Telecommunications – Radiotelephone system – Zoned or cellular telephone system
Reexamination Certificate
1999-12-29
2001-07-24
Hunter, Daniel (Department: 2749)
Telecommunications
Radiotelephone system
Zoned or cellular telephone system
C455S453000, C455S451000, C455S552100, C455S553100
Reexamination Certificate
active
06266532
ABSTRACT:
FIELD OF THE INVENTION
This invention generally relates to the field of wireless telecommunication. This invention particularly relates to optimizing the number of analog and digital radios used in a dual-mode wireless telecommunication network.
BACKGROUND OF THE INVENTION
Dual-mode capable wireless telecommunications networks permit wireless telephone subscribers to access the wireless network using either analog or digital radio telephones. In order to permit wireless communication using both analog cellular telephones and digital cellular telephones, dual-mode networks must be equipped with both analog and digital radios at every receiving station. Typically, each cell, or sector, within a dual-mode wireless network is equipped with both analog and digital radios at each receiving station to handle both types of signals.
When a wireless subscriber accesses a dual-mode wireless network using an analog radio telephone, the call is completed through an analog radio located at the nearest receiving station if an analog radio channel is available. If no analog communication channels are available at the receiving station, the subscriber is “blocked” from completing a call, and a long busy signal is played to the subscriber indicating that no call-handling capacity is currently available. The subscriber is then forced to hang up and to retry the call until an analog channel becomes available at the receiving station to handle the communication. If subscribers are frequently blocked in this manner, subscribers may become dissatisfied with their wireless service provider. Therefore, wireless service providers seek to provide enough analog radios to supply a sufficient number of analog radio channels so that subscribers are not frequently blocked.
When a subscriber accesses a dual-mode wireless network using a digital radio telephone, the call is completed through a digital radio located at the receiving station if a digital radio channel is available. However, if a digital channel is not available at the receiving station, the subscriber using a digital radio telephone is not “blocked” like the subscriber using an analog radio telephone. Rather, the communication from the subscriber using the digital radio telephone will “overflow” onto an analog radio channel if one is available. This is possible because most digital cellular telephones are capable of operating in both digital and analog modes. Therefore, if a digital radio channel is unavailable to handle the call, the call overflows onto an available analog channel.
If no analog or digital channels are available, the subscriber using the digital radio telephone will be blocked from completing the call. As discussed above, frequent call blocking is undesirable because it may frustrate wireless subscribers. The number of analog and digital radios installed in each sector throughout a dual-mode wireless network must therefore be chosen in a manner so as to provide enough radio channels to minimize call blocking. The number of analog and digital radios must also be chosen to minimize the total number of radios so that equipment costs may be kept low.
The number of analog and digital radios installed in a sector of a dual-mode wireless network is, in general, determined based upon predicted offered analog and digital loads. Typically, an estimate is made of the amount of digital and analog communication traffic that will be received in a given cell, or sector. The number of analog and digital radios necessary for the cell may then be calculated with several factors influencing the calculation. First, as described above, the total number of analog and digital radios should be chosen so as to minimize blocking. Second, the number of digital radios should be maximized because wireless subscribers prefer digital sound and because digital is a more efficient communications medium than analog. Third, the total number of analog and digital radios should be minimized so as to keep costs low for the wireless service provider while ensuring that wireless service can be provided at a competitive price.
Accordingly, there is a need for determining the number of analog and digital radios in a dual-mode wireless network that provides sufficient call-handling capacity so that call blocking is minimized, while also minimizing the total number of cellular radios. There is also a need for determining the number of analog and digital cellular radios in a dual-mode wireless network that maximizes the number of digital cellular radios and minimizes the number of analog cellular radios.
SUMMARY OF THE INVENTION
The present invention meets the needs described above by providing a method and apparatus for optimizing the number of analog and digital radios in a dual-mode wireless telecommunication system. The method and apparatus of the present invention calculates the number of analog and digital radios for each sector of a dual-mode wireless telecommunication network so that the total number of radios is minimized and so that the number of digital radios is maximized. This advantageously ensures that the amount of digital bandwidth will be maximized while also keeping costs low. The method and apparatus of the present invention also advantageously calculates the number of analog and digital radios so that call blocking is reduced, thereby increasing customer satisfaction.
Generally described, the present invention calculates the optimal number of digital and analog radios in a dual-mode wireless telecommunication system based upon a predicted offered digital load, a predicted offered analog load, and an analog blocking factor. The predicted analog and digital loads are estimates of the actual analog and digital communication traffic that will be encountered when the radios are installed. The predicted analog and digital loads may be estimated by examining a number of factors, including the number of subscribers, current analog and digital loads in the sector or network, and the average digital and analog subscriber talk time. The offered analog and digital loads can be predicted based upon these and other factors apparent to those skilled in the art.
The analog blocking factor represents the percentage of the time calls on an analog communication channel are blocked, or not permitted to complete. For instance, an analog blocking factor of 5% indicates that 5% of all analog calls are being blocked. A high analog blocking factor indicates that a high percentage of calls are being blocked and will result in customer dissatisfaction. A low analog blocking factor indicates that few calls are being blocked and may indicate that there is too much analog capacity for the load being served. Typically, an analog blocking factor of about 5% is chosen so as to balance these considerations.
Once the offered loads have been predicted and the analog blocking factor has been determined, the present invention calculates the needed number of analog radio channels necessary to support the offered analog load at the analog blocking factor. Because the capacity of the needed number of analog radio channels is typically greater than the offered analog load, some excess capacity is usually available on the analog channels. The present invention subtracts the offered analog load from the capacity of the needed analog radio channels to determine the excess capacity of the needed channels.
Once the excess capacity of the needed analog channels has been determined, the present invention calculates a digital blocking factor based upon the excess analog capacity. The present invention may also advantageously compare the digital blocking factor to minimum and maximum overflow values to ensure that the digital blocking factor is neither too high nor too low. This advantageously ensures that neither too many nor too few calls are blocked.
Once the predicted offered digital load and the computed digital blocking factor have been determined, the present invention calculates the number of needed digital radio channels necessary to support the predicted offered digital load at the calculate
BellSouth Intellectual Property Management Corporation
Hunter Daniel
Kilpatrick & Stockton LLP
Zewdu Meless
LandOfFree
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