Subsampling Multi-standard receiver design, Part-1
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The document discusses the design and architecture of multi-standard, multi-band receivers used in communication systems, detailing various receiver types such as super-heterodyne, direct conversion, and digital IF receivers. It outlines the specifications and requirements for different communication standards, including GSM, UMTS, Bluetooth, and WLAN, highlighting the challenges and trade-offs involved in receiver design. Additionally, it provides insights into advanced concepts like software-defined radio and cognitive radio for enhancing multi-standard capabilities.
![Multi-Standard transceiver:
A Multi-Band/Multi-Standard transceiver
(TRX) is a radio front-end that can be
operated in a number of frequency bands.
The frequency bands can be changed
easily without modifying the hardware.[Ref.1]
The modern upgrades of the Multi-standard
transceiver are:
Software-Defined-Radio, which is a multi-
standard radio with reconfigurable digital
processing using embedded systems or
computers.
And cognitive radio, which is a SDR with the
ability of sensing the surrounding spectrum
to use the unused frequency bands for
better spectrum efficiency.](https://image.slidesharecdn.com/multi-standardreceiverdesign-151106163630-lva1-app6891/85/Subsampling-Multi-standard-receiver-design-Part-1-4-320.jpg)
![Receiver Architecture
Direct conversion Receiver (Zero-IF receiver)
Disadvantages:
DC offset [added DC voltage to the signal causing distortion and losses].
Even order distortion.
Flicker noise.
LO leakage.
Self-mixing[adds undesired signal at zero IF].](https://image.slidesharecdn.com/multi-standardreceiverdesign-151106163630-lva1-app6891/85/Subsampling-Multi-standard-receiver-design-Part-1-12-320.jpg)
![GSM
GSM frequency plan
Global system for mobile
communications.
Was developed by the European
Telecommunications Standards
Institute (ETSI) to describe the protocols
for second-generation (2G)
digital cellular networks used by mobile
phones, first deployed in Finland in July
1991.
As of 2014 it has become the default
global standard for mobile
communications - with over 90% market
share, operating in over 219 countries
and territories. [Wikipedia]
Specifications](https://image.slidesharecdn.com/multi-standardreceiverdesign-151106163630-lva1-app6891/85/Subsampling-Multi-standard-receiver-design-Part-1-27-320.jpg)
![GSM
AM suppression test
GMSK is used as modulation in GSM. This modulation form has a DC peak
making it vulnerable to DC offset problems.[Ref]
This test was introduced in order to avoid receiver desensitization in
presence of a GMSK pulse jammer, as produced by the on/off-switching
signal on another carrier.
a -99-dBm desired signal has to be correctly demodulated in presence of
a -31-dBm AM modulated interferer.
IIP2> 2PAM – noise floor.
IIP2 > +49 dBm.
Challenging.](https://image.slidesharecdn.com/multi-standardreceiverdesign-151106163630-lva1-app6891/85/Subsampling-Multi-standard-receiver-design-Part-1-29-320.jpg)
![WLAN
IEEE 802.11a-1999
Operates on the UNII ( Universal Networking information
infrastructure):
UNII-1&2 : From 5.15GHz –to- 5.35GHz: for indoor and outdoor use.
UNII-3 : From 5.725GHz –to- 5.85 GHz for outdoor use only.
Each UNII band provides four 16.6MHz OFDM modulated non-
overlapping channels.
OFDM [orthogonal frequency division multiplexing] is used for its high
spectral efficiency and reduced multipath inter-symbol-
interference.](https://image.slidesharecdn.com/multi-standardreceiverdesign-151106163630-lva1-app6891/85/Subsampling-Multi-standard-receiver-design-Part-1-42-320.jpg)
![IEEE 802.11n - 2009
Its purpose is to improve network throughput over
the two previous standards—802.11a and 802.11g,
with a significant increase in the maximum net
data rate from 54 Mbit/s to 600 Mbit/s by using
MIMO [Multiple-input Multiple-output].
Channel bandwidth increased from 20 MHz to 40
MHz which, besides using MIMO, increase the
transfer rate of the system.
IEEE 802.11n allows up to 4×4:4 MIMO.
