STATUS: Shelved 2012

Description

The AT&T microcell is a box with an ethernet port and a GSM cell phone radio.
It connects to the internet using the ethernet port, and establishes an encrypted tunnel to AT&T's network. It then uses this encrypted channel to transport voice call and GSM data information from AT&T GSM phones which connect to the onboard radio.

Microcell network requirements

According to AT&T, the microcell requires the following network services:

  • DHCP is on
  • MTU is set to 1492
  • MAC address filtering is either turned off or allowing the MAC address of the AT&T 3G MicroCell
  • IPSec Pass-Through is Enabled
  • Block Fragmented Packets is Disabled
  • TCP/UDP Ports
    NOTE: All ports listed need to be configured for inbound and outbound connections.
    o 123/UDP: NTP timing (NTP traffic)
    o 443/TCP: Https over TLS/SSL for provisioning and management traffic
    o 4500/UDP: IPSec NAT Traversal (for all signaling, data, voice traffic)
    o 500/UDP: IPSec Phase 1 prior to NAT detection (after NAT detection, 4500/UDP is used)
    o 4500/UDP: After NAT detection, 4500/UDP is used

Source: http://www.wireless.att.com/answer-center/main.jsp?t=solutionTab&solutionId=KB110286

Other Requirements

  • The microcell can register a maximum of 10 users
  • The microcell can serve only 4 users at a time
  • The signal range is approximately 40 feet in all directions, or about 5000 square feet
  • The microcell is designed to provide limited coverage to predetermined users and would not be a good solution for tunnels, linear or otherwise

The AT&T RF Engineering manager told us that the solution for the tunnels is an "enterprise" femto which is not available yet.

Microcell at SLAC

  • The SLAC border firewall blocks IPSec for all the SLAC internal networks. Therefore, internal SLAC networks cannot be used, unless a specific security policy exception is granted.
  • The Visitor network blocks all incoming TCP traffic (i.e. TCP connections initiated from outside SLAC). It also blocks the NTP port. This makes the visitor network unusable for the microcell.

Additional requirements

The microcell requires a GPS signal. Therefore, it needs to be placed by a window, or to be connected to a roof GPS antenna.

Update 2016

In response to the following question from Tom Glanzman

The cellular phone reception at IR-2 is dismal to non-existent. With the general reduction in land-line phones and the proliferation of personal cell phones, it would be very convenient if people working in and around IR-2 had that option for communication.  This might be especially true for those working inside the Clean Room.  I was told you had estimated $10k to install and operate a cellular repeater that would serve IR-2.  But I am wondering whether an IP-based microCell might also work -- and be more cost effective?

You can also get a Skype subscription and use WiFi from your Smartphone to make and receive calls. 

I believe when you refer to microcell  you may be referring to  a femtocell at least the AT&T branded Microcell is a femtocell. We looked at femto cells  a few years ago so my information is outdated especially since at the time they were aiming at the residential market. At the time it had limitations, e.g. you need one for each carrier, a limited number of users can register (e.g. AT&T 10), there is a limitation on the number of instantaneous connections (AT&T 4), there is limited coverage in terms of area (I do not think this would be a problem for you), is there any handover, it probably needs a GPS signal so will need a cable (that can be expensive) to a GPS antenna on the roof.  Not sure about interference, security issues (may need exception for some protocols used) etc.  It would need some research, especially since my information is out of date.  Now might be a good time for someone motivated to do this. This would be a project. I do have an old AT&T femto/micro cell you can play with. If you decide to go ahead please keep me in the loop

It is not currently on our portfolio to support special indoor WiFi coverage, basically we work with carriers to get access via macro cell phone sites. If their coverage fails as it does in tunnels, underground etc. then we recommend Building Distribution Amplifiers or WiFi. There are a few BDAs successfully in use at SLAC and they used to cost about $10K ($5K parts, $5K labor, actual costs can depend on difficulty of getting cable to the roof). Ray Rodriguez is the person who has done this in the past. Another possibility is a WiFi phone such as developed by Avaya, however they are expensive ($1K) and no longer fully supported (e.g. one cannot get a pouch or their type of headset from Avaya any more).

Soft Phones and SIP

Once we have SIP access to the Avaya PBX then we can use the Cisco Call Manager to support softphones to the PBX using the Cisco Jabber client on a smartphone. There is probably a similar set up from Avaya.

 

 

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