Method and apparatus for baseband signal processing for distributed fifth generation new radio uplink signals

Abstract

Methods and apparatuses for baseband signal processing for distribution of fifth generation (5G) new radio uplink signals. In embodiments, a method includes receiving an uplink transmission having user data, receiving configuration parameters, and performing a first portion of baseband processing that compresses the uplink transmission using the configuration parameters to generate compressed packets. The method also includes transmitting the compressed packets over a transmission medium to a central office that performs a second portion of the baseband processing to obtain the user data. In embodiments, an apparatus includes a radio frequency interface that receives an uplink transmission having user data, and a first baseband processing portion that receives configuration parameters, compresses the uplink transmission using the configuration parameters to generate compressed packets, and transmits the compressed packets over a transmission medium to a central office in which a second baseband processing portion processes the compressed packets to obtain the user data.

Description

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS

[0002] This application claims priority to U.S. Provisional Application No. 62 / 853,638, filed on May 28, 2019, entitled “METHOD AND APPARATUS FOR BASEBAND SIGNAL COMPRESSION OF 5G NR UPLINK,” which is hereby incorporated by reference in its entirety. Technical Field

[0003] The exemplary embodiments of the present invention relate to the operation of telecommunications networks. More particularly, the exemplary embodiments of the present invention relate to receiving and processing data streams for use in wireless telecommunications networks. Background Art

[0004] With the rapidly increasing trend towards mobile and remote data access through high-speed communication networks such as Long Term Evolution (LTE), fourth generation (4G), fifth generation (5G) New Radio (NR) cellular services, accurately delivering and decrypting data streams is becoming increasingly challenging and difficult.

[0005] During uplink operations, radio frequency (RF) signals received from user equipment at remote sites need to be transmitted to the central office. Typically, wireless carriers utilize leased data lines to transmit information between the central office and remote sites. It is desirable to use these leased lines as efficiently as possible, allowing for the use of less expensive lines or allowing for the use of more channels on existing lines.

[0006] Therefore, it is desirable to have a system that supports efficient transmission of received uplink signals from a remote site to a central office. Summary of the Invention

[0007] In various exemplary embodiments, methods and apparatus for a distributed baseband processing system are provided. The distributed baseband processing system operates to facilitate efficient transmission of received uplink signals from remote sites to a central office. In an embodiment, the distributed baseband processing system utilizes a first baseband processing section that includes an uplink front-end signal compressor that integrates FFTs, filters, and front-end signal processing for 5G NR uplink signals, so that all information channels of the 5G uplink can be significantly compressed without any loss of accuracy. The output of the compressor is easily packetized for Ethernet transmission. A second baseband processing section at the central office receives the packetized transmission and recovers the uplink data. The second baseband processor also transmits configuration parameters that control the operation of the first baseband processing section. As a result, the transmission lines between the central office and the remote site are efficiently utilized, allowing the use of less expensive transmission lines or allowing existing lines to be used to transmit more channels.

[0008] In an embodiment, the baseband signal processor at the central office directly controls the compression device and implements flexible data compression based on 5G uplink traffic in the time / frequency domain without losing any information. Since the uplink signal front-end processing is completed at the remote radio head, the baseband signal processor at the central office will have a larger processing margin.

[0009] In an embodiment, a method is provided that includes receiving an uplink transmission having user data, receiving configuration parameters, and performing a first portion of baseband processing that compresses the uplink transmission using the configuration parameters to generate compressed packets. The method also includes transmitting the compressed packets over a transmission medium to a central office, where the central office performs a second portion of the baseband processing to obtain the user data.

[0010] In an embodiment, an apparatus is provided that includes: a radio frequency interface that receives an uplink transmission having user data; and a first baseband processing portion that receives configuration parameters, uses the configuration parameters to compress the uplink transmission to generate compressed packets; and transmits the compressed packets over a transmission medium to a central office, where a second baseband processing portion processes the compressed packets to obtain the user data.

[0011] Other features and benefits of exemplary embodiments of the present invention will become apparent from the detailed description, drawings, and claims set forth below. BRIEF DESCRIPTION OF THE DRAWINGS

[0012] Exemplary aspects of the present invention will be more fully understood from the detailed description given below and from the drawings of various embodiments of the present invention, which, however, should not limit the present invention to specific embodiments but are only for explanation and understanding.

[0013] Figure 1 A block diagram of a communication network including an exemplary embodiment of a distributed uplink baseband processing system is shown.

