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Anatomy of an AP

  1. 1. #ATM16 The Anatomy of an AP Onno Harms, Product Management March, 2016 @ArubaNetworks |
  2. 2. 3#ATM16
  3. 3. #ATM16 The Anatomy of an AP Subject: Aruba AP-325 Dissect the 320 Series to get below the surface
  4. 4. 5#ATM16 Agenda 1. Introduction: Basic capabilities, vital stats, aging, life expectancy 2. Skin & bones: Housing, enclosure, mounting, plenum 3. Senses: External Interfaces 4. Internal Organs: Main Functional Blocks 5. Digestive tract and Circulation: Power input, consumption, efficiency, output 6. Brain: CPU, Memory and TPM 7. Guts: Ethernet, Wi-Fi radios 8. Sixth sense: BLE radio 9. Heart & Soul: Software
  5. 5. 6 Introduction Basic capabilities, vital stats, aging & life expectancy
  6. 6. 7#ATM16 Patient Introduction – Name: AP-325, part of the 320 Series family – Primary job description: Interface between the wired and wireless networking domains – Qualifications: Dual-radio 4x4 802.11ac MU-MIMO Access Point with two 1Gbps Ethernet ports – Differentiators: Highest performance, latest technology, immune to RF interference, highly secure (TPM module), location aware (BLE radio) – Age: 7 months (born August 2015), about 5 years in human terms – Total world population: Approaching 100k and growing rapidly, joining its 7M+ cousins – HPE Aruba Family: Sister AP-324 (external antennas), half-siblings IAP-324/325 (controller-less software load), many cousins (103 Series, 200/210/220 Series, 310/330 Series), further removed (and a little weird): outdoor, hospitality and branch platforms – Character: hard-working and serious, all about speed and efficiency, thrives in challenging environments, model-like features, tough but indoorsy type, proud member of the Aruba family
  7. 7. 8#ATM16 Basic physical exam of the AP-325 – Dimensions: 203mm x 203mm x 57mm, or 2.35liter (8” x 8” x 2.24”, 79oz) – Weight: 950g (2.1lb) – Range: from AP-103 at 300g (0.66lb) to AP-335 at 1150g (2.54lb) – Total number of components: about 1,900 parts – Temperature: – Thriving in 0C to +50C or +32F to +122F (typical operating range for the Enterprise AP race) – Skin temp can reach as high as +70C (+158F) but that’s perfectly normal when patient is busy in a stressful environment – Heart rate: 1.4GHz (dual core CPU). That’s 1,400,000,000 beats per second – Expecting 440,000,000,000,000,000 beats over its projected active lifetime (10 years) AP-103 AP-205 AP-215 AP-225 AP-325 AP-335 AP-315
  8. 8. 9#ATM16 Life expectancy and susceptibility to illnesses – As all electronic devices, AP-325 is subject to aging and typical component failure mechanisms – Failure rate is generally high when a product is first deployed (“infant mortality”) and when it is approaching the end of its useful life. In between, failure rate is modelled as a constant statistical parameter (defining MTBF) – This is often referred to as the “bathtub curve” – To avoid early failures from happening in the field, products go through “burn-in” in the factory – When failure rate starts to increase again, the product has reached the end of its useful life – The expected product life is often determined by the one component (or class of components) that first reaches the end of its useful life – All HPE Aruba access points are designed with a minimum useful life target of 10 years to support 5 years of active life followed by 5 years in retirement (support)
  9. 9. 10#ATM16 Life expectancy and susceptibility to illnesses – The flat portion of the bathtub curve determines the rate of failure of products deployed in the field – Component and product failure rate in the is expressed using “FIT” (Failures in Time): number of failures expected to happen in one billion hours of active operation (that’s 115,000 years) – It’s assumed to be a constant statistical parameter, meaning that if a product has a FIT of 1000 that product is expected to fail once every 115 years, but also that you should anticipate a failure every year when deploying 115 such products – The failure rate of a complex electronic product is simply the sum of the failure rate of all components. In general, a handful of components will dominate the failure rate of a product, even though there may be thousands of them – There are many models to predict failure rate, but for an accurate prediction, it’s important to account for the “stress” applied to each component (voltage, current, etc.) and the temperature it’s operating at – Mean Time Between Failure (MTBF) is the inverse of FIT: MTBF (hours) = 1,000,000,000 x 1/FIT – MTBF target for any Aruba AP is at least 500,000 hours (57 years) – Actual MTBF is well above that, and our actual failure or return rates indicate that “real” MTBF is much higher still (500 years based on a typical 0.2% annual failure rate)
