IR-UWB Link Budget Analysis Comparison with NB Signaling
Explore the link budget analysis and comparison between IR-UWB, BT LE, and 15.4 OQPSK signaling schemes. Discuss the efficiency of NB signaling compared to IR-UWB signaling for wireless personal area networks. This document delves into interference mitigation techniques, proposed solutions for enhancing link budget, and technologies of interest for performing the link budget analysis.
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July 2021 Project: IEEE P802.15 Working Group for Wireless Personal Area Networks (WPANs) doc.: < 15-21-0394-00-04ab> Submission Title: IR-UWB link budget analysis and how it compares with NB signaling Date Submitted: July 2021 Source: Koorosh Akhavan (Qualcomm Inc.) Address: 5775 Morehouse Drive San Diego, CA 92121 USA E-Mail: kka200@gmail.com Abstract: Go over link budget analysis and comparison between IR-UWB, BT LE and 15.4 OQPSK Purpose: To start a discussion whether NB signaling is more efficient that IR-UWB signaling. Notice: discussion and is not binding on the contributing individual(s) or organization(s). The material in this document is subject to change in form and content after further study. The contributor(s) reserve(s) the right to add, amend or withdraw material contained herein. Release: The contributor acknowledges and accepts that this contribution becomes the property of IEEE and may be made publicly available by P802.15. This document has been prepared to assist the IEEE P802.15. It is offered as a basis for Slide 1 Koorosh Akhavan (Qualcomm Inc.) Link budget
July 2021 doc.: < 15-21-0394-00-04ab> PAR Objective Safeguards so that the high throughput data use cases will not cause significant disruption to low duty-cycle ranging use cases Interference mitigation techniques to support higher density and higher traffic use cases Other coexistence improvement Proposed Solution (how addressed) UWB traffic can be reduced by offloading data to NB Backward compatibility with enhanced ranging capable devices (ERDEVs) Improved link budget and/or reduced air-time Offloading status signaling to NB will improve LB and UWB airtime by focusing UWB energies towards channel sounding Propose to look for spectral regions allowing narrowband operation close to UWB bands Additional channels and operating frequencies Improvements to accuracy / precision / reliability and interoperability for high-integrity ranging Reduced complexity and power consumption Prospect for antenna sharing between NB and UWB; efficient use of NB vs UWB for their respective strengths Link budget analysis for IR-UWB and how it compares with NB signaling schemes like BT-LE or 15.4-OQPSK Can build such mechanisms on NB subsystem Hybrid operation with narrowband signaling to assist UWB Enhanced native discovery and connection setup mechanisms Sensing capabilities to support presence detection and environment mapping Low-power low-latency streaming Higher data-rate streaming allowing at least 50 Mbit/s of throughput Support for peer-to-peer, peer-to-multi-peer, and station-to- infrastructure protocols Infrastructure synchronization mechanisms These mechanisms could benefit from NB based signaling Slide 2 Koorosh Akhavan (Qualcomm Inc.) Link budget
July 2021 doc.: < 15-21-0394-00-04ab> Technologies of interest We would like to perform a link budget analysis for the following technologies Technology ?(MHz) ?? (Mb/s) 6.8 (0.85 ) IR-UWB, BPRF mode Bluetooth Low Energy (BLE) 15.4 OQPSK 500 1 1 2 0.25 The 0.85 Mb/s only applies to the BPRF header. Here ? is bandwidth and ?? is data rate Slide 3 Koorosh Akhavan (Qualcomm Inc.) Link budget
July 2021 doc.: < 15-21-0394-00-04ab> PER as a function of ??/?0 QPSK-like signal constellation for all. Thus, same PER formula for all. ?2?? ?0 PER ?? ?: Num bits per packet ?: Coding gain Slide 4 Koorosh Akhavan (Qualcomm Inc.) Link budget
July 2021 doc.: < 15-21-0394-00-04ab> Required ??/?0 - uncoded Assume a 20-byte packet, i.e., ? = 160 At 1%PER we get: Technology IR-UWB BLE OQPSK ??/?0 [dB] 8.7 8.7 8.7 Slide 5 Koorosh Akhavan (Qualcomm Inc.) Link budget
July 2021 doc.: < 15-21-0394-00-04ab> Required ??/?0, FEC coded Coding gain can be obtained by simulation. Here are the results: Technology IR-UWB BLE OQPSK FEC scheme CL3 + RS No FEC (32,4) block code ? [dB] 5.6 0 2 Slide 6 Koorosh Akhavan (Qualcomm Inc.) Link budget
