Directed maximum ratio combining and scheduling of high rate transmission for data networks

Disclosed are systems and methods which proactively determine particular access terminals which are compatible for simultaneous communication at a high data rate and preferred embodiments provide scheduling of simultaneous communications such that data communication is optimized. Preferred embodiments of the present invention utilize a multiple element antenna array, and associated array response vectors associated with narrow antenna beam forming techniques, (adaptive array antennas) to identify compatible access terminals, such as by calculating a correlation between particular access terminals and, preferably utilizing a predetermined correlation threshold, identifying suitably uncorrelated access terminals. Using such information embodiments of the present invention may determine which particular access terminals may be controlled to transmit at a high data rate at a same time. Embodiments of the present invention are operable with respect to the forward and/or reverse links.

TECHNICAL FIELD

The present invention relates to, and finds utility within, wireless information communications systems and, more particularly, providing implementation of directed maximum ratio combining and scheduling of access terminal communication.

BACKGROUND OF THE INVENTION

In communication networks it is often desirable to provide optimized data communication (e.g., a plurality of simultaneous individual communication sessions and/or a high data communication rate while maintaining an acceptable signal quality). For example, wireless communication networks implementing CDMA communication protocols provide for a plurality of access terminals (ATs) transmitting simultaneously to thereby provide at least a portion of available data communication capacity to each of a plurality of ATs. In a cellular telephony network, where a plurality of ATs disposed in a particular cell or sector of a cell have data to transmit, each such AT may be permitted to transmit such data simultaneously, irrespective of the operation of the remaining ATs in the plurality.

However, wireless communication networks often are limited with respect to the amount of interference which may be tolerated in providing data communication. For example, the above mentioned systems utilizing CDMA protocols are typically interference limited in that a maximum number of ATs which may be simultaneously accommodated while maintaining a minimum acceptable signal quality is a function of the interference energy present with respect to each such AT's signal. Accordingly, wireless communication networks may implement a technique of substantially arbitrarily reducing the data rate of all or particular ones of the ATs as a function of interference energy when a number of such ATs are being provided simultaneous communications.

Systems implementing such techniques include cdma2000 1XRTT systems and QUALCOMM HDR (high data rate) systems. For example, QUALCOMM HDR systems generally allow simultaneous communications with respect to a plurality of ATs at a high data rate and monitors the communication channels. With QUALCOMM HDR systems, any and all ATs having data to communicate within a particular area, such as within the boundaries of a cell or a sector of a cell, may be allowed to transmit simultaneously. If it is determined that too much interference is being experienced, particular ATs may be restricted to a low data rate, such as based upon a random variable generated by the system. AT data rates will continue to be reduced until an acceptable level of interference is experienced.

It should be appreciated, however, that such systems may not provide optimized data communication. For example, although perhaps providing improved data communication capacity over a system in which a single AT is provided communication at a high data rate or a system in which a plurality of ATs are provided communication at a low data rate, such systems simply accommodate as many simultaneous communication sessions as possible typically without consideration of the effects upon data communication rates experienced. Accordingly, such systems are reactionary in their operation, responding to communication demands by the various ATs, and do not proactively operate to optimize data communication.

Accordingly, a need exists in the art for systems and methods providing optimized data communication with respect to a plurality of ATs.

BRIEF SUMMARY OF THE INVENTION

The present invention is directed to a system and method which proactively determines particular ATs, of a plurality of ATs having data associated therewith for communication, which are compatible for simultaneous communication at a high data rate, referred to herein as directed maximum ration combining (DMRC). Preferably, the present invention determines such compatible ATs and operates to schedule simultaneous communications such that data communication is optimized. For example, a preferred embodiment of the present invention provides structure for calculating compatibility between various ATs and protocols for selecting specific groups of ATs for simultaneous communication in an efficient manner.

Preferred embodiments of the present invention utilize a multiple element antenna array, and associated array response vectors associated with narrow antenna beam forming techniques, (adaptive array antennas) to identify compatible ATs. Specifically, by analyzing such array response vectors preferred embodiments of the invention may calculate a correlation between particular ATs and, preferably utilizing a predetermined correlation threshold, may identify suitably uncorrelated ATs. Using such information embodiments of the present invention may determine which particular ATs may be controlled to transmit at a high data rate at a same time, instead of allowing all ATs to transmit simultaneously as in prior art systems. Accordingly, an arrangement of a plurality of particular ATs is selected and controlled to transmit simultaneously which, although perhaps experiencing mutual interference, each such AT will cause less mutual interference and therefore allow a high data rate to be used by all selected ATs. Compatible ATs which are identified according to a preferred embodiment of the invention are preferably scheduled for simultaneous communication using a high data rate during a next time interval, such as during a next communication burst period, communication frame, communication super frame, or the like.

Embodiments of the present invention are operable with respect to the forward and/or reverse links. For example, a preferred embodiment of the present invention operable with respect to a cdma2000 1XRTT system assigns supplemental channels (SCHs) utilized in both the forward and reverse links to provide optimized forward link capacity as well as optimized reverse link capacity.

Preferably, embodiments of the present invention implement circuitry adapted to efficiently make AT compatibility determinations. Specifically, preferred embodiments allow for implementation not only at a reasonable expense, but facilitate operation in a real time environment in which highly mobile ATs are experiencing rapid changes in their associated communication channel.

A preferred embodiment of the present invention utilizes an infinite impulse response (IIR) filter having instantaneous, preferably normalized, correlation information of a plurality of array response vectors, each of which is associated with a particular AT, applied thereto. For example, a preferred embodiment provides an instantaneous compatibility coefficient between two array response vectors using the product of a first array response vector matrix and the conjugate of a second array response vector matrix and squaring the absolute value thereof. The instantaneous compatibility coefficient is preferably normalized, e.g., normalized to have enough precision for fixed point implementation. This preferred embodiment may provide this normalized instantaneous compatibility coefficient and a filtered normalized compatibility coefficient from a previous time interval n−1 to an IIR filter to provide a filtered correlation between the two array response vectors, and therefore between the two ATs associated with the array response vectors, at a current time interval n. Additionally, this embodiment preferably provides a reference compatibility coefficient with respect to one of the two array response vectors using the product of the first array response vector matrix and the conjugate of the first array response vector matrix and squaring the absolute value thereof. The reference compatibility coefficient is preferably normalized. The preferred embodiment may provide this normalized reference compatibility coefficient and a filtered normalized reference compatibility coefficient during a previous time interval n−1 to an IIR filter to provide a filtered reference correlation at a current time interval n.

