Signalling between base stations and cell phones

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  • Proposals: 1
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  • #19944
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Sebastián T.
has already sent a proposal.
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Experience Level: Expert
The two uploaded files provide background and a flowchart. Here are specs for the job:

The revised phones must, when in a moving passenger vehicle, detect the presence of switched on phones in the same vehicle by simulating a base station for all phones of one type (CDMA or GSM). Sensitivities should be set to rarely allow false negatives (phone not detected) and occasionally allow false positives (the detected phone is actually in a nearby moving vehicle). A revised phone will only search for nearby phones when it is moving faster than a threshold speed. How the speed is determined is beyond the scope of this project.

Base station simulation signals sent to nearby phones must not interfere with the normal functioning of each phone detected. Each nearby phone should be elicited to respond with its mobile number (for retransmission by the revised phone to verify that the detected phone qualifies as a phone that should allow the revised phone to be not crippled while moving).

Create one text document and a separate document (Word or Powerpoint) with any charts drawings or figures. Use only black and white, no color. Assign a figure number to each figure and refer to it in the text as “Figure 1â’€’, etc. You may use the existing Powerpoint flow chart as a figure of the work product if you wish.

Include at least these elements:

1. Find and provide, or provide a web link to, documents that specify base station signaling to phones, for both CDMA and GSM.

2. Copy into the text two lists of all signals (GSM and CDMA) that might be useful for an aspect of the system described. Propose one subset of the listed signals as the preferred signals to use in the system for GSM and another for CDMA.

3. Describe how standard phone hardware may need to be modified, if at all, to perform the proposed sets of base station signaling for CDMA and GSM (to communicate with all existing phones of that type).

4. Describe in words how the software should work, at a high level, to perform the signaling. Include at least one high level chart as a figure showing a central aspect of the signaling. Provide an outline of the required signaling applicable to all handsets so that a programmer familiar with a particular handset would then be able to program it for that handset.

5. Describe how the signaling should be repeated to optimize chances that the detected phone is moving with the revised phone and not in another vehicle. (Only vehicles big enough for 9 passengers need to be planned for.) Address whether, and if so how, the strength of signal coming from the detected phone should be checked for changes over time.

6. If the revised phone detects only one other nearby phone, the revised phone will send to its base station and mobile switching center a query with the discovered mobile number. (If it detects two or more phones, it will send no query.) It expects to receive back either a verification that the mobile number is not disallowed for use to uncripple the revised phone or a response that it is disallowed, in which case the revised phone will cripple itself. If no response is received within a specified period of time, the revised phone will report again the discovered mobile number and await a response and remain uncrippled. Propose formats for these signals for addition to the CDMA and GSM signaling systems.

7. Is there a risk that if the revised phone detects many nearby switched-on phones it will become confused or have some problem? If so, propose a solution.

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