Data rates up to 600 Mbit/s are achieved only
with the maximum of four spatial streams using
one 40 MHz-wide channel.](https://image.slidesharecdn.com/multi-standardreceiverdesign-151106163630-lva1-app6891/85/Subsampling-Multi-standard-receiver-design-Part-1-50-320.jpg)
Subsampling Multi-standard receiver design, Part-1
- 1. Multi-Standard Multi-Band Receiver Design. THEORY AND RF FRONT END DESIGN. PART-1 Supervised by: Prof. Aziza I. Hussein, Minia Univ., CSE Dept. & Dr. Mahmoud A. Abdelghany By: Ahmed Sakr [email protected], +20 101 658 487
- 2. Multi-Standard Multi-Standard transceiver is like a man who can speak multiple languages, it can operate in different communications standards. For example, the receiver inside the cellular phone in your hand, it can operate over 2G (GSM), 2.5G (EDGE, GPRS), 3G (UMTS) and 4G. Multi-standard RF front-end GSM EDGE GPRS LTE UMTS WiMAX Digital processing Subsystem Data
- 3. Multi-Band There are standards that operate on different frequency band for the same standard, for example: WLAN IEEE 802.11 standard: 802.11a : from 5.15 to 5.35 GHz in/out Door. from 5.725 to 5.85 GHz outdoor. 802.11b/g: 2.4-2.4835-GHz. WiMAX IEEE 802.16e: 2.5 GHz band & 3.5 GHz band. For a Multi-Standard transceiver it should operate over different frequency bands with different bandwidths depending on each standard it supports.
- 4. Multi-Standard transceiver: A Multi-Band/Multi-Standard transceiver (TRX) is a radio front-end that can be operated in a number of frequency bands. The frequency bands can be changed easily without modifying the hardware.[Ref.1] The modern upgrades of the Multi-standard transceiver are: Software-Defined-Radio, which is a multi- standard radio with reconfigurable digital processing using embedded systems or computers. And cognitive radio, which is a SDR with the ability of sensing the surrounding spectrum to use the unused frequency bands for better spectrum efficiency.
- 6. Receiver Architecture Super-Heterodyne Receiver The signal of interest is down-converted to an intermediate-frequency, then re- down-converted to DC (Zero IF) or very low IF.
- 7. Receiver Architecture Super-Heterodyne Receiver Image problem. if an interferer locates in frequency equals to fRF – 2fIF for LO < fRF or at fRF+ 2 fIF for LO> fRF, that interferer will be down-converted to the IF band of interest, interrupting the desired signal and reducing the selectivity and sensitivity of the system.
- 8. Receiver Architecture Super-Heterodyne Receiver Image problem- low side injection. Desired Signal LO signal Interfere @ fRF-2fLO Down- converted signal Up- converted signal Interferer’s image appears at fIF
- 9. Receiver Architecture Super-Heterodyne Receiver Advantages Immunity to LO leakage and interferer leakage. Negligible mismatch between I and Q channels because I&Q split is done after the second mixer where the IF is low enough. Pitfalls: Requires more external components, not suitable for SoC. More complicated in design. Image problem while image rejection is not easily achievable.
- 10. Receiver Architecture Direct conversion Receiver (Zero-IF receiver) A simple structure where the signal is directly down-converted to zero or very low IF. Simple LNA and channel selection filters are replaced with LPF.
- 11. Receiver Architecture Direct conversion Receiver (Zero-IF receiver) Advantages: Solve the problem of image. LNA doesn’t have to drive a 50 Ohms load since there are no Image Rejection BPF. Suitable for full integration. Suitable for multi-standard if programmable LO frequency and LPF are used.
- 12. Receiver Architecture Direct conversion Receiver (Zero-IF receiver) Disadvantages: DC offset [added DC voltage to the signal causing distortion and losses]. Even order distortion. Flicker noise. LO leakage. Self-mixing[adds undesired signal at zero IF].
- 13. Receiver Architecture Quasi-IF Receiver To solve the problems of Direct-conversion- receivers. The signal is down-converted to a very low IF. Image problem is re-introduced!
- 14. Receiver Architecture Digital-IF Receivers The signal is down-converted to intermediate frequency IF. Then it is converted to digital using ADC. The second down-converting and demodulation are performed in digital domain effectively.