Preferably, the filtered correlation between the two array response vectors at current time interval n is normalized and compared to the product of the filtered reference correlation and a threshold value to determine if the two ATs associated with the array response vectors are potentially compatible for simultaneous communications. This embodiment of the present invention preferably also performs the above process, reversing the array response vector for which the conjugate is used and the array response used in determining the reference correlation coefficient in the above product computation, to determine if each of the two ATs is compatible with the other AT according to the present invention. If each such normalized filtered correlation between the two array response vectors at current time interval n compares favorably to the threshold value, the two associated ATs are preferably identified for simultaneous communication.

Another preferred embodiment of the present invention preferably normalizes array response vectors associated with ATs with respect to a sector beam. A product of normalized array response vector information associated with a first AT and the conjugate of normalized array response vector information associated with a second AT is preferably determined to thereby provide a normalized compatibility coefficient. According to a preferred embodiment, the normalized compatibility coefficient is rescaled by a predicted average digital gain unit (DGU). A product of the normalized array response vector information associated with the first AT and the conjugate of the normalized array response vector information associated with the first AT is preferably determined to thereby provide a normalized reference compatibility coefficient. According to a preferred embodiment, the normalized reference coefficient is rescaled by a predicted average digital gain unit (DGU).

According to this preferred embodiment, the compatibility determination with respect to particular ATs is made with reference to the data rate. For example, in a preferred embodiment the quotient of the rescaled compatibility coefficient and the rescaled reference coefficient is multiplied by a data rate scalar, such as may be provided by the quotient of an intended data rate and a minimum channel data rate, and compared to a threshold value to determine if the two ATs associated with the array response vectors are potentially compatible for simultaneous communications. This embodiment of the present invention preferably also performs the above process, reversing the array response vector information for which the conjugate is used and the array response used in determining the reference correlation coefficient in the above product computation, to determine if each of the two ATs is compatible with the other AT according to the present invention. If each such normalized filtered correlation between the array response vector information at current time interval n compares favorably to the threshold value, the two associated ATs are preferably identified for simultaneous communication.

Embodiments of the present invention are adapted to accommodate more than two simultaneous beams in the forward and/or reverse links. Accordingly, the present invention may implement compatibility analysis, substantially as described above, with respect to a number of ATs in excess of two to determine if the multiple ATs are compatible and may be served in a single service group.

From the above, it should be appreciated that the present invention provides for optimized data communication with respect to a plurality of ATs through implementing directed maximum ration combining techniques and scheduling of AT communication.

DETAILED DESCRIPTION OF THE INVENTION

Systems and methods of the present invention preferably operate to proactively determine particular communication terminals, communication nodes, subscriber units, or other information communication sources or targets, collectively referred to herein as access terminals (ATs), which are compatible for simultaneous communication at a high data rate, referred to herein as directed maximum ration combining (DMRC). Preferably, the present invention determines such compatible ATs and operates to schedule simultaneous communications such that data communication is optimized.

For example, directing attention toFIG. 1, a communication system, such as cellular base transceiver station (BTS)100, may provide wireless communication within a service area, such as cell110, to a plurality of ATs, AT121–125. Airlink channels may be established between BTS100and ATs121–125using a multiple element antenna array, such as may be provided by adaptive array antenna panels101–103, having a plurality of antenna elements disposed in a predetermined geometry suitable for use in beamforming by applying beamforming weighting (phase and/or amplitude) with respect to signals of antenna elements of the array. Accordingly, communication signals associated with each of ATs121–125, whether in the forward or reverse links, may each have associated therewith an array response vector providing information with respect to a wireless communication signal as received at or provided to antenna elements of the antenna array, such as angle of arrival (AOA) information. One array response vector is preferably an M by 1 complex vector, where M corresponds to a number of antenna elements or antenna element columns providing communication with respect to an AT.

A preferred embodiment of the present invention provides structure for calculating compatibility between various ATs and protocols for selecting specific groups of ATs for simultaneous communication in an efficient manner. Specifically, by analyzing array response vector information preferred embodiments of the invention may calculate a correlation between particular ATs and may identify suitably uncorrelated ATs. Using such information embodiments of the present invention may determine which particular ATs may be controlled to communicate at a high data rate at a same time, instead of allowing all ATs to communicate simultaneously as in prior art systems. Accordingly, an arrangement of a plurality of particular ATs, or a service group, is selected and controlled to communicate simultaneously.

For example, each of ATs121–125may have data for transmission to BTS100at a particular point in time. However, if each AT is permitted to transmit at this same point in time, mutual interference may result in various ones of the ATs experiencing excessive interference, e.g., bit error rates may be too high due to interference. As may be appreciated fromFIG. 1, AT121and/or AT122may experience unacceptable levels of interference energy from the other one of AT121and AT122. Similarly, AT124and/or AT125may experience unacceptable levels of interference energy from the other one of AT124and AT125. However, it may be possible to allow each one of the combination of AT121, AT123, and AT124, the combination of AT121, AT123, and AT125, the combination of AT122, AT123, and AT124, or the combination of AT122, AT123, and AT125to simultaneously communicate without experiencing unacceptable levels of mutual interference at any of the simultaneously communicating ATs. Accordingly, a group of such ATs may be selected for simultaneous high data rate communication during a subsequent time interval (a service group) and the remaining ones of the ATs may be scheduled for communication at a different suitable time interval. Moreover, through careful selection of the particular ATs of a service group, data rates used therewith may be maximized to thereby further optimize information communication.

Accordingly, an initial task in implementing directed maximum ratio combining according to the present invention may be to select particular ATs which can communicate simultaneously without causing excessive interference with respect to one another. Ideally, directed maximum ratio combining would utilize ATs with orthogonal array response vectors (ARVs) for simultaneous communication so that there would be no intra-cell interference with respect to these ATs and, therefore, a maximum carrier to interference ratio (C/I) and highest capacity with respect to these ATs. However, in practical system implementations, having a limited number of antenna elements and configurations, it is typically not feasible to achieve true orthogonality between many ATs. Accordingly, preferred embodiments of the present invention operate to select ATs having signals associated therewith which are substantially uncorrelated, although perhaps not achieving orthogonality, for simultaneous communication.

According to a preferred embodiment instantaneous compatibility coefficients are calculated for every combination of ATs having data for communication associated therewith. For example, where Aidenotes the array response vector of the ithAT (i=1, 2, . . . N) and Ajdenotes the array response vector of the jthAT (j=1, 2, . . . N), instantaneous compatibility coefficients with respect to each Aiand Aj(i≠j) are preferably calculated. A preferred embodiment instantaneous compatibility coefficient may be computed as |Ai*·Aj|, where Ai* denotes the conjugate transpose of Ai.

