ALLOCATING TRANSMISSION RESOURCES

PRIORITY CLAIM UNDER 35 U.S.C. § 1 19(e

This application claims the benefit of U.S. Provisional Application No.

61/356,797, filed June 21, 2010, entitled "Control Allocation for Multiple Large Uplink

Control Information Payloads," which is incorporated by reference in its entirety.

TECHNICAL FIELD OF THE INVENTION

This disclosure relates in general to wireless communication and, more particularly, to resource allocation for multi-antenna transmissions.

BACKGROUND OF THE INVENTION

Multi-antenna transmission techniques can significantly increase the data rates and reliability of wireless communication systems, especially in systems where the transmitter and the receiver are both equipped with multiple antennas to permit the use of multiple-input multiple- output (MIMO) transmission techniques. Advanced communication standards such as Long Term Evolution (LTE) Advanced utilize MIMO transmission techniques that may permit data to be transmitted over multiple different spatially-multiplexed channels simultaneously, thereby significantly increasing data throughput.

While MIMO transmission techniques can significantly increase throughput, such techniques can greatly increase the complexity of managing radio channels. Additionally, many advanced communication technologies, such as LTE, rely on a substantial amount of control signaling to optimize the configuration of transmitting devices and their use of the shared radio channel. Because of the increased amount of control signaling in advanced communication technologies, it is often necessary for user data and control signaling to share transmission resources. For example, in LTE systems, control signaling and user data are, in certain situations, multiplexed by user equipment ("UE") for transmission over a physical uplink shared channel ("PUSCH").

However, conventional solutions for allocating transmission resources are designed for use with single layer transmission schemes in which only a single codeword of user data is transmitted at a time. Additionally, conventional solutions may not consider the size of the control information to be transmitted, when determining the number of vector symbols to allocate to each bit of control information. As a result, such resource allocation solutions fail to provide optimal allocation of transmission resources between control information and user data when MIMO techniques are being utilized to transmit data on multiple layers simultaneously, especially when a large amount of control information must be transmitted. SUMMARY OF THE INVENTION

In accordance with the present disclosure, certain disadvantages and problems associated with wireless communication have been substantially reduced or eliminated. In particular, certain devices and techniques for allocating transmission resources between control information and user data are described.

In accordance with one embodiment of the present disclosure, a method for wirelessly transmitting data and control information using a plurality of transmission layers includes determining a number of bits in one or more user data codewords to be transmitted during a subframe and calculating, for each of M control signals to be transmitted during the subframe, a value (2 based at least in part, on the number of bits in the one or more user data codewords, and an estimated number of user data vector symbols onto which the one or more user data codewords will be mapped. The estimate of the number of user data vector symbols for a particular one of the M control signals depends, at least in part, on a number of control vector symbols to be allocated to one or more others of the M control signals. The method also includes determining a number of control vector symbols onto which to map each of the M control signals based on a respective value Q' calculated for that control signal, mapping the control signals for that control signal, and transmitting the control vector symbols.

In accordance with another embodiment, a method for receiving user data and control information transmitted wirelessly over a plurality of transmission layers, includes receiving a plurality of vector symbols over a plurality of transmission layers. The vector symbols carry encoded user data and encoded control information. The method also includes determining a number of bits in one or more user data codewords carried by the vector symbols and calculating, for each of M control signals received for the subframe, a value (Q ^f ). The value Q' calculated based, at least in part, on the number of bits in the one or more user data codewords and an estimated number of user data vector symbols onto which the one or more user data codewords will be mapped. Additionally, the estimate of the number of user data vector symbols for a particular one of the M control signals depends, at least in part, on a number of control vector symbols to be allocated to one or more others of the M control signals. The method also includes decoding the received vector symbols based on the calculated number of control vector symbols. Additional embodiments include apparatuses capable of implementing the above methods and/or variations thereof.

Important technical advantages of certain embodiments of the present invention include reducing the overhead associated with transmitting control signaling by matching the allocation to the quality of the channel indicated by the payloads of the data codewords. Particular embodiments may provide additional benefits by accounting for the amount and type of control information to be transmitted when determining how much transmission resources to use in transmitting each bit of control information, as well as by providing differentiated treatment of different types of control information. Other advantages of the present invention will be readily apparent to one skilled in the art from the following figures, descriptions, and claims. Moreover, while specific advantages have been enumerated above, various embodiments may include all, some, or none of the enumerated advantages.

BRIEF DESCRIPTION OF THE DRAWINGS

For a more complete understanding of the present invention and its advantages, reference is now made to the following description, taken in conjunction with the accompanying drawings, in which:

FIGURE 1 is a functional block diagram illustrating a particular embodiment of a multi-antenna transmitter;

FIGURE 2 is a functional block diagram illustrating a particular embodiment of a carrier modulator that may be used in the transmitter of FIGURE 1 ;

FIGURE 3 is a structural block diagram showing the contents of a particular embodiment of the transmitter;

FIGURE 4 is a flowchart detailing example operation of a particular embodiment of the transmitter;

FIGURE 5 is a structural block diagram showing the contents of a network node that is responsible for receiving and/or scheduling transmissions of the transmitter;

FIGURE 6 is a flowchart showing example operation of a particular embodiment of the network node of FIGURE 5 in receiving transmissions from the transmitter; and

FIGURE 7 is a flowchart showing example operation of a particular embodiment of the network node in scheduling transmissions of the transmitter.

DETAILED DESCRIPTION OF THE INVENTION

FIGURE 1 is a functional block diagram illustrating a particular embodiment of a multi-antenna transmitter 100. In particular, FIGURE 1 shows a transmitter 100 configured to multiplex certain control signaling with user data for transmission over a single radio channel. The illustrated embodiment of transmitter 100 includes a splitter 102, a plurality of channel interleavers 104, a plurality of scramblers 106, a plurality of symbol modulators 108, a layer mapper 110, and a carrier modulator 1 12. Transmitter 100 allocates transmission resources to control signaling on multiple transmission layers based on an estimate of the quality of the radio channel over which transmitter 100 will transmit. As described further below, particular embodiments of transmitter 100 reduce the overhead for transmitted control information by using an estimate of the data payloads of multiple layers and/or codewords as a measure of the channel quality.

Control signaling can have a critical impact on the performance of wireless communication systems. As used herein, "control signaling" and "control information" refers to any information communicated between components for purposes of establishing communication, any parameters to be used by one or both of the components in communicating with one another (e.g., parameters relating to modulation, encoding schemes, antenna configurations), any information indicating receipt or non-receipt of transmissions, and/or any other form of control information.

