Method and system for wireless telecommunications

A method for transmitting data is provided. The method includes receiving a service request for a standby subscriber terminal, such as when a call is placed to or from the standby subscriber terminal. The number of telecommunications channels carried by a trunk group is then changed, such as by increasing or decreasing the number of encoded telecommunications channels carried by the trunk group. The standby subscriber terminal is then assigned to one of the telecommunications channels of the trunk group.

FIELD OF THE INVENTION 
This present invention relates in general to telecommunications systems and 
more particularly to a method and system for wireless data communications, 
including a system for dynamically allocating data channels to trunk 
groups. 
BACKGROUND 
Wireless communications systems use electromagnetic radiation to carry 
encoded data between a transmitter and a receiver. In wireless 
communication systems that include a central terminal that services a 
large number of subscriber terminals, each with the capability to receive 
and transmit data, it is necessary to efficiently use the electromagnetic 
frequency spectrum to accommodate the largest number of subscribers. 
For example, a wireless local loop system may be used to provide service to 
residential areas. Such environments are typically multi-path 
environments, which are characterized by radio frequency signals being 
reflected by intervening objects, such that a large number of duplicate 
signals may be received at the receiver. In such environments, it is 
necessary to perform additional signal processing to improve the quality 
of the received signal. 
In addition to the phenomenon of multi-path signal generation, radio 
frequency licensing entities often allocate available radio frequency 
spectrum space to telecommunications service providers in segments of 
varying bandwidth size. The number of users of the system also varies as a 
function of time, which can cause the signal quality to subscriber 
terminals that are remote from the central terminal to be degraded even 
though additional unused system capacity exists that could be used to 
improve the signal quality. Existing systems and methods for data 
communications that are used in multi-path environments are not easily 
reconfigured to accommodate changes in bandwidth, signal strength, number 
of users, or other variables. Therefore, it is difficult to optimize the 
data communication systems for the service environment, number of users, 
licensing variables, and other variables. 
SUMMARY OF THE INVENTION 
Therefore, a system and method for wireless data communications are 
required that substantially eliminate or reduce the problems associated 
with conventional systems and methods for wireless data communications. 
In particular, a system method for wireless data communications is required 
that allows the signal strength to users that are remote from the central 
terminal to be improved when additional system resources are available. 
In accordance with the present invention, a method is provided for 
transmitting data. The method includes receiving a service request for a 
standby subscriber terminal, such as when a call is placed to or from the 
standby subscriber terminal. The number of telecommunications channels 
carried by a trunk group is then changed, such as by increasing or 
decreasing the number of encoded telecommunications channels carried by 
the trunk group. The standby subscriber terminal is then assigned to one 
of the telecommunications channels of the trunk group. 
Another embodiment of the present invention is a system for transmitting 
data. The system includes a central terminal coupled to a 
telecommunications network. The central terminal transmits and receives 
channels of data from the telecommunications network. The system also 
includes a plurality of subscriber terminals. Each subscriber terminal is 
operable to transmit and receive a channel of data from the central 
terminal. A trunk group having an effective radiated power level is 
modulated by a first group of one or more data channels. The effective 
radiated power level may be increased or decreased as a function of the 
distance between one or more subscriber terminals and the central 
terminal. Another trunk group is modulated by another one or more data 
channels. The effective radiated power level of the other trunk group may 
be increased or decreased as a function of the distance between the other 
group of one or more subscriber terminals and the central terminal. 
The present invention provides many important technical advantages. One 
important technical advantage of the present invention is a method for 
improving the quality of data communications that allows the number of 
telecommunications channels carried by a trunk group to be dynamically 
increased and decreased. This dynamic assignment allows signal quality to 
be improved when system usage is light. 
Another important technical advantage of the present invention is a system 
for transmitting data that allows the amplification power levels of trunk 
groups to be dynamically assigned. Dynamic assignment of power levels 
between trunk groups allows power to be reassigned from trunk groups that 
are servicing subscriber terminals that are near to the central terminal 
to trunk groups that are servicing subscriber terminals that are remote 
from the central terminal. Thus, the signal quality may be improved for 
one channel without adversely affecting the signal quality of other 
channels.

DETAILED DESCRIPTION OF THE DRAWINGS 
FIG. 1 is a diagram of a wireless data communications system 10 in 
accordance with one embodiment of the present invention. System 10 
includes central terminals 12, subscriber terminals 14, and service cells 
16. Central terminals 12 communicate by radio frequency electromagnetic 
radiation with subscriber terminals 14. Each central terminal 12 and 
subscriber terminal 14 is associated with a service cell 16. 
