHY using SDR platforms (e.g., fullduplex wireless). Majority of wireless papers at SIGCOMM, MobiCom and NSDI of this type. Phase? Research Community (academia) Public-domain research Phase 2 Industrial R&D (incl. third-party interoperability testers) Closed proprietary research Experimentation with commerical products or operational networks with limited flexibility (i.e., testing black boxes) Phase 3 Research Community (academia/industry) Public-domain research

6 Growing Mobile Data Traffic Source: Ericsson June 15 Annual Global Mobile Data Traffic (in Exabytes) Source: GSMA

7 Growing Mobile Data Traffic Annual Global Mobile Data Traffic (in Exabytes) Source: Ericsson June 15 Source: GSMA Some forecast 1000-fold increase in traffic by 2020 E.g., Qualcomm s 1000x Mobile Data Challenge ( Surely some truth in these forecasts, when we consider that: ~20 times more traffic from 4G connection than a non-4g connection 15% of mobile traffic from 4G connections even though they make up less than 1% of the connections

8 Cooper s Law Wireless capacity (measured in simultaneous conversations ) doubles every 2.5 years So we could say mobile networks have done well so far in terms of capacity scaling What does it take to continue this trend?

9 Growing Mobile Data Traffic Source: Ericsson June 15 Growth can continue so long as cost of meeting the demand remains the same There in lies the challenge

10 Infrastructure Cost [Zander-MCOM 13] Capacity Cell Size Where: C iiiii = C BB N BB = C BB c A N uuuu R uuuu A sssssss C BS = base station cost N BS = number of base stations N user = number of users R user = average user data rate A service = service area W = spectrum bandwidth η = spectrum efficiency η W Spectrum Efficiency (physical layer technology) Spectrum

11 Three Knobs for Capacity Scaling Densification Spectrum Technology (Spectrum Efficiency) GSMA (in June 2015) estimated that MHz of additional (globally harmonized) spectrum below 6GHz needed for mobile broadband by 2020 to meet growing traffic demand

12 Spectrum of Spectrum Access Models Unlicensed (e.g., 2.4GHz) OSA: Opportunistic Spectrum Access (e.g., TV white spaces, 5GHz) LSA: Licensed Shared Access (e.g., GHz) Licensed (e.g., 2G/3G/4G cellular spectrum) Cost, Access Barrier, Allowed Power Levels, Interference Protection and QoS

13 Nature of Future Spectrum Below 6GHz We examined this question considering UK as a case study M. Kassem and M. K. Marina, Future Wireless Spectrum Below 6GHz: A UK Perspective to appear in Proceedings of 8 th IEEE Symposium on Dynamic Spectrum Access Networks (DySPAN 2015).

14 Nature of Future Spectrum Below 6GHz We examined this question considering UK as a case study Key finding: most (close to 80%) of the new spectrum will be shared M. Kassem and M. K. Marina, Future Wireless Spectrum Below 6GHz: A UK Perspective to appear in Proceedings of 8 th IEEE Symposium on Dynamic Spectrum Access Networks (DySPAN 2015).

15 Nature of Future Spectrum Below 6GHz We examined this question considering UK as a case study Key finding: most (close to 80%) of the new spectrum will be shared M. Kassem and M. K. Marina, Future Wireless Spectrum Below 6GHz: A UK Perspective to appear in Proceedings of 8 th IEEE Symposium on Dynamic Spectrum Access Networks (DySPAN 2015).

16 Nature of Future Spectrum Below 6GHz We examined this question considering UK as a case study Key finding: most (close to 80%) of the new spectrum will be shared, and also fragmented Distribution of New Spectrum Below 6GHz M. Kassem and M. K. Marina, Future Wireless Spectrum Below 6GHz: A UK Perspective to appear in Proceedings of 8 th IEEE Symposium on Dynamic Spectrum Access Networks (DySPAN 2015).

