Robert Liu verifies early speculation that the Philly network needs indoor bridges: A CPE (customer premises equipment) could be a T1 modem, a cable modem, or a DSL modem--or, in the case of many Wi-Fi mesh networks, a Wi-Fi to Ethernet bridge with a high-gain antenna. This has been the missing piece in much of the coverage of Wi-Fi mesh networks.
Critics have said that cards built into laptops or added to desktop machines couldn't receive signals from ubiquitous outdoor metropolitan networks. They're generally correct. But until this fact-finding pre-proposal meeting in Philadelphia that Liu attended at which potential vendors had a chance to ask questions for the first time it was unclear that a CPE was required. The RFP states on page 10:
Should additional customer premise equipment ("CPEs") be required or assumed in order to deliver this in-building coverage, Respondents are expected to state this in their Proposals and elaborate on this requirement and their assumptions.
Liu says this is now a given, not a "should."
I disagree on this adding substantial cost, however, as Liu writes: a Senao 200 mW 802.11b bridge retails for under $100; in quantity, it would be substantially less. Because the network builder will be a wholesaler, they can't recover the cost of this device from the consumer directly, but it appears they'll be responsible for CPE selection. This could be built into the price of the network, representing a couple dollars per month of the wholesale cost. Or they could offset the cost to ISPs who recover it from end-user fees or leases. The Senao is being used in some Tropos deployments right now as a CPE.
Liu reports as well that the information provided to vendors who want to bid is probably inadequate for true RF planning: building footprints date to 1996; no building heights were provided. Other topographical details about poles and other city facilities was available, however.