The effective radiated power from each subscriber terminal 14 is controlled 
via feedback from the associated central terminal 12 so as to maintain the 
power level of the signal received at the corresponding central terminal 
12 at a predetermined level, such as -90 decibels below 1 milliwatt (dBm). 
Thus, the power level at each subscriber terminal 14 is a function of the 
location of the subscriber terminal 14 relative to the central terminal 
12. 
In a similar manner, the effective radiated power from each central 
terminal 12 may be controlled as a function of the location of the 
subscriber terminals 14 that are being serviced by the central terminal 12 
at any given time. For example, if the majority of active subscriber 
terminals 14 are located far from the central terminal 12, it may be 
necessary to increase the power of the signal radiated by the central 
terminal 12. This may be accomplished by decreasing the number of 
telecommunications channels that are being transmitted, such as to 
increase power for the remaining channels, or by increasing the power for 
certain channels and decreasing the power for other channels. In this 
manner, the amplification power of the central terminal may be optimized 
for use in serving the subscriber terminals of the cell. 
FIG. 2 is a frequency diagram 18 for a data transmission system in 
accordance with one embodiment of the present invention. Frequency diagram 
18 includes 3.5 MHZ frequency band 20, which is an inbound or outbound 
radio frequency band modulated by suitable means to occupy a predetermined 
portion of the radio frequency spectrum. For example, frequency band 20 
may be converted to occupy the radio frequency spectrum between 2.259 and 
2.2625 gigahertz in an outbound direction from the central terminal 12 to 
subscriber terminals 14, and to occupy the radio frequency spectrum from 
2.434 to 2.4375 gigahertz in an inbound direction from subscriber 
terminals 14 to the central terminal 12. Alternatively, frequency band 20 
may be used in accordance with licensing requirements for any suitable 
portions of the radio spectrum frequency. Frequency band 20 is used for 
transmitting data from a transmitter to a receiver. For example, frequency 
band 20 may be used to transmit data from a single transmitter to a single 
receiver, from a central transmitter to two or more receivers, or from two 
or more transmitters to a central receiver. 
Frequency band 20 is further divided into one slot of five trunk groups 22, 
each of which occupy one 700 kHz band of frequency band 20. Each trunk 
group provides the necessary bandwidth for transmitting telecommunications 
data by a suitable modulation techniques, such as to a group of 
subscribers. For example, code division multiple access, time division 
multiple access, quadrature phase shift keying, or other suitable data 
transmission techniques may be used alone or in combination to encode and 
transmit data between the central terminal and the subscriber terminals. 
In addition, the use of two or more trunk groups allows a data transmission 
system utilizing frequency diagram 18 to be easily organized in service 
areas and classes of service. For example, a predetermined number of trunk 
groups may be selected for provision of Integrated Service Digital Network 
service, while other trunk groups may provide dedicated 32,000 bits per 
second service and 64,000 bits per second service. Alternatively, 
predetermined trunk groups may provide service to predetermined areas, 
such that the effective radiated power level of some trunk groups may be 
increased or decreased to better serve the subscriber terminals in the 
associated service area. The assignment of trunk groups to service classes 
or service areas may also be performed dynamically, when service in those 
classes or service areas are required. 
In operation, a data communications system such as system 10 uses the 
available frequency spectrum in accordance with frequency diagram 18 in 
order to facilitate communications between a central terminal 12 and a 
plurality of subscriber terminals 14. The system utilizing frequency 
diagram 18 may include a single central terminal that is connected to the 
public switched telecommunications network by copper conductor, optical 
fiber, radio waves, or other suitable means. The central terminal is 
connected by radio waves to a suitable number of standby subscriber 
terminals and to a suitable number of active subscriber terminals for each 
trunk group 22. By way of example and not by limitation, the central 
terminal may be connected to 256 standby subscriber terminals and to 28 
active subscriber terminals. 
The 28 active subscriber terminals may each receive a 32 kilobit per second 
data stream that is encoded using a suitable wireless data transmission 
encoding technique, and is transmitted between the central terminal and 
the active subscriber terminals. Each 700 kHz trunk group 22 operates 
independently of the other trunk groups 22. This structure allows the 
number of trunk groups 22 to be increased or decreased as appropriate to 
accommodate a portion of the radio spectrum allocated by the licensing 
agency. In addition, the 700 kHz bandwidth may be further divided into 
sub-carrier bands in order to provide for efficient use of the available 
amplification power for each 700 kHz band and to improve the efficiency of 
data transmission in a multi-path environment. Depending upon the data 
transmission requirements of the wireless communication system, a greater 
or lesser number of sub-carrier bands may be used. 
