Security Level: Building versatile network upon new waveforms Chan Zhou, Malte Schellmann, Egon Schulz, Alexandros Kaloxylos Huawei Technologies Duesseldorf GmbH
5G networks: A complex ecosystem 5G service categories Massive Internet of Things Amazingly fast (Data-rate, delay) Great service in a crowd (Accessibility, crowds) Ultra-reliable communication Ultra-low-latency communication Ubiquitous communication Ubiquitous things communicating (Devices, coverage, energy & cost) High-mobility communication (V2X) life-line communication Broadcast-like communication Best experience follows you (Accessibility, mobility) Super real-time and reliable connections (Delay, reliability) Page 2
Requirements on 5G network Latency V2X, teleprotection, industrial automation and remote control applications require an endto-end latency less than several milliseconds LTE 100 ms Since CP-OFDM has high synchronicity requirements, LTE applies a Timing Advance (TA) procedure before the start of actual data transmission TA causes at least one up- and downlink transmission cycle for connection setup Preamble collision may occur, particularly in massive MTC scenario High mobility Applications for road traffic safety, high-speed train communication may have to support speeds up to 500kmh Doppler shift will largely impact the performance of the communication link. CP-OFDM may need to increase the subcarrier spacing in order to adapt to the high mobility scenario Page 3
Requirements on 5G network Coverage New 5G services require wireless access everywhere, even in critical environments. Coverage range can be increased if transmission power can be confined within narrow band Increasing transmission power in narrow sub-band will raise the out-of-band radiation Reliability 99.999% for e.g. V2X communication Critical in coverage holes or high mobility situation Energy-efficiency MTC requires long battery life to reduce the maintenance cost The active time of the devices should be as short as possible Page 4
Requirements on 5G network Support of low-cost devices Complex signal processes and control mechanisms cannot be implemented in low-cost devices Requirements on accurate synchronization have to be relaxed Signaling overhead in massive connectivity Massive IoT services will dramatically increase the signaling overhead The system may become extremely inefficient if the network is dominated by small-package traffic Flexibility Network should be flexible and have the ability to adapt to different services with particular requirements in different environments Also a variety of devices with special characteristics should be supported by the network Network resources, including the spectrum, have to be split and optimized for special services End-to-End network slicing Page 5
P-OFDM enabling waveform for a flexible air interface General description of multi-carrier systems : System design parameters = degrees of freedom - symbol period, - subcarrier spacing, - transmit pulse shape Additional degrees of freedom by adapting the pulse shape g tx Many waveform designs can be captured by the generalized function CP-OFDM: rectangular g tx Windowed OFDM: extended rectangular g tx with smoothened edges F-OFDM and UF-OFDM can be covered by applying additional subband-wise filtering Page 6
P-OFDM transceiver Implementing P-OFDM Efficient implementation of pulse shape filters by poly-phase network (PPN), plugged into transmission chain next to FFT In particular, all algorithms developed for OFDM can be reused, incl. MIMO schemes Complexity PPN based synthesizer and analyzer 10-30% higher complexity than CP-OFDM modulator / demodulator Binary Source RF to Baseband Sync. S/P PPN FFT Symbol FEC π S/P Pilots IFFT PPN P/S Mod. Chan. Est. Channel Chan. Equa. P/S Baseband to RF Symbol Demod. π -1 FEC -1 Binary Sink Page 7
End-to-end network slicing and adaptive airinterface Network resources are assigned to several network slices for special service groups. Each slice may apply different network functions and protocols Slice 1 configuration Slices are distinguished by their unique physical layer configurations including the g tx, T and F Different Numerology and Pulse shaping on different subbands Slice 2 configuration Page 8
TA-Free and grant free access P-OFDM using optimized Gaussian pulse shape is robust against large timing offsets TA procedure can be omitted TA-free asynchronous transmission + SDMA uplink request can be removed further Grant-free scheme significantly reduces the signaling overhead and delay Effectively reduces the energy consumption by reducing the active time Page 9
TA-Free and grant free access OFDM +orth. access OFDM +nonorth. Access P-OFDM +non-orth. Access Max. Connection number Connection Success Rat OFDM-LTE 59K 90% 53K Net Connection Number @3kmh 237K 88% 208K @12kmh 237K 63% 149.3K @30kmh 237K 36% 85.3K @3kmh 237K 90% 213K @12kmh 237K 88% 208K @30kmh 237K 80% 194K Random access at different velocity BLER for a single user with timing offsets (asynchronous scenario) Blue: P-OFDM with optimized pulse shape Red: CP-OFDM grant-free scheme based on optimized pulse shape exhibits much more robust performance Page 10
High mobility and vehicle communication Sensor Range V2V Vehicle-to-Vehicle Communication V2I Vehicle-to-Infrastructure Communication V2B Vehicle-to-Backend Communication Bi-Directional Communication System bandwidth 10 MHz Duplex TDD Subcarrier spacing 60 KHz TF 1.25 Antenna configuration 2 or 4 Tx at BS 2 Rx at UE PRB allocation 15 PRBs to one UE MIMO mode Full rank open loop-mimo Channel estimation Real channel and noise estimation MCS LTE MCS 4, 9, 16, 25 Channel models 802.11p 250kmh Onway Hybrid ARQ Not modeled Receiver LMMSE or QRD-ML Reference signal LTE R-s DL CRS Pulse shaping OFDM (K=1): rectangular pulse P-OFDM (K=1):Orthogonalized Gaussian pulse BLER in high mobility scenario. Blue: P-OFDM, red: CP-OFDM 1~3dB SINR gain compared to CP-ODFM P-OFDM as promising technology in high mobility scenario Page 11
Spectrum shaping and out-of-band leakage P-OFDM has lower out-of-band leakage compared to CP-OFDM Only 1-2% overhead is required for the guard band to achieve an interference isolation of -50 db (CP-OFDM 10%) Supports in-band coexistence of different numerologies in one unified air interface Also facilitates the efficient implementation of a narrow band system relevant for the coverage enhancement K = 4 K 1 TF = 1.07 Guard Subc. 9 27 Overhead (comp. 0.7% 2% 20MHz) EVM for Edge Subc. -48.9 db -57.2 db EVM for Central Subc. -48.9 db -57.3 db TF = 1.25 Guard Subc. 7 14 Overhead (comp. 0.53% 1.05% 20MHz) EVM for Edge Subc. -56.8 db -55.8 db EVM for Central Subc. -56.8 db -55.8 db Page 12
Conclusions CP-OFDM is not always the best solution for the air-interface of future mobile radio networks In many key scenarios for 5G, i.e. massive IoT and high mobility communication, optimized pulse shapes can provide much better performance P-OFDM is proposed as the generalized implementation of the adaptive air-interface End-to-end network slicing can be build on the P-OFDM based adaptive air-interface reducing the required guard bands between PHY configurations of different network slices supporting the implementation of different waveforms and numerologies on one platform Page 13
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