Preferred embodiments of the present invention, in addition to calculating compatibility coefficients for combinations of ATs, further calculate instantaneous reference coefficients for every AT having data for communication associated therewith. For example, instantaneous reference coefficients with respect to each Aiare preferably calculated. It should be appreciated that the instantaneous reference coefficients of the preferred embodiment provide the instantaneous calculations with respect to Aiand Ajwhere i=j, excluded from the instantaneous compatibility coefficients calculated above. A preferred embodiment instantaneous reference coefficient may be computed as |Ai*·Aj|.

The instantaneous compatibility coefficient is preferably compared to the instantaneous reference coefficient to determine if the corresponding ATs are compatible for simultaneous communication as a service group. For example, if |Ai*·Aj|<thresholdA*·|Ai*·Ai|, where thresholdA is a predetermined threshold value for identifying suitably uncorrelated ATs according to the present invention, it may be determined that ATjis compatible with ATi, and therefore a compatibility indicator Bijmay be set to true (1). However, since the signal power associated with each AT is different, such as due to fading and imperfect power control, it should be appreciated that the above determination that ATjis compatible with ATi(Bij=1) does not necessarily mean that AT1is compatible with ATj. In other words, even if ATjcontributed little interference to ATi, AT1may contribute a substantial amount of interference to ATj. Accordingly, the present invention preferably further determines if ||Aj*·Ai<thresholdA·|Aj*·Aj| to determine is ATiis compatible with ATj, and therefore that a compatibility indicator Bjimay be set to true (1).

It should, therefore, be appreciated that the compatibility indicator matrix B may be non-symmetrical, where the matrix B is as shown below.

In order to select only ATs which have a least amount of interference, or an acceptably low amount of interference, for simultaneous service as a service group, preferably only mutually compatible ATs are selected as a compatible combination. For example, establishing a compatible combination indicator Sij=Bij∩Bji, if Sij=1 AT1and ATjare a compatible combination according to a preferred embodiment of the present invention.

It should, therefore, be appreciated that the compatible combination indicator matrix S is symmetrical, where the matrix S is as shown below.

FIGS. 2–4show systems for a preferred embodiment implementation for making the above described compatibility determinations. However, it should be appreciated that various implementation issues have been addressed in the system implementations ofFIGS. 2–4. For example, instead of determining |Ai*·Aj|, the system implementation ofFIG. 2determines |Ai*·Aj|2to thereby avoid square root computation. Additionally, each array response vector A1is expressed in n bits as Ai≈A1nBits·2EXPa, wherein AinBitsis the most significant n bits of Aiand EXPa is the number of bits shifted to normalize AinBits. It should be appreciated that use of such an approximation of Aiprovides for normalization requiring only shifting of bits and, therefore, hardware implementation is simplified.

Directing attention toFIG. 2, a preferred embodiment system for use in implementing directed maximum ratio combining according to the present invention is shown as compatibility coefficient calculator200. Specifically, the preferred embodiment ofFIG. 2provides instantaneous coefficient calculator220, to accept array response vector information input and provide an instantaneous compatibility coefficient result, and IIR filter230, to accept instantaneous compatibility coefficient results for time n and filtered compatibility correlation results for time n−1 and provide a filtered compatibility correlation result for time n.

Preferably, two sets of in-phase and quadrature array response vector information are provided to instantaneous coefficient calculator220for providing a calculated instantaneous coefficient x[n], where x[n] is the instantaneous result of an input vector conjugate multiplied with an input vector at time n. For example, providing in-phase and quadrature array response vector information for array response vector Aiand in-phase and quadrature array response vector information for array response vector Ajto instantaneous coefficient calculator220, the output x[n] will be an instantaneous compatibility coefficient (|Ai*·Aj|2) of the present invention.

It should be appreciated that, in addition to providing instantaneous compatibility coefficients, instantaneous coefficient calculator220may be utilized in providing instantaneous reference coefficients utilized according to the present invention. For example, providing in-phase and quadrature array response vector information for array response vector Aitwice to instantaneous coefficient calculator220, the output x[n] will be the instantaneous reference coefficient (|Ai*·A1|2) of the present invention.

Accordingly, it should be appreciated that multiple ones of the system ofFIG. 2may be implemented in parallel to accommodate such calculations, if desired. Additionally or alternatively, particular ones of the ATs may be selected for compatibility calculations or excluded from compatibility calculations, such as through reference to AOA information or other information providing a reliable indication of suitability or non-suitability for simultaneous communication which does not require compatibility calculations according to the present invention.

Referring still toFIG. 2, it is assumed that in the illustrated system the array response vectors associated with the various ATs are known and are input in complex in-phase and quadrature form to instantaneous coefficient calculator200. Methods and structures for providing rapid beamforming for both uplink and downlink channels using adaptive antenna arrays are described in the above referenced United States patent applications entitled “Practical Space-Time Radio Method for CDMA Communication Capacity Enhancement”.

According to the illustrated embodiment, the in-phase and quadrature components for the input array response vectors are preferably multiplied by complex multiplier201, e.g., the real and imaginary parts of each matrix component of Aiconjugate are multiplied with the real and imaginary parts of each corresponding matrix component of Aj. Accumulators202and203preferably accumulate the real and imaginary parts, respectively, resulting from the matrix component multiplication of complex multiplier201. Absolute value and truncation circuits204and205preferably take the absolute value of the real and imaginary parts, respectively, and truncate the result to a predetermined number of most significant bits to maintain a certain bit package.

The real part truncated absolute values from absolute value and truncation circuit204and the imaginary part truncated absolute values from absolute value and truncation circuit205are preferably provided to complex conjugate adder206to implement a square. Accordingly, the output of complex conjugate adder206, and therefore instantaneous coefficient calculator220, x[n] may be |Ai*·Aj|2or |Ai*·Ai|2depending upon the vector information input at complex multiplier201.

