The following set of slides addresses the basics of quo5ng, designing and building an in- building wireless solu5on. At Hu;on we provide a complete

Transcription

1 The following set of slides addresses the basics of quo5ng, designing and building an in- building wireless solu5on. At Hu;on we provide a complete set of solu5ons for in- building wireless systems, typically called DAS (Distributed Antenna Systems) in the industry. For assistance in designing and quo5ng DAS solu5ons to your customer Hu;on is here to help you. 1

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3 Basic Components of a passive DAS. Though instead of a BDA the signal source could also be a base sta5on radio. 3

4 This diagram of a simple passive DAS shows a 8 story apartment building with a single riser. Note the direc5onal coupler or tappers in the ver5cal. Each unit taps some frac5on of the power of to that floor. 4

5 Here s a much more complex passive DAS. There s a variety of omni and direc5onal antennas to match the coverage areas. 5

6 The components of an ac5ve DAS are quite different. Though the signal source may be the same,either a BDA or base radio, the remainder of the system uses ac5ve components to distribute the RF signal. Most ac5ve DAS solu5ons use fiber op5c cable due to the low loss over long distances. 6

7 This shows the signal flow from the signal sources out to each fiber remote and back. The MobileAccess solu5on is very typical for ac5ve DAS. It uses a central radio interface unit to filter, measure and condi5on the incoming RF. All RF streams are combined here and sent to an op5cal base unit where the signals are converted to light for the fiber op5cs. At the remote end another device converts the op5cs back to RF over coax for distribu5on over some coax and antennas. 7

8 The Zinwave solu5on is very different in that it s fiber to the antenna. A small fiber remote is located at the antenna s loca5on. Therefore there is minimal coaxial loss. RF is injected into the main hub which can then be connected to fiber remotes or to secondary hubs. This allows many remotes to be fed by a single primary hub. 8

9 When to use a passive DAS 9

10 When to use an ac5ve DAS 10

11 Simplified diagram of a BDA or repeater. Inside are 2 RF paths with filtering and combining at each end to handle both the uplink and downlink RF paths simultaneously. 11

12 What do we need to know to get started. Whether you re doing your own designs or looking for assistance from Hu;on there s certain minimum pieces of informa5on that we must have. The more info we have the more accurate the design can match the actual. For VHF and UHF BDAs it s important that we have actual frequencies. Cost of a BDA can vary from $5K to over $50k depending on the channel mix. 12

13 Let s talk about the importance of donor signal strength. If you don t know what the donor signal is, or at least a good es5mate, all we can do is guess as to what solu5on we need and how much gain we need in the BDA. 13

14 Defini5on of a link budget 14

15 An example of the elements of an in- building link budget 15

16 The form that I use for a simplified in- building link budget. Enter donor strength, antenna and BDA info, spli;er losses based on the number of antennas, desired coverage area of each antenna plus addi5onal path loss components and this tool will give you an es5mate of the signal level at the handset radio. me if you d like a copy for yourself. 16

17 Examples of typical wall losses as provided in the ibwave tool. I typically use higher values for concrete as my experience has shown me the actual losses through concrete are much higher then shown here. I typically use 6dB per cinder block wall and 20dB for a poured concrete wall. 17

18 Visual of the drop in RF signal strength over distance and as RF penetrates walls. Overall wall losses cause degrada5on in coverage area. 18

19 Now let s talk about power and the importance of filtering the incoming signal into the BDA. I men5oned in the first slide that composite power is the sum of all signals coming into the BDA/Repeater. All BDAs have a max composite power. This is the point at which the BDA starts limi5ng the gain applied to the incoming signals in order to not exceed it s rated power output. So if your BDA is receiving more than you intended you may not be gefng the signal amplifica5on that you planned on. 19

20 Repeater gain of 85dB, max composite power 27 dbm. ( Like the CSI DSP85- PSS8) Add 85dB gain and you d think you would have dBm,That would be more than10 wa;s out of the BDA. But the BDA is limited to 27dBm max (half wa;) so it s only going to operate at 71dB gain Now your per channel power of the desired signals is - 75dBm + 71dB gain = - 4dBm per channel out of the BDA. Or milliwa;s (a li;le less than zero point 4 wa;s) 20

