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Effect of Bandwidth and Sampling Rate on Performance

Effect of Bandwidth and Sampling Rate on Performance. Date: 2017-03-13. Authors:. Introduction. As shown in the PAR document [1], one of the objectives of 11ba is a low power consumption “ The WUR has an expected active receiver power consumption of less than one milliwatt ”

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Effect of Bandwidth and Sampling Rate on Performance

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  1. Effect of Bandwidth and Sampling Rate on Performance Date: 2017-03-13 Authors: Eunsung Park, LG Electronics

  2. Introduction • As shown in the PAR document [1], one of the objectives of 11ba is a low power consumption • “The WUR has an expected active receiver power consumption of less than one milliwatt” • In order to meet this goal, a low sampling rate (SR) at the receiver may be preferred • Another objective of 11ba is the same range as the primary connectivity radio [1] • “The WUR is a companion radio to the primary connectivity radio and meets the same range requirement as the primary connectivity radio” • In order to see whether the range requirement is met, we can simply use the PER performance although it is not an exact metric • A low SR may degrade a performance if the bandwidth (BW) used for the symbol computation is not chosen properly • Thus, it is important to verify the relation between the SR and the BW in terms of the performance • In this contribution, we investigate the performance according to the BW and the SR Eunsung Park, LG Electronics

  3. Simulation Assumption (1/2) • The conventional Wi-Fi transmitter is used for the OOK symbol computation as depicted in [2] • We consider various BWs such as 1MHz, 2MHz, 4MHz, 5MHz, 10MHz and 20MHz • These BWs use 3, 6, 13, 16, 32 and 64 subcarriers, respectively • In each BW, sequence is optimized in terms of the PAPR • WUR frame is composed of preamble and payload • Each symbol is 4us ON- or OFF- symbol • Preamble has 9 symbols • First 3 symbols are designed to conduct timing synchronization • Only the last symbol for the timing synchronization part is OFF-symbol and others are ON-symbols, i.e., the sequence for the preamble is {1 1 0 1 1 1 1 1 1} • Using all of the preamble symbols except for the last timing synchronization symbol (i.e., OFF-symbol), the received signal power is measured to set the threshold for decoding Eunsung Park, LG Electronics

  4. Simulation Assumption (2/2) • Payload consists of 48 symbols • PER for the payload will be shown • If 48 bits are set to the MAC address, PER is equivalent to the miss detection • At the receiver, raised cosine filter is applied to see only the desired signal within the BW used for the symbol computation and various SRs such as 1MHz, 2MHz, 4MHz, 5MHz, 10MHz and 20MHz are considered • WUR performs timing synchronization by the cross-correlation between the envelop of the received signal and the known timing synchronization sequence • Please see Appendix A for details • Phase noise is not considered • Simulation results for TGnD and UMi NLoS channels are presented • L-SIG performance is also shown • SNR is defined considering 20MHz Eunsung Park, LG Electronics

  5. PER for the BW according to the SR • As shown in the figures in this slide and in Appendix B, SRs lower than the BW lead to a performance degradation • To adopt a low SR in 11ba for a low power consumption, the BW should be also carefully selected by considering the SR BW = 4MHz Eunsung Park, LG Electronics

  6. PER for the SR according to the BW (1/2) SR = 4MHz SR = 2MHz Eunsung Park, LG Electronics

  7. PER for the SR according to the BW (2/2) • As shown in the figures in slide 6 and 7 and in Appendix C, for the case with the SR larger than or equal to 4MHz, the BW of 4MHz has the best performance and BWs of 1MHz, 2MHz and 5MHz have a comparable performance given the target PER of 10% • If we consider an extremely low SR, i.e., 1MHz, it seems that there is no possible candidate considering the target PER of 10% SR = 1MHz Eunsung Park, LG Electronics