For example, in LTE systems, control signaling in the uplink direction includes, for example, Hybrid Automatic Repeat reQuest (HARQ) Acknowledgments/Negative Acknowledgements (ACK/NAKs), precoder matrix indicators (PMIs), rank indicators (RIs), and channel quality indicators (CQIs), which are all used by the eNodeB to get confirmation of successful reception of transport blocks or to improve the performance of downlink transmissions. Although control signaling is often transmitted on separate control channels, such as the physical uplink control channel (PUCCH) in LTE, it may be beneficial or necessary to transmit control signaling on the same channel as other data.

For example, in LTE systems, when a periodic PUCCH allocation coincides with a scheduling grant for a user equipment (UE) to transmit user data, the user data and control signaling share transmission resources to preserve the single- carrier property of the discrete Fourier transform, spread orthogonal frequency- division multiplexing (DFTS-OFDM) transmission techniques used by LTE UEs. Furthermore, when a UE receives a scheduling grant to transmit data on the physical uplink shared channel (PUSCH), it typically receives information from the eNodeB related to the characteristics of the uplink radio propagation channel and other parameters that can be used to improve the efficiency of PUSCH transmissions. Such information may include modulation and coding scheme (MCS) indicators as well as, for UEs capable of using multiple transmission antennas, PMIs or RIs. As a result, UEs may be able to use this information to optimize PUSCH transmissions for the radio channel, thereby increasing the amount of data that can be transmitted for a given set of transmission resources. Thus, by multiplexing control signaling with the user data transmitted on PUSCH, a UE can support significantly larger control payloads than when transmitting control signaling by itself on PUCCH.

It may be possible to multiplex control signaling and user data by simply dedicating a set amount of the time-domain transmission resources to control information and then perform carrier modulation and precoding of the control signaling along with the data. In this way control and data are multiplexed and transmitted in parallel on all sub-carriers. For example, in LTE Release 8, DFTS- OFDM symbols are formed from a predetermined number of information vector symbols. As used herein, a "vector symbol" may represent any collection of information that includes an information element associated with each transmission layer over which the information is to be transmitted. Assuming a normal cyclic prefix length, fourteen of these DFTS-OFDM symbols can be transmitted in each uplink subframe. A predetermined number and distribution of these symbols are used to transmit various types of control signaling and the remaining symbols may be used to transmit user data.

Since control signaling and user data may each be associated with different block error-rate requirements, control signaling is often encoded separately and using a different encoding scheme from user data. For example, user data is often encoded with turbo codes or low-density parity-check (LDPC) codes that are highly efficient for longer block lengths (i.e., larger blocks of information bits). Control signaling that uses only a small amount of information bits, such as HARQ ACK/NAK signaling or rank indicators, is often most efficiently encoded using a block code. For medium-sized control signaling, such as larger size CQI reports, a convolutional code (possibly tail biting) often provides the best performance. Consequently, fixed or predetermined allocations of transmission resources to control signaling and user data can lead to inefficient use of such resources as the optimal resource allocation will often depend on numerous factors, including the channel quality, the type of control signaling, and various other considerations.

In addition, it may be beneficial to allocate different types of control information differently. Different types of control information may have different robustness requirements. Furthermore, certain types of control signaling may be replicated and multiplexed with every codeword of user data transmitted during a subframe, while other types may only be multiplexed with one or a subset of the user data codewords transmitted during the subframe. As a result, the optimal allocation for specific types of control information may differ.

The use of multiple transmit antennas can further complicate the allocation of transmission resources between control signaling and user data when the two types of information are multiplexed together on a common channel. When MIMO techniques are used to simultaneously transmit multiple data codewords in parallel, control signaling may be transmitted on multiple different codewords and/or layers of the transmission scheme. The optimal allocation of resources in such situations may differ from the optimal allocation under the same circumstances when a single transmission antenna is used. Moreover, the multiple-antenna technique used for control signaling may be different from that used for user data. Control signaling is often encoded for maximum robustness (e.g., with maximum transmission diversity) rather than for maximum throughput. By contrast, user data is often combined with a retransmission mechanism that allows for more throughput- aggressive multiple- antenna encoding techniques. Thus, if transmitter 100 has information indicating the supported pay load of user data, transmitter 100 may not be able to assume the supported payload for control signaling is the same when determining the optimal allocation of transmission resources for control signaling. For example, the supported peak spectral efficiency of the encoded user data may be significantly larger than the supported peak spectral efficiency of the encoded control signaling.

In many circumstances, it may be desirable to determine the amount of transmission resources to use for each bit of control signaling based on the quality of the channel over which the multiplexed control signaling will be transmitted. As part of this process, transmitter 100 may estimate an inverse spectral efficiency for the user data to be transmitted, based on the data payloads of one or more of the user control codewords to be transmitted, and use this estimate to determine the amount of transmission resources to use for each bit of control signaling. In such situations, it may be acceptable for transmitter 100 to determine the amount of transmission resources to devote to each bit of control signaling using an estimated spectral efficiency for user data without accounting for the fact that some of the transmission resources will ultimately be allocated to control signaling.

While this manner of allocating may be acceptable in many situations, the impact that neglecting the differences between specific types of control signaling has on this estimate can become significant when a large amount of control signaling must be transmitted. Consequently, the effectiveness of the resulting allocation may be greatly diminished. Specifically, this may result in inaccurate estimates of the inverse spectral efficiency for user data, causing transmission resources to be sub- optimally allocated to the various types of control signaling. The result may be especially detrimental as the amount of control signaling increases to satisfy the requirements of advanced communication technologies, such as LTE- Advanced. As the amount of control signaling increases, control overhead may, in effect, grow approximately quadratic with the control payload, rather than linearly.

To address this problem, particular embodiments of transmitter 100 determine an allocation of transmission resources per bit of control codeword 120 that takes into consideration the amount of control signaling to be transmitted under the allocation and the different manner in which the various types of control signaling will be transmitted. More specifically, particular embodiments of transmitter 100 estimate the inverse spectral efficiency supported by the current multi-layer encoding scheme to determine an appropriate allocation of transmission resources between user data and control signaling. As part of estimating the spectral efficiency, transmitter 100 estimates the amount of transmission resources to be allocated to user data, and in doing so, considers the amount of transmission resources that transmitter 100 would allocate to different types of control signaling given the estimated inverse spectral efficiency that would result in actuality from this user data allocation. Transmitter 100 may then transmit the relevant control signaling using an amount of transmission resources that corresponds to this estimated spectral efficiency. Turning to the example embodiment illustrated by FIGURE 1 , transmitter 100, in operation, generates or receives control codewords and data codewords (represented, in FIGURE 1, by control codeword 120 and data codewords 122a and 122b, respectively) for transmission to a receiver over a radio channel. To permit multiplexing of control codewords 120 and data codewords 122 over a common channel, splitter 102 splits control codeword 120 for use by multiple channel interleavers 104. Splitter 102 may split control codeword 120 in any appropriate manner between channel interleavers 104, outputting a complete copy or some suitable portion on each datapath. As one example, splitter 102 may split control codeword 120 for use in the multiple datapaths by replicating control codeword 120 on both datapaths, outputting a complete copy of control codeword 120 to each channel interleaver 104. As another example, splitter 102 may split control codeword 120 by performing serial-to-parallel conversion of control codeword 120, outputting a unique portion of control codeword 120 to each channel interleaver 104.