In order to provide for meaningful comparisons according to a preferred embodiment of the present invention, the output of instantaneous coefficient calculator220is preferably normalized. Accordingly, the preferred embodiment system ofFIG. 2includes normalizer207coupled to instantaneous coefficient calculator220, accepting x[n] as an input and providing a corresponding normalized output X[n]. Preferably, normalization is accomplished using a relatively simple to implement bit shifting and truncating technique. Accordingly, normalizer207includes input m providing information with respect to a number of bits by which to shift x[n] to obtain normalized output X[n]. The normalizer value m is preferably derived as a function of a number of bit shifts utilized to normalize the array response vectors multiplied by instantaneous coefficient calculator220, e.g., EXPa and EXPb, and a number of bit shifts utilized to normalize a filtered correlation between the two array response vectors, e.g., EXPy. Specifically, according to the illustrated embodiment, m=(EXPa·2)+(EXPb·2)+EXPy.

It should be appreciated that the instantaneous result x[n] of instantaneous coefficient calculator220, e.g., |Ai*·Aj|2, and correspondingly X[n], may be relatively noisy. Accordingly a preferred embodiment of the present invention implements a 1storder infinite impulse response (IIR) filter, such as IIR filter230ofFIG. 2, to filter the noisy result. The preferred embodiment IIR filter230provides filtered correlation result y[n]=y[n−1]+k·(x[n]−y[n−1]), where y[n] is the filtered result at time n, and x[n] is the instantaneous result of at time n, and k is the filter coefficient determining the bandwidth of the IIR filter. To simplify the implementation, k is preferably chosen to be 2−kBits, where kBits is an integer determined by the filter bandwidth.

Preferably, the normalized instantaneous coefficient for time n (X[n]) and a filtered normalized coefficient from time n−1 (Y[n−1]) are provided to IIR filter230to provide a filtered correlation between the two array response vectors at time n (y[n]). For example, providing in-phase and quadrature array response vector information for array response vector Aiand in-phase and quadrature array response vector information for array response vector Ajto instantaneous coefficient calculator220, the output y[n] of IIR filter230will be a filtered compatibility correlation with respect to Aiand Aj(Zij).

It should be appreciated that, in addition to providing filtered compatibility correlation results, IIR filter230may be utilized in providing filtered reference correlation results utilized according to the present invention. For example, providing in-phase and quadrature array response vector information for array response vector Aitwice to instantaneous coefficient calculator220, the output y[n] of IIR filter230will be a filtered reference correlation with respect to Ai(Zii). Accordingly, as mentioned above, multiple ones of the system ofFIG. 2may be implemented in parallel to accommodate such calculations, if desired.

According to the illustrated embodiment, the normalized instantaneous coefficient for time n (X[n]) and the filtered normalized coefficient from time n−1 (Y[n−1]) are provided to low pass filter208of IIR filter230. Preferably low pass filter208provides filtering according to the equation x[n]−y[n−1]. The filtered result provided by low pass filter208is preferably provided to filter bandwidth circuit209, also preferably accepting filter bandwidth coefficient k, to thereby provide k·(x[n]−y[n−1]). The result of filter bandwidth circuit209is preferably provided to high pass filter210which provides filtering according to the equation y[n−1]+z[n], wherein z[n] is the input signal (here k(x[n]−y[n−1])). Accordingly, the filtered result (y[n]) provided by high pass filter210is preferably y[n−1]+k·(x[n]−y[n−1]).

In order to provide for meaningful comparisons according to a preferred embodiment of the present invention, the output of IIR filter230is preferably normalized. Accordingly, the preferred embodiment system ofFIG. 2includes normalizer211coupled to IIR filter230, accepting y[n] as an input and providing a corresponding normalized output Y[n]. Preferably, normalization is accomplished using a relatively simple to implement bit shifting and truncating technique. Accordingly, normalizer211preferably shifts the result y[n] a number of bits to place most significant bits of y[n] in desired positions to thereby prevent overflow and underflow conditions. The number of bit shifts utilized (EXPy) is preferably provided as feed back for use in normalizing the instantaneous coefficient x[n] as discussed above.

Directing attention toFIG. 3, a preferred embodiment system for use in implementing directed maximum ratio combining according to the present invention is shown as compatibility comparitor300. Specifically, the preferred embodiment ofFIG. 3provides comparison of a filtered reference correlation, e.g., Zii, multiplied by a predetermined threshold value, e.g., thresholdA, with a filtered compatibility correlation, e.g., Zij.

The correlation threshold, thresholdA, of the preferred embodiment is determined by a carrier to interference ratio (C/I) which is acceptable according to system operating parameters. However, to avoid long multiplication, thresholdA is preferably chosen such that thresholdA≈thresholdAmBits·2EXPthresholdA, where thresholdAmBitsare preferably 1 to 3 bits. Accordingly, assuming Zijis n bits representation, operation of thresholdA·Z1iis mBits by n bits multiplication followed by EXPthresholdA bits of shift. Such multiplication and shift functionality is preferably provided by multiplication and shift circuitry312having the filtered reference correlation Zii, such as may be provided by compatibility coefficient calculator200described above, and threshold value thresholdA, such as described above, input thereto.

Comparison circuit313preferably provides a determination as to whether the filtered reference correlation Ziias multiplied by the threshold value thresholdA is less than the filtered compatibility correlation Zij. If the filtered reference correlation Ziias multiplied by the threshold value thresholdA is less than the filtered compatibility correlation Zij, then the compatibility indicator Bijis preferably set to true (1) by compatibility comparitor300. However, if the filtered reference correlation Ziias multiplied by the threshold value thresholdA is not less than the filtered compatibility correlation Zij, then the compatibility indicator Bijis preferably set to false (0) by compatibility comparitor300.

However, as discussed above, since the signal power associated with each AT may be different, the above determination that ATjis compatible with ATi(Bij=1) does not necessarily mean that AT1is compatible with ATj. Accordingly, compatibility comparitor300is preferably further utilized to determine reverse compatibility through providing Zjjand Zjifor Ziiand Zij, respectively, and determining compatibility indicator Bji. Accordingly, as mentioned above with respect toFIG. 2, multiple ones of the system ofFIG. 3may be implemented in parallel to accommodate such determinations, if desired.

Directing attention toFIG. 4, mutual compatibility is preferably determined through implementation of AND circuit400. Specifically, compatibility indicator Bijand reverse compatibility indicator Bjiare preferably provided to AND circuit400to determine compatible combination indicator Sij. Specifically, if Bijand Bjiare true (1), Sijis also true (1). However, if either or both of Bijand Bjiare false (0), then Sijis also false (0).

It should be appreciated that when the matrix M is obtained for a plurality of ATs having data for communication, compatible combinations with multiple ATs, such as 2, 3, and more ATs, may readily be derived. However, according to a preferred embodiment when more than one group of compatible ATs are found, other criteria are applied in identifying particular ATs for a service group. For example, as shown and described in the above referenced patent application entitled “Directed Maximum Ratio Combining Methods and Systems for High Data Rate Traffic,” a combination with a least transmission power may be used, such as to present a least amount of interference to other cells or cell sectors.