[0014] Figure 2 Shown Figure 1 An exemplary detailed embodiment of a central office and remote sites is shown in FIG.

[0015] Figure 3 Shown Figure 2 A detailed embodiment of the uplink compressor is shown in .

[0016] Figure 4 It shows how the 4G / 5G uplink baseband signal is processed in an embodiment of the uplink compressor and input to the compression and packetizer.

[0017] Figure 5 Shown by Figure 3 1 and 2. Example compressed antenna packets generated by the exemplary embodiment of the compression and grouping unit shown in FIG.

[0018] Figure 6 Shown by Figure 3 1 and 2. Example time slot packets generated by the exemplary embodiment of the compression and packetizer shown in FIG.

[0019] Figure 7 It shows how an embodiment of a distributed baseband compression system can transmit uplink signals from a remote site to a central office with greater efficiency than conventional systems.

[0020] Figure 8 An exemplary method for performing uplink baseband compression in accordance with an exemplary embodiment of a distributed baseband processing system is shown. DETAILED DESCRIPTION

[0021] Aspects of the present invention are described below in the context of methods and apparatus for compressing 5G New Radio uplink signals.

[0022] The purpose of the following detailed description is to provide an understanding of one or more embodiments of the present invention. Those skilled in the art will appreciate that the following detailed description is merely illustrative and is not intended to be limiting in any way. Other embodiments will readily suggest themselves to such skilled persons having the benefit of this disclosure and / or description.

[0023] For the sake of clarity, not all conventional features of the implementations described herein are shown and described. Of course, it should be understood that when developing any such actual implementation, many implementation-specific decisions may be made to achieve the developer's specific goals, such as compliance with application and business-related constraints, and that these specific goals will vary from one implementation to another and from one developer to another. Furthermore, it should be understood that such development work may be complex and time-consuming, but it will still be a routine task for those of ordinary skill in the art who benefit from the embodiments of the present disclosure.

[0024] The various embodiments of the present invention shown in the accompanying drawings may not be drawn to scale. Rather, the dimensions of various features may be enlarged or reduced for clarity. In addition, some drawings may be simplified for clarity. Therefore, the accompanying drawings may not depict all components of a given device (e.g., apparatus) or method. The same reference numerals will be used throughout the accompanying drawings and the following detailed description to refer to the same or similar parts.

[0025] The term "system" or "device" is used generally herein to describe any number of components, elements, subsystems, devices, packet switching elements, packet switches, access switches, routers, networks, modems, base stations, eNBs (eNodeBs), computers, and / or communication devices or mechanisms, or combinations of components thereof. The term "computer" includes a processor, memory, and bus capable of executing instructions, where a computer refers to one or a cluster of the following: a computer, a personal computer, a workstation, a mainframe, or a combination of computers.

[0026] Figure 1 A block diagram of a communication network 100 is shown that includes an exemplary embodiment of a distributed uplink baseband processing system. The network 100 may be configured as a fourth generation ("4G"), long term evolution (LTE), fifth generation (5G), new radio (NR), or a combination of 4G and 5G cellular network configurations.

[0027] Network 100 includes a central office 120 and remote sites 104 that communicate with each other using transmission lines 118. In an embodiment, central office 102 and remote sites 104 are separated by a significant distance. Transmission lines 118 are optical fiber or other suitable transmission media.

[0028] Remote site 104 includes a baseband (BB) processing section (A) 106 and an RF interface 108. RF interface 108 receives uplink communications from user equipment, such as user equipment 116, using antenna 110. RF interface 108 provides the received uplink communications to baseband processing section 106. BB processing section 106 performs a first portion of baseband processing on the received uplink communications and generates compressed uplink BB packets 112, which are transmitted to central office 102 using transmission line 118.

[0029] In an embodiment, the central office 102 includes a baseband processing section (B) 120 that receives the compressed uplink baseband packets 112 and performs additional baseband processing functions to obtain the transmitted uplink information. In an embodiment, the baseband processing section (B) 120 generates configuration parameters 114 that are transmitted to the remote site 104 using the transmission line 118. The configuration parameters 114 are used by the baseband (BB) processing section (A) 106 to control the compression process used to generate the packets 112.