  10. 10. 11#ATM16 Taking a first look inside – X-ray image of AP-325, courtesy of Philips Medical Systems – AP-325 is a sandwich of: – Front cover (plastic) – Sheet metal plate with antennas – Thermal pads (conductive, flexible, sticky) – Main printed circuit board, with components and metal shield on both sides – Radio boards (2x) with components and metal shields on both sides – More thermal pads – Rear cover (die-cast aluminum) – BLE antenna module* – Labels
  11. 11. 12#ATM16
  12. 12. 13 Skin and Bones Housing, enclosure, mounting, plenum
  13. 13. 14#ATM16
  14. 14. 15#ATM16
  15. 15. 16#ATM16 Enclosure or housing – Consists of just two parts: a plastic front cover and die-cast aluminum rear cover – Rear cover contains all parts, front cover screws to that assembly – Using “secure” TorX screws (regulatory requirement) – Enclosure us not just a “box”, but serving a variety of purposes: – Protection of internal components (elements, handling, FIPS) – Defining the look and feel of the product (neutral, unobtrusive, but can still be striking) – Strength and structure, mounting support – Heat sink – RF shielding – Enclosure is an integral part of the AP as a system. It’s not so easy to just “take the guts and put it in a different housing” – But we have some customers who do just that (for example, a European company integrates the IAP-225 in their system to provide in-flight Wi-Fi) – Painful and time-consuming, taking as much or more time then designing the AP from scratch
  16. 16. 17#ATM16
  17. 17. 18#ATM16 AP-325 front cover – Defines the look and feel, but there’s more – There are lots of things to consider when selecting the plastic material – Strength and durability (impact, thermal) – Color and finish / texture, initial and over time – RF transparency – Flammability – Banned substances (environment, health, RoHS, REACH) – Aesthetics: since not everybody may like the shiny finish, Aruba logo and/or white color, we do offer snap-on covers that are neutral and matte, and can easily be painted – RF transparency should still be considered though. Paint may contain metal or graphite. – Plenum rating (UL2043): rules concerning flammability and smoke/fumes in case of a fire, for equipment that can be deployed in the plenum (in our case that translates to above ceiling) – Plastics are a critical contributor for this – Restricts our material choices, adds cost – Much easier for devices with metal enclosures, but newer plastics can pass – Early versions of “plenum rated” plastic would discolor over time. There are some orange/brown AP-65 still out there
  18. 18. 19#ATM16
  19. 19. 20#ATM16
  20. 20. 21#ATM16
  21. 21. 22#ATM16 AP-325 rear cover 1. RF shielding: metal cover is integral part of overall RF and EMC design 2. Heat sink – Using metal and thermal pads, heat from many components is distributed to the metal back – Critical ones: CPU, Ethernet PHY, wireless chipset, power amplifiers. Some of these are cozy operating at +100C or higher (+212F) – Effectively spreading the heat and offering a large surface for heat to radiate from and transfer to air flow – Touch temperature – The AP rear cover is an effective heatsink, and its temperature can raise significantly above ambient temperature – But it’s perfectly normal and does not indicate any issue – Safety regulations are very clear: any user accessible metal surface cannot exceed +70C (+158F) – That gives us a max increase over worst-case ambient of 20 degrees (36F) – Some more about thermal testing – AP thermals are directly related to worst-case (conditions and operation) average (time) power consumption – Power consumption varies significantly between idle (beaconing) and worst-case. Can be up to 2x – It takes time for the AP to reach steady state (many minutes or even hours)
  22. 22. 23#ATM16
  23. 23. 24#ATM16 AP-325 rear cover 3. Mount support – Mount features on the rear cover include two screwed-in plastic parts (can’t create those in the die-casing process) – Supporting a variety of mount kits for different mount surfaces and orientations – Ceiling rail (many types), solid surface (wall, ceiling), attached to an existing wall-box, inside (third-part) enclosures, integrated into existing ceiling tiles – Earthquake testing – We subject these APs to a broad range of environmental tests – Where relevant, these tests are done with the AP mounted as intended, and exploring worst-case situations – Most of our mounts are made out of plastic, sometimes people worry about that..