FIGS. 5–11show alternative preferred embodiments of systems for making the above described compatibility determinations. The systems ofFIGS. 5–11are particularly well suited for use in determining compatible ATs for scheduling supplemental channels in systems such as those implementing 1XRTT cdma2000 protocols. Specifically, the systems ofFIGS. 5–8provide a preferred embodiment solution with respect to forward link scheduling andFIGS. 9–11provide a preferred embodiment solution with respect to reverse link scheduling.

It should be appreciated that optimum beams used for 1XRTT cdma2000 data beam forming, whether forward link or reverse link, may be obtained from learning or other methods, such as beam correlation. Moreover, it may be, in particular system implementations, the optimum beam for data may be the same as that for voice. For example, for forward beam forming, the optimum beams may be obtained from the learning results of a voice channel to shorten the learning cycle, although the optimum beam for a data channel may be more narrow than for the voice channel if the beam widths for the data channel were to be learned separately.

In operation according to a preferred embodiment of the present invention, such as in operation with respect to a 1XRTT cdma2000 system, fundamental channel (FCH) beam forming is done as in a normal operational mode, such as a normal mode of voice communication. That is, when there is a fundamental channel, the optimum beam is preferably used instead of the sector beam. However, in operation according to this preferred embodiment, for supplemental channels (SCHs), although the optimum beams for each individual AT having information to be communicated via an SCH may be known, scheduling of such communications takes into account the compatibility of communications with respect to the ATs. Specifically, beams with mutually little interference are considered to be compatible and, therefore, may be scheduled in a service group, such as a service group of up to 4 ATs where 4 supplemental channels are supported. It should be appreciated that, at any point in time, many service group combinations of ATs may be found. However, according to the preferred embodiment of the present invention, which service group is selected for communication is determined by a scheduling algorithm which takes into account additional considerations, such as available power, channel conditions, priority, and the like.

Directing attention toFIGS. 5–8, preferred embodiment systems for providing directed maximum ratio combining in the forward link according to the present invention are shown. InFIG. 5a preferred embodiment system for use in implementing the present invention is shown as compatibility coefficient calculator520. Specifically, the preferred embodiment compatibility coefficient calculator ofFIG. 5accepts normalized array response vector information input and provides an instantaneous compatibility coefficient result for time n.

Preferably, two sets of normalized in-phase and quadrature array response vector information are provided to compatibility coefficient calculator520for providing a calculated instantaneous compatibility coefficient W[n], where W[n] is the normalized instantaneous result of an input vector conjugate multiplied with an input vector at time n. For example, the beam coefficients trained for an AT disposed at grid location i (wi) may be normalized (Wi) with respect to sector beam coefficients (Wp) at target direction AOAifor input as first normalized array response vector information as shown below.
∥ARVAOAi·conj(Wp)∥2=∥ARVAOAi·conj(Wi)∥2
Where, in the above equation, ARVAOAiis the antenna manifold vector at AOAi. Similarly, the beam coefficients trained for an AT disposed at grid location j (wj) may be normalized (Wj) with respect to sector beam coefficients (Wp) at target direction AOAjfor input as second normalized array response vector information as shown below.
∥ARVAOAi·conj(Wp)∥2=∥ARVAOAj·conj(Wj)∥2
The above normalization preferably provides a constant effective radiated power (ERP) with respect to a sector beam to thereby provide meaningful compatibility comparisons according to the present invention.

According to the illustrated embodiment, and substantially as described above with respect toFIG. 2, the in-phase and quadrature components for the input array response vector information are preferably multiplied by complex multiplier501. Accumulators502and503preferably accumulate the real and imaginary parts, respectively, resulting from the matrix component multiplication of complex multiplier501. Absolute value and truncation circuits504and505preferably take the absolute value of the real and imaginary parts, respectively, and truncate the result to a predetermined number of most significant bits to maintain a certain bit package.

The real part truncated absolute values from absolute value and truncation circuit504and the imaginary part truncated absolute values from absolute value and truncation circuit505are preferably provided to complex conjugate adder506to implement a square, and square root circuit551preferably computes the square root of the output of complex conjugate adder506. Accordingly, the output of square root circuit551, and therefore compatibility coefficient calculator520, W[n] may be ∥Wi*·Wj∥ or ∥Wi*·Wi∥, where Wi* is the conjugate transpose of Wi, depending upon the vector information input at complex multiplier501.

For example, providing normalized in-phase and quadrature array response vector information Wiand normalized in-phase and quadrature array response vector information Wjto compatibility coefficient calculator520, the output W[n] will be an instantaneous compatibility coefficient (∥Wi*·Wj∥) of the present invention. It should be appreciated that, as the array response vector information input to compatibility coefficient calculator520is normalized, ∥Wi*·Wj∥=∥Wj*·Wi∥. Accordingly, a compatibility indicator Cij=Cji=∥Wi*·Wj∥=∥Wj*·Wi∥.

It should be appreciated that, in addition to providing instantaneous compatibility coefficients, compatibility coefficient calculator520may be utilized in providing instantaneous reference coefficients utilized according to the present invention. For example, providing in-phase and quadrature array response vector information Witwice to instantaneous compatibility calculator520, the output W[n] will be the instantaneous reference coefficient (∥Wi*·Wi∥) of the present invention.

Accordingly, it should be appreciated that multiple ones of the system ofFIG. 5may be implemented in parallel to accommodate such calculations, if desired. Additionally or alternatively, particular ones of the ATs may be selected for compatibility calculations or excluded from compatibility calculations, such as through reference to AOA information or other information providing a reliable indication of suitability or non-suitability for simultaneous communication which does not require compatibility calculations according to the present invention.

According to a preferred embodiment of the present invention, the compatible combination indicator for active ATs are rescaled to reflect the actual power levels, or appropriate relative power levels, and therefore reflect the actual interference associated therewith. For example, a scaled instantaneous compatibility coefficient w[n] may be determined as a function of the compatible combination indicator W[n] associated with a particular AT and the predicted digital gain unit (DGU) for that AT. For example, the scaled instantaneous compatibility coefficient w[n] associated with ATiand ATj(Dij) may be determined as shown below.
Dij=Cij·DGU2j

A preferred embodiment implementation of a system for providing the above calculations is shown inFIG. 6. Specifically, multiplier600accepts inputs W[n], wherein when array response vector information with respect to Wiand Wjare input at complex multiplier501W[n]=Cij, and DGU2a=DGU2j, when W[n]=Cij. Multiplier600outputs w[n], wherein w[n]=Dijwhen the above conditions are met.