Channel interleavers 104 each interleave a data codeword 122 with control codeword 120 (a complete copy of control codeword 120, a particular portion of control codeword 120, or some combination of both). Channel interleavers 104 may be configured to interleave data codewords 122 and control codeword 120 so that layer mapper 1 10 will map them to vector symbols in a desired manner. The interleaved outputs of channel interleavers 104 are then scrambled by scramblers 106 and modulated by symbol modulators 108.

The symbols output by symbol modulators 108 are mapped to transmission layers by layer mapper 1 10. Layer mapper 1 10 outputs a series of vector symbols 124 that are provided to carrier modulator 1 12. As an example, for embodiments of transmitter 100 that support LTE, each vector symbol 124 may represent an associated group of modulation symbols that are to be transmitted simultaneously on different transmission layers. Each modulation symbol in a particular vector symbol 124 is associated with a specific layer over which that modulation symbol will be transmitted.

After layer mapper 1 10 maps the received symbols into vector symbols 124, carrier modulator 1 12 modulates information from the resulting vector symbols 124 onto a plurality of radiofrequency (RF) subcarrier signals. Depending on the communication technologies supported by transmitter 100, carrier modulator 1 12 may also process the vector symbols 124 to prepare them for transmission, such as by precoding vector symbols 124. The operation of an example embodiment of carrier modulator 1 12 for LTE implementations is described in greater detail below with respect to FIGURE 2. After any appropriate processing, carrier modulator 1 12 then transmits the modulated subcarriers over a plurality of transmission antennas 1 14.

As explained above, proper allocation of transmission resources to control signaling and user data may have a significant impact on the performance of transmitter 100. In particular embodiments, this allocation of transmission resources is reflected in the number of vector symbols 124 transmitter 100 uses to transmit control codewords 120 (such vector symbols referred to herein as "control vector symbols"). Transmitter 100 may determine the number of vector symbols 124 to use for a particular control codeword 120 based on a measure of the quality of the channel or some other indication of the likelihood that the receiver will erroneously detect control codeword 120 after being transmitted over the radio channel.

In particular, certain embodiments of transmitter 100 may use the data payload of the multiple layers or codewords that will be used to transmit control signals 120 (or a subset of such layers/codewords) to estimate the inverse spectral efficiency currently supported by the multi-layer encoding scheme to be used. Certain embodiments may also consider the type of control information to be transmitted and may account for differing amounts of overhead associated with the various types. As a result, such embodiments may be able to more effectively allocate transmission resources to both user data and control information.

More specifically, in particular embodiments, transmitter 100 determines a data payload for the multiple layers or codewords based on information included in a scheduling grant received by transmitter 100. Such information may include any suitable information from which transmitter 100 can directly or indirectly determine the data payload to be used for the multiple layers or codewords. For example, transmitter 100 may receive a scheduling grant that includes a total resource allocation, a coding rate, and a modulation scheme, and may determine from this information, the data payload of the transmission layers transmitter 100 will be using for the transmission. Using the determined payload, transmitter 100 may then determine an estimate of the spectral efficiency for the current allocation. Additionally, the estimate of the inverse spectral efficiency used by transmitter 100 to determine the number of control vector symbols 124 may itself depend, in turn, on the number of control vector symbols 124 that would result from the estimate. Moreover, in particular embodiments, transmitter 100 takes the overhead of multiple control signals into consideration in performing the resource allocation by, for example, accounting for the multiple control signals when forming a nominal inverse spectral efficiency estimate. As part of this process, transmitter 100 may consider the types of control information to be transmitted as well as the manner in which each type will be transmitted.

In general, transmitter 100 may determine the inverse spectral efficiency estimate and the corresponding number of control vector symbols 124 in any suitable manner. In particular embodiments, transmitter 100 may base the nominal inverse spectral efficiency estimate for the radio channel on an estimate of the number of vector symbols 124 that will be allocated to user data (for a particular codeword k), Q _{data , k >} where Q _{data Λ} is itself a function of the respective allocations for M different control signals to be transmitted during the subframe. Specifically, transmitter 100 may determine a value Q' _m for each of the M control signals such that:

Q = f ^^ _a Q^ ^ _a .^- QXfi _ojfie ^ M , Equation (1) In Equation (1), Q'= [Q ₀ ' ,K , Q _M ' _ and P = [„,K , P _Ncw _ _x ] with P _A being the payload of the k -th data codeword {e.g. , P _k - K _{k r} for certain LTE embodiments, in which r=0

K _k , _r represents the number of bits of the r-th code block in the k-th user data codeword, and C„, _k is the number of code blocks in the k-th user data codeword). Additionally, in Equation (1), _{OFFSET M} is an offset value specific to the m-th control signal that can be predetermined or dynamically configured to scale the value of Q _m ' determined for that control signal, and O _m is the number of bits in the m-th control signal.

In particular embodiments, the implementation of Equation (1) may result in transmitter 100 using a recursive process to determine the appropriate allocation size for the various control signals, since Q _{data - k} itself depends on Q _m ' , and may also introduce a coupling between the resource allocation of different control signals. In other words, in such embodiments, transmitter 100 may, in allocating resources to a particular control signal, account for the overhead of all other control signals. As a result, in such embodiments, the estimation of the inverse spectral efficiency of the data may be based on the actual amount of resources allocated to user data (or an improved estimate thereof).

In particular embodiments, the resource allocation can be performed using the generic formulation in Equation (1) by solving the system of equations. Alternatively, if the system of equations is unsolvable, the resource allocation may be determined by optimization algorithms that, for example, minimize the total overhead, subject to the constraints:

Qm' Qdata , N _cw -\ (Q')> X ^K N _cw -l,r > β offset ' ⁰ m ) ^{■ E} ¾" ( ² )

In particular embodiments, the allocation may also be corrected or otherwise processed to ensure a certain type of result (such as to ensure integer-valued results and/or results within a particular range). For example, the Q ' _m value for one or more control signals may be rounded to an integer-value or adjusted to satisfy a maximum or minimum value. The value Q ' _m (and/or the result of any such post-processing performed on Q ' _m ) for each control signal may then be used by transmitter 100 as an indication of the amount of transmission resources to use in transmitting that particular (i.e., the m-th) control signal.