21 Same repeater Repeater gain of 85dB, max composite power 27 dbm. - 66dBm + 85dB = 19dBm (so we have not exceeded our max composite power) Now your per channel power of the desired signals is - 75dBm + 85dB gain = +10dBm per channel out of the BDA. Or 10 milliwa;s, over 20 5mes as much power per channel! Our previous example we only had - 4dBm per channel real power available! So I hope you can see the importance of being selec5ve with what your BDA sees 21

22 Same repeater Repeater gain of 85dB, max composite power 27 dbm. - 66dBm + 85dB = 19dBm (so we have not exceeded our max composite power) Now your per channel power of the desired signals is - 75dBm + 85dB gain = +10dBm per channel out of the BDA. Or 10 milliwa;s, over 20 5mes as much power per channel! Our previous example we only had - 4dBm per channel real power available! So I hope you can see the importance of being selec5ve with what your BDA sees 22

23 With so many carriers in the PCS bands it s especially important to only look at what you really need. 23

24 With so many carriers in the PCS bands it s especially important to only look at what you really need. 24

25 So be sure to get a BDA that offers mul5ple pass windows 25

26 Many repeaters offer solware controlled band select filters to bring in only what you want. Without a site survey the proposal carries risk. 26

27 Always get permission from the license holder before rebroadcas5ng their signal. 27

28 These slides discuss project management aspects of an in- building project. 28

29 This is my list of things that we really need to know to do a design. We have floor plans We have a frequency band, or list of frequencies. This is where it s best to know what s going on in the frequency band (explain rebanding, channelized) Donor signal - Anything less is an educated guess, not a design. And what standard are we expected to meet. 29

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31 As you can see, the list of things we don t know is always a lot bigger than what we do know. From experience we can be pre;y good at our assump5ons Stairs will have either fire rated drywall, CMU, or poured in place concrete depending on the height of the building. Plenum rated cable is almost always required above drop ceilings, generally you can use plenum in place or fire resistant, but not the inverse Riser loca5ons are olen near elevator or stairs, usually closets and usually stacked, some5mes labeled Comm, Data or Elect. 31

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33 Does the building actually look like the original plans provided? Then we see if the public safety signal is good enough in some areas Aler all, the building code says that if the signal inside a building falls below the threshold (usually - 95) then a BDA system must be installed. So if the signal is already strong in the upper floors, leave them alone unless you somehow feel commi;ed to the original design (choose your wording carefully in your proposal). This is a good 5me to bring up an edge that you may have over the compe55on when you bid. If there is a building to take measurements in then do so at the 5me of the bid. You might win the job by installing the DAS only where it s needed, while all the others are bidding the whole building. Compare cable rou5ng in design with actual in building Verify donor antenna and cable Take a roolop measurement of the donor signal Confirm where the BDA will be mounted If anything above changed, review these changes with the designer. Changes to cable rou5ng, floor- to- floor penetra5ons and BDA loca5on may change the design substan5ally. Changes to the donor signal can also have a big impact, good or bad! 33

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36 A CW test is one of the most overlooked tools of the trade. Trying to troubleshoot a problem with live signal s5nks! CW tes5ng allows you to measure everything without the variables of live signal. Why 8l? Because it s easy to see the length of 2 ceiling 5les 36

37 Be sure to filter out unwanted signals, Examples Do your own walk test before the inspector gets there Have you ever done a grid test? Divide the floor plan into 20 equal grid squares. Inspector can test signal from anywhere within each square. If they want to be difficult they ll find the farthest corner. Or perhaps if they trust that you do good work they 37

38 The actual requirements will be wri;en into the city s building codes. But inspector has the la5tude to determine cri5cal coverage areas. Cellular systems with 3G or 4G technology we re now designing to a - 75, 100 5mes more signal than public safety! 38

39 What are cri5cal areas? Usually defined as exit pathways, places of public gathering in an emergency, pump and fire control rooms. 39

40 Much more is involved in boos5ng cellular services, especially if mul5ple carriers are involved. 40

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