July 2021 doc.: < 15-21-0394-00-04ab> Required ??/?0, FEC coded This will give us the required ??/?0 for the FEC coded case Technology Uncoded ??/?0 [dB] 8.7 Coding gain ? [dB] FEC Coded ??/?0 [dB] 3.1 IR-UWB BLE OQPSK 5.6 8.7 0 8.7 8.7 2 6.7 Slide 7 Koorosh Akhavan (Qualcomm Inc.) Link budget
May 2021 doc.: < 15-21-0394-00-04ab> How good are those three schemes? Shannon capacity, AWGN BLE (??= 1 Mbps, ? = 1 MHz ) 8.7 dB 8.2 dB OQPSK (??= 0.25 Mbps, ? = 2 MHz ) 4.7 dB IR-UWB (??= 6.8 Mbps, ? = 500 MHz ) 4.7 dB IR-UWB, (??= 0.85 Mbps, ? = 500 MHz ) Refers to 1% PER performance (N=160 bits) Slide 8 Koorosh Akhavan (Qualcomm Inc) Link budget
July 2021 doc.: < 15-21-0394-00-04ab> Bits vs. chips After going through the process of FEC coding and/or spreading, bits are converted to modulation symbols (also called chips when there is spreading) Let ?? be the modulation symbol rate. Since shaping occurs at the symbol level we can write ? = ?? Slide 9 Koorosh Akhavan (Qualcomm Inc.) Link budget
July 2021 doc.: < 15-21-0394-00-04ab> From ??/?0 to SNR Let s now calculate the SNR at sensitivity ? SNR =? ?=???? ?0?=???? =?? ?0 ?? ?? ?0?? Remember received signal power ? can be expressed as ? = ????= ????= Slide 10 Koorosh Akhavan (Qualcomm Inc.) Link budget
July 2021 doc.: < 15-21-0394-00-04ab> Required SNR Here are the SNR values at sensitivity (i.e., 1% PER for a 20-byte packet) Technology IR-UWB BLE OQPSK ??/?0[dB] 3.1 ??/?s[dB] 18.7 ( 27.7) SNR [dB] 15.6 ( 24.6) 8.7 0 8.7 6.7 9 2.3 When there is no coding or spreading as in the case for BLE, ??= ?? Slide 11 Koorosh Akhavan (Qualcomm Inc.) Link budget
July 2021 doc.: < 15-21-0394-00-04ab> Receiver Sensitivity To calculate receiver sensitivity ? we write ? dBm = SNR dB + ?0[dBm/Hz] + ? dB Hz + NF dB Here ?0= 174 dBm/Hz. Also, we ignore the NF Technology IR-UWB BT LE 15.4 OQPSK ??? [dB] ? [MHz] ? [dBm] 15.6 ( 24.6) 500 102.6/ 111.6 +8.7 1 105.3 2.3 2 113.3 Slide 12 Koorosh Akhavan (Qualcomm Inc.) Link budget
July 2021 doc.: < 15-21-0394-00-04ab> Path loss and effect of carrier frequency Recall 2 ?? ?? ? = 4?? We calculate the pathloss, ??, at ? = 30? Technology IR-UWB BLE OQPSK ?? [GHz] 8.0 ?? [dB] 80 2.4 70 2.4 70 * IR-UWB channel 9 Slide 13 Koorosh Akhavan (Qualcomm Inc.) Link budget
May 2021 doc.: < 15-21-0394-00-04ab> Link margin so far At this point the Link Margin is LM [dB] = ??[dB] ?[dB] ??[dB] Technology IR-UWB BLE OQPSK ?? [dBm] 14.3 +10 +10 ? [dBm] LM [dB] 102.6/ 111.6 8.3/17.3 105.3 45.3 113.3 53.3 * For BLE and OQPSK, the Tx power can go up to +20 dBm Slide 14 Koorosh Akhavan (Qualcomm Inc.) Link budget
July 2021 doc.: < 15-21-0394-00-04ab> Effect of fading Large-scale shadow fading Can we assume similar shadow fading effect on all signaling schemes? Small-scale multipath fading There is something important to be said about the effect of multipath Slide 15 Koorosh Akhavan (Qualcomm Inc.) Link budget
July 2021 doc.: < 15-21-0394-00-04ab> NB transmission In NB transmission there is significant overlap between received pulses giving rise to NB fading channel ?1 ?2 ? ? ?3 ??? = ??? = ??(?)cos ??? + ?? ?3 ?1 ?2 0 ? Received via the 1st path ?1??(? ?1)cos ??? + ??1 ? Received via the 2nd path ?2??(? ?2)cos ??? + ??2 ? Received via the 3rd path ?3??(? ?3)cos ??? + ??3 ? Slide 16 Koorosh Akhavan (Qualcomm Inc.) Link budget
July 2021 doc.: < 15-21-0394-00-04ab> Multipath is not necessarily bad NB systems don t like multipath 25-35 dB narrowband fading margin is usually assumed UWB systems love multipath The resolvable signals from different paths can be coherently combined by the Rake receiver. Slide 17 Koorosh Akhavan (Qualcomm Inc.) Link budget
July 2021 doc.: < 15-21-0394-00-04ab> UWB transmission In ultrawideband transmission, there is very little overlap between pulses arriving from different paths frequency selective fading ?1 ?2 ? ? ?3 ??? = ??? = ??(?)cos ??? + ?? 0 ? ?1??(? ?1)cos ??? + ??1 Received via the 1st path (DP) ? ?2??(? ?2)cos ??? + ??2 Received via the 2nd path ? ?3??(? ?3)cos ??? + ??3 Received via the 3rd path ? Slide 18 Koorosh Akhavan (Qualcomm Inc.) Link budget
July 2021 doc.: < 15-21-0394-00-04ab> Relative Link margin Add effect of multipath Technology Start LM [dB] Multipath fading effect [dB] +9 (Rake combining) 30 (fading margin) 30 (fading margin) End LM [dB] IR-UWB BLE OQPSK 8.3/17.3 +17.3/+26.3 45.3 15.3 53.3 +23.3 Does NB systems provide a better link than IR-UWB? Can t make a conclusive decision. Slide 19 Koorosh Akhavan (Qualcomm Inc.) Link budget
May 2021 doc.: < 15-21-0394-00-04ab> Thank you Slide 20 Koorosh Akhavan (Qualcomm Inc.) Link budget