In alternative embodiments, transmitter 100 may solve for Q _m ' using a closed form equation that likewise takes the overhead for multiple control signals into account. For example, transmitter 100 may use an estimate of the nominal inverse spectral efficiency that depends on one or a plurality of O ₀ ,K ,0 _M _ _X and/or one or a plurality of β _{φε1 0} ,Κ , β _{φα M l} . That is the estimate may depend on

O = [<¾,K , 0 and/or B _oJfiet = [β _φε1-0 ,Κ

Transmitter 100 may determine such closed form expressions by, for example, solving for Q' in Equation (1). In particular embodiments, the overhead of a control signal affects the overhead of a codeword linearly, in which case Q _{data t k} (Q' ) can be expressed as: £L (Q') = 0, _fl Equation (3)

where ¾ _m are linear (typically, non-negative) weights. One specific example is given by:

O (Q') = Qaii ^~ ∑QL ^ , Equation (4)

m

where a _{k m} - d _m≡I equals 1 if i G l _k , and zero otherwise, and I _k is the set of control signals (or indices thereof) that affect the k-t codeword.

In certain embodiments, transmitter 100 allocates control signals iteratively as Q _M ' - _{\ >} Q _M ' - _{2JL ,} Q _O wherein the allocation of Q _M ' _ _x is given in a closed form, Q _M ' _ ₂ only depends on Q _M ' _X , and, in general, Q' _n only depends on Q' _n+X ,K , Q' _M _ _X . For example, in particular embodiments, transmitter 100 does not account for the overhead of any other control signals in Q _M ' _ _X , accounts for only the overhead in Q _M ' _ _X in Q _M ' _ ₂ , and, in general, when determining Q' _n , accounts for only the overhead of Q' _n+X ,K , Q' _M _ _X .

As one example, transmitter 100 may use an expression for f _m (·) such that:

(Qall ^~ Σ ^a m,m Qm ) ' β offset, m ^'

Q' = ^ , for all m Equation (5)

In such embodiments, Q ₀ ' ,K , Q _M ' _ _X can be expressed in terms of the matrix [AL _,S = ¾. _, « _> ^{and the} diagonal matrices [G]^ = g _M (P) and [c] _{m m} = β _φ ^ _η ^■ O _m as

(CA + G)Q'= Q _all C\ Q'= e _flfl (CA + G) ^_1 Cl Equation (6) where [x] _m „ denotes the element on row m (index starting at 0) and column n of a matrix X.

As another example, transmitter 100 may use an expression for f _m (·) that is further simplified such that:

(Qall ^~ Σ Qm ) ' fioffset,m ^'

Q' _m = _> Equation (7)

k=0

In such embodiments, transmitter 100 can solve for Q' _m , from the system of equations, as:

Transmitter 100 may use the first equality to triangularize the system of equations, so that transmitter 10 can then solve Q' _M _ _X in closed form, solve for a value of Q _M _ ₂ that only depends on Q' _M _ _X and. in general, solve for a value of Q' _n that only depends on Q' _n+l ,K , Q' _M . The second equation is useful since transmitter 100 can obtain

Q' _m in a closed form in which the nominal inverse spectral efficiency estimate,

depends on O and Β _{ο βί} .

In particular embodiments, transmitter 100 may determine the values for Q ' _m from Equations (7) and/or (8) by first solving for (?' ₀ in the allocation equation for

Q' ₀ . Transmitter 100 may then substitute the so obtained expression forg' ₀ in all equations for Q ,K , Q' _M _ _X such that the dependence on Q is eliminated from all equations. Transmitter 100 may then repeat the process for Q , and so on. When computing Q' _n possible post-processing (such as rounding to integer values, capping to maximum value, etc.) of Q' _n+l ,K , Q' _M _ _X may or may not be included. Moreover, in triangularized formulas below where Q may depend on Q' _n+l ,K , Q' _M _ _X , postprocessing of the latter may or may not be applied prior to computing Q .

Additionally, to provide greater control over the allocation, transmitter 100 may use a second offset parameter, _{offset m} for the nominal inverse spectral efficiency estimation that differs from _{oJfset m} - In particular embodiments, _{offset m} may be independently configurable, or may be a configurable function of _{offset m} - As one example, in particular embodiments, transmitter 100 may use a value of β _β , _m such that / _{oJJset m} = a _m fi _{offset m} , where a _m can be configured to be zero or one. As another example, transmitter 100 may estimate the nominal inverse spectral efficiency as: N _cw -l M-l

■ oj„jset,m ~ 0 m~

k=0 m=0

Furthermore, transmitter 100 may calculate the values Q ' _m using an expression for f _m (·) that is designed not to exceed a certain maximum spectral efficiency, s _{max m} ,

Q'm = Equation (9)

Moreover, transmitter 100 may determine the various values of 2' _m such that i _{mi Ill} > s _{max m+1} Vm . In such embodiments, then transmitter 100 can triangularize the system of equations in a similar fashion to that described above with respect to

M-l N _cw -l

Equations (7) and (8) based on the fact that if (g _fl „ -∑g~) /∑ _t ≤l/« _max,m then

Qm = βφ«Μ ^■ ° ^■ (Qau -∑Q~ ) ∑P _k , Vm≤m. Thus, the dependence on m=0 k=0

Q'~ , m≤m can be eliminated using the same process as for the case without the max(.) operator. By doing so, transmitter 100 can, in such embodiments, triangularize Equation (9) to produce an expression for Q ' _m :

Q _m = ^■ β 'offset, _m - O _m , Equation (10) such that the nominal inverse spectral efficiency depends on Q ~ , rh > m , and β offset ίη For the special case where s _{^ m} = s _^ /m > then

^■ offset, _m - O _m Eq. (1 1),

with a special case being s _max =∞ .

Particular embodiments of transmitter 100 may use a different offset parameter (e.g., P _offsetim ) in determining the nominal inverse spectral efficiency estimation as well as setting a maximum value for the spectral efficiency. As a specific example, transmitter 100 may calculate a nominal inverse spectral efficiency estimation such that:

Qm = ^maX off _sel,m - O _m , Equation (12)

and similarly a different β _{ε1 m} can be used in the nominal inverse spectral efficiency estimate above for s _{max m} = s _max Vm > M .

For particular embodiments of transmitter 100, it may be especially useful to utilize the above formulas when all control signals affect each codeword equally— i.e., the control signals are all multiplexed with all user data codewords. However, in scenarios in which different control signals affect the codewords differently, transmitter 100 may be configured to take such asymmetries into account when estimating the nominal inverse spectral efficiency.