  8. Conclusion • We presented PER performance by considering the SR and the BW to show the relation between them • We verified that the BW should be carefully determined by taking into account the performance which varies according to the SR • For the case with the SR equal to 4MHz, BWs of 1MHz or 4MHz are advisable assuming the target PER of 10% • In order to use the BW of 4MHz when an extremely low SR such as 1MHz or 2MHz is applied, it seems that a robust scheme (e.g. the symbol repetition type [3]) is needed Eunsung Park, LG Electronics

  9. Straw Poll #1 • Which bandwidth do you support to use in 11ba? • Less than or equal to 1MHz • 2MHz • 4MHz • Larger than or equal to 5MHz Eunsung Park, LG Electronics

  10. Straw Poll #2 • Which sampling rate do you prefer to use in 11ba by considering the power consumption and the PER performance? • Less than or equal to 1MHz • 2MHz • 4MHz • Larger than or equal to 5MHz Eunsung Park, LG Electronics

  11. References [1] IEEE 802.11-16/1045r9-0wur-a-par-proposal-wur-sg [2] IEEE 802.11-16/0341r0-LP-WUR (Low-Power Wake-Up Receiver) Follow-Up [3] IEEE 802.11-17/xxxxr0-00ba-various-symbol-types-for-wur [4] WCNC 2005, Low Power Synchronization for Wireless Sensor Network Modems Eunsung Park, LG Electronics

  12. Appendix Eunsung Park, LG Electronics

  13. Appendix A • Timing synchronization is performed by cross-correlation as in [4] • WUR only knows the transmitted sequence (antipodal sequence) conveyed in symbols for the timing synchronization part • e.g.) If the number of symbols for the timing synchronization part is 3, WUR knows the sequence for the timing synchronization of {1 1 -1} • The envelope of the received signal is correlated with the known sequence for timing recovery • To this end, WUR also adjusts the length of the known sequence considering SR • E.g.) If SR is 1MHz and the number of symbols for the timing synchronization part is 3, each symbol has 4 samples and the total length of the known sequence should be 12 • So, the known sequence is reformulated as {1 1 1 1 1 1 1 1 -1 -1 -1 -1} Eunsung Park, LG Electronics

  14. Appendix B (1/6) • PER for the BW according to the SR inthe TGnD channel BW = 20MHz BW = 10MHz Eunsung Park, LG Electronics

  15. Appendix B (2/6) • PER for the BW according to the SR inthe TGnD channel BW = 5MHz BW = 2MHz Eunsung Park, LG Electronics

  16. Appendix B (3/6) • PER for the BW according to the SR inthe TGnD channel BW = 1MHz Eunsung Park, LG Electronics

  17. Appendix B (4/6) • PER for the BW according to the SR inthe UMi NLoS channel BW = 20MHz BW = 10MHz Eunsung Park, LG Electronics

  18. Appendix B (5/6) • PER for the BW according to the SR inthe UMi NLoS channel BW = 5MHz BW = 4MHz Eunsung Park, LG Electronics

  19. Appendix B (6/6) • PER for the BW according to the SR inthe UMi NLoS channel BW = 2MHz BW = 1MHz Eunsung Park, LG Electronics

  20. Appendix C (1/5) • PER for the SR according to the BW inthe TGnD channel SR = 20MHz SR = 10MHz Eunsung Park, LG Electronics

  21. Appendix C (2/5) • PER for the SR according to the BW inthe TGnD channel SR = 5MHz Eunsung Park, LG Electronics

  22. Appendix C (3/5) • PER for the SR according to the BW inUMi NLoS channel SR = 20MHz SR = 10MHz Eunsung Park, LG Electronics

  23. Appendix C (4/5) • PER for the SR according to the BW inUMi NLoS channel SR = 5MHz SR = 4MHz Eunsung Park, LG Electronics

  24. Appendix C (5/5) • PER for the SR according to the BW inUMi NLoS channel SR = 2MHz SR = 1MHz Eunsung Park, LG Electronics

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