- 15. Receiver Architecture Digital-IF Receivers design issues: Adjacent interferers or blockers are directly added to the ADC’s input, so a wide dynamic range is required in the ADC to prevent ADC saturation by high power level blockers and to sense the very low level signal. To relax the image problem, IF cannot be very low. If the signal’s BW is comparable to the IF, Low Pass ADCs are used instead of band pass. To relax the requirements, subsampling is used.
- 16. Subsampling Receiver THEORY AND DESIGN
- 17. Subsampling: Subsampling is the process of sampling a signal with a frequency lower than twice the highest signal frequency, but higher than two times the signal bandwidth, the signal is down-converted by subsampling instead of mixing.
- 18. Subsampling: selecting subsampling frequency 𝟐(𝒇 𝒄 − 𝑩𝑾 𝟐 ) 𝒎 − 𝟏 > 𝒇 𝒔 > 𝟐(𝒇 𝒄 − 𝑩𝑾 𝟐 ) 𝒎 Where: fs : Subsampling frequency. BW : signal bandwidth. fc : carrier frequency. m : number of replicas between 0Hz and (fc-BW/2). m 1, 𝑓𝑙𝑜𝑜𝑟 𝒇 𝒄 − 𝑩𝑾 𝟐 𝑩𝑾
- 19. Subsampling: selecting subsampling frequency An appropriate value for fs is 𝑓𝑠 = 4𝑓𝑐 𝑚 𝑜𝑑𝑑 Here, choosing an odd value for m ensures that a replica of the signal is produced at fs/4, which results in a larger subsampling frequency bandwidth and relaxes the filtering requirements after the sampling-and- hold stage. While using even value for m will generate the low-frequency aliasing of the signal at 3fs/4 and degrade the signal quality.
- 20. Subsampling: Architecture Because carrier, subsampling, and intermediate frequencies are all related, there is a trade-off between bandwidth and subsampling frequency.
- 21. Subsampling: The effect of selected subsampling frequency, which results in the presence of 2nd order effects.
- 22. Specifications.
- 23. Specifications Specific requirements: Programmable gain. Programmable tuning over bands of interest. Programmable bandwidth. Resources reuse whenever applicable. Multi-band Frequency synthesizer. General requirements: High dynamic range. High sensitivity. High selectivity. Over all supported standards! Input Output
- 24. Specifications The specifications of MS radio should meet the requirements of all the supported standards in the common parts, as the UWB LNA, Mixers, …etc. Depending on the specifications and blocking profiles, the system requirements are extracted by using the equations in the next slide.
- 25. Specifications Equations BW: Bandwidth. C/N: Carrier to Noise Ratio. PN: Phase Noise. NF: noise figure. SIR: Signal-to-Interferer ratio. Safety margin is considered after calculating the system requirements.
- 26. GSM Global System for Mobile communications. REQUIREMENTS.
- 27. GSM GSM frequency plan Global system for mobile communications. Was developed by the European Telecommunications Standards Institute (ETSI) to describe the protocols for second-generation (2G) digital cellular networks used by mobile phones, first deployed in Finland in July 1991. As of 2014 it has become the default global standard for mobile communications - with over 90% market share, operating in over 219 countries and territories. [Wikipedia] Specifications
- 28. GSM intermodulation test The intermodulation test specifies a Gaussian minimum shift keying (GMSK) signal 3 dB above the sensitivity level has to be detectable in presence of a 49-dBm continuous wave and a 49-dBm GMSK modulated interferer placed at 800- and 1600-kHz frequency offset from the desired signal, respectively. Therefore, the required third-order input intercept point (IIP3) is -18 dBm. -99 dBm Desired signal @fo -49 dBm tone @fo±0.8 MHz -49dBm GMSK signal @fo±1.6 MHz
- 29. GSM AM suppression test GMSK is used as modulation in GSM. This modulation form has a DC peak making it vulnerable to DC offset problems.[Ref] This test was introduced in order to avoid receiver desensitization in presence of a GMSK pulse jammer, as produced by the on/off-switching signal on another carrier. a -99-dBm desired signal has to be correctly demodulated in presence of a -31-dBm AM modulated interferer. IIP2> 2PAM – noise floor. IIP2 > +49 dBm. Challenging.