  24. 24. 25#ATM16
  25. 25. 26 Senses External Interfaces
  26. 26. 27#ATM16 Network and POE power DC power USB Console port Reset button Kensington slot BLE radio antenna
  27. 27. 28#ATM16 Physical interfaces – Network and POE power (Ethernet) – AP-325 has two equivalent physical interfaces (RJ45 8-pin jacks). Fully interchangeable – Both are 100/1000Base-T capable (bidirectional speeds up to 1Gbps) – Ports can be LAGged in case there’s a concern that 1Gbps is not sufficient to support peak wireless throughput – Some future AP platforms will support higher speeds (2.5Gbps, 5Gbps and possibly even 10Gbps; Nbase-T, Smart Rate) – In reality it’s highly unlikely that there’s a real need for >1Gbps in most 802.11ac deployments – Both support POE (either/or, failover, not combined) – USB 2.0 Type A host jack – Can supply up to 1A/5W to attached device – Supports some cellular modems and HPE Aruba BLE beacon dongles. Mostly “reserved for future use” – Console port: RJ45 jack, RS232, default speed 9,600 baud – Debugging only – Do not confuse with Ethernet..
  28. 28. 29#ATM16 Physical interfaces – the simple stuff – DC Power: 12V, center-positive circular plug – Any compatible source can be used (12V +/- 5%, minimum 18.5W to 24.5W, physically compatible plug) – HPE Aruba model is AP-AC-12V30UN (accessory) – Reset: paperclip-hole push button – Reset to factory defaults when pressed during power-up – Toggle LED mode in normal use* – Kensington lock for physical security – LEDs – Default mode: convey basis status info, restrictions, errors – Optional: blink mode to help identify an AP – Optional: off mode if blinking lights are annoying – AP-325 has two tri-color LEDs (red/green/amber) – The physical LED lights are on the board; the front cover integrates some plastic parts to guide the light
  29. 29. 30#ATM16 Antennas - General – Antennas convert electrical into radiated RF energy, and vice-versa. Behavior is completely reciprocal for both directions (transmit, receive) – Reference antenna is the isotropical radiator, which radiates energy evenly in all directions (3D) and has zero loss (sphere) – Practical antennas focus energy in a desired direction and have 50%-70% efficiency. Antennas do not amplify the RF signal – The resulting 3D pattern will have a peak in a certain direction. The relative strength of this peak, when compared with the isotropical radiator, is known as antenna gain, expressed in dBi – Those patterns can get quite complex and “messy”, see next page for an example – Depending on the type and orientation of the antenna, the radiated RF energy pulsates in a particular direction (polarization), and antennas are “deaf” to signals pulsating in a direction perpendicular to that of the antenna – Polarization is typically vertical, horizontal or circular – A vertically polarized antenna does not pick up a horizontally polarized RF signal – Finally, for best MIMO performance, antenna patterns of the individual radio chains should generally be overlapping and omni-directional
  30. 30. 31#ATM16 Elevation (side) 3D pattern plot Sidelobes Backlobe Front Back Side Azimuth (top) Sector Antenna (Logarithmic View)
  31. 31. 32#ATM16 Antennas – AP-325 – AP-325 has a total of 9 built-in antennas: four for each 4x4 MIMO Wi-Fi radio, and one for the integrated BLE (Bluetooth Low Energy) radio – BLE radio is primarily used for locationing services (beacons) – All antennas are vertically polarized – Energy pulsating up&down when ceiling mounted – AP-325 antennas focus energy down, in a more or less omni-directional pattern around the AP, optimized for the typical ceiling mounted deployment – Creating a cone-shaped pattern – Remember: there are no abrupt transitions and energy is really transmitted in all directions – Amplified by reflections in a typical environment
  32. 32. 33#ATM16 Antennas – AP-325 – Larger structures are for 2.4GHz, smaller ones for 5GHz – Higher frequency = smaller structures – Spaced and oriented to minimize coupling and interference – Very similar patterns.
