Patent Description:
The present disclosure describes an antenna subsystem that can be used in either a two-hop or three-hop repeater system to optimize the gain of the repeater by increasing the isolation between the donor and server antennas.

Typically, repeater products maximize isolation between the donor and server antennas through the use of highly directive antennas that point away from each other. However, with multiband antennas that cover broad frequency ranges (e.g. from <NUM> to <NUM>), the size of such highly directive antennas prohibits such an arrangement. In a three hop repeater, the separation between the donor and server antennas helps to increase this isolation. However, normally directional antennas are used even in three hop repeaters to improve isolation and maximize system gain. <CIT> discloses a wireless repeater with an antenna array which determines the antenna weights using an error minimizing algorithm to modify the spatial selectivity of the antenna array to reduce interference and improve the quality of signal reception.

The <CIT> disclosed a repeater system with donor and server antenna arrays and an antenna weight computation module configured to perform calculations of antenna weights for the donor and server antenna arrays. The calculations using one of an error minimizing algorithm and an adaptive metric optimization algorithm.

Disclosed is an antenna subsystem that can be used in either a two-hop or three-hop repeater system to optimize the gain of the repeater by increasing the isolation between the donor and server antennas.

Preferred embodiments of the invention are stipulated in the dependent claims. While several embodiments and/or examples have been disclosed in this description, the subject matter for which protection is sought is strictly and solely limited to those embodiments and/or examples encompassed by the scope of the appended claims. Embodiments and/or examples mentioned in the description that do not fall under the scope of the claims are useful for understanding the invention.

The accompanying drawings show certain aspects of the subject matter disclosed herein and, together with the description, help explain some of the principles associated with the disclosed implementations.

In some implementations, a system and method utilizes omni-directional antennas at both the donor and server sides. Increased isolation is obtained by using additional degrees of freedom in the antenna design to maximize isolation. For example, in some implementations, at the donor side, a system uses a vertically polarized omni-directional antenna. Additionally or alternately, at the server side, the system can deploy two antennas, one with vertical polarization and one with horizontal polarization. The system can then automatically determine which of the polarizations will yield the biggest isolation and therefore the best system gain.

The degrees of freedom that can be utilized are not limited to polarization. Other orthogonal options may be used as well. For example the donor and server antennas could each have multiple orthogonal beam patterns such as the beam patterns that can be achieved using a circular array antenna. The system could then search through all the combinations of donor and server antenna patterns to find the one that will yield the biggest isolation between donor and server and therefore the highest system gain.

In addition to the isolation, other cost functions may also be used to optimize the antennas used. For example, a cost function to maximize the output power level at the server antenna can be used. In this case, the cost function will take into account the isolation between the donor and server antennas as well as the signal strength of a particular base station. The optimization may be performed in two stages, where the donor antenna subsystem is first optimized to provide the strongest input signal level and then the server antenna is optimized to achieve maximum isolation. The combination of maximum isolation plus maximum input signal could yield the highest output power at the server antenna. Alternatively, the input signal level and isolation may be jointly optimized to achieve the same effect. As an alternative to isolation and server antenna output power, the system may use a cost function that optimizes the signal-to-noise ratio of the signal at the output of the server antenna. In this case, the donor antenna sub-system will include a cost function that will adapt the antennas to null out interfering base stations. This action will improve the signal to noise ratio of the donor signal. The server antenna can then be adapted to optimize the isolation to provide maximum coverage of the best quality donor signal from the server antenna.

<FIG> shows a schematic of a basic system for an antenna sub-system for optimizing gain in a repeater in a multi-hop repeater system <NUM>.

In one specific embodiment in a three-hop repeater, the Donor Antenna Sub-system <NUM> consists of four vertically polarized omni-directional antennas, each being tuned to a specific frequency of operation. The Server Antenna Sub-system <NUM> consists of two dual-band antennas, tuned to the same frequencies as the Donor antennas <NUM>, but with horizontal and vertical polarization. During operation, the repeater <NUM> will measure the isolation between the donor and server <NUM> for the two different server antenna polarizations (cost function <NUM>) and then direct a processor to run an algorithm to maximize the isolation between the donor and server antenna sub-systems (Antenna optimization algorithm <NUM>) which will return the optimal gain for the system.

<FIG> is a flow diagram of an exemplary antenna optimization method 123A for optimizing gain in the system of <FIG>, as executed by a processor. The method 123A in <FIG> accepts a start state, as in <NUM>, and iterates through antenna sub-system configurations until a configuration that optimizes the cost function is found. From the initial, or start, state <NUM>, the method 123A tunes to the donor or server antenna's operating frequency, as in <NUM>. From there, the repeater (<NUM> in <FIG>) measures the inputs to the cost function, and the method 123A receives those input values, as in <NUM>. The inputs to the cost function may include the transmitting and receiving power levels, such as in dBm. The method 123A then calculates and stores the output of the cost function, as in <NUM>. After a number of iterations, the output values of the cost function are compared. During each iteration, the processor that executes the method 123A may be associated with one or more memory components where the cost function outputs (and optionally the input values) may be stored.