- 30. GSM Receiver Requirements Parameter Value Sensitivity -102 dBm, with BER<10-4 Max Noise figure 9dB @200 kHz BW Antenna referred noise floor -111 dBm IIP3 -18 dBm IIP2 +49 dBm LO tuning range 60 MHz LO Phase Noise (PN) -141 dBc/Hz. Problems: • Sensitive to the 1/f noise of the CMOS in the zero-IF receiver. • Image effect in the low-IF receiver. • Very high IIP2.
- 32. UMTS Universal Mobile Telecommunications System. A third generation mobile cellular system for networks based on the GSM standard. UMTS uses wideband code division multiple access (W-CDMA) radio access technology to offer greater spectral efficiency and bandwidth to mobile network operators. It uses WCDMA for better spectrum using efficiency. The WCDMA coded signal modulates the carrier using QPSK. The code used in the receiver should be well synchronized with the one used in coding the signal in transmitter.
- 33. UMTS frequency plan In the user equipment side: TX : from 1920 to 1980 MHz. RX: from 2110 to 2170 MHz. Signal BW: 8 - 384 kHz. Code BW: 3.84 MHz, FIXED. Channel spacing: 5 MHz. TX-RX spacing: 135 MHz. Data rates: 384 kbps outdoor. Up to 2 Mbps indoor.
- 34. UMTS Out-of-Band Intermodulation test The transmitter leakage is responsible for intermodulation products due to third-order nonlinearity, together with an out-of-band continuous wave interferer. In the worst case, these two interfering signals are placed, respectively, 135 and 67.5 MHz apart from the receive band. Since the desired signal power is 3 dB above the sensitivity level in presence of out-of-band interferers and the noise level is -99 dBm, the upper limit for the third-order intermodulation product is set at -99 dBm as well. The required out-of-band IIP3 , evaluated at the receiver input, is given by -4.6 dBm. -99dBm Desired signal @fo -40 dBm tone @fo±67.5 MHz -49dBm GMSK signal @fo±135 MHz
- 35. UMTS In-band Intermodulation test -46 dBm continuous wave and a -46 dBm WCDMA-modulated interfering signal, placed 10 and 20 MHz apart from the desired signal carrier frequency. The resulting antenna referred in-band IIP3 requirement is -17 dBm. Notice that, while the in-band requirement demands high linearity throughout the receiver (including the baseband circuits), the out-of-band specification mainly affects the RF front-end because the interferers can be strongly attenuated at the down- converter output, at least in the zero-IF or low- IF architectures. -99 dBm Desired signal @fo -46 dBm tone @fo±10 MHz -46dBm GMSK signal @fo±20 MHz
- 36. UMTS Receiver Requirements From the standard specifications and blocking profile the receiver requirements are calculated as following Parameter Value Sensitivity -117 Max Noise figure 6.15 dB Antenna referred noise floor -99 dBm IIP3 -4.6 dBm IIP2 +46 dBm LO tuning range 60 MHz LO Phase Noise (PN) -150 dBc/Hz. &135MHz offset.
- 37. Bluetooth ISM BAND SHORT RANGE COMMUNICATION TECHNIQUE.
- 38. Bluetooth A low-cost, low-power communication protocol designed for short- range radio connectivity between electronic devices, invented by 1999. Operates on the ISM (Industrial-Scientific-Medical) 2.4 GHz frequency band which is license-free worldwide. Using FHSS (Frequency-Hopping-Spread-Spectrum) has the advantage of interferer immunity. Channel BW: 1-MHz. Modulation scheme: Binary Frequency Shift Keying (BFSK) with Gaussians shaping filter. The Gaussian-shaped BFSK signal has most of its energy in approximately 200 kHz (3-dB bandwidth) so that a zero-IF CMOS solution would require some effort to address 1/f noise. Low-IF receiver is selected because it allows very good sensitivity with low power consumption. Commercially, a 1 or 2 -MHz IF is chosen.