It should be appreciated that compatible beams or ATs may be determined substantially as described above with respect to the preferred embodiment ofFIGS. 2–4using a threshold value (e.g., thresholdA), such that Dij<thresholdA Dii. However, a preferred embodiment of the present invention also takes data rate information into account when determining a service group of the present invention to thereby further optimize information communication. For example, a lowest supported data rate for a supplemental channel (SCH) may be represented as Rminand the data rate for the supplemental channel intended to be used with a particular ATimay be represented as Ri. Using the scalar Ri/Rmin, a preferred embodiment of the invention may determine compatible beams or ATs as a function of data rate information as shown below.

DijDii·RiRmin≤threshold1i
If the above condition is true, then the ATjmay be determined to cause sufficiently small interference with respect to the ATiand, therefore, beam Wjis compatible with Wi. However, it should be appreciated that beam Wjbeing compatible with beam Widoes not guarantee that beam W1is compatible with beam Wj. Accordingly, a preferred embodiment of the present invention further makes a reverse compatibility determination for identifying ATs for a service group as shown below.

DijDii·RiRmin≤threshold1i⁢⁢and⁢⁢DjiDjj·RjRmin≤threshold1j
If the above conditions are true, then ATiand ATjmay be placed in a same service group according to this embodiment of the present invention.

As previously discussed, operation of the present invention is not limited to identification of pairs of compatible ATs, but may provide service groups including any number of compatible ATs. When there are more than two beams in one service group, all such beams are preferably compatible with respect to each other. For example, according to a preferred embodiment, when there are three ATs at locations i, j, and k, the following equations are to be true for identifying the three ATs as compatible ATs.

A preferred embodiment implementation of a systems for providing calculations according to the above are shown inFIGS. 7 and 8. Specifically, directing attention toFIG. 7, summer701provides addition of the appropriate scaled instantaneous compatibility coefficients, divider702provides division by the appropriate scaled instantaneous compatibility coefficient, and multiplier703provides multiplication by the data rate scalar Ri/Rmin. Comparison circuit704preferably provides a determination as to whether the result is less than a threshold value, here threshold1. If the result is less than the threshold, then the compatibility indicator B is preferably set to true (1). However, if the result is not less than the threshold, then the compatibility indicator B is preferably set to false (0). For example, where the scaled instantaneous compatibility coefficients provided to summer701are Dijand Dik, and the scaled instantaneous compatibility coefficient provided to divider702is Dii, B1=1 indicates that beams Wjand Wkare compatible to Wiand Bi=0 indicates that beams Wjand Wkare not compatible to beam Wi. Similarly, where the scaled instantaneous compatibility coefficients provided to summer701are Djiand Djk, and the scaled instantaneous compatibility coefficient provided to divider702is Djj, Bj=1 indicates that beams Wiand Wkare compatible to Wjand Bj=0 indicates that beams Wiand Wkare not compatible to beam Wj. Likewise, where the scaled instantaneous compatibility coefficients provided to summer701are Dkiand Dkj, and the scaled instantaneous compatibility coefficient provided to divider702is Dkk, Bk=1 indicates that beams Wiand Wjare compatible to Wkand Bk=0 indicates that beams Wiand Wjare not compatible to beam Wk.

Directing attention toFIG. 8, AND circuit801is provided such that a true output (1) results if Bi, Bj, and Bkare each true and a false output (0) results if any one of Bi, Bj, or Bkis false. Comparison circuit802determines if the output of AND circuit801is true (1) or false (0). If true, a determination is made that beams Wi, Wj, and Wkmay be selected as a service group according to this preferred embodiment. However, if false, a determination is made that beams Wi, Wj, and Wkmay not be selected as a service group according to this preferred embodiment.

Directing attention toFIGS. 9–11, preferred embodiment systems for providing directed maximum ratio combining in the reverse link according to the present invention are shown. InFIG. 9a preferred embodiment system for use in implementing directed maximum ratio combining according to the present invention is shown as compatibility coefficient calculator920. Specifically, the preferred embodiment compatibility coefficient calculator ofFIG. 9accepts normalized array response vector information input and provides an instantaneous compatibility coefficient result for time n.

Preferably, two sets of normalized in-phase and quadrature array response vector information are provided to compatibility coefficient calculator920for providing a calculated instantaneous compatibility coefficient V[n], where V[n] is the normalized instantaneous result of an input vector conjugate multiplied with an input vector at time n. For example, the beam coefficients for the narrowest beam at directions AOAi(v1) and AOAj(vj) may be normalized (Viand Vj, respectively) for input as first and second normalized array response vector information as shown below.
∥ViT·Vi∥=1 and ∥VjT·Vj∥=1

According to the illustrated embodiment, and substantially as described above with respect toFIG. 5, the in-phase and quadrature components for the input array response vector information are preferably multiplied by complex multiplier901. Accumulators902and903preferably accumulate the real and imaginary parts, respectively, resulting from the matrix component multiplication of complex multiplier901. Absolute value and truncation circuits904and905preferably take the absolute value of the real and imaginary parts, respectively, and truncate the result to a predetermined number of most significant bits to maintain a certain bit package.

The real part truncated absolute values from absolute value and truncation circuit904and the imaginary part truncated absolute values from absolute value and truncation circuit905are preferably provided to complex conjugate adder906to implement a square, and square root circuit951preferably computes the square root of the output of complex conjugate adder906. Accordingly, the output of square root circuit951, and therefore compatibility coefficient calculator920, V[n] may be ∥Vi*·Vj∥ or ∥Vi*·Vi∥, where Vi* is the conjugate transpose of Vi, depending upon the vector information input at complex multiplier901.

For example, providing normalized in-phase and quadrature array response vector information Viand normalized in-phase and quadrature array response vector information Vjto compatibility coefficient calculator920, the output V[n] will be an instantaneous compatibility coefficient (∥Vi*·Vj∥) of the present invention. It should be appreciated that, as the array response vector information input to compatibility coefficient calculator920is normalized, ∥Vi*·Vj∥=∥Vj*·Vi∥. Accordingly, a compatibility indicator Qij=Qj1=∥Vi*·Vj∥=∥Vj*·Vi∥.