In addition, each 700 kHz trunk group 22 may be amplified to varying levels 
or may be modulated to provide varying numbers of telecommunications 
channels in order to provide additional control for the provision of 
service to subscriber terminals 14. For example, central terminal 12 may 
increase the amplification of all channels of certain trunk groups 22 by 
up to 3 dB by decreasing the amplification of the channels in other trunk 
groups 22 by 3 dB. An additional 3 dB of gain can also be provided to the 
channels of predetermined trunk groups 22 by decreasing the number of 
channels carried per trunk group 22, such as from 32 to 16. The number of 
channels and amplification power levels of each trunk group 22 may be 
changed dynamically to provide improved signal quality and service as a 
function of subscriber access to system 10. 
FIG. 3a is a diagram of an exemplary embodiment of power levels for channel 
signals of trunk groups broadcast by a central terminal. All channels of 
each trunk group have the same nominal power level, such as 35.7 
milliwatts. The composite power level for an exemplary trunk group 
consisting of 28 trunks would thus be one watt. Thus, the subscriber 
terminals of service area 126 serviced by the central terminal will 
receive a weaker signal than the subscriber terminals of service area 122 
if they are located at a greater distance from the central terminal. 
Likewise, the subscriber terminals of service area 128 will receive a 
weaker signal than the subscriber terminals of service areas 122 and 126 
if service area 128 is at a greater distance from the central terminal 
than service areas 124 and 126. 
FIG. 3b is a diagram showing system usage and available power level 
adjustments for each trunk group to improve signal quality in accordance 
with the exemplary embodiment of the present invention shown in FIG. 3a. 
The number of subscriber terminals for service cell 120 with a central 
terminal 122 and three service areas, 124, 126, and 128, is shown in 
parentheses, e.g. service area 124 has 28 subscriber terminals. 
Cell size is established by the path loss between the central terminal 122 
and the subscriber terminals, by the transmit power of a channel signal, 
and by the minimum level at which the receiver achieves an acceptable bit 
error rate. This minimum level is known as the receiver threshold. The 
path loss is affected by environmental factors such as trees and 
buildings. The transmit power of a channel signal is determined by the 
power amplifier at the central terminal, which couples the signals for a 
predetermined number of channels to the antenna. The receiver threshold is 
related to the receiver design, but may be altered by intefering signals, 
such as signals generated by neighboring cells. Thus, cell size may be 
varied by controlling the transmit power of the signal channel. 
The total available power for each signal is set by the number of channels 
and by the maximum power output of the power amplifier. Power can be 
varied to trunk groups of channels to change the sub-cell service area. In 
this manner, subscriber terminals that are physically located close to the 
central terminal may be served by a sub-cell having a smaller service 
area, while subscriber terminals that are physically located farther away 
from the central terminal may be served by a sub-cell having a greater 
service area. In addition, sub-cell size may be varied as a function of 
subscriber use to improve fade margin and susceptibility to interference. 
At the limit, the number of sub-cells may be equal to the number of active 
subscribers being serviced, and amplifier power may be allocated to a 
subscriber based upon a predetermined level of power for the location of 
the subscriber, taking into account path loss and variables. 
FIG. 4a shows the associated power level of the trunk group signals 
broadcast by central terminal for another exemplary embodiment of the 
present invention. The channel power levels of the trunk group for service 
area 134 and one of the trunk groups for service area 136 have been 
decreased by 3 dB, and the power level of one of the trunk groups for 
service area 136 has been increased by 3 dB. This change in power level in 
this exemplary embodiment is achieved by decreasing the amplification 
power for the channels in two trunk groups by a predetermined amount 
corresponding to 3 dB, and using the surplus power to increase the 
amplification power for the one increased trunk group by a predetermined 
amount corresponding to 3 dB. In this manner, the fixed total magnitude of 
power amplification may be re-allotted between trunk groups to increase 
the effective range of one trunk group while decreasing the effective 
range of other trunk groups. 
FIG. 4b shows exemplary locations of subscriber terminals for a service 
cell 130 with a central terminal 132 and three service areas, 134, 136, 
and 138 in accordance with the trunk group power levels shown in FIG. 4a. 
