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[70.114.247.242]) by smtp.googlemail.com with ESMTPSA id 6-20020a544186000000b003af5f6e40d7sm1945180oiy.15.2023.10.24.07.26.07 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Tue, 24 Oct 2023 07:26:07 -0700 (PDT) Message-ID: <3d2c3d76-e08c-4d71-8a72-7193dd51cbfc@gmail.com> Date: Tue, 24 Oct 2023 09:26:06 -0500 Precedence: bulk X-Mailing-List: iwd@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: Is the data rate estimation for 5GHz channels overly pessimistic? Content-Language: en-US To: James Prestwood , Simonas Kazlauskas Cc: iwd@lists.linux.dev References: <5780e1b2-8956-46bb-8116-b513cc564cea@gmail.com> <5ff58310-c5ee-4694-821a-0c802cdedb89@gmail.com> <05aedfe6-82ad-4e41-a9fa-e9f8a5619947@gmail.com> <30b6dad4-64b2-41ca-8712-053cb1396eaf@gmail.com> <29094eca-dcf8-4234-8afc-13d37db8450c@gmail.com> <9e12bf94-aa83-4fe6-b045-8dab45b264ae@gmail.com> From: Denis Kenzior In-Reply-To: <9e12bf94-aa83-4fe6-b045-8dab45b264ae@gmail.com> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 8bit Hi James, On 10/24/23 07:32, James Prestwood wrote: > Hi Denis/Simonas, > >> >> Now the question is, how do we make sure iwd is estimating the HE rate if >> available?  Also, how do we tweak the estimation logic with sensitivity >> numbers (obtained from a spec sheet, or through experimentation) for specific >> hardware being used. > > Trying to catalog different hardware performance and act on it for ranking is an > impossible task :) We can actually have our own hwdb of sorts for this. Hardware sensitivity is a differentiator (think marketing), so should be fairly easy to find. Also, it doesn't have to be absolutely perfect, just reflect the hw capability a bit more closely. > > The only simple solution I can think of would be to add a user-option for some > threshold RSSI in the rate calculation. If set and the RSSI is below the lowest > of ht_vht_he_base_rssi just use the last index (-82) (and maybe force a 20MHz > channel width?). This would at least let the rate logic return _something_, > albeit maybe not accurate. But again, those RSSI thresholds were sorta made up > anyways :) They are not made up, they're direct from 802.11. But again, they're the _minimum_ specified sensitivity. Hardware typically does better. > > So you could set: > [Rank].LowSignalRateThreshold=-90 > > Any RSSI between -82 and -90 would use -82 for the rank calculation. No idea how > this would play out in practice, but its at least simple and not tied to any > given hardware. No, I was more thinking about: /* Added to the rssi value prior to looking up in the ht_vht_he_base_rssi */ SensitivityFudgeFactor=4 /* Width penalty */ SensitivityWidthPenalty=0 (3 today) /* NSS penalty */ SensitivityNSSPenalty=3 /* Same as SensitivityFudgeFactor, but for HE */ SensitivityHEFudgeFactor=10 Regards, -Denis