[0030] Thus, network 100 illustrates a distributed baseband processing system that efficiently utilizes the transmission lines between a central office 102 and a remote site 104. A baseband processing portion (A) 106 at the remote site 104 performs a portion of the baseband processing to generate compressed packets 112, which are transmitted to the central office 102 via the transmission line 112. The compressed packets 112 contain the received uplink data in a compressed format without sacrificing efficient utilization of the transmission line 118, thereby allowing the use of less expensive transmission lines or allowing more information channels to be transmitted over existing transmission lines. A more detailed description of the distributed baseband processing system is provided below.

[0031] Figure 2 Shown Figure 1 Detailed exemplary embodiments of central office 102 and remote site 104 are shown. In an embodiment, central office 102 includes one or more baseband (BB) DSPs, such as DSP 202, as part of BB processing section (B) 120. Central office 102 also includes an interface 204 for transmitting and receiving information over transmission line 118. In an embodiment, a DSP, such as DSP 202, transmits configuration parameters 214 to remote site 104 using interface 204 and transmission line 118.

[0032] The remote site 104 includes an interface 206 that receives the configuration parameters 114 and transmits this information to an uplink compressor 208, which is part of the BB processing portion (A) 106. The compressor 208 compresses the uplink signal received by one or more RF interfaces, such as the RF interface 108. For example, each RF interface receives the uplink transmission using an antenna, such as the antenna 110, and converts the received analog signal to a digital format using a digital-to-analog converter (ADC). Thus, the RF interface generates a time-domain uplink signal 218 that is transmitted to the uplink compressor 208. The uplink compressor 208 compresses the received uplink signal according to the received configuration parameters 114 and generates compressed uplink baseband packets 112, which are transmitted to the central office 102 using the interface 206 and the transmission line 118. In various embodiments, any type of packetized transmission format may be utilized.

[0033] Figure 3 Shown Figure 2 Detailed embodiment of uplink compressor 208 is shown in FIG. In an embodiment, compressor 208 includes: a DC canceller 304, a frequency shifter 306, a cyclic prefix (CP) canceller 308, an FFT block 310, a guard carrier (GC) canceller 312, a frequency domain power measurement circuit 314, a time domain power measurement circuit 316, a compression and grouping unit 318, a frequency shifter 320, a sample rate converter 322, and a controller 324.

[0034] During operation, the digital time-domain uplink baseband signal 218 output from the RF interface (e.g., 108) is input to the DC canceller 304 of the compressor 208. The DC canceller 304 removes the DC offset from the uplink time-domain signal and outputs a DC-adjusted signal, which is input to the frequency shifter 306 and the time-domain (TD) measurement circuit 316. The frequency shifter 306 frequency-shifts the signal it receives and outputs a frequency-shifted signal, which is input to the CP canceller 308. The CP canceller removes the cyclic prefix and outputs a CP-cancelled signal, which is input to the FFT block 310. The FFT block 310 performs a Fourier transform on the CP-cancelled signal to generate a frequency-domain signal, which is input to the GC canceller 312. The GC canceller 312 generates a GC-cancelled signal, which is input to the frequency-domain measurement circuit 314 and the compression and packetization block 318. The time domain measurement circuit 316 performs time domain power measurement and outputs the result to the compression and grouping circuit 318. The frequency domain measurement circuit 314 performs frequency domain power measurement and outputs the result to the compression and grouping circuit 318.

[0035] The output of the DC canceller 304 is also input to a frequency shifter 320, which shifts the frequency of its received signal to separate the user access preamble (UAP) and outputs the frequency-shifted signal separating the UAP to a sampling rate conversion block 322. The sampling rate conversion block 322 performs rate conversion on the UAP and inputs the rate-converted UAP to the compression and packetization block 318.

[0036] Compression and packetizer 318 performs compression on the baseband signal and generates compressed uplink baseband packets 112 for transmission to central office 102 using transmission line 118. A more detailed description of the operation of compression and packetizer 318 is provided below.

[0037] In an embodiment, controller 324 receives configuration parameters 114 and uses these parameters to control the operation of uplink compressor 208. For example, controller 324 uses configuration parameters 214 to control the operation of FFT block 310, CP canceller 308, DC canceller 304, frequency shifters 306 and 320, and rate converter 322. More information about configuration parameters 214 is provided below.

[0038] Configuration parameters

[0039] In an embodiment, controller 324 controls the operation of uplink 208 based on received configuration parameters 114. The following is a non-exhaustive list of configuration parameters utilized by controller 324. It should be noted that in other embodiments, other configuration parameters may be utilized.