After storing the cost function output for a given set of inputs, the processor determines, according to an algorithm, whether or not there are any further antenna sub-systems for which the cost function calculation must be run, as in <NUM>. The system has more than one configuration, and the algorithm will proceed to calculate the cost function for each configuration until cost function outputs have been calculated for all configurations. Accordingly, if the processor executing the method 123A has not yet exhausted all antenna sub-system configurations, the processor executing the method 123A will cause the system to change to the next antenna sub-system configuration, as in <NUM>. The processor executing the method123A will then receive the measured inputs to the cost function, as in <NUM>; calculate and store the output of the cost function, as in <NUM>; and once again determine whether any further antenna sub-system configurations need to be evaluated for their cost function values, as in <NUM>.

Once the processor executing the method 123A has evaluated all antenna sub-system configurations, the cost function outputs stored in memory are compared, the configuration that best optimizes the cost function is selected, and then the system is directed to set the antenna sub-systems to the configuration that corresponds to the best optimized cost function output values, as in <NUM>. The processor executing the method does not start another iteration of the method until a user or other portion of the system reconfigures one or both antenna sub-systems or a portion of the system that would alter the cost function outputs, as in <NUM>.

<FIG> is a flow diagram of another exemplary antenna optimization method 123B for optimizing gain in the system of <FIG>. The method 123B in <FIG> begins with an initial configuration of the donor and server antenna sub-systems, as in <NUM>, and continually optimizes the cost function calculation by altering the antenna sub-system configurations. From the initial, or start, state <NUM>, the method 123B includes tuning the donor or server antenna's operating frequency, as in <NUM>. From there, the inputs to the cost function are measured, and those input values, as in <NUM>, are received by a processor executing the method. The inputs to the cost function may include the transmitting and receiving power levels, for example in dBm. The optimized antenna sub-system settings are determined based upon an optimization of the cost function, as in <NUM>. The antenna sub-system configuration that optimizes the cost function is passed along and applied to cause the antenna sub-systems to conform to the optimized configuration, as in <NUM>. The gain, based upon the initial values of components of the system, is also optimized with the cost function.

This newly optimized system is used as the starting point for the next iteration of the method 123B. Once again, the inputs to the cost function are received, as in <NUM>, and further changes to the antenna sub-system configuration are determined that will optimize the output from the cost function, as in <NUM>. These changes are applied, as in <NUM>, and the next iteration begins. The one or more configurations are iterated through. When no changes to the antenna sub-systems configuration can be determined that will further optimize the cost function at <NUM>, then no changes are applied in <NUM>. However, should the system be changed, such as by a user or a part of the system that is not influenced by the method 123B, then a new start or initial state <NUM> is defined and the method <NUM> progresses as described above. In this way, the method 123B is always optimizing the cost function, and thus finding the configuration of the system that optimizes system gain.

<FIG> are schematics showing various exemplary donor antenna (105A, 105B, 105C, 105D) and server antenna (110A, 110B, 110C, 110D) sub-systems for use with a system for optimizing gain.

<FIG> shows a schematic displaying a donor antenna sub-system 105A and a server antenna sub-system 110A in which the physical orientation and null position of the antenna sub-system components can be varied. In the donor antenna sub-system 105A, there can be two or more antenna elements 106A and 106B. These antenna elements 106A and 106B may have different physical orientations with respect to each other. In the case where there are more than two antenna elements, there may be a pattern to the difference in orientation between any two adjacent antenna elements. Conversely, when more than two antenna elements are present, there may be no distinct pattern to the difference in orientation between any two adjacent antenna elements. Each antenna element 106A, 106B may receive a signal that is passed through a weighting coefficient multiplier, 107A, 107B, respectively. The weight assigned to each signal can be optimized to achieve the best output from the cost function (i.e. the best gain for the system). The weighted signals can then be passed to a summing unit <NUM> that then passes along a composite signal as the donor antenna sub-system output <NUM> to the rest of the system.

Similarly, in <FIG>, the server antenna sub-system 110A can have there can be two or more antenna elements 111A and 111B. These antenna elements 111A and 111B may have different physical orientations with respect to each other. In the case where there are more than two antenna elements, there may be a pattern to the difference in orientation between any two adjacent antenna elements. Conversely, when more than two antenna elements are present, there may be no distinct pattern to the difference in orientation between any two adjacent antenna elements. Each antenna element 111A, 111B may receive a signal that is passed through a weighting coefficient multiplier, 112A, 112B, respectively. The weight assigned to each signal can be optimized to achieve the best output from the cost function, and in turn the optimal gain from the system. The weighted signals can then be passed to a summing unit <NUM> that then passes along a composite signal as the server antenna sub-system output <NUM>.

