Return-Path: Message-ID: Date: Tue, 12 Dec 2006 21:52:32 -0800 From: "Uichin (Eugene) Lee" To: bluez-users@lists.sourceforge.net MIME-Version: 1.0 Subject: [Bluez-users] periodic inquiry mode. Reply-To: BlueZ users List-Id: BlueZ users List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Type: text/plain; charset="us-ascii" Sender: bluez-users-bounces@lists.sourceforge.net Errors-To: bluez-users-bounces@lists.sourceforge.net Hello, I need some more helps/comments with periodic inquiry mode. As Marcel told, I checked the D-Bus based API, which is assumed to be defined in HCID. I mainly want to use this for P2P applications, i.e., for content sharing/advertisement application, and thus minimizing peer discovery latency (or, symmetric discovery latency) is the key issue. It seems like the actual configuration in HCID is a bit absurd. It uses inquiry window length of 8, and min and max were set to 16 and 24 respectively; i.e., by multiplying 1.28s, they are 20.48s and 30.72s. We need to WAIT8*1.28=10.24s to get a response. It seems like nobody has been working on optimizing the periodic inquiry mode. I saw a number of papers, but they misunderstood the units of various parameters, and thus proposed their own schemes, which are yet another version of this "periodic inquiry mode." Some analysis work simplified the mode too much, thus failing to reflect the reality. (I tried, but it seems like it's non-trivial to exactly model the overall system). I'm actually working on optimizing the parameter configuration for "symmetric" peer discovery. What I found is that unless we're using Bluetooth v1.1, we need inquiry window size at most 2, and the min and max are set to [0, 2*1.28] (assuming that inquiry scan is adjusted accordingly). When I tested it with Bluetooth 2.0 (Broadcom chipset), the latency was less than 3 seconds, which is a pretty well match with simulation. Any comments on this? -- Uichin (Eugene) Lee Ph.D. Student UCLA CS Dept. ------------------------------------------------------------------------- Take Surveys. Earn Cash. Influence the Future of IT Join SourceForge.net's Techsay panel and you'll get the chance to share your opinions on IT & business topics through brief surveys - and earn cash http://www.techsay.com/default.php?page=join.php&p=sourceforge&CID=DEVDEV _______________________________________________ Bluez-users mailing list Bluez-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/bluez-users