Even though 3GPP would not preclude the use of Sub 6 Ghz deployment of 5G NRat least based on the current status it seems that most of the deployment would be in very high frequency millimeter wave and this high frequency deployment would be one of the most important characteristics of 5G NR.
Why we need Beam? Mostly by Nature of the wave by Physicswhen we use low and mid range of frequency, we can transmit a signal in all direction as in A or relatively wide angles as in B. However, when we use very high frequency, we would not have much choice except using a huge antenna array. As a result of using this kind of huge antenna array, the resulting radiation would be a beam as in C.
It is a kind of 'MUST' implementation. All of these collection of idea would fall into the title of "Beam Management" in the specification. In thise page, I would describe on general idea. As an example, let's think of following case. Once the UE is turned on, it would start Synchronization process.
For this step, the Base Station would transmit the special signal called Synchronization Signal and the signal should be able to reach to every UEs around the base station.
However, here comes a serious problem with the base station sending signal in Beam. It is the fact that the signal beam can point to a very narrow area and it cannot cover a very wide area at the same time. Simply put, now you have the following question. What would be the answer for this? If everything works as you draw in power point, you may draw a solution as follows.
You may want to transmit a lot of beams in all direction simultaneously. Looks good? Looks like a flower :. The simple answer is NO I would not explain why. You may easily guess why. Then what can be another idea possible soultion for the problem? There can be multiple ideas and proposals, but the most popular proposal as of now seems to be that the base station transmit the beam to a specific direction at a specific time and then change the direction a little bit in a next time frame and so on until it can scan all the area it should cover.
You may jump to NR Beam Management in a Nutshell section and read from there if you are interested in the formal specification. Now let's talk about more serious case of Beam Management. Once UE gets into a connection states with a Network, at least one beam or multiple beam is properly in connection between UE and the network.
Theretically there can be so many different ways in which UE and Network beam is connected, but we can reduce it down to roughly four differences case as shown below. You may think of many other cases and ask "How about this case?
How about that case?Great background information from Keysight and Ericsson respectively. The next question I then had was how mobile device and the network communicate with each other to adapt downlink transmission in mobility situations. To start with the specs to find out how this is done is quite tricky, one really needs to know what to look for. Fortunately, there are a number of public sources that give an intro of how 5G NR beam control works in practice which makes the exercise a bit easier.
So this is how I understand beamforming control to work on a high level today:. In practice, beamforming control can be done with several mechanisms. All SSBs are broadcast with the same signal strength but in different directions. This means that a mobile device receives the SSBs with different signal strengths.
When connecting to the network, a device signals to the network which of the SSBs is received best. This way, the network knows which beam to use to communicate with a particular mobile device in the downlink direction. Once a radio bearer exists the network then has to keep track of the device so that it can switch a device to another beam when it moves out of the coverage area of the initial beam.
5G NR: The Next Generation Wireless Access Technology by Johan Skold, Stefan Parkvall, Erik Dahlman
Also, it can narrow the beam to a particular device to further improve the signal strength during transmissions to that device by sending Channel State Information Reference Signals CSI-RS and asking the device to report back on how these were received.
The second option for the network is to instruct a mobile device to send periodic Sounding Reference Signals SRS in the uplink direction. The gNB knows how the SRS transmissions should look like, compares them to what is actually received and then adapts the beam accordingly. Quite a number of different options that can be used in practice.
Once configured, the actual reporting in the uplink direction and commands in the downlink direction are done on the MAC layer, there is no further RRC messaging. This obviously has the advantage that feedback can be given and processed very quickly.
It should be noted at this point that beam measurement results can also be included in RRC measurement reports. However, this is not for beam level mobility management but rather when there is a need for inter-cell mobility.
So this is my current understanding of beam management. If you have further things to contribute, please consider leaving a comment. From what I am seeing the whole subject of multiple SSB beams and beam management is only being used in highband mm-wave deployments. In the midband deployments e.