If the control signals (or the overhead of the control signals) are indexed as (m, k) : 0≤ k≤ N _cw ,0≤ m < M _k , where the overhead of a control signal

(m, k), k < N _cw , only affects the k -th data codeword {i.e., it is multiplexed only with the & -th user data codeword), and (m, N _cw ) denotes a control signal that affects all data codewords equally (i.e., it is multiplexed with all user data codewords). M _k denotes the number of control signals that affect the overhead of the k -th user data codeword (or that affects all user data codewords for k = N _cw ).

If the allocation of resources that transmitter 100 calculates satisfies the following set of equations (e.g., if the control signals are spatially multiplexed along with the user data):

Then, transmitter 100 can be triangularize the set of equations as:

^N cw

(Qa, ~∑, Qm,N _cw ) ^' β ₀ o)ffset, (n

Eq. (15)

P _k +∑β offset ,(m,k) ^m,k

(Q, all / > m. N. fffset,(m,N _cw ) O ^,πι,Ν,

m=m+\

Ncw - Q' ,-l

Σ ^{+ '} Σ, β offset, (in,k) ^' Offi,k \ ⁺ V Σ β a offset, (in, N _cw ) O . nff =0 m=0 J m=0

g (16)

where the expressions for Q' _mJc , k < N _cw only depend on Q' _miN , which transmitter

100 can compute in closed form or from a triangularized set of equations. As noted above, transmitter 100 may use a different offset parameter, ? _{0 (¾ m} , in the above nominal inverse spectral efficiency estimations.

A special case with particular importance to technologies such as LTE- Advanced is the resource allocation for such control signals as Channel Quality

Indication (CQI) / Precorder Matrix Indication (PMI), Hybrid Automatic Repeat reQuest (HARQ) Acknowledgement (ACK) / Negative Acknowledgement (NAK), and Rank Indication (RI). In particular embodiments, transmitter 100 multiplexes

CQI/PMI only with one user data codeword, k _CQI e {0,1} , (let k _CQI - 1 - k _CQI denote the complementary user data codeword) but multiplexes HARQ-ACK and RI with all user data codewords. Formulas for determining values of Q ' (using, in each case, the nominal spectral efficiencies) for the various control signals could then be expressed as:

^CQI Eq. (17)

nRI ₀ RI

Q< = P^ Eq.(19) p _k p—

Qall ^~ Q CQI ^~ Q HARQ-ACK -Q , Q _M -Q HARQ-ACK ^ RI

Accordingly, to perform such a resource allocation, transmitter 100 can use allocation formul ) as:

HARQ-ACK M _cw

∑ P _l_ nee' n ^C Q' 4- RHARQ-ACK _n HARQ-ACK

rk ⁺ P offset ^{' U +} P offset ^{' U}

k=0 Eq. (21) β nHARQ-ACK HARQ-ACK

all ^' P offset ^{' U}

∑ P _l_ R ^C 0' n ^C Q' 4- RHARQ-ACK _n HARQ-ACK nRI _n h

rk ⁺ P offset ^{' U +} P offset ^{' U +} P offset ^{' U}

∑ P _i_ R ^C Q' n ^C e' 4- ^HARQ-ACK _n HARQ-ACK nRI _n RI

rk ^~ r P offset ^{' ~} r P offset ^' ^ ^~ r P offset ^' ^

k=0

As noted above, in particular embodiments, transmitter 100 may utilize a different offset parameter, _offsetm , in the nominal inverse spectral efficiency estimation of the large control signal payload compensation. Additionally, the resource allocation formulas above can likewise be generalized to cope with a maximum allowed spectral efficiency for each of the control signals that affects all codewords, or for any other suitable subset of control signals. In other words, if transmitter 100 performs the allocation such that:

M _k -\ M _Ncw -\

(Qall ^~ Σ Qm,k ^~ Σ Qm,N _cw ) ' β 'offset, (m,k) ^' ^m,k

< New = — ^ Eq.(23) and then transmitter 100 can utilize a set of equations to perform the allocation that can be triangularized (and solved) as: where the control signals are ordered such that s _→mJfar) ≥ ₍ »i,½) ^{Vffl and the} values , k < N _cw are obtained from Equation (15).

If in addition the allocation of _k , k < N _cw are to ensured to be non- negative: then

N _cw : Q _mJc = ^Ε ¾· ( ²⁷ )

and are still given by Equation (25).

In particular embodiments (such as, for example, certain embodiments implementing LTE-Advanced), transmitter 100 may utilize the following equations in situations in which a rank one diversity encoding is used for RI and HARQ-ACK, allowing only the maximum spectral efficiency of a layer one transmission, while

CQI/PMI is spatially multiplexed with a single user data codeword, providing the same peak spectral efficiency as the user data codeword it is multiplexed with

i2 ,c -→ ^ 5 .— ^{)■ β} 2 ^ΛΕΚ■ o"^-

^Q « =™* ⁽ _p jr .7- ^)■ ¾L ^■ o ^a

I

The above expression can be rewritten as: _&cei = max( ^g - ,0)■ ■ _E q. (28)

Q« = max(^ ) ^■ ¾L ^■

∑ + ¾ ^■ O ^C « + /¾L ^■ o" ^s ™ Eq. (30)

= ^max fe; — >— ) ^■ K,

∑ ^p _k + /¾£, ^■ o^' + β^- ^{ί Κ■} o ^HiRa - ^iCK + ¾L -o" ^J»

As explained above, a different offset parameter, _{offset m} , may be used in the large control payload compensation in the nominal inverse spectral efficiency estimation.

Additionally, in particular embodiments, transmitter 100 may ignore the overhead of the HARQ-ACK when performing the allocation for RI and CQI/PMI. This may provide the advantage that the Q ^HAR Q- ^ACK determined by transmitter 100 may not be perfectly known at the relevant receiver, due for example to downlink grants that where missed by transmitter 100. It may therefore be detrimental to introduce a dependence on Q ^HAR Q- ^ack [ _{η 0} t e allocation for the other control signals. Hence, transmitter 100 may use values for Q _CQI and Q _s/ that can be expressed as

™ ^χ ( - _P ^{1 >} -> ^{' ■}

I from which Q _{C I} and Q _RI can be solved in closed (triangularized) form as:

. _Q *i _{Equation (3 1}}

/ , ^r k ^† P offset ^{17 †} P offset ^{1 7} ■ 0 ^RI Equation (32) However, the asymmetry introduced by ignoring the overhead of Q' _HARQ _ _ACK in the expressions Q' _CQI and Q' _RI makes it more difficult to derive a closed- form expression for Q' _HARQ _ _ACK ■ Nonetheless, transmitter 100 may use any of several closed-form allocation formulas for Q _HARQ _ _ACK that closely approximate the desired allocation. One technique for doing so is to also ignore the overhead of Q _HARQ _ _{A CK} ^m the estimate of the nominal inverse spectral efficiency for the allocation of Q' _HARQ _ _{A CK} such that:

In such embodiments, transmitter 100 may obtain a closed-form expression for Q' _HARQ - _ACK ^{m a} similar manner to Q' _RI . That is, transmitter 100 may use the following expression:

Q' _HARe - _{A CK} _ _oHARe - _{A CK} _ _Eq . ₍₃₄₎

As one alternative, particular embodiments of transmitter 100 may use the following expression for

)

, =

which is motivated by the inequality:

≥max( 1 _^ -yp^a

p _t

The inequality results from the fact that, if the overhead of Q' _HARQ _ _ACK was accounted for when computing and the equality would hold. By accounting for the overhead, Q' _CQI ^an d Q' are reduced, which yields the inequality. If no maximum spectral efficiency cap is required, transmitter 100 may perform the allocation using the formulas above but forgoing the max( ) operation.

