Differences

This shows you the differences between two versions of the page.

--- networking:wireless_topic:wi-fi_standards:wi-fi_4-8 [2025/07/16 17:47] – aperez
+++ networking:wireless_topic:wi-fi_standards:wi-fi_4-8 [2026/03/25 03:00] (current) – aperez
@@ Line 177: / Line 177: @@
 {{ :networking:wireless_topic:wi-fi_6:mcs-table-he-ofdm-3ss_orig.png?1000 |}}
+----
+----
+{{ :networking:wireless_topic:wi-fi_standards:noise_floor.png?600 |}}
+{{ :networking:wireless_topic:wi-fi_standards:ap.png?600 |}}
+<code bash>
+SNR = RSSI – Noise
+SNR = (–75) – (–81)
+SNR = 6 dB
+</code>
+====== Wi-Fi RF Metrics Guide (RSSI, Noise, SNR) ======
+===== What Do These Acronyms Mean? =====
+^ Acronym ^ Full Name ^ What It Measures ^
+| RSSI | Received Signal Strength Indicator | How strong the Wi-Fi signal from the AP is when it reaches the client |
+| Noise | Noise Floor | The amount of background radio interference on the channel |
+| SNR | Signal-to-Noise Ratio | How much stronger the signal is compared to the noise (true link quality) |
+----
+===== RSSI — Received Signal Strength Indicator =====
+^ RSSI (dBm) ^ Signal Quality ^ Technical Meaning ^ User Experience Impact ^
+| -30 to -50 | Excellent | Very strong signal, client is close to AP | Maximum speed and stability |
+| -51 to -60 | Very Good | Strong signal, high modulation possible | HD video, VoIP, fast transfers |
+| -61 to -67 | Good | Adequate signal for most applications | Stable browsing and video |
+| -68 to -72 | Fair | Signal getting weak, MCS begins to drop | Possible speed reductions |
+| -73 to -80 | Poor | Weak signal, retransmissions increase | Video buffering, VoIP issues |
+| < -80 | Very Poor | Signal too weak for reliable link | Frequent disconnections |
+**Interpretation:**
+RSSI tells you **how strong the AP signal is at the client**.
+More negative = weaker signal.
+----
+===== Noise Floor =====
+^ Noise (dBm) ^ Interference Level ^ Technical Meaning ^ Network Impact ^
+| -95 to -100 | Excellent | Channel is very clean | Maximum possible performance |
+| -90 to -94 | Very Good | Low interference | Stable operation |
+| -85 to -89 | Acceptable | Moderate interference present | Reduced top speed |
+| -80 to -84 | High | Significant interference | Retransmissions, lower MCS |
+| > -80 | Very High | Very noisy channel | Low throughput, high latency |
+**Interpretation:**
+Noise shows **how much interference exists on the channel**.
+Closer to zero = worse (more noise).
+----
+===== SNR — Signal-to-Noise Ratio =====
+^ SNR (dB) ^ Link Quality ^ Technical Meaning ^ User Experience Impact ^
+| > 40 | Excellent | Signal is much stronger than noise | Maximum throughput and stability |
+| 25 – 40 | Good | Good signal margin | HD video and VoIP stable |
+| 15 – 24 | Fair | Limited margin, medium modulation | Reduced speeds |
+| 10 – 14 | Poor | Small margin, frequent errors | Buffering and latency spikes |
+| < 10 | Very Poor | Signal nearly equal to noise | Unstable or dropped connection |
+**Interpretation:**
+SNR is the **most important indicator of real link quality**.
+Formula:
+SNR = RSSI – Noise
+Example:
+RSSI = -70 dBm
+Noise = -90 dBm
+SNR = 20 dB → Fair link quality
+----
+===== Support Troubleshooting Logic =====
+^ Situation ^ Likely Problem ^
+| Good RSSI + Good Noise = Good SNR | Healthy connection |
+| Good RSSI + Bad Noise = Low SNR | Interference issue |
+| Bad RSSI + Good Noise = Low SNR | Coverage issue |
+| Bad RSSI + Bad Noise | Coverage and interference problem |
+----
+===== Quick Field Reference =====
+| Metric | Main Question It Answers |
+| RSSI | How strong is the signal from the AP? |
+| Noise | How much interference is on the channel? |
+| SNR | How usable is the connection really? |
+===========================================
+----
+----
 **Example: Aruba 650 Series Wi-Fi 6E APs**
@@ Line 273: / Line 391: @@
 {{ :networking:wireless_topic:unlicensed-spectrum-and-channel-allocations_6-ghz.png?1000 |}}
+{{ :networking:wireless_topic:wi-fi_standards:the-5.9ghz-portion-of-5ghz-wi-fi-6-band.jpg?600 |}}
+**La paradoja de alta densidad:**
+  Con 40/80 MHz tienes canales más anchos pero solo 9 canales disponibles → 8.7 APs compitiendo por el mismo espacio de radio → contención masiva → los APs pasan más tiempo esperando turno que transmitiendo → throughput real de 12 Mbps.
+  Con 20 MHz tienes canales más angostos pero 25 canales disponibles → 3.1 APs por canal → mucho menos contención →    cada AP transmite libremente → throughput real sube a 40-60 Mbps.
+   La tasa PHY (lo que negocia la NIC) baja de 300 Mbps a 144 Mbps — eso es lo que ves en la asociación. Pero la   tasa real que llega al usuario sube, porque el canal está disponible para transmitir en lugar de estar bloqueado    por interferencia co-canal.
+  La analogía simple: prefiero una autopista de 2 carriles sin tráfico que una de 4 carriles con 9 carros por carril frenando constantemente.
 **The Industrial, Scientific, and Medical (ISM)** frequency bands are designated radio frequency bands as defined by the ITU Radio Regulations. These frequency bands were set aside for RF use for purposes other than telecommunications.
@@ Line 685: / Line 820: @@
 {{pdfjs 46em >:networking:wireless_topic:wi-fi_6:ap_90_4c_81_c1_bf_2a_analysis.pdf}}
+----
+----
+{{ :networking:wireless_topic:wi-fi_standards:promethean_analisis_en.pdf |Executive Summary with Visual Evidence
+Wi-Fi Performance at 5 GHz (20/40 MHz)}}
+{{pdfjs 46em >:networking:wireless_topic:wi-fi_standards:promethean_analisis_en.pdf}}
+{{ :networking:wireless_topic:wi-fi_standards:promethean_analisis_sp.pdf |Síntesis Ejecutiva con Evidencia Gráfica
+Rendimiento Wi-Fi 5 GHz (20/40 MHz)}}
+{{pdfjs 46em >:networking:wireless_topic:wi-fi_standards:promethean_analisis_sp.pdf}}
+----
+----
+**{{ :networking:wireless_topic:wi-fi_standards:the-history-and-future-of-wi-fi_po_en_3609-6206-82_v0300.pdf |The-history-and-future-of-wi-fi}}**
+{{pdfjs 46em >:networking:wireless_topic:wi-fi_standards:the-history-and-future-of-wi-fi_po_en_3609-6206-82_v0300.pdf}}
 ----
 ----