Skip to content. So this is how I understand beamforming control to work on a high level today: In practice, beamforming control can be done with several mechanisms.Beamforming is the application of multiple radiating elements transmitting the same signal at an identical wavelength and phase, which combine to create a single antenna with a longer, more targeted stream which is formed by reinforcing the waves in a specific direction.
The general concept was first employed in for trans-oceanic radio communications. The more radiating elements that make up the antenna, the narrower the beam. An artifact of beamforming is side lobes. These are essentially unwanted radiation of the signal that forms the main lobe in different directions. The more radiating elements that make up the antenna, the more focused the main beam is and the weaker the side lobes are.
While digital beamforming at the baseband processor is most commonly used today, analog beamforming in the RF domain can provide antenna gains that mitigate the lossy nature of 5G millimeter waves. Beam steering is achieved by changing the phase of the input signal on all radiating elements.
Phase shifting allows the signal to be targeted at a specific receiver. An antenna can employ radiating elements with a common frequency to steer a single beam in a specific direction. Different frequency beams can also be steered in different directions to serve different users. The direction a signal is sent in is calculated dynamically by the base station as the endpoint moves, effectively tracking the user.
If a beam cannot track a user, the endpoint may switch to a different beam. This granular degree of tracking is made possible by the fact that 5G base stations must be significantly closer to users than previous generations of mobile infrastructures. The successful operation of MIMO systems requires the implementation of powerful digital signal processors and an environment with lots of signal interference, or "spatial diversity"; that is a rich diversity of signal paths between the transmitter and the receiver.
The diversity of arrival times, as the signal is bounced from different obstacles, forms multiple time-division duplexing TDD channels that can deliver path redundancy for duplicate signals or increase the channel capacity by transmitting different parts of the modulated data. First conceived of in the s, there are a few differences between classic multi-user MU-MIMO and Massive MIMO, but fundamentally it is still the large number of antennas employed and the large number of users supported.
The degree of MIMO is indicated by the number of transmitters and the number of receivers, i. Blog Support Search. Menu Close. Beamforming Beamforming is the application of multiple radiating elements transmitting the same signal at an identical wavelength and phase, which combine to create a single antenna with a longer, more targeted stream which is formed by reinforcing the waves in a specific direction.
Figure 1: Beamforming with two and four radiating elements While digital beamforming at the baseband processor is most commonly used today, analog beamforming in the RF domain can provide antenna gains that mitigate the lossy nature of 5G millimeter waves.
Beam steering and beam switching Beam steering is achieved by changing the phase of the input signal on all radiating elements. Figure 2: Beam steering and beam switching This granular degree of tracking is made possible by the fact that 5G base stations must be significantly closer to users than previous generations of mobile infrastructures.
Figure 3: Multiple input and multiple output MIMO The diversity of arrival times, as the signal is bounced from different obstacles, forms multiple time-division duplexing TDD channels that can deliver path redundancy for duplicate signals or increase the channel capacity by transmitting different parts of the modulated data. Contact us.In recent years, wireless communication systems exploit higher and higher frequency ranges, in order to find necessary radio resources to serve the raising traffic demand.
Some WRC bands selected for studies in the context of 5G, as well as the 28 GHz band chosen in large markets for 5G deployments, span over hundreds of MHz and allow straightforward handling of bandwidth hungry broadband services .
However, propagation of radio waves in millimetre waves region, differs strongly from radio propagation at traditional cellular frequencies. Firstly, radio signals face much higher path losses and, secondly, the role of propagation phenomena such as, diffraction or reflection for most materials, is much less prominent.
5G Massive MIMO and Beamforming
This leads inevitably to exploitation of massive MIMO antenna systems at millimetre waves bands. As described in previous blog entries cf.
MIMO techniques and architectures for millimetre wave mobile communicationsmassive MIMO antennas that exploit beamforming are used at higher frequencies to cope with increased path losses. A critical factor for wideband equipment is the power consumption of digital-to-analog converters DAC that scales with the sampling rate and the number of bits per sample.