Thus, transmitter 100 may provide improved resource allocation techniques in a variety of different forms. Using these resource allocation techniques, certain embodiments of transmitter 100 may be able to match the allocation of control- signaling transmission resources to the quality of the relevant radio channel and to account for the use of multiple codewords or layers in making the allocation. Additionally, certain embodiments accurately account for the amount of transmission resources that will be used for control signaling when estimating the supported inverse spectral efficiency of the transmission channel, resulting in a more accurate estimate and, thus, an improved allocation. As a result, such embodiments may reduce the amount of overhead used to transmit control signaling when the control signaling is multiplexed with user data. Consequently, certain embodiments of transmitter 100 may provide multiple operational benefits. Specific embodiments, however, may provide some, none, or all of these benefits.

Although the description above focuses on implementation of the described resource allocation techniques in a transmitter, the above concepts can also be applied at a receiver. For example, when decoding transmissions received from transmitter 100, a receiver may utilize certain aspects of the described techniques to estimate the amount of transmission resources that have been allocated to control signaling.

Furthermore, the described concepts may be applied for purposed of scheduling use of transmission resources in wireless communication systems that utilize centralized resource management. For example, an eNode B may utilize certain aspects of the described techniques to estimate the amount of transmission resources a UE that incorporates transmitter 100 will allocate to control signaling for a given period of time or for a given amount of transmitted data. Based on this estimate, the eNode B may determine an appropriate number of transmission resources to schedule for use by the relevant UE. FIGURES 5-7 describe in greater detail the contents and operation of example devices capable of performing such receiving and/or scheduling. Additionally, although the description herein focuses on implementation of the described resource allocation techniques in wireless communication networks supporting LTE, the described resource allocation techniques may be utilized in conjunction with any appropriate communication technologies including, but not limited to LTE, High-Speed Packet Access plus (HSPA+), and Worldwide Interoperability for Microwave Access (WiMAX).

FIGURE 2 is a functional block diagram showing in greater detail the operation of a particular embodiment of carrier modulator 112. In particular, FIGURE 2 illustrates an embodiment of carrier modulator 1 12 that might be used by an embodiment of transmitter 100 that utilizes DFTS-OFDM as required for uplink transmissions in LTE. Alternative embodiments may be configured to support any other appropriate type of carrier modulation. The illustrated embodiment of carrier modulator 1 12 includes a DFT 202, a precoder 204, an inverse DFT (IDFT) 206, and a plurality of power amplifiers (PAs) 208.

Carrier modulator 1 12 receives vector symbols 124 output by layer mapper 1 10. As received by carrier modulator 1 12, vector symbols 124 represent time domain quantities. DFT 202 maps vector symbols 124 to the frequency domain. The frequency-domain version of vector symbols 124 are then linearly precoded by precoder 204 using a precoding matrix, W, that is ( N _T x r ) in size, where Nj represents the number of transmission antennas 1 14 to be used by transmitter 100 and r represents the number of transmission layers that will be used by transmitter 100. This precoder matrix combines and maps the r information streams onto N _T precoded streams. Precoder 204 then generates a set of frequency- domain transmission vectors by mapping these precoded frequency-domain symbols onto a set of sub-carriers that have been allocated to the transmission.

The frequency-domain transmission vectors are then converted back to the time domain by IDFT 206. In particular embodiments, IDFT 206 also applies a cyclic prefix (CP) to the resulting time-domain transmission vectors. The time-domain transmission vectors are then amplified by power amplifiers 208 and output from carrier modulator 1 12 to antennas 1 14, which are used by transmitter 100 to transmit the time-domain transmission vectors over a radio channel to a receiver.

FIGURE 3 is a structural block diagram showing in greater detail the contents of a particular embodiment of transmitter 100. Transmitter 100 may represent any suitable device capable of implementing the described resource allocation techniques in wireless communication. For example, in particular embodiments, transmitter 100 represents a wireless terminal, such as an LTE user equipment (UE). As shown in FIGURE 3, the illustrated embodiment of transmitter 100 includes a processor 310, a memory 320, a transceiver 330, and a plurality of antennas 1 14.

Processor 310 may represent or include any form of processing component, including dedicated microprocessors, general-purpose computers, or other devices capable of processing electronic information. Examples of processor 310 include field-programmable gate arrays (FPGAs), programmable microprocessors, digital signal processors (DSPs), application-specific integrated circuits (ASICs), and any other suitable specific- or general-purpose processors. Although FIGURE 3 illustrates, for the sake of simplicity, an embodiment of transmitter 100 that includes a single processor 310, transmitter 100 may include any number of processors 310 configured to interoperate in any appropriate manner. In particular embodiments, some or all of the functionality described above with respect to FIGURES 1 and 2 may be implemented by processor 310 executing instructions and/or operating in accordance with its hardwired logic.

Memory 320 stores processor instructions, equation parameters, resource allocations, and/or any other data utilized by transmitter 320 during operation.

Memory 320 may comprise any collection and arrangement of volatile or nonvolatile, local or remote devices suitable for storing data, such as random access memory (RAM), read only memory (ROM), magnetic storage, optical storage, or any other suitable type of data storage components. Although shown as a single element in FIGURE 3, memory 320 may include one or more physical components local to or remote from transmitter 100.

Transceiver 330 transmits and receives RF signals over antennas 340a-d. Transceiver 330 may represent any suitable form of RF transceiver. Although the example embodiment in FIGURE 3 includes a certain number of antennas 340, alternative embodiments of transmitter 100 may include any appropriate number of antennas 340. Additionally, in particular embodiments, transceiver 330 may represent, in whole or in part, a portion of processor 310.