- 39. Bluetooth Receiver Specifications Low IF receiver Analog Demodulator Tx maximum power: 0, 4, 20 –dBm for a range of 10-50 m. Receiver sensitivity: -70 dBm. BFSK allows the use of limiters and analog demodulators which are more power efficient. 21- dB SNR for 10-3 maximum BER. 23-dB Noise Figure. VCO tunable range 2.4-2.48 GHz. -15 dBm IIP3 with -39 dBm interferers and - 64 dBm received signal. Low-IF receiver architecture is selected because the 1/f noise problem,
- 40. Wireless LAN HIGH-RATE WIRELESS NETWORK CONNECTIVITY.
- 41. WLAN IEEE 802.11 Standard Formalized in 1999, to allow high-rate wireless communication between personal computers and workstations, avoiding the use of expensive and bulky wires. IEEE 802.11 had a maximum 2Mbps using FHSS or DSSS in the 2.4 GHz ISM band. IEEE 802.11a has up to 54 Mbps in the 5GHz band. IEEE 802.11b extended the throughput of IEEE 802.11 to reach 11Mbps. IEEE 802.11g supports up to 54Mbps in the 2.4 GHz ISM band, supporting the IEEE 802.11b standard.
- 42. WLAN IEEE 802.11a-1999 Operates on the UNII ( Universal Networking information infrastructure): UNII-1&2 : From 5.15GHz –to- 5.35GHz: for indoor and outdoor use. UNII-3 : From 5.725GHz –to- 5.85 GHz for outdoor use only. Each UNII band provides four 16.6MHz OFDM modulated non- overlapping channels. OFDM [orthogonal frequency division multiplexing] is used for its high spectral efficiency and reduced multipath inter-symbol- interference.
- 43. IEEE 802.11a Receiver Requirements The most stringent receiver requirements are set in the 54Mbps mode. Parameter Value Frequency band 5.15GHz –to- 5.35GHz : in/outdoor. 5.725GHz –to- 5.85 GHz : outdoor. Channel BW 16.6MHz Sensitivity -65 Max Noise figure 7.5 dB Signal-to-receiver-noise ratio 28 dB 1-dB compression point -20 dBm LO tuning range 20-40 MHz LO Phase Noise (PN) -102 dBc/Hz. &1MHz offset.
- 44. IEEE 802.11a Receiver Requirements OFDM modulation has a hard requirements to achieve. Receiver should has low NF less than other standards at more than twice the operating frequency. The baseband/IF chain is also challenging because of the large bandwidth and high SNR. For zero-IF receiver, it is required to have low 1/f noise corner frequency and HP filtering frequency to avoid signal corruption. While the training time for DC cancellation is much smaller than 802.11b, only 8μSec. Many commercial 802.11a receivers are using zero-IF architecture. For low-IF receivers, DC offset cancellation is not a huge problem because the edges of the channel don’t carry information, and image suppression required is lower than zero-IF. The main disadvantage is the higher power consumption.
- 45. WLAN IEEE 802.11b-1999 Operates on the ISM licence-free 2.4: 2.4835 GHz band. Channel bandwidth: 14MHz. Two operation modes: 5-11 Mbps The most challenging is the 11Mbps mode, whose spectral efficiency is 0.78 bps/Hz.
- 46. IEEE 802.11b Linearity parameters -30 dBm continuous wave interferer or a -35 dBm adjacent signal interferer, placed 30 and 25 MHz apart from the desired signal carrier frequency. The CW interferer sets the receiver 1-dB compression point to -26 dBm taking a 4dB safety margin. It also sets the LO Phase noise to -103 dBc/Hz at 1-MHz offset with a VCO tuning range of 80 MHz. -70 dBm Desired signal @fo -35 dBm adjacent signal @fo±25 MHz -30dBm tone@fo±30 MHz
- 47. IEEE 802.11b Receiver Requirements The most stringent receiver requirements are set in the 54Mbps mode. for IEEE 802.11b can be implemented by the zero IF receiver, where the dc offset problem is solved using HP filter and 1/f noise is integrated over the band of interest. Parameter Value Frequency band 2.4-2.4835 GHz Channel bandwidth 14 MHz Sensitivity -76 dBm Max Noise figure 14.8 dB Signal-to-noise ratio 11.5 dB 1-dB compression point -26 dBm LO tuning range 80 MHz LO Phase Noise (PN) -103 dBc/Hz. &1MHz offset.