17 Spectrum Aggregation is the Key to making use of all available spectrum resources Carrier aggregation (CA) introduced in LTE-Advanced (3GPP Rel-10) is the enabler Three different types of CA 1. Intra-band contiguous 2. Intra-band non-contiguous 3. Inter-band non-contiguous Inter-band CA and CA beyond licensed spectrum (to span unlicensed and shared spectrum) will be important in future

18 Experimental Research on Carrier Aggregation in the Public Domain Even though standardized in early 2011, only 3 papers come up in search! One paper from NTT DOCOMO Labs in 2012 using commercial LTE-A transceiver Two papers focusing on very limited forms of CA and specific/niche use cases from Eurecom researchers, both using the OpenAirInterface platform (more on it shortly) Autonomous component carrier selection, an elementary aspect of CA studied as part of EU SAMURAI project Using LTE in TV white spaces as part of EU SOLDER project But CA is now widely being supported, even in commodity smartphones (e.g., Samsung Galaxy Note 4) and wireless testing equipment (e.g., Sanjole s WaveJudge)

19 Evaluation Approaches Field Experimentation (realistic) E.g., CREW, FLEX Emulation Desirable attributes Flexibility in experimentation modes Open (instead of closed/commercial) Reference implementation of standards Simulation (controllable, scalable and low cost) E.g., LENA, LTE-Sim, SimuLTE

20 OpenAirInterface (OAI) Offers a flexible and open alternative to the two common extremes: LTE testbeds (based on commercial equipment) and simulators Created by Mobile Communications department at EURECOM OAI platform based on a PC hosted software radio frontend architecture Unique features: Open-source software implementation of 4G LTE (3GPP Rel. 10), spanning the full protocol stack of 3GPP standard With a SDR frontend, can be used in field experimentation mode indoor/outdoor Two built-in emulation modes seamlessly allows repeatable and scalable evaluation within the same execution environment 1. PHY Abstraction mode 2. Full PHY Layer mode

21 Implemented LTE Software in OAI Illustrated

22 Supported Software Radio Frontends ExpressMIMO2 USRP B210

23 OAI Usage Configurations 1. OAI UE OAI enb + OAI EPC 2. OAI UE OAI enb + Commercial EPC 3. OAI UE Commercial enb + OAI EPC 4. OAI UE Commercial enb + Commercial EPC 5. Commercial UE Commercial enb + OAI EPC 6. Commercial UE OAI enb + Commercial EPC 7. Commercial UE OAI enb + OAI EPC

24 Carrier Aggregation Support in OAI CA implemented to an extent but some key missing features such as: Cross-carrier scheduling in the PHY layer UE capability transfer procedure, SCell addition/reconfiguration/release and few measurement events at RRC layer Moreover, with USRPs only one component carrier supported Edinburgh role: Contributing towards complete CA implementation and testing Also in the midst of deploying a HetNet testbed with a mix of PC hosted USRP B210s, ExMIMO2s, smartphones and USB dongles

25 Two More Cases 1. Downlink/Uplink Decoupling (DUDe) 2. Software-defined mobile networks (SDMNs)

26 Downlink/Uplink Decoupling (DUDe) Conventional approach to user association: coupled user association UE associates with the same BS in uplink (UL) and downlink (DL) directions With shift towards dense HetNets, preference for general form of user association with downlink/uplink decoupling emerging UE can be associated with different BSs in UL and DL directions Benefits [Boccardi et al., 2015]: improved uplink SNR and data rate different/better load balancing in UL and DL allow more D2D transmissions

27 DUDe Implementation and Evaluation Can already be realized within the context of LTE/LTE-A specifications Three different realizations differing in deployment scenario and backhaul properties [Boccardi et al., 2015] 1. Centralized processing (aka C-RANs) 2. Shared Cell-ID 3. Dual Connectivity OAI for prototyping and comparing these three approaches

28 Software-Defined Mobile Networks (SDMNs) Applying SDN principles in mobile networks can: Reduce complexity, increase modularity, allow flexibility in management, promote innovation, Especially beneficial in the RAN Radio Resource Management Simplifies cooperative operations (CoMP, eicic etc) Improves utilization of resources Mobility Management Reduces signaling overhead Simplifies seamless handovers in Multi-RAT HetNets Traffic Management Simplifies control based on traffic type (M2M, H2H ) OAI platform allows quantifying these benefits vis-à-vis standard RAN

29 Other emerging mobile technologies/ideas that can benefit from experimentally driven research Cloud Radio Access Networks (C-RANs) Machine-to-machine (M2M) communication Ultra-Dense HetNets Device-to-device (D2D) communication Millimeter wave networks Massive MIMO Visible light communications N. Nikaein, M. K. Marina et al., OpenAirInterface: A Flexible Platform for 5G Research in ACM SIGCOMM Computer Communications Review (CCR), October 2014.

30 Summary Publicly accessible experimental studies by the research community have played a limited role in the evolution of mobile networks till date Carrier aggregation is a case in point Open and flexible platforms like OpenAirInterface are bringing about change Let s experiment our way towards 5G! Grow the community and bridge the fragmented communities