The number of subscriber terminals in each service area is shown in 
parentheses, e.g. service area 134 has 28 subscriber terminals. Thus, the 
number and location of subscriber terminals serviced by central terminal 
132 is identical to the number and location of subscriber terminals 
serviced by central terminal 122 of FIG. 3b. Nevertheless, the relative 
size of service cell 130 may be greater than that of service cell 120, as 
a function of the amplification power used to reach the subscriber 
terminals that are located within service area 138. 
If the service cell is of the same size and has the same geographical 
features as service cell 120 of FIG. 3b, then the subscriber terminals of 
service area 138 serviced by central terminal 132 receive a stronger 
signal than subscriber terminals for the corresponding area 128 of the 
system shown in FIG. 3b. Likewise, the 28 subscriber terminals of service 
area 134 and 28 of the 56 subscriber terminals of service area 136 receive 
a weaker signal than for the corresponding areas of the system shown in 
FIG. 3b. 
The allocation of amplification power shown in FIGS. 4a and 4b may be used 
when the signal quality of the signal received at subscriber terminals in 
service area 138 is worse than the signal quality of the signal received 
at subscriber terminals in service area 134. Subsequent modifications may 
likewise be made if the signal quality of the signal received by 
subscriber terminals in service areas 134 or 136 becomes worse than the 
signal quality of the signal received by subscriber terminals in service 
area 138. 
FIG. 5a shows yet another exemplary embodiment of the associated power 
levels for trunk group signals broadcast by a central terminal. The 3 dB 
increase for the channels of the first trunk group for service area 148 is 
realized in this exemplary embodiment by decreasing the number of channels 
serviced by that trunk group from 28 to 14, thus permitting a power 
increase of 3 dB. The 6 dB increase for the second trunk group for service 
area 148 is realized in this exemplary embodiment by re-allocating the 
power from the trunk groups for areas 144 and 146, for a 3 dB gain, and by 
decreasing the number of channels from 28 to 14 and increasing the power 
of the remaining channels by 3 dB, for 6 dB of total system gain for the 
channels. 
In this manner, the 28 subscriber terminals of service area 148 serviced by 
the central terminal receive a stronger signal than for the corresponding 
areas of the system shown in FIG. 3b, assuming identical cell geography. 
The system for increasing the signal strength of the present invention may 
also be used to compensate for signal degradation caused by environmental 
factors, multi-path effects, subscriber terminal locations, or other 
factors. 
FIG. 5b shows yet another exemplary embodiment of a service cell 140 with a 
central terminal 142 and three service areas, 144, 146, and 148. The 
number of subscriber terminals in each service area is shown in 
parentheses, e.g. service area 144 has 28 subscriber terminals. Thus, the 
number and location of subscriber terminals serviced by a central terminal 
142 is different from the number and location of subscriber terminals 
serviced by central terminal 122 of FIG. 3b and central terminal 132 of 
FIG. 4b. 
FIG. 5b is one example of the changes in the number of subscriber terminals 
over time in each service area that may occur. The present invention 
allows these changes to be accommodated by re-allocating amplification 
power and telecommunications channels to trunk groups, such that improved 
signal quality may be obtained. 
The allocation of amplification power shown in FIG. 5a may be used when the 
signal quality of the signal received at subscriber terminals in service 
area 148 is worse than the signal quality of the signal received at 
subscriber terminals in service area 144 and 146. Subsequent modifications 
may likewise be made if the signal quality of the signal received by 
subscriber terminals in service areas 144 or 146 becomes worse than the 
signal quality of the signal received by subscriber terminals in service 
area 148. 
In addition to the three exemplary embodiments shown in FIGS. 3a, 3b, 4a, 
4b, 5a, and 5b, many other suitable combinations of channels per trunk and 
amplification power per trunk may be used in order to increase the signal 
quality of the communications system of the present invention. At the 
lower limit, a single power level and service area may be designated to 
simplify tracking and processing of subscriber terminals. At the upper 
limit, the location of each subscriber terminal may be determined and a 
corresponding minimum power level may be assigned, such that each 
subscriber terminal has a dedicated service area. Additional amplification 
power may be allocated if available to increase signal quality. The number 
and power levels of the service areas may also be dynamically assigned so 
as to increase the signal quality for the average subscriber terminal 
without substantially increasing the administrative requirements for the 
system that would otherwise be needed if each subscriber terminal had a 
dedicated service area. 