It should be appreciated that, in addition to providing instantaneous compatibility coefficients, compatibility coefficient calculator920may be utilized in providing instantaneous reference coefficients utilized according to the present invention. For example, providing in-phase and quadrature array response vector information Vitwice to instantaneous compatibility calculator920, the output V[n] will be the instantaneous reference coefficient (∥Vi*·Vi∥) of the present invention.

Accordingly, it should be appreciated that multiple ones of the system ofFIG. 9may be implemented in parallel to accommodate such calculations, if desired. Additionally or alternatively, particular ones of the ATs may be selected for compatibility calculations or excluded from compatibility calculations, such as through reference to AOA information or other information providing a reliable indication of suitability or non-suitability for simultaneous communication which does not require compatibility calculations according to the present invention.

According to a preferred embodiment of the present invention, the compatible combination indicator for active ATs are further processed to determine the compatibility for more than two ATs. For example, taking as an example ATs i, j, and k, each having associated therewith angles of arrival AOAi, AOAj, and AOAk, respectively, the compatibility coefficient of ATjand ATkwith respect to ATi(Ii) may be determined as shown below.

Ii=Qij·RjRmin+Qik·RkRmin
Similarly, the compatibility coefficient of ATiand ATkwith respect to ATj(Ij) and the compatibility coefficient of ATiand ATjwith respect to ATk(Ik) may be determined as shown below.

Ij=Qji·RiRmin+Qjk·RkRminIk=Qki·RiRmin+Qkj·RjRmin
In the above preferred embodiment formulas for determining the compatibility coefficients, Rminis probably the lowest data rate one reverse supplemental channel supports, and Rxis preferably the intended data rate on the supplemental channel for the AT disposed at the direction AOAx, e.g., Riis the intended data rate on the supplemental channel for ATi.

A preferred embodiment implementation of a system for providing the above calculations is shown inFIG. 10. Specifically, multiplier1001accept input V[n], wherein when array response vector information with respect to Viand Vjare input at complex multiplier901V[n]=Qij. Similarly, multiplier1002accepts another input V[n], wherein when array response vector information with respect to Viand Vkare input at complex multiplier901V[n]=Qik. As described above with respect toFIG. 7, preferred embodiments of the present invention takes data rate information into account when determining a service group of the present invention. Accordingly, a corresponding scalar Rx/Rmin, where Rminis a lowest supported data rate for a supplemental channel (SCH) and the data rate for the supplemental channel intended to be used with a particular ATimay be represented as Ri, is also input in to each of multipliers1100and1002for determining compatible beams or ATs as a function of data rate information. The resulting products of multipliers1001and1002are preferably summed by summer1003to provide the results Ii, Ij, and Ik, corresponding to the particular inputs V[n] provided to multipliers1001and1002.

Thereafter, a determination may be made as to AT or beam compatibility, preferably through reference to a threshold value by comparison circuit1004. Specifically, according to the illustrated embodiment, if Iiis less than threshold2, where Iiis provided when Qijand Qikand the corresponding data rate scalars are input to multipliers1001and1002, then ATjand ATkare compatible with ATiaccording to this preferred embodiment. Similarly, if Ijis less than threshold2, where Ijis provided when Qjiand Qjkand the corresponding data rate scalars are input to multipliers1001and1002, then ATiand ATkare compatible with ATjaccording to this preferred embodiment. Likewise, if Ikis less than threshold2, where Ikis provided when Qk1and Qkjand the corresponding data rate scalars are input to multipliers1001and1002, then ATiand ATjare compatible with ATkaccording to this preferred embodiment.

If the result is less than the threshold, then the compatibility indicator B is preferably set to true (1). However, if the result is not less than the threshold, then the compatibility indicator B is preferably set to false (0). For example, where the compatibility coefficients provided to multipliers1001and1002are Qijand Qik, Bi=1 indicates that beams Vjand Vkare compatible to Viand Bi=0 indicates that beams Vjand Vkare not compatible to beam Vi. Similarly, where the compatibility coefficients provided to multipliers1001and1002are Qjiand Qjk, Bj=1 indicates that beams Viand Vkare compatible to Vjand Bj=0 indicates that beams Viand Vkare not compatible to beam Vj. Likewise, where the compatibility coefficients provided to multipliers1001and1002are Qk1and Qkj, Bk=1 indicates that beams Viand Vjare compatible to Vkand Bk=0 indicates that beams Viand Vjare not compatible to beam Vk.

Directing attention toFIG. 11, AND circuit1101is provided such that a true output (1) results if Bi, Bj, and Bkare each true and a false output (0) results if any one of Bi, Bj, or Bkis false. Comparison circuit1102determines if the output of AND circuit1101is true (1) or false (0). If true, a determination is made that beams V1, Vj, and Vkmay be selected as a service group according to this preferred embodiment. However, if false, a determination is made that beams Vi, Vj, and Vkmay not be selected as a service group according to this preferred embodiment.

It should be appreciated that alternative embodiments of the directed maximum ratio combining systems ofFIGS. 5–11may adopt implementation aspects as discussed above with respect to the systems ofFIGS. 2–4. For example a particular implementation of the system ofFIGS. 5and/or9may adopt the absolute square implementation ofFIG. 2to thereby avoid a square root computation. Similarly, the systems ofFIGS. 5–11may further implement an IIR filter as shown inFIG. 2, or other noise dampering circuit, where undesirable noise is experienced in the instantaneous results of the systems ofFIGS. 5 and 9.

As previously mentioned, it is typically not possible to select ATs for a service group which have truly orthogonal signal attributes associated therewith and, accordingly, the preferred embodiments of the present invention operate to select ATs for a service group having sufficiently diverse attributes so as to result in an acceptable level of interference associated with simultaneous use thereof in a service group. Accordingly, the preferred embodiments above have been discussed with respect to a predetermined threshold value utilized in determining AT compatibility for use in a service group. Such threshold values may preferably be derived as described below. In determining threshold values for use according to a preferred embodiment, various assumptions may be made, such as that the ATs are uniformly distributed over a sector of interest, that supplemental channels are not uniformly distributed over the sector of interest, that additive white Gaussian noise (AWGN) in ATs may be ignored, and Nuis the number of users supported in a sector of interest.

In determining a preferred embodiment threshold for use in the forward link, threshold11, BTS transmission power for fundamental channel i and supplemental channel j in an adaptive array antenna system may be denoted as PFCHiand PSCHj, respectively. When there are only fundamental channels in the sector of interest, the received signal to interference ratio (SIRFCHi) for the AT using the fundamental channel i is shown below.