<FIG> shows a schematic displaying a donor antenna sub-system 105B and a server antenna sub-system 110B in which the mode or pattern of the antenna sub-system components can be varied. The donor antenna sub-system 105B can have one or more antenna elements 106A that accept an incoming signal that can be processed by more than one mode of resonance. In <FIG>, the signal is shown to have four modes that the system can switch between to find an optimal setting on the donor antenna sub-system. After the signal is modified by a mode, it is passed to the rest of the system as the donor antenna sub-system output <NUM>. The server antenna sub-system 110B has a similar configuration with one or more antenna elements 111A, multiple modes to select from, and a server antenna sub-system output <NUM>. A mode that optimizes the performance of the system can be selected from the multiple modes of the server antenna sub-system 110B. The total number of possible combinations depends on the number of possible modes at both the donor antenna sub-system 105B and the server antenna sub-system 110B. The product of the number of modes at each sub-system yields the total number of possible combinations that can be iterated through to find the overall configuration that optimizes the cost function, and thus the gain of the system.

<FIG> shows a schematic displaying a donor antenna sub-system 105C and a server antenna sub-system 110C in which the polarization of the antenna sub-system components can be varied. The donor antenna sub-system 105C has at least one antenna element 106A that sends the received signal along to the rest of the system as the donor antenna sub-system output <NUM> without any modification. The server antenna sub-system 110C has two or more antenna elements with different polarization. In <FIG>, the server antenna sub-system 110C antenna elements include an antenna element with horizontal polarization 115A and an antenna element with vertical polarization 115B. The output from each antenna element leads to a switch <NUM>. The processor executing the method can cause the server antenna sub-system switch <NUM> to toggle between the different polarizations 115A and 115B while the cost function is calculated for each configuration. Once the configuration is found that optimizes the cost function, the switch is toggled to the appropriate position, and the resulting signal is the output <NUM> from the server antenna sub-system.

<FIG> shows an embodiment of the invention. It shows a schematic displaying a donor antenna sub-system 105D and a server antenna sub-system <NUM> in which the sectors of the antenna sub-system components can be varied. The donor antenna sub-system 105D has one or more antenna elements 120A and 120B that may send the received signal along to the rest of the system as the donor antenna sub-system output <NUM> without any modification. A switch <NUM> may be used to toggle between the donor antenna elements 120A and <NUM>. The server antenna sub-system 110D has two or more antenna elements with different sectors 130A and 130B. In <FIG>, the server antenna sub-system 110D includes a switch <NUM> for toggling between the different server antenna elements 130A and 30B. The processor executing the method can cause the donor antenna sub-system switch to toggle between the different sectors, each associated with an antenna element 120A and 120B, as well as causing the server antenna sub-system switch to toggle between the different sectors, each associated with an antenna element 130A and 130B, while the cost function is calculated for each configuration. Once the configuration is found that optimizes the cost function, the switches <NUM> and/or <NUM> may be toggled to the appropriate position, and the resulting signal is the output <NUM> from the server antenna sub-system. The number of sectors and/or antenna elements at each antenna sub-system may differ. For example, each antenna sub-system may have two sectors. Alternatively, the donor antenna sub-system may have two sectors and the server antenna sub-system may have more than two sectors, or vice-versa.

A system (<NUM> in <FIG>), can employ of the combinations of donor and server antenna sub-systems described above. In some implementations, a system can include more than one of the combinations of donor and server antenna sub-systems described above.

Claim 1:
An antenna system (<NUM>) for optimizing gain of a repeater (<NUM>) comprising:
a donor antenna sub-system (<NUM>, 105D) configured to accept an incoming signal and to operate in one or more donor operational configurations;
a server antenna sub-system (<NUM>, 110D) configured to relay an optimized version (<NUM>) of the incoming signal and to operate in one or more server operational configurations;
a processor to determine a configuration for the antenna system for generating the optimized version of the incoming signal, the configuration being based on an optimized value of a cost function (<NUM>) of operating the donor antenna sub-system in each of the one or more donor operational configurations and the server antenna sub-system in each of the one or more server operational configurations, the cost function being based on one or more operational inputs,
wherein both the donor and server operational configurations include multiple antenna elements each having a different sector, the antenna system further comprising:
a first switch (<NUM>) configured to toggle between the different donor sectors (120A, 120B); and
a second switch (<NUM>) configured to toggle between the different server sectors (130A, 130B),
wherein the processor is configured to:
cause the first switch to toggle between the different donor sectors;
cause the second switch to toggle between the different server sectors;
calculate the cost function for each configuration;
determine the configuration for the antenna system for generating the optimized version of the incoming signal; and
cause the first and second switches to toggle to the appropriate position according to the determined configuration.