  33. 33. 34#ATM16 Antennas – AP-325
  34. 34. 35 Internal Organs Main Functional Blocks
  35. 35. 36#ATM16 AP-325 Building Blocks – Radios. AP-325 has two radios (2.4GHz/5GHz), each with four complete bi-directional chains (4x4) – Antennas (8) – Filters (some special ones to deal with interference from cellular systems) – Amplifiers (Tx/Rx), combined in two sets of four “front end modules” (FEM) – MAC/Baseband/Radio (integrated in two “wireless chipsets”) – Processing core – CPU, memory, TPM – Wired network interfaces: Ethernet. Separate PHY components, MAC/BB integrated in CPU – Power: DC, POE, lots of conversions and filters – Other stuff: USB, BLE, console, reset, clocks, timers, test interfaces, LEDs – Lots of shields and covers to contain RF energy – Minimize “self-interference”, avoid unwanted emissions and susceptibility to external interference – Filters do a similar job for electrical signals, but are much more selective
  36. 36. 37#ATM16 AP-325 Functional Block Diagram Flash NOR 4MB 512MB/ DDR3 12VDC-in Jack 32-bit Voltage Converters GPIOs SPIMemCtrl UART_1 Test interfaces Clocks and timers Reset Circuit RJ45 POE GE MAG EMI Filter TPM Serial Line driver Push button SW RJ45 Serial IPQ8064 2.4G-4x4 MAC/BB/ Radio QCA9990 PD Isolated DC-DC 5Ghz-4x4 MAC/BB Radio QCA9990 4x4 FEM (PA+LNA) PCIe_1 4x4 FEM (PA+LNA) GMAC3 RJ45 POE PCIe_0 Rectifier Filters GE MAG 88E1514 GE PHY GMAC4 NAND I/F Flash NAND 128MB USB_1 Pwr Driver USB Port 88E1514 GE PHY BLE UART_2USB_2 GPIO Mux LEDs
  37. 37. 38 Digestive tract and Circulation Power input, consumption, efficiency, output
  38. 38. 39#ATM16 Power sources and failover – AP-325 can be powered by POE or direct DC power – POE source can be 802.3af or 802.3at compliant, delivering an AP power budget of 12.95W or 25.5W – Some restrictions when limited to 802.3af power budget: – Other Ethernet port disabled (can be either) – USB interface disabled – 2.4GHz radio in 1x1 mode – Slight reduction in max transmit power level from 5GHz radio – When both sources are used, DC power is prioritized on AP-325 – But POE will still be negotiated and drawing a small current – When two POE sources are used, the first one to initiate negotiation will supply power – Other one is inactive for POE – Can be hard to predict – AP software actually does not “know” which one is used – Failover: hitless between DC and POE, causing AP reboot when failing over between POE ports
  39. 39. 40#ATM16 Power consumption and efficiency – AP circuitry requires multiple supply voltages – 5V, 3.3V, 2.5V, 1.8V, 1.35V, 1.25V, 1.05V – Input voltage from POE can vary widely (37V – 57V at AP), but is 48V nominally – Since DC supply voltage is 12V on AP-325, POE voltage is generally converted down to 12V first. From there, all other voltages are generated – Some platforms use 48V for DC supply to avoid this additional conversion step (improved efficiency) – POE to 12V conversion efficiency is ~88% – To lower voltages anywhere between 55% and 92% – Overall efficiency is ~76% – Assuming RF transmit power is 18dBm per radio chain, that’s 63mW. For 8 chains: 505mW total “on the air” – For Ethernet, we may put a total of another 500mW “on the wire” (250mW per interface, 62.5mW per pair) – So, AP-325 is generating just 1W of effective energy. The rest (19W) is heat (and a fraction of LED light)
  40. 40. 41#ATM16 DC jack RJ45 RJ45 88%Ethernet / POE DC power 12V 37V – 57V 12V 74% 74% 70% 90% 92% 91% 95% 95% 55% 68% 85% 86% 1.05V 1.05V 1.05V 3.3V 3.3V 3.3V 5V 5V 1.25V 2.5V 95% 5V 0.675W 0.627W 1.696W 2.95W 3.3W 5.287W 0.266W 0.597W 0.038W 0.075W (5W) Total: 15.5WTotal: 17.6WTotal: 20W
  41. 41. 42#ATM16
  42. 42. 43 Brain CPU, Memory, TPM
  43. 43. 44#ATM16 CPU – Picking the right CPU for an access point is tricky, and our choices are limited – Cost: always critical but there’s no hard limit – Power consumption: affecting thermal profile and size. Exceeding the 802.3af POE budget is an obstacle, exceeding 802.3at POE+ budget is not (really) an option – Performance: sometimes hard to assess how well it will do in an enterprise AP scenario, especially if switching to a new type of CPU (MIPS to ARM for example, single to multi-core) – Interfaces and capabilities to support required AP components and capabilities (for example: number of radio cards and Ethernet ports we can connect, USB, crypto acceleration for VPN, built-in TPM, supported memory types and size, etc.) – The AP-325 uses a Qualcomm-Atheros (QCA) IPQ8064 dual-core 1.4GHz CPU (“Akronite”) – Two ARM-v7 cores, high performance DSP, 1MB L2 cache, 5Gbps network accelerator, etc. – Several Ethernet MACs (we use two) – Three PCIe 2.0 interfaces (we use two; one per radio) – Two USB interfaces (we use one) – Etc.