SIRFCHi=PFCHi⁢(1-ρ)(Pother+∑k⁢PFCHi)⁢1Gi⁢ρ+Pinteri
In the above formula, Piinteris the inter-cell interference, Giis the traffic beam gain over the sector beam, Potheris the total power of all the common channels in the same sector (such as pilot channel, sync channel, paging channel, etc.), and ρ represents the ratio of the interference power due to multi-path over the total power in a particular beam of interest.

When supplemental channels are provided in the sector of interest, the received signal to interference ratio (SIRSCHi) for the AT using the supplemental channel i is shown below.

SIRSCHi=⁢PSCHi⁡(1-ρ)(Pother+∑k⁢PFCHi)⁢1Gi⁢ρ+(∑j⁢Cij⁢dguj2)⁢ρ+Pinteri=⁢dgui2⁢Cii⁡(1-ρ)(Pother+∑k⁢PFCHi)⁢1Gi⁢ρ+(∑j⁢Cij⁢dguj2)⁢ρ+Pinteri=⁢1-ρ(∑j⁢Dij/Dii)⁢ρ+((Pother+∑k⁢PFCHi)⁢1Gi⁢ρ+Pinteri)/dgui2⁢Cii
In the above equation, Cijand Dijare as defined above, and dguiis the digital gain unit for supplemental channel i.

To support a particular data rate according to the preferred embodiment, SIRSCHi≧SIRFf(Ri/Rmin), where SIRFis the SIR required for data rate Rminand f(Ri/Rmin) represents a function of Ri/Rmin. It should be appreciated that, in determining compatible ATs for service groups above, f(Ri/Rmin) was assumed to equal Ri/Rmin. From the above equation, the following equations can be derived.

It should be appreciated that

Pother+∑k⁢PFCHi
is the total transmission power of the base station except for the supplemental channels. Accordingly, where SIRFis known, f(Ri/Rmin) is specified, and ρ and Piinterare assumed based on empirical data, threshold1can be readily found.

In determining a preferred embodiment threshold for use in directed maximum ratio combining in the reverse link, threshold2it is noted that the received power from the ATs should be approximately the same for a same data rate (due to power control algorithms according to various communication protocols, such as the aforementioned cdma2000 and HDR protocols). The received power for fundamental channels in an adaptive array antenna system may be denoted as PRX, the data rate of a fundamental channel may be denoted as Ri, and the received power for a supplemental channel supporting data rate Rimay be denoted as PRSCHi. Accordingly, PRSCH1=PRXr1, where ri=g(Ri/Rmin) which is a function of Ri/Rmin. It should be appreciated that, in determining compatible ATs for service groups above, g(R1/Rmin) was assumed to equal Ri/Rmin. When only one fundamental channel is present in a sector of interest, the received signal to interference ratio (SIR) for the AT using the fundamental channel is as shown below.

SIRRX=PRX(Nu-1)⁢PRX⁢1G+Iinter·1G
In the above equation, Iinteris the inter-cell interference and G is the traffic beam gain over the sector beam. When supplemental channels are provided in the sector of interest, the received signal to interference ratio (SIRRSCHi) for the AT using the supplemental channel i is as shown below.

SIRSCHiR=PRX⁢riNu⁢PRX⁢1G+(∑j≠i⁢Qij⁢ri)⁢PRX+Iinter⁢1G
In the above equation, Qijis as defined above.

To support a particular data rate according to a preferred embodiment, SIRRSCHi≧SIRR·r1, where SIRRis the SIR required for data rate Rmin. From the above equation, the following equations can be derived.

It should be appreciated that, when SIRris known, and Iinteris assumed based upon empirical data, threshold2can readily be determined.

After compatible ATs are determined according to the present invention, preferred embodiments further operate to schedule communications with respect to the ATs to further optimize information communication. For example, in an HDR system when a particular AT does not have data to communicate, but that AT is scheduled to communicate at a high data rate, network capacity is wasted. Accordingly, preferred embodiments of the invention implement scheduling techniques to more fully utilize network capacity. Two preferred embodiment scheduling techniques are described below which implement the principal that when an AT is scheduled to communicate at a high data rate that AT should have a high probability of having data to communicate associated therewith.

According to a first preferred embodiment scheduling technique, it is assumed that ATs measure if a packet of data to be communicated is a relatively short data packet or a relatively large data packet. Preferably, short data packets are transmitted at a lowest possible data rate, such as 9.6 Kbps in the aforementioned HDR systems. Correspondingly, large data packets are preferably not transmitted unless the corresponding ATs are controlled to transmit at a high data rate. Accordingly, in operation according to a preferred embodiment, ATs which do communicate when they are scheduled to communicate are presumed to have a large data packet to communicate and, therefore, have a higher probability to be scheduled for high data rate communication in a subsequent epoch.

It should be appreciated that selection of a threshold demarcating large and small data packets can affect the efficiency of the preferred embodiment scheduling technique. For example, if the threshold is too high, a large number of ATs will communicate at the lowest data rate. However, when the threshold is too low, even if an AT has data to communication in the current scheduled slots, the probability that there will still be data waiting for transmission in later epochs will not be high and, as such, the conclusion that ATs that do communicate when they are scheduled to communicate have a large data packet to communicate will not be an accurate predictor. Instead, scheduling would likely be substantially random, approaching that of prior art systems, resulting in network capacity waste.

According to another preferred embodiment scheduling technique, packet size measurements are not utilized. In this preferred embodiment, every AT communicates at the lowest possible rate, such as 9.6 Kbps in the aforementioned HDR systems, when the AT is not scheduled to transmit at a high data rate. Scheduling epochs then, preferably, look back n slot to roughly predict if an AT is likely to have data to transmit. For example, an AT having most of the past n slots at rate 0 probably does not have much data to transmit and, therefore, no high data rate will be scheduled in a current scheduling epoch. However, if all the past n slots are at a nonzero rate, the AT is determined to likely have more data to communicate and, therefore, high data rate communication will be scheduled.

It should be appreciated that the high data rate scheduling predicted based upon past data communication according to this preferred embodiment of the present invention may not always accurately predict the presence of data for high data rate communication. However, this preferred embodiment provides an advantage in not relying upon data packet measurements in determining scheduling and, therefore, may be implemented in existing protocols, such as the aforementioned HDR systems, without requiring modification to existing ATs.

It should be appreciated that the above described preferred embodiment systems may be implemented in hardware, such as using application specific integrated circuits (ASIC), or in software, such as using a general purpose processor based system having a central processing unit, memory, and suitable input/output devices operating under control of an instruction set defining operation as described herein.