Methods and systems for frequency domain gain control in OFDM MIMO systems

#Certain embodiments of the present disclosure generally relate to wireless communications and, more particularly, to gain control in frequency domain for orthogonal frequency division multiplexing (OFDM) multiple input multiple output (MIMO) systems.

#An OFDM multiple input multiple output (MIMO) signal may exhibit high peak to average power ratios (PAPR) in both time and frequency domains. Traditionally, a time domain gain control scheme is used to get constant signal level to maximize finite precision performance while minimizing hardware complexity. However, in an OFDM MIMO system, a frequency domain signal (i.e., the signal after FFT) may still show high PAPR even after time domain gain control is applied.

#The high PAPR values of frequency domain OFDM MIMO signals may require a large dynamic range for hardware architectures of OFDM MIMO decoders to preserve their original performance, which is expensive.

#So that the manner in which the above-recited features of the present disclosure can be understood in detail, a more particular description, briefly summarized above, may be had by reference to embodiments, some of which are illustrated in the appended drawings. It is to be noted, however, that the appended drawings illustrate only certain typical embodiments of this disclosure and are therefore not to be considered limiting of its scope, for the description may admit to other equally effective embodiments.

#FIG. 1 illustrates an example wireless communication system, in accordance with certain embodiments of the present disclosure.

#FIG. 2 illustrates various components that may be utilized in a wireless device in accordance with certain embodiments of the present disclosure.

#The word “exemplary” is used herein to mean “serving as an example, instance, or illustration.” Any embodiment described herein as “exemplary” is not necessarily to be construed as preferred or advantageous over other embodiments.

#Exemplary Wireless Communication System

#The techniques described herein may be used for various broadband wireless communication systems, including communication systems that are based on an orthogonal multiplexing scheme. Examples of such communication systems include Orthogonal Frequency Division Multiple Access (OFDMA) systems, Single-Carrier Frequency Division Multiple Access (SC-FDMA) systems, and so forth. An OFDMA system utilizes orthogonal frequency division multiplexing (OFDM), which is a modulation technique that partitions the overall system bandwidth into multiple orthogonal sub-carriers. These sub-carriers may also be called tones, bins, etc. With OFDM, each sub-carrier may be independently modulated with data. An SC-FDMA system may utilize interleaved FDMA (IFDMA) to transmit on sub-carriers that are distributed across the system bandwidth, localized FDMA (LFDMA) to transmit on a block of adjacent sub-carriers, or enhanced FDMA (EFDMA) to transmit on multiple blocks of adjacent sub-carriers. In general, modulation symbols are sent in the frequency domain with OFDM and in the time domain with SC-FDMA.