FIG. 6 is a flow chart of a method 160 for providing access to a 
telecommunications system in accordance with one embodiment of the present 
invention. Method 160 may be used to test the signal quality of 
telecommunications channels and to adjust the number of telecommunications 
channels per trunk group and the amplifier power allocated to one or more 
trunk groups in order to improve signal quality. 
Method 160 begins at 162, where the signal quality of channels in a trunk 
group is tested at subscriber receivers. If it is determined that the 
trunk group signal quality is acceptable at step 164, the method 
terminates at step 166. Otherwise, the method proceeds to step 168. 
At step 168, it is determined whether the number of telecommunications 
channels for the trunk group being tested is less than one-half of the 
maximum number of allowable telecommunications channels. If the number of 
telecommunications channels is less than one-half of the maximum, the 
method proceeds to step 170. At step 170, the number of telecommunications 
channels for the trunk group being tested is decreased to one-half of the 
previous value while the composite power level is maintained. For example, 
if the number of telecommunications channels for the trunk group was 32, 
it is decreased to 16. The method then proceeds to step 172. 
At step 172, it is determined whether the signal quality is acceptable. If 
the signal quality is acceptable, the method proceeds to step 174 and 
terminates. Otherwise, the method proceeds to step 176. In addition, if 
the number of telecommunications channels for the trunk group being tested 
is determined to be greater than one-half of the maximum allowable number 
at step 168, the method proceeds directly to step 176. 
At step 176, it is determined whether power is available for use in other 
trunk groups, such as if one of the other trunk groups provides 
telecommunications channels to subscriber terminals that are physically 
located close to the central terminal. An example of such subscriber 
terminals would be those within zones 124, 134, or 144 of FIGS. 3a, 4a, or 
5a, respectively. If a trunk group having this characteristic is currently 
operating at the nominal power level, such as that shown in FIGS. 3b, 4b, 
and 5b, then the power to that trunk group may be decreased to a level 
such as the -3 dB level as shown in FIGS. 3b, 4b, and 5b. 
At step 178, the amplifier power for the trunk group having surplus power 
is decreased to the minus 3 dB level. The method then proceeds to step 
180, where the extra amplifier power is allocated to the trunk group being 
tested to increase the signal quality. The method then terminates at step 
182. 
In operation, the signal quality for the telecommunications channels 
carried by a trunk group is tested. If the signal quality is acceptable, 
the method terminates. Otherwise, it is determined whether the number of 
telecommunications channels for that trunk group may be decreased. If the 
number of telecommunications channels for the trunk group being tested may 
be decreased, this is performed, and it is determined whether the signal 
quality is acceptable. If the signal quality is acceptable, the method 
terminates. 
If the signal quality is not acceptable, or if the number of 
telecommunications channels for the trunk group being tested cannot be 
decreased, it is determined whether amplification power is available from 
other trunk groups. If excess amplification power is available from other 
trunk groups, the amplification power for those trunk groups is decreased 
and the amplification power for the trunk group being tested is increased. 
The method of FIG. 6 is exemplary, such that any suitable change in 
amplification power or number of channels may be utilized. Amplification 
power may be increased or decreased in increments other than +/-3 dB. The 
number of channels per trunk group may also be increased or decreased by 
amounts other than a factor of two. 
FIG. 7 is a flow chart of a method 200 for providing access to a 
telecommunications system in accordance with one embodiment of the present 
invention. Method 200 may be used when a call is placed to or from a 
standby subscriber terminal. 
Method 200 starts at step 202, where a service request is received at a 
central terminal to place a call to a standby subscriber terminal, or 
place a call from a standby subscriber terminal. The method then proceeds 
to step 204, where it is determined whether a telecommunications channel 
slot is presently available in any of the trunk groups servicing the 
subscriber terminal. If a telecommunications slot is available, the method 
proceeds to step 206. At step 206, the call is assigned to the available 
telecommunications channel slot, and the method terminates. 
If a telecommunications channel slot is not presently available, the method 
proceeds to step 208. At step 208, it is determined whether the 
telecommunications channels can be increased for one of the trunk groups. 
For example, one of the trunk groups may be operating at the +6 dB level 
shown in FIGS. 3b, 4b, or 5b. For trunk groups operating at this level, it 
is possible to double the number of telecommunications channels with a 
corresponding decrease in effective radiated power level to +3 dB. This 
effective radiated power level may be sufficient to overcome any signal 
quality problems that previously existed and that caused the effective 
radiated power level to be increased. If a trunk group has this effective 
radiated power level, the method proceeds to step 210. 