[0040] 1. Logical antenna index

[0041] 2. FFT size

[0042] 3. Cyclic prefix size

[0043] 4. Subcarrier spacing

[0044] 5. Number of resource blocks

[0045] 6.DC cancellation (on / off)

[0046] 7. Frequency shift (Hz)

[0047] 8. Semitone downshift (on / off)

[0048] 9. User-defined phase rotation

[0049] 10.FFT input signal scale

[0050] 11.CP eliminates offset

[0051] 12. Antenna calibration (on / off)

[0052] 13.PRACH rate converter (on / off)

[0053] 14.PRACH frequency shift

[0054] 15. Rate conversion ratio

[0055] Figure 4 1 illustrates how a 4G / 5G uplink baseband signal is processed and input to the compression and packetizer 318 in an embodiment of the uplink compressor 208. During operation, a received uplink signal is input to the DC canceller 304, which generates a DC-canceled signal, which, as described above, is input to the frequency shifter 306 and the frequency shifter 320. The frequency shifter 306 generates a frequency-shifted output 404, which includes a cyclic prefix 406 and FFT data 408. The frequency-shifted output 404 is input to the CP canceller 308, which removes the CP 406 to generate a CP-canceled signal 410, which includes the FFT data 408. The FFT data 408 is input to the FFT block 310, which performs a Fourier transform to generate a frequency-domain signal 412 including a guard carrier 414 and user data 416. Frequency domain signal 412 also shows the location of user access preamble 418, which may also be referred to as a control signal. Frequency domain signal 412 is input to a GC canceller, which removes guard carrier 414 and outputs user data 416 to compression and packetizer 318. In an embodiment, user data 416 includes twelve samples per resource block (e.g., num_rb x 12 samples). GC canceller also provides the user data to frequency domain measurement circuit 314.

[0056] The DC-canceled signal 402 is also input to the frequency shifter 320, which frequency shifts the signal to allow for separation of the UAP 418. The sample rate converter 322 performs rate conversion, including a low-pass filter, which filters the frequency-shifted signal output from the frequency shifter 320 to separate the UAP 418 and rate converts the UAP 418 to generate rate-converted (RC) UAPs 420, which are also input to the compression and packetization unit 318. In an embodiment, the compression and packetization unit 318 operates to compress and packetize the signals it receives to generate compressed uplink baseband packets 112 as described in more detail below.

[0057] Figure 5 Shown by Figure 3An exemplary compressed antenna packet 500 generated by an exemplary embodiment of the compression and packetizer 318 is shown. During operation, the compression and packetizer 318 generates the antenna packet 500 to have a header 502 that includes an antenna index, a packet timestamp, and a (frame: slot: symbol) number that identifies the packet. User data 416 and rate-converted UAP 420 are also inserted into the packet 500. The packet also includes a time domain power measurement 504 measured by the TD measurement circuit 316 and a frequency domain power measurement 506 measured by the FD measurement circuit 314.

[0058] Figure 6 Shown by Figure 3 An exemplary time slot packet 600 generated by an exemplary embodiment of the compression and grouping unit 318 is shown. In an embodiment, each time slot packet includes seven symbol packets, and each symbol packet includes up to N antenna packets. Thus, the compression and grouping unit 318 generates a stream of time slot packets, each of which includes a selected number of antenna packets containing a selected amount of baseband data. It should be noted that because each time slot packet includes identification information, the stream of time slot packets can be transmitted in any order at the central office.

[0059] Figure 7 Illustrated is how an embodiment of a distributed baseband compression system can transmit uplink signals from a remote site to a central office with greater efficiency than conventional systems. Figure 7 A conventional uplink processing system 702 is shown in which a received uplink RF signal is digitized at a remote site 704 and transmitted as an inefficient digital baseband signal to a central office 706 via transmission line 118. All baseband processing is performed at the central office, so that all overhead and additional information is transmitted to the central office 706 for baseband processing. As a result, received uplink communications are transmitted inefficiently over transmission line 118.

[0060] In contrast, the distributed baseband compression system 100 operates to perform a first portion of baseband processing at the remote site 104. For example, the BB processing portion (A) 106 performs a first portion of baseband processing at the remote site 104, and the BB processing portion (B) 120 performs a second portion of baseband processing at the central office 102. Because a portion of the baseband processing is performed at the remote site 104, the system 100 generates efficiently compressed baseband packets that are transmitted over the transmission line 118. Therefore, the transmission line 118 is more efficiently utilized by embodiments of the system 100.

