From owner-freebsd-wireless@FreeBSD.ORG Mon Feb 18 21:28:41 2013 Return-Path: Delivered-To: freebsd-wireless@freebsd.org Received: from mx1.freebsd.org (mx1.FreeBSD.org [8.8.178.115]) by hub.freebsd.org (Postfix) with ESMTP id 1CE9CE7C; Mon, 18 Feb 2013 21:28:41 +0000 (UTC) (envelope-from adrian.chadd@gmail.com) Received: from mail-we0-x22b.google.com (mail-we0-x22b.google.com [IPv6:2a00:1450:400c:c03::22b]) by mx1.freebsd.org (Postfix) with ESMTP id 8BDD48A2; Mon, 18 Feb 2013 21:28:40 +0000 (UTC) Received: by mail-we0-f171.google.com with SMTP id u54so4999040wey.2 for ; Mon, 18 Feb 2013 13:28:39 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20120113; h=mime-version:x-received:sender:in-reply-to:references:date :x-google-sender-auth:message-id:subject:from:to:cc:content-type; bh=UsrifQAl1xF1LBGERtjtMIEqqGym930N1vg+frf2hrI=; b=vgF9H6XBxkMirKWnKOxqOJ4ITygY9qYmGd2xQFSnQAIGAqJDWYgUT/n4TtTsFqCkz2 NlGtGxPNCa7szJRzmOnhabGTiqSZE1L7Jkw4pdCVLADhMwJpP4IHyhZH3AuRyPaio05j eGi7iTA/S7t/cvQfXlsQ7tGflEBkkZMtCQxWBr2FUGe52ifKR+0SGhOBYyRzT7KK/xyJ iaRjFLgnIsXt3TDeY/hVW7OBOFhG3FYGBDEBOMWU23mxyP7L7eldthVE7cQmDzPioRjZ fMLqtA6TA1eARJ5Z0QYQSJSpTArq9d5BszToFLOZwdMK9lxCTZyk0BHeNRyfvT+y2Z0a UE3w== MIME-Version: 1.0 X-Received: by 10.180.84.165 with SMTP id a5mr23275696wiz.6.1361222919799; Mon, 18 Feb 2013 13:28:39 -0800 (PST) Sender: adrian.chadd@gmail.com Received: by 10.216.236.88 with HTTP; Mon, 18 Feb 2013 13:28:39 -0800 (PST) In-Reply-To: References: Date: Mon, 18 Feb 2013 13:28:39 -0800 X-Google-Sender-Auth: RjmfwrzQ8zaK0hYP4H9kIIrKgtI Message-ID: Subject: Re: WiFi TDMA AR7161, results and moving forward From: Adrian Chadd To: Mukunda Haveri Content-Type: text/plain; charset=ISO-8859-1 Cc: freebsd-wireless@freebsd.org, freebsd-mips@freebsd.org X-BeenThere: freebsd-wireless@freebsd.org X-Mailman-Version: 2.1.14 Precedence: list List-Id: "Discussions of 802.11 stack, tools device driver development." List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Mon, 18 Feb 2013 21:28:41 -0000 On 18 February 2013 03:31, Mukunda Haveri wrote: > > Thanks to Adrian's WiFi scripts, we were able to get the TDMA working on the > Compex-AR7161 board. The results were surprising; we are able to do, close > to 100 mbps one way iperf tests and 40 mbps bidirectional Iperf in non-TDMA > mode. We were able to achieve this, only after disabling all the debug > options in the kernel. Porting the U-Boot to the Compex-boards did take lot > of effort, but not the "FreeBsd". Many thanks to all the "scientists" who > made this possible. Nice! Which wireless cards are you using? > Moving forward, it is observed that the TDMA throughput peaks at 9 mbps and > refuses to move beyond. After reducing the slot duration to 1 ms, the > throughput increased to around 12 mbps. I was expecting the TDMA to yield a > better throughput because of collision-less scheme. I would like to > understand if our observation is expected or if there's some inherent > limitation within the TDMA controller. > > It will be good to have some feedback from TDMers with similar experience or > better. Right now the TDMA code doesn't implement MCS rates or TX aggregation. Thus you're not going to get 11n like throughput. The first thing to implement is allowing for MCS rates (non-aggregation) and make sure all the packet duration calculations are being done "right". After that, we need to implement delayed blockack support in net80211 and the ath driver. That requires the stack to support handling BA requests/responses and ath(4) to mark all frame descriptors in a delayed-BA TID to be no-ack. Once that's done, we can tie it all together to make it work over TDMA. :-) Thanks, Adrian