From mboxrd@z Thu Jan 1 00:00:00 1970 From: =?UTF-8?Q?Javier_Fern=C3=A1ndez_Pastrana?= Date: Wed, 19 Oct 2016 09:33:31 +0200 Subject: [ath9k-devel] 802.11p - Switching Channel Message-ID: List-Id: MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit To: ath9k-devel@lists.ath9k.org Greetings everyone! I have been working in 802.11p for several months. I used the 802.11p CTU-IIG as a basis of all my work. I achieved to work in OCB mode as well as establish communication between different devices. But Now I would like to check it in a real environment, therefore it is compulsory changing between channels (from Control channel to Service channel and vice versa) , as it is said in ETSI ITS G5 standard. It means change one frequency to other, for example from 5900MHz(CCH) to 5880MHz (SCH1). I am able to change the channel through iw program *(ocb leave* and *ocb join*). The problem that I saw, is that when you change to one channel o other, you always lose the first packet (in the receiver station) since you changed the channel, the second packet is received correctly. Someone have an idea that shy is happening this? I want to explain the problem with an example 1: It is always a station sending packets in 5900 MHz, the packets are sent per 2 seconds. Then it is a receiver station that waits *1.5 second* to receive a packet, if not receive packets, then it leaves and joins the channel (the same frequency 5900MHz). Besides, if it receives a packet, the station reads it and then leaves and joins the channel too. I am always sending and receiving in the same channel, therefore I should receive all the packets because I give enough time to the receiver station to compute them. On the other hand, I made a second test, example 2: It is always sending packets in 5900 MHz and the packets are sent per 2 seconds. Now the receiver station waits *2.5 seconds*, and it changes the channel if it receives a packet or if it waits 2.5 seconds without receiving anything. In this case I give enough time to the receiver station to receive 2 packets without leaving and joining the channel, and curiously it is able to read the half of the packets. To sum up, it looks that the receiver station needs one packet to read the next one, maybe it is something relating with the station have to stablish the bitrate or the modulation before. Have someone work before with WLANp? Any idea? Suggestions are always welcome! Thank you very much! Javier. -------------- next part -------------- An HTML attachment was scrubbed... URL: http://lists.ath9k.org/pipermail/ath9k-devel/attachments/20161019/55888db8/attachment.htm