November 2005 doc IEEE 802 15 0697 004

November 2005 doc. : IEEE 802. 15− 0697− 004 a Project: IEEE P 802. 15 Working Group for Wireless Personal Area Networks (WPANs) Submission Title: [Preamble length and packet efficiency for TG 4 a] Date Submitted: [16 -Nov-2005] Source: [Laurent Ouvry] Company [CEA-Leti] Address [17 rue des Martyrs 38054 Grenoble] Voice: [+33 -4 -38 -38 -93 -88 ], FAX: [+ 33 -4 -38 -38 -51 -59 ], E−Mail: [laurent. ouvry@cea. fr] Re: [802. 15. 4 a. ] Abstract: [Show the resulting “packet efficiency” for different options of bit rates, preamble lengths, packet length, PRF and propose a short preamble length] Purpose: [To promote discussion in 802. 15. 4 a. ] Notice: This document has been prepared to assist the IEEE P 802. 15. It is offered as a basis for 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 P 802. 15. Submission 1 L. Ouvry — CEA-Leti

November 2005 doc. : IEEE 802. 15− 0697− 004 a Objective • Determine impact of : – – Preamble length PSDU length Bit rate Mean PRF on “packet efficiency” • Propose a shorter preamble length value adapted to higher bit rates communications Submission 2 L. Ouvry — CEA-Leti

November 2005 doc. : IEEE 802. 15− 0697− 004 a Assumptions • « Packet efficiency » definition there is : PSDU length / (PSDU length + Preamble length) Preamble Header Payload (PSDU) • This is an upper bound value – PHR length is set to 0 • FEC is taken into account (PSDU length calculated with PD-SAP bit rates) Submission 3 L. Ouvry — CEA-Leti

November 2005 doc. : IEEE 802. 15− 0697− 004 a Mean PRF 15. 875 MHz, PSDU 32 octets Acceptable Too low In black : highest values In red : proposal Submission 4 L. Ouvry — CEA-Leti

November 2005 doc. : IEEE 802. 15− 0697− 004 a Mean PRF 3. 96875 MHz, PSDU 127 octets Acceptable Too low In black : highest values In red : proposal Submission 5 L. Ouvry — CEA-Leti

November 2005 doc. : IEEE 802. 15− 0697− 004 a Mean PRF 15. 875 MHz, PSDU 127 octets Very Good Still Too low Here is the proposal In black : highest values In red : proposal Submission As a comparison, 802. 15. 4 -2003 efficiency is > 95% with the maximum PSDU length 6 L. Ouvry — CEA-Leti

November 2005 doc. : IEEE 802. 15− 0697− 004 a Conclusions • With the existing preamble length, the packet efficiency is not satisfactory, especially for : – For optional higher bit rates even with the longest packets – For low PRF with medium packet size at mandatory bit rate • The existing preamble lengths are 64, 256, 1024, 4096 expressed in code duration • The proposed fifth preamble length is 16 code durations (resp 16 us and 64 us with 16 and 4 MHz PRF) • This proposal is also good to reduce duty cycle Submission 7 L. Ouvry — CEA-Leti