[0061] Figure 8 An exemplary method 800 for performing uplink baseband compression according to an exemplary embodiment of a distributed baseband processing system is shown. For example, the method 800 is suitable for use with Figure 2The uplink compressor 208 is shown for use with the same.

[0062] At block 802, an uplink transmission is received at a front end. For example, an uplink transmission from a user equipment is received by the RF front end 108 at the remote site 104.

[0063] At block 804 , the received uplink transmission is passed to the first baseband processing section. For example, the uplink transmission received by the front end 108 is passed to the uplink compressor 208 of the first baseband processing section 106 .

[0064] At block 806, configuration information is received by the first baseband processing section. For example, configuration information 114 transmitted by the central office 102 to the remote site 104 via the transmission line 118 is received by the interface 206 and passed to the uplink compressor 208 of the first baseband processing section 106.

[0065] The DC offset is removed from the received uplink transmission at block 808. For example, DC canceller 308 removes the DC offset from the received uplink 218 to generate a DC-cancelled transmission.

[0066] The DC-canceled transmission is frequency shifted at block 810. For example, frequency shifter 306 frequency shifts the DC-canceled transmission to generate a frequency-shifted transmission.

[0067] The cyclic prefix is ​​removed from the frequency shifted transmission at block 812. For example, the CP canceller 308 removes the CP from the frequency shifted transmission to generate a CP-cancelled transmission.

[0068] An FFT is performed on the CP-canceled transmission at block 814. For example, FFT block 310 performs an FFT on the CP-canceled transmission to generate a frequency domain transmission.

[0069] The guard carrier is cancelled from the frequency domain transmission at block 816. For example, the GC canceller 312 cancels the GC from the frequency domain transmission to generate a GC cancelled transmission.

[0070] The DC-canceled transmission is frequency shifted at block 818. For example, frequency shifter 320 frequency shifts the DC-canceled transmission to generate a second shifted transmission.

[0071] At block 820, sample rate conversion is performed on the second frequency shifted transmission. For example, the sample rate converter 322 performs a low pass filter to separate the UAP signal and performs rate conversion on the second frequency shifted transmission to generate a rate converted UAP signal.

[0072] At block 822, the GC-eliminated transmission and the rate-converted UAP are used to generate compressed baseband signal packets. For example, the compressor and packetizer 318 receives the GC-eliminated transmission and the rate-converted transmission and generates compressed baseband signal packets 112. In an embodiment, compression is performed based on received configuration parameters. For example, Figure 5-Figure 6 Generate the grouping as shown.

[0073] At block 824, the compressed BB signal packets are transmitted to the central facility using transmission line 218. Since a portion of the baseband processing is performed at the remote site 104 (which processes non-essential information), using transmission line 118 to transmit the compressed BB signal packets to the central office 102 is very efficient.

[0074] Thus, the method 800 operates to perform uplink baseband compression according to an exemplary embodiment of a distributed baseband processing system.It should be noted that the operations of the method 800 may be modified, added, deleted, rearranged, or otherwise altered within the scope of the embodiments.

[0075] While particular embodiments of the present invention have been shown and described, it will be apparent to those skilled in the art based on the teachings herein that changes and modifications may be made without departing from the exemplary embodiments of the present invention and its broader aspects. It is therefore intended that the appended claims include all such changes and modifications within the true spirit and scope of the exemplary embodiments of the present invention.

Claims

1. A method for network communication, comprising: receiving, by a remote site, an uplink transmission comprising user data; Receive configuration parameters; performing a first portion of baseband processing that compresses the uplink transmission using the configuration parameters to generate compressed packets; as well as The compressed packets are transmitted from the remote site via a transmission line to a central office, where a second portion of the baseband processing is performed to obtain the user data, wherein the first portion of performing the baseband processing includes removing a DC offset from the received uplink transmission to generate a DC-canceled signal, frequency shifting the DC-canceled signal to generate a frequency-shifted signal, and removing a cyclic prefix, CP, from the frequency-shifted signal to generate a CP-canceled signal. 2 . The method of claim 1 , wherein performing the first portion of baseband processing comprises performing a Fourier transform on the CP-canceled signal to generate a frequency domain signal. 3 . The method of claim 2 , wherein performing the first portion of baseband processing comprises removing a guard carrier (GC) from the frequency domain signal to generate a GC-removed signal.

4. The method of claim 3 , wherein performing the first portion of baseband processing comprises: measuring a power level of the DC-canceled signal; as well as The power level of the GC-eliminated signal is measured.