FIGURE 4 is a flowchart detailing example operation of a particular embodiment of transmitter 100. In particular, FIGURE 4 illustrates operation of an embodiment of transmitter 100 in allocating transmission resources to the transmission of control codewords 120 conveying M different control signals. The steps illustrated in FIGURE 4 may be combined, modified, or deleted where appropriate. Additional steps may also be added to the example operation. Furthermore, the described steps may be performed in any suitable order.

Operation begins at step 402 with transmitter 100 determining a number of bits in one or more user data codewords 122 to be transmitted during a subframe. In particular embodiments, user data codewords 122 may include CRC bits, and transmitter 100 may consider these CRC bits when counting the bits in the relevant user data codewords 122. Additionally, in particular embodiments, the plurality of user data codewords counted by transmitter 100 may represent all of the user data codewords 122 to be transmitted during the sub frame or only a subset of those user data codewords 122. For example, in certain embodiments, transmitter 100 may determine the number of bits in step 402 based only on the user data codewords 122 to be transmitted on certain transmission layers.

In particular embodiments, transmitter 100 may be configured to selectively utilize the techniques described above to provide more accurate estimates of the optimal allocation for control signaling. For example, in particular embodiments, transmitter 100 may utilize the above described techniques when a compensation feature of transmitter 100 has been activated (e.g., as a result of instructions from a serving base station). Therefore, in such embodiments, transmitter 100 may determine whether a compensation feature of transmitter 100 is activated as part of allocating vector symbols to user data and control signaling. For the illustrated example, it is assumed that transmitter 100 determines that the compensation feature is activated as shown at step 404. In the illustrated embodiment, transmitter 100 will then use the resource allocation techniques described above, because the compensation feature is activated, rather than using an alternative allocation technique that does not account for the effect of control signaling allocation on the available resources for transmitting user data or does not account for each of the control signals separately. Alternative embodiments of transmitter 100 may be configured to always use such compensation.

At step 406, transmitter 100 then uses the number of bits of user data codewords 122 to be transmitted during the sub frame to calculate a number of vector symbols 124 to allocate to the payload of each of the M control signals. As discussed above, transmitter 100 also bases this calculation in part on an estimate of the number of user data vector symbols onto which the user data codewords 122 will be mapped (e.g., as reflected by an estimated inverse spectral efficiency for user data). In particular embodiments, the estimated number of user data vector symbols depends on the number of control vector symbols that would result if the calculated number of user data vector symbols were in actuality allocated to the transmission of user data. The estimated number of user data vector symbols also depends on the amount of transmission resources allocated to the payload for at least one other of the M control information signals. As discussed above, in particular embodiments, the estimated number of user data vector symbols may depend on the transmission resources allocated to the payload of a particular subset of control signals selected based on how the relevant control signals are multiplexed with and/or affects the overhead of the various user data codewords to be transmitted during the subframe in question.

For the purposes of the example in FIGURE 4, transmitter 100 calculates a nominal number of control vector symbols ( Q ^r ) for each of the M control signals such that:

Q m ~ fm 0 Qdata.O (Q) ' (Q)' β offset, m ' )

As discussed above, transmitter 100 may estimate the number of vector symbols 124 to be allocated to user data codewords 122 in any suitable manner including, but not limited to, using any of the formulations of discussed above. Because Q _m ' is a function of Q _{data k} , which itself depends on Q _m ' , in particular embodiments, transmitter 100 may solve for the values of Q _m ' and Q _{data k} recursively. Alternatively, transmitter 100 may utilize a formulation that permits Q _m ' for each control signal to be expressed in a closed form, and thereby enables transmitter 100 to solve for Q _m ' explicitly. For example, as part of step 406, transmitter 100 may estimate Q _data as:

-l

Qdata,k (Q ) ⁼ Qall ^~ ^ _j ^a k,m Qm ' where a _{k m} are linear, typically non-negative, weights.

In particular embodiments, Q _m ' may represent a nominal number of control vector symbols for the m-t control signal, and transmitter 100 may apply certain additional processing steps to this nominal number of control vector symbols to produce an appropriate final number of control vector symbols 124 for the transmission. Non-limiting examples of this processing are shown in steps 408-412. For example, the illustrated embodiment of transmitter 100 compares the nominal number of control vector symbols 124 for each of the control signals to a minimum number that transmitter 100 is configured to use in transmitting control codewords 120 at step 408. This minimum number of control vector symbols 124 may be a generic minimum threshold applied to all control codeword 120 transmissions or may be a minimum determined by transmitter 100 for this specific transmission (for example, based on the payload of the control codewords 120 to be transmitted). Transmitter 100 may then select the greater of the nominal calculated number and the minimum number as the number of vector symbols 124 to allocate to control information, as shown at step 410.

In addition, or as an alternative, to ensuring a minimum allocation, transmitter

100 may be configured to perform any other appropriate post-processing to the nominal number of vector symbols 124 for each of the M control signals, such as converting these nominal numbers to integer values {e.g., by applying a ceiling operation) or otherwise increasing or decreasing the nominal numbers to ensure a final number for each control signal within a certain range, as represented by step 412.

Transmitter 100 may then use the respective nominal number or the output of any additional post-processing as the final number of vector symbols 124 to allocate to a particular control signal.

After determining the final number of vector symbols 124 to allocate to each of the M control signals, transmitter 100 then maps each of the M control codewords

120 available for transmission to the calculated final number of vector symbols 124 for that particular control codeword at step 414. Transmitter 100 may perform any appropriate processing of the control vector symbols 124 to permit transmission of the control vector symbols 124 to a receiver in communication with transmitter 100 including, for example, the processing described above with respect to FIGURE 2.

After completing any appropriate processing of vector symbols 124, transmitter 100 then transmits control vector symbols 124 over a plurality of transmission layers using the plurality of antennas 114 at step 416. Operation of transmitter 100 with respect to transmitting these particular control codewords 120 may then end as shown in FIGURE 4.

FIGURE 5 is a structural block diagram showing the contents of a network node 500 that may serve as a receiver for control codewords 120 transmitted by transmitter 100 and/or that may serve as a scheduler for scheduling transmission of control codewords 120 by transmitter 100. As noted above, the described resource allocation techniques may also be utilized by devices in decoding transmissions received from transmitter 100 or in determining the appropriate amount of transmission resources to schedule for use by transmitter 100 in a given subframe. For example, in particular embodiments, transmitter 100 may represent a wireless terminal (such as an LTE UE) and network node 500 may represent an element of a radio access network that receives uplink transmission from the wireless terminal or that is responsible for scheduling the wireless terminal's use of transmission resources (such as an LTE eNodeB).

As shown in FIGURE 5, the illustrated embodiment of network node 500 includes a processor 510, a memory 520, a transceiver 530, and a plurality of antennas 540a-d. Processor 510, memory 520, transceiver 530, and antennas 540 may represent identical or analogous elements to the similarly-named elements of FIGURE 3. In particular embodiments of network node 500, some or all of the functionality of network node 500 described below with respect to FIGURES 6 and 7 may be implemented by processor 510 executing instructions and/or operating in accordance with its hardwired logic.