  44. 44. 45#ATM16 Memory – FLASH – Non-volatile and programmable – Used to store bootloader, full software image, manufacturing data, config & settings, etc – AP-325 uses a combination of NOR (4MB) and NAND (128MB) FLASH – NAND type is more cost effective but NOR is more reliable and flexible – For various reasons we use a combination of both (but this may change in the future) – SDRAM – Random Access Memory, contents are volatile (lost when power cycling the AP) – Used to store run-time code, variables, data, etc – AP-325 has 512MB SDRAM, using two 2Gb parts, 16bits data interface on both – CPU can support up to 2GB of SDRAM – 533MHz clock speed – DDR3 type (speed, efficiency)
  45. 45. 46#ATM16 TPM – Trusted Platform Module (TPM) is used to store and generate security credentials – Programmed in the factory using secure encrypted data from an Aruba server – Used to confirm product identity to controller, software image, etc. – On all HPE Aruba APs we use a dedicated standalone TPM component
  47. 47. 48 Guts Ethernet, Wi-Fi Radios
  48. 48. 49#ATM16 More about Ethernet interfaces – Each Ethernet interface uses four “twisted pairs” (so eight wires) to carry the data – Data is the differential signal on the pairs, making it relatively immune to interference picked up on that Ethernet cable (up to 100m / 300ft) – The common mode of the pairs is used to carry POE power (DC voltage differential between pairs) – After the RJ45 jack, the first critical component is a transformer, to extract the POE DC power and transfer & isolate the data from the rest of the AP circuitry – Lots of filtering and protection components as well – After that, Ethernet PHY component which exchanges Ethernet MAC frames with the CPU 88E1514 GE PHY 88E1514 GE PHY GE MAG GE MAG RJ45 RJ45 Akronite CPU POE
  49. 49. 50#ATM16
  50. 50. 51#ATM16 Ethernet (802.3) MAC frame format – Ethernet PHY frame (on the wire) – Preamble: 7 bytes – Start of Frame Delimiter (SFD): 1 byte – Ethernet frame: 64 – 1522/9022 bytes (below) – Interpacket gap: 12 bytes – Ethernet MAC frame: – MAC destination: 6 bytes – MAC source: 6 bytes – 802.1Q tag (optional): (4 bytes) – Type/Length: 2 bytes – Payload: 46 – 1500/9000 bytes – FCS: 4 bytes
  51. 51. 52#ATM16 Transmitter Terms – Conducted Power – This is the power that leaves the connectors – EIRP: Effective Isotropic Radiated Power – This is the conducted power (dBm) + antenna gain (dBi) – cable losses (dB) – Peak EIRP – This is what is regulated – It is the conducted power + peak gain – cable losses – Power level reaching receiver: – EIRP at receiver antenna + antenna gain (dBi) – cable losses – dBm: log power ratio to milliwatt – dB: log gain/multiplier – dBi: antenna gain relative to isotropic
  52. 52. 53#ATM16 RF Power Basics – RF power of an AP is specified at the antenna ports in a 50 ohm system – RF power is measured in milliWatts (linear) or dBm (logarithmic) – dBm = dB relative to 1 milliwatt (mW) – 0dBm = 1mW, 10dBm = 10mW, 20dBm = 100mW, etc. – To convert power to dBm and back: 𝑃𝑑𝐵𝑚 = 10 × log10 𝑃 𝑚𝑊 𝑃 𝑚𝑊 = 10 𝑃 𝑑𝐵𝑚 10
  53. 53. 54#ATM16 Why Use dBm Instead of milliWatts? – Due to Free Space Path Loss (FSPL), the RF signal attenuates quickly – mW represents the data linearly, dBm represents the data logarithmically – Example: the amount of power received from a 2.4 GHz, 100mW (20dBm) transmitted signal: – dBm is much easier to work with Distance (m) dBm signal mW signal 1 -20 0.01000000 10 -40 0.00010000 20 -46 0.00002500 100 -60 0.00000100 1000 (1km) -80 0.00000001
  54. 54. 55#ATM16 dBm and mW Relationships – Increase dBm power by 3 = double the power – Decrease dBm power by 3 = half the power – Increase dBm power by 10 = ten times the power – Decrease dBm power by 10 = one tenth the power dBm mW +20 100 +19 80 +16 40 +13 20 +10 10 +9 8 +6 4 +3 2 0 1 -3 0.5 -6 0.25 -9 0.125 -10 0.1 -13 0.05 -16 0.025 -19 0.0125 -20 0.01