At step 210, the number of telecommunications channels for an acceptable 
trunk group is increased. The standby subscriber terminal is then assigned 
to one of the additional telecommunications channels slots available on 
that trunk group. The method then proceeds to step 212, where the signal 
quality for the telecommunications channels on that trunk group is 
checked. If the signal quality is determined that it be acceptable, the 
method proceeds to step 213 and terminates. Otherwise, the method proceeds 
to step 214. 
At step 214, it is determined whether the telecommunications channels for 
all trunk groups of the system may be optimized. For example, a 
predetermined period of time may have elapsed since the last time the 
telecommunications channels for all trunk groups have been optimized. If 
it is determined that the telecommunications channels for the trunk groups 
may be optimized, the method proceeds to step 218. 
At step 218, the power levels for the trunk groups are adjusted. For 
example, it may be determined that the subscriber terminals assigned to 
the telecommunication channels of one trunk group are all physically 
located close to the central terminal, such as the area shown by service 
areas 124, 134, and 144 of FIGS. 3a, 4a, and 5a, respectively. The 
amplification power for a trunk group having this characteristic is 
decreased to a level corresponding to the -3 dB level of FIGS. 3b, 4b, or 
5b. The method then proceeds to step 220. At step 220, the number of 
telecommunications channels for the trunk group that is currently 
operating at the +3 dB level shown in FIGS. 3b, 4b, and 5b, is increased. 
Doubling the number of telecommunications channels for such a trunk group, 
while keeping the composite power of the trunk group constant, will cause 
the effective radiated power level of each channel to drop to the nominal 
level. The amplification power for this trunk group is then increased to 
bring the effective radiated power level for the trunk group with the 
increased number of channels to be increased back up to +3 dB. The method 
then proceeds to step 222. 
At step 222, the standby subscriber terminal is assigned to the additional 
telecommunications channel of the trunk group with the increased number of 
telecommunications channels from step 220. The method then proceeds to 
step 224, where the signal quality of all of the effected trunk groups is 
checked. If it is determined that the signal quality is acceptable, the 
method proceeds to step 226 and terminates. Otherwise, the method proceeds 
to step 216. 
If it is determined at step 214 that there are no trunk groups that may 
have optimized telecommunications channels, or if the signal quality of 
optimized trunk groups is determined to be unacceptable at step 224, The 
method proceeds to step 216. At step 216, a busy signal is transmitted to 
the caller. The method then terminates. 
The method of FIG. 7 is exemplary, such that any suitable change in 
amplification power or number of channels may be utilized. Amplification 
power may be increased or decreased in increments other than +/-3 dB. The 
number of channels per trunk group may also be increased or decreased by 
amounts other than a factor of two. 
In operation, a call is placed to a standby subscriber terminal or from a 
standby subscriber terminal, requiring an additional telecommunications 
channel. If a telecommunications channel is available, the call is 
assigned to that slot. Otherwise, it is determined whether a trunk group 
is operating at an effective radiating power level that would allow the 
number of telecommunications channels to be increased without affecting 
the power level of other trunk groups. If such a trunk group is available, 
the telecommunications channels for that trunk group are increased, and 
the call is assigned to one of the additional telecommunications channels. 
The signal quality is also checked to verify that an acceptable level of 
signal quality is available. 
If a trunk group is not available with excess power and channel capacity, 
it is determined whether the amplification power for a trunk group may be 
decreased and provided to another trunk group such that the number of 
channels may be increased without a corresponding decrease in signal 
quality. If this condition exist, the power is reallocated between trunk 
groups, and the number of telecommunications channels for the other trunk 
group is increased accordingly. The standby subscriber terminal is then 
assigned to one of the additional telecommunications channels, and the 
signal quality is verified to determine whether a decrease in acceptable 
signal quality has occurred. If the signal quality is determined to be 
acceptable, the method terminates. Otherwise, a busy signal is transmitted 
indicating that no available telecommunications channels may be created or 
assigned to the standby subscriber terminal. 
The present invention provides many important technical advantages. One 
important technical advantage of the present invention is a method for 
improving the quality of data communications that allows the number of 
telecommunications channels carried by a trunk group to be dynamically 
increased and decreased. Another important technical advantage of the 
present invention is a system for transmitting data that allows the 
amplification power levels of trunk groups to be dynamically assigned. 
Although a particular embodiment has been described herein, it will be 
appreciated that the invention is not limited thereto and that many 
modifications and additions thereto may be made within the scope of the 
invention as defined by the following claims.