FIGURE 6 is a flowchart detailing example operation of a particular embodiment of network node 500. In particular, FIGURE 6 illustrates operation of an embodiment of network node 500 in receiving and decoding control codewords 120 for M different control signals received from transmitter 100. The steps illustrated in FIGURE 6 may be combined, modified, or deleted where appropriate. Additional steps may also be added to the example operation. Furthermore, the described steps may be performed in any suitable order.

Operation of network node 500 begins at step 602 with network node 500 receiving a plurality of vector symbols 124 from transmitter 100. The plurality of vector symbols 124 include vector symbols 124 carrying control associated with M different control signals. For purposes of decoding the vector symbols 124, network node 500 may need to determine the manner in which transmitter 100 allocated these vector symbols 124 between user data and the various control signals. As a result, network node 500 may determine the number of the received vector symbols 124 that transmitter 100 used to transmit control codewords 120 for each of the M control signals.

To properly decode the received vector symbols 124, network node 500 may need to follow the same or an analogous procedure to what transmitter 100 used to determine the resource allocation on the transmitting side. Thus, depending on the configuration of the relevant transmitter 100, network node 500 may be configured to determine the number of vector symbols 124 allocated to control codewords 120 (referred to herein as "control vector symbols") for each of the M control signals using any of the techniques described above. An example of this process for the example embodiment is shown at steps 604-608 of FIGURE 6. In particular, FIGURE 6 describes operation of an embodiment of network node 500 that communicates with the transmitter 100 described by FIGURES 1-3. Thus, network node 500 performs steps 604-614 in a similar or analogous fashion to that described above for the similarly-captioned steps in FIGURE 3.

After network node 500 has determined the final number of vector symbols 124 that transmitter 100 allocated to control codewords 120 for each of the M control signals, network node 500 decodes vector symbols 124 received for each control signal based on this number at step 616. For example, network node 500 may use this information to determine which of the received vector symbols 124 are carrying control codewords 120 and which are carrying user data codewords 122 and/or which control signal a particular vector symbols 124 is carrying information for. If transmitter 100 has encoded control signaling and/or user data using different encoding schemes, network node 500 may then apply a different decoding scheme to the two types of vector symbols 124 or to the vector symbols carrying the various control signals. Operation of network node 500 with respect to decoding the received symbol vectors may then terminate as shown in FIGURE 6.

FIGURE 7 is a flowchart detailing example operation of a particular embodiment of network node 500 responsible for scheduling the use of transmission resources by transmitter 100. The steps illustrated in FIGURE 7 may be combined, modified, or deleted where appropriate. Additional steps may also be added to the example operation. Furthermore, the described steps may be performed in any suitable order.

In FIGURE 7, operation of network node 500 begins at step 702 with network node 500 receiving a request for transmission resources from transmitter 100. This request may represent any appropriate information indicating network node 500 has information, including one or both of control signaling and user data, to transmit in a geographic area served by network node 500. In particular embodiments, network node 500 may represent an LTE eNodeB and this request may represent a scheduling request transmitted by transmitter 100 on PUCCH. Additionally, network node 500 may possess information regarding transmissions transmitter 100 is expected to make during the relevant subframe. For example, in the relevant subframe, transmitter may expect a HARQ ACK/NACK transmission from transmitter 100 responding to a previous transmission from network node 500. Alternatively or additionally, in particular embodiments, the scheduling request received by network node 500 may indicate the amount and/or type of information transmitter 100 is intending to transmit.

In response to receiving the request, network node 500 may determine an allocation of transmission resources to grant to transmitter 100 for use in transmitting the requested transmission. To determine this allocation, network node 500 may determine the amount of control information and user data network node 500 expects transmitter 100 to transmit in conjunction with the request. Network node 500 may determine these amounts based on information included in the request itself, information maintained locally by network node 500 itself (e.g., information on expected control information transmissions), and/or information received from any other suitable source.

Furthermore, in particular embodiments, network node 500 determines this overall allocation based on the assumption that transmitter 100 will determine an allocation for control vector symbols for the requested transmission based on the techniques described above. Thus, network node 500 may also use the techniques above to grant an appropriate amount of transmission resources to transmitter 100 for the requested transmission. Because the above techniques may involve transmitter 100 determining an allocation of control vector symbols that depends in part on the allocation of user data vector symbols, network node 500 may likewise estimate the control allocation based on an estimated allocation for user data. Furthermore, in determining a total allocation for transmitter 100, network node 500 may also account for the fact that, as described above, transmitter 100 will consider the resulting control vector symbol allocation when allocating vector symbols 124 to user data. This may result in network node 500 determining a total allocation for transmitter 100 comprised of a user data allocation and a control information allocation, which are dependent upon one another. Thus, in particular embodiments, network node 500 may determine the total allocation recursively. An example of this is shown by step 704 of FIGURE 7. Depending on the configuration of transmitter 100, network node 500 may process the estimated number of control vector symbols in an appropriate manner as described above before using the value to make the determination of step 704. For example, network node 500 may calculate a nominal number of control vector symbols based on the estimated number of data vector symbols, the estimated number of bits of control codewords 120 for each of M control signals, and the number of bits of user data to be carried by each of the user data codewords. Network node 500 may then scale this nominal number by an offset, increase the nominal number to meet a minimum number, apply a ceiling operation to the nominal, and/or perform any other appropriate processing to the nominal number to calculate the final estimated number of control vector symbols.

Network node 500 then uses this determination in responding to the request sent by transmitter 100. In particular embodiments, if network node 500 decides to grant the request, network node 500 may communicate aspects of the determined allocation to transmitter 100. Therefore, in particular embodiments, network node

500 may respond to the request by generating a particular response {e.g., a scheduling grant) to the request based on the determined allocation and transmitting the response to transmitter 100, as shown by steps 706-708 of FIGURE 7. For example, in certain LTE embodiments, network node 500 may generate a scheduling grant that includes information indicating the determined transmission rank, the determined total number of vector symbols, and the number of bits to be used for each data codeword and send this scheduling grant to transmitter 100. Alternatively or additionally, network node 500 may use the determined allocation in deciding whether to grant the request or in deciding how to prioritize the request. Operation of network node 500 with respect to scheduling transmitter 100 for this subframe may then terminate as shown in FIGURE

7.

Although the present invention has been described with several embodiments, a myriad of changes, variations, alterations, transformations, and modifications may be suggested to one skilled in the art, and it is intended that the present invention encompass such changes, variations, alterations, transformations, and modifications as fall within the scope of the appended claims.