  55. 55. 56#ATM16 Access Point Radio Basics – Typical Enterprise Wi-Fi APs incorporate two Wi-Fi radios, for concurrent operation in the 2.4GHz and 5GHz bands. Each radio can have multiple radio chains for both receiver and transmitter MIMO operation – a x b radio: number of transmit chains = a, number of receive chains = b – Both radios can have different MIMO configuration. For example 2x2 2.4GHz radio and 3x3 5GHz radio – Remember: MIMO does not automatically imply the use of multiple data spatial streams (SDM) – The number of (SU-MIMO) spatial streams = c for an a x b : c radio, where c ≤ a, b – Parameter c is the multiplier for the maximum datarate supported by the radio. A radio with c=3 (3SS) will support a maximum data that is 3x that of an equivalent radio with c=1 (1SS) – Transmit and receive chains within the same radio normally share antennas, so the number of antennas per radio is 𝒎𝒂𝒙 𝒂, 𝒃 – In some cases, APs use dual-band antennas that are shared between radios, so the total number of antennas in that case becomes 𝒎𝒂𝒙 𝒂 𝟐.𝟒𝑮𝑯𝒛, 𝒃 𝟐.𝟒𝑮𝑯𝒛, 𝒂 𝟓𝑮𝑯𝒛, 𝒃 𝟓𝑮𝑯𝒛 – Things get more complicated still with MU-MIMO – The number of MU-MIMO spatial streams can be smaller or equal to the number of SU-MIMO streams – The number of max simultaneous MU-MIMO clients can be smaller or equal to the number of MU-MIMO streams – Lost? Next slide tries to summarize this
  56. 56. 57#ATM16 Numerology – Wave2 AP Capabilities CTX x CRX: NSU_STS : NMU_STS : SMU_STAS Transmit chains Receive chains SU spatial streams MU spatial steams MU group size Examples: Aruba AP-215: 3x3:3:0:0 Aruba AP-325: 4x4:4:3:3 Aruba AP-335: 4x4:4:4:3 Competitor flagship product: 4x4:3:3:3 802.11ac Wave 2 Maximum: 8x8:8:8:4
  57. 57. 58#ATM16
  58. 58. 59#ATM16
  59. 59. 60#ATM16
  60. 60. 61#ATM16
  61. 61. 62#ATM16 AP Wi-Fi Radio Basics – CPU and radio exchange layer 3 frames; Wi-Fi chipset handles conversion to MAC, BB and RF – Physical interface between CPU and radio is PCIe interface – On AP-325 we used separate radio cards, and these interfaces are implemented across two radio connectors – Radio handles en/de-coding to/from OFDM encoded RF data – A large number of “sub carriers” are individually modulated – VHT40 has 108 usable sub carriers (example below), VHT80 provides 234, VHT160 doubles that – Using 256-QAM, we can modulate each of these in 256 distinct ways (8 bits)
  62. 62. 63#ATM16 802.11 packet/frame format
  63. 63. 66#ATM16 Wideband Noise – The quantization noise generated in the transmitter is present across all frequencies (DC to daylight) – Since the radios may be tuned over either the entire 2.4 or 5 GHz band no in-band filtering can be applied – If the radio is transmitting 18dBm conducted, per the 802.11 spec the wideband noise could be as high as -27dBm (45dB below transmit level) – Our typical noise floor is at -98 dBm (20MHz BW) – To operate with no impact radios in the same band need to be isolated by 71 dB (-27 + 98) – Wideband noise at or below the noise floor – In reality out radios are about 10 dB better on wideband noise so the isolation requirement drops to 61 dB
  64. 64. 67#ATM16 DAS Interference: An example why filtering adds real value – Without filtering any OOB signal that hits the receiver above -45 dBm will cause a reduction of sensitivity – This applies to any Wi-Fi receiver; the basic architecture and components are the same – The degradation continues until about -15 dBm at which point the receiver is totally blocked – With a 100 mW (20 dBm) DAS system at 2100 MHz – Tx power: 20 dBm – Effective Rx antenna gain: 3 dBi – 1st meter at 2100 MHz: -39 dB – Resulting power at 1m: -16 dBm – No impact distance (-45dBm): 30 meters – Summary: without special filtering the AP receiver performance will be impaired is a typical DAS antenna is within 30m (100ft) – A high power outdoor cell tower can have similar impact (at a much larger distance; transmit power can be as high as 50W or 47dBm)
  65. 65. 68#ATM16 Advanced Cellular Coexistence – Proliferation of DAS and new LTE bands at 2.6 GHz are creating issue for Wi-Fi solution – All HPE Aruba APs have implemented significant filtering into the 2.4 GHz radio portion to combat this – Design solution – Use high-linear LNA followed with a high-rejection filter to achieve rejection target and little sensitivity degradation; – Design target: Minimal Sensitivity degradation with -10dBm interference from 3G/4G networks (theoretical analysis).