5. The method of claim 4, wherein performing a first portion of baseband processing comprises frequency shifting the DC-canceled signal to generate a separated user access preamble signal.

6. The method of claim 5, wherein performing the first portion of baseband processing comprises performing sample rate conversion on the user access preamble signal to generate a rate-converted user access preamble signal.

7. The method of claim 6, wherein performing the first portion of baseband processing comprises generating antenna groups from: the GC-canceled signal, the rate-converted user access preamble, the power level of the DC-canceled signal, and the power level of the GC-canceled signal.

8. The method of claim 7 , wherein performing the first portion of baseband processing comprises: adding an identification header to the antenna packet; combining the antenna groups into symbol groups; as well as The symbol groups are grouped into slot groups, which form the compressed packets.

9. The method of claim 1 , wherein receiving the uplink transmission comprises receiving the uplink transmission as a fourth generation (4G), 5G, or Wi-Fi transmission.

10. A device for network communication, comprising: A radio frequency (RF) interface for receiving uplink transmissions including user data; as well as A first baseband processing part BPS receives configuration parameters, compresses the uplink transmission using the configuration parameters to generate compressed packets, and transmits the compressed packets to a central office via a transmission line through a transmission medium, where the compressed packets are processed in a second baseband processing part of the central office to obtain the user data, wherein the first BPS includes: a DC offset eliminator that eliminates DC offset from the received uplink transmission to generate a DC-eliminated signal, a first frequency shifter that frequency shifts the DC-eliminated signal to generate a frequency-shifted signal, a Fourier transform FT block that performs FT on the CP-eliminated signal to generate a frequency domain signal, and a guard carrier GC eliminator that eliminates the guard carrier GC from the frequency domain signal to generate a GC-eliminated signal.

11. The apparatus of claim 10, wherein the first baseband processing section comprises: a time domain measurement circuit to measure the power level of the DC-cancelled signal; as well as The frequency domain measurement circuit measures the power level of the GC-eliminated signal.

12. The apparatus of claim 11, wherein the first baseband processing section comprises: a second frequency shifter for frequency shifting the DC-canceled signal to generate a separated user access preamble signal; as well as A rate converter performs rate conversion on the separated user access preamble signal to generate a rate-converted user access preamble signal.

13. The apparatus of claim 12, wherein the first baseband processing portion generates antenna groups from: the GC-canceled signal, the rate-converted user access preamble, the power level of the DC-canceled signal, and the power level of the GC-canceled signal.

14. The apparatus of claim 13, wherein the first baseband processing section adds an identification header to the antenna groups, combines the antenna groups into symbol groups; and combines the symbol groups into time slot groups, the time slot groups forming the compressed packets.

15. The apparatus of claim 10, wherein the RF interface receives the uplink transmission as one of a 4G, 5G, or Wi-Fi transmission.

16. A device for network communication, comprising: a DC canceller of the baseband processing section configured to receive an uplink transmission including user data; a controller of the baseband processing section, coupled to the DC canceller and capable of receiving configuration parameters; a compression and packetizer of the baseband processing portion, coupled to the controller and capable of performing a first portion of baseband processing, the first portion of baseband processing compressing the uplink transmission using the configuration parameters to generate compressed packets; as well as An interface is coupled to the controller and is capable of transmitting the compressed packets via a transmission line through a transmission medium to a central office, where a second portion of the baseband processing is performed to obtain the user data, wherein the DC canceller cancels a DC offset from the received uplink transmission to generate a DC-canceled signal, wherein the baseband processing portion includes a frequency shifter for frequency shifting the DC-canceled signal to generate a frequency-shifted signal, and wherein the baseband processing portion includes a cyclic prefix (CP) canceller for canceling a CP from the frequency-shifted signal to generate a CP-canceled signal. 17 . The apparatus of claim 16 , wherein the baseband processing section comprises an FFT block for performing Fourier transform on the CP-canceled signal to generate a frequency domain signal.

18. The apparatus of claim 16, wherein the baseband processing section comprises a guard carrier GC canceller for canceling GC from the frequency domain signal to generate a GC-canceled signal.

19. The apparatus of claim 16, wherein the baseband processing section comprises a time domain measurement circuit for measuring a power level of the DC cancelled signal.

20. The apparatus of claim 16, wherein the baseband processing section comprises a frequency domain measurement circuit for measuring a power level of a GC-canceled signal.

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