- 48. WLAN IEEE 802.11g-2003 IEEE 802.11g is an improvement to the IEEE 802.11 specification that extended throughput to up to 54 Mbit/s using the same 2.4 GHz band as 802.11b. 802.11g hardware is fully backwards compatible with 802.11b hardware In an 802.11g network, the presence of a legacy 802.11b participant will significantly reduce the speed of the overall 802.11g network. 802.11g suffers from the same interference as 802.11b in the already crowded 2.4 GHz range. 802.11g receivers have to meet the most critical requirements set by 802.11b and 802.11a. However, the 1-dB compression point is set to -10dBm in the receiver low-gain mode.
- 49. IEEE 802.11b/g channels. To prevent interference, there are only three non-overlapping usable channels in the U.S. and other countries with similar regulations (channels 1, 6, 11, with 25 MHz separation), and four in Europe (channels 1, 5, 9, 13, with only 20 MHz separation) Zero-IF receiver architecture is efficiently used for IEEE 802.11g.
- 50. IEEE 802.11n - 2009 Its purpose is to improve network throughput over the two previous standards—802.11a and 802.11g, with a significant increase in the maximum net data rate from 54 Mbit/s to 600 Mbit/s by using MIMO [Multiple-input Multiple-output]. Channel bandwidth increased from 20 MHz to 40 MHz which, besides using MIMO, increase the transfer rate of the system. IEEE 802.11n allows up to 4×4:4 MIMO. Data rates up to 600 Mbit/s are achieved only with the maximum of four spatial streams using one 40 MHz-wide channel.
- 52. Multi-Standard RF front-end summary: Multi-standard receiver can be easly implemented by making a transceiver for each standard, but this will increase both the cost and power consumption. By carefully designed system where sharing of hardware whenever possible, and use of tunable, programmable gain & bandwidth elements are guaranteed, the power consumption and total cost can be minimized.
- 53. THE END OF PART-1
- 54. References: “Toward Multistandard Mobile Terminals—Fully Integrated Receivers Requirements and Architectures”, IEEE TRANSACTIONS ON MICROWAVE THEORY AND TECHNIQUES, VOL. 53, NO. 3, MARCH 2005, Massimo Brandolini and others. Multi-standard radio transceiver architecture and radio frequency front end design, The Ohio state university, Hyung Joon Kim, 2005. Multi-Standard Mixed-Signal Transceivers for Wireless Communications —A Research Overview, Troels Emil Kolding, Aalborg University, Denmark, December 1996. MULTI-STANDARD CMOS WIRELESS RECEIVERS: Analysis and Design, Consulting Editor: Mohammed Ismail. Ohio State University.
Editor's Notes
- #19: Subsampling Receivers with Applications to Software Defined Radio Systems José R. Garcيa Oya, Andrew Kwan, Fernando Muٌoz Chavero, Fadhel M. Ghannouchi, Mohamed Helaoui, Fernando Mلrquez Lasso, Enrique Lَpez-Morillo and Antonio Torralba Silgado
- #20: Subsampling Receivers with Applications to Software Defined Radio Systems José R. Garcيa Oya, Andrew Kwan, Fernando Muٌoz Chavero, Fadhel M. Ghannouchi, Mohamed Helaoui, Fernando Mلrquez Lasso, Enrique Lَpez-Morillo and Antonio Torralba Silgado
- #21: Subsampling Receivers with Applications to Software Defined Radio Systems José R. Garcيa Oya, Andrew Kwan, Fernando Muٌoz Chavero, Fadhel M. Ghannouchi, Mohamed Helaoui, Fernando Mلrquez Lasso, Enrique Lَpez-Morillo and Antonio Torralba Silgado
- #22: Subsampling Receivers with Applications to Software Defined Radio Systems José R. Garcيa Oya, Andrew Kwan, Fernando Muٌoz Chavero, Fadhel M. Ghannouchi, Mohamed Helaoui, Fernando Mلrquez Lasso, Enrique Lَpez-Morillo and Antonio Torralba Silgado