  66. 66. 69 Sixth Sense BLE radio
  67. 67. 70#ATM16 AP-325 built-in BLE radio – BLE beacons are rapidly gaining traction for use in locationing services – HPE Aruba offers a complete solution for locationing with BLE beacons – The physical beacons are offered as battery-powered standalone units, USB dongles, AC-plug-in sensor devices, and starting with the AP-325 also integrated in HPE Aruba access points – With previous AP models, USB dongle BLE radios could be plugged in – Co-locating with APs offers the ability to interface with the BLE network from the Wi-Fi infrastructure (management, stats) – Note that the AP is not “self-aware” of its location (no on-board GPS..). It still needs to be placed on a map or floorplan to be used as a locationing reference point – Secondary use-case: IOT gateway (future) – Bonus: wireless console interface (using app on smartphone or tablet)
  68. 68. 71#ATM16
  69. 69. 72 Heart and Soul Software
  70. 70. 73#ATM16 The softer side of the AP-325 – We’ve been talking much about the body (inside and out) of the AP, the hardware – Until now, we haven’t touched the heart and soul of the AP: the software. – The AP code written by hundreds of engineers interacts with the radio chipsets, wired networking components, and many of the other components we’ve been discussing here. – The primary task of the AP software running on the CPU is to efficiently moving data packets between the two primary networking interfaces without ever becoming a bottleneck for performance. – In addition to that basic task, the software maintains and reports tons of data for the many devices and datastreams associated with the AP, and it manipulates the data it’s handling in many ways – The AP-325 can have up to 255 active clients per radio, although 100 is a more practical limit – Along with manufacturing and product data, the software image is stored (in compressed format) in FLASH. It executes from SDRAM memory, where it also maintains data, variables, tables, etc. – It’s the software that makes these devices truly shine. Features like ClientMatch, AppRF, UCC, etc. couldn’t exist without the right AP platform. But it wouldn’t be much without the software either.
  71. 71. Thank you Onno Harms,
  72. 72. 75#ATM16 Join Aruba’s Titans of Tomorrow force in the fight against network mayhem. Find out what your IT superpower is. Share your results with friends and receive a free superpower t-shirt.

Editor's Notes

  • The anatomy lesson of Dr. Nicolaes Tulp - Rembrandt van Rijn, 1632
  • Plenum burn pic
    Earthquake test video
    Sample. Camera?
  • 7 month > 5 years: 10 versus 80 year life
  • A human heart is expected to beat about 200,000,000,000 times in 80 years
  • MTBF 500,000 translates to one unit failing every 500 hours if you have 1,000 units. That’s over 17 every year!
  • Stripping
  • Most geeks have a set of secure screw drivers now..
  • Inside a closet in in the Vdara hotel. AP-65 started shipping in 2005, and reached EOS in June 2011
  • Example of thermal test results (AP-225). Straight line is ambient (+50C) in test chamber

    Stability after ~2 hours
  • Will bring some samples
  • This video is showing an AP-135, but we do these tests with every new AP
  • Baud rate configurable up to 115,200

    Future: console moving to 4-pin header
  • LED mode toggle: currently supported on some AP models only (not on AP-325)

    Light-guide, light-pipe
  • Antenna losses/efficiency reduces the volume of the sphere. Antenna gain changes the shape. Balloon

    Polarization: in reality there are no perfectly perpendicular signals or antennas. Also, polarization flips with every reflection.
  • Showing horizontal (azimuth) patterns for all four 2.4GHz elements
  • Showing horizontal (azimuth) and elevation patterns for all four 2.4GHz elements. AP face up for elevation plot
  • Memory: SDRAM (volatile) and FLASH (persistent)

    Filters: keep interference out or contained. Can be low frequency (and even DC) to extremely high frequency
  • 12.95W turn into 13.8W when using CAT5E or better
  • Starting with 20W, almost 5W is lost in the conversion circuitry

    Of the remaining 15W, 14W is used to drive all the activity on the AP, 1W is delivered to the wires and airwaves

    Eventually, even that remaining Watt of energy will turn into heat
  • Create simplified version in visio
  • DDR: double data rate. Latest version is DDR4. DDR3 is most popular currently
  • >1500: Jumbo frame
  • Cable losses: between connector and actual antenna
  • The unit of measure used to measure Wi-Fi transmissions is either milliwatts or dBm. When an RF signal is transmitted, due to Free Space Path Loss the amount of signal received is magnitudes less than what was transmitted.
    As signal moves away from the source, it naturally decreases in power due to the broadening of the wave. This decrease in power is know as Free Space Path Loss (FSPL).
    When using milliwatts, working with values ranging from 100 milliwatts to .000025 milliwatts or even less can be very confusing. Due to this huge variance, a different scale known as dBm is used to make working with RF communications easier. A signal transmitted at 100mW is equal to 20dBm. The .000025 mW signal that is received is equal to -46 dBm. dBm is known as decibels relative to milliwatts, with 0 dBm equal to 1 mW.
    As illustrated in the table, for a 2.4GHz transmitter, the signal drops by 40dB in the first meter (more later)
  • When dealing with milliwatts and dBm’s, it is important to know the rule of 10’s and 3’s. A 3 dBm increase is equal to double the power. A 10 dBm increase is equal to 10 times the power. This rule is also inversely true for a 3 dBm decrease or a 10 dBm decrease.
  • Any system with multiple antennas qualifies as “MIMO” but we typically use MIMO when really talking about MIMO SDM (Spatial Division Multiplexing)
  • This is 5GHz
    Pretty simple.. QCA chipset with MAC/BB/radio, FEMs
  • This is the 2.4GHz radio
    Same here
  • 8 bits x 108 subcarriers = 864 bits
    312,500 symbols per second
    864 x 312,500 = 270Mbps
    After cyclic extension, FEC: 200Mbps
    VHT160: 867Mbps
    MIMO: multiplier
  • On the right is the PHY layer frame
    Left is MAC frame
    Payload is 0 to 11,426 bytes
  • DAS: Distributed Antenna System
    OOB: Out Of Band
  • Unimpaired operation at 50 cm from DAS

    Strangely enough, we’re the only ones to implement this
  • BLE antenna on AP-325 is a bit of an after-thought..

  • Contest Overview
    - Aruba is running a marketing campaign where we ask “What is your IT superpower?”
    - Go to to take a quick quiz to discover your superpower.
    - Share your results with friends and encourage others to play the game
    - Once you share, go to the Social and Community Hub, Gracia Commons, 3rd fl to pick up your free superpower shirt.

    1. What do I have to do to get a shirt?
    Share your IT superpower results with friends and encourage them to play the game. Then come to the Social & Community Hub, 3rd Floor Gracia Commons to pick up your shirt. We just need your name and badge for verification.
    2. Where do I get my shirt?
    Come to the #ATM16 Social & Community hub located at Gracia Commons on the 3rd Floor
    3. Do I have to be at the event to get the shirt?
    Yes. You have to be at #ATM16 to get a shirt.
    4. Can I get my colleague a shirt? He/she is in a session right now.
    Unfortunately not. We encourage your colleague to participate so that they can win a shirt for themselves.
    5. Can I bring a shirt home for my colleague?
    Unfortunately not. You have to be at #ATM16 to get a shirt.
    6. You don’t have a shirt in my size, can you ship the right size to me later?
    Unfortunately not. Please select the best size from our inventory on site.