For this reason, at higher frequencies analog beamforming solutions with low number of DACs are preferred over digital beamformers that require a separate DAC for each processed transmission stream. After analog beamforming, the radio beam offers high antenna gain tens of dB and is much narrower several degrees for 3 dB beam width comparing to the output of contemporary sector antennas. This narrowness brings several novel system level design implications that were not present in the previous cellular generations.
During transition from idle to connect mode e.
In order to facilitate this selection, 3GPP specify details of selected radio time slots that will be used by gNB to sweep several spatial directions with transmissions of so called synchronization signal blocks. In each block spanning over OFDM symbolsa transmission over one beam direction will consist of synchronization signals and broadcast information that needs to be obtained before exchange of initial access information .
If there is a fixed time relation between the transmission and reception at a given beam, the UE will be able to calculate it based on system information broadcasted in synchronization signal blocks, and will use appropriate timing for transmission of initial access preamble to indicate suitable radio beam.
Alternative solutions are also possible, e. In previous cellular generations, UE had to monitor radio signals from neighbouring radio cells to facilitate potential switch of the serving cell. When the radio signals are limited to narrow beams a different approach is needed. Further on, instead of reporting measurements for the best cells, UE will report measurements for a number of best beams that were detected.
Additional standardization efforts are put for development of a mechanisms that will be used to recover after beam failure:. Therefore the most accessible scheme is a beamformed transmission toward single user in a single slot. To enable efficient resource and interference management in 5G, 3GPP work to design of specific reference signals and feedback types. When operating at higher frequencies, UE need to track specific reference signals for phase tracking, to avoid additional phase noise errors resulting from drifts in the local oscillators.
Finally, as cloud deployments are gaining more and more traction, more centralized scheduling mechanisms will also come into play in 5G. This is also reflected in 3GPP decision for the split of gNB into centralized and distributed unit . Skip to content Month: May Figure 1 : Operations with sector antennas left and mMIMO with analog beamforming right Initial access During transition from idle to connect mode e.
Mobility management In previous cellular generations, UE had to monitor radio signals from neighbouring radio cells to facilitate potential switch of the serving cell. Additional standardization efforts are put for development of a mechanisms that will be used to recover after beam failure: detection of the beam failure, identification of the new beam candidate, beam failure recovery request transmission, and response for the beam failure recovery request.In this article, I will explain the Beamforming technique in 5G to compensate for path loss especially in the mmWave spectrum range.
As the range of mmWaves is between 30 GHz and GHz, a wavelength is between 1 millimeter and 10 millimeters and this is the intensive motive for Beamforming. The beamforming technique focuses the RF energy into a narrow direction to allow the RF beam to propagate farther in that direction. If the direction becomes blocked, either because of UE movement or changes in the environment e. Thus, in order to ensure that the UE has continuous, seamless coverage, multiple beams in as many different directions as possible may be available.
Beam sweeping: is the first operation of the four of Beam Management operations. The gNB transmits m beams in different spatial directions. Based on the performed beam sweeps, the UE determines a channel quality associated with the performed beam sweeps.
Then the UE sends the channel quality information to the gNB. The channel quality is affected by a variety of factors. The factors include 1- Movement of the UE along a path or due to rotation e. Also the UE and the gNB exchange other information e. Based on the received information, the gNB determines various configuration information, such as mmW network access configuration information, information for adjusting beam sweeping periodicity, information regarding overlapping coverage for predicting a handoff to another gNBs.
The measurement process is carried out with an exhaustive search, i. A Beam Set may contain eight different beams. For example as below figure 8 beams for eight directions.
The UE selects a beam by measuring values for a received power or received quality associated with each of the first set of beams, the received power may be referred to as a BRS received power BRSRP. Your email address will not be published. Save my name, email, and website in this browser for the next time I comment. Notify me of follow-up comments by email.
Notify me of new posts by email. Yes, add me to your mailing list.All Rights Reserved. UE does beam measurements and determines the best beam during synchronization. Collectively these aid beam management, as well as narrowing the beam towards a device. These can assist beamforming. However, during the NSA, improvement has been made in terms of time-saving.
Due to the integration of the control plan with overlay Networks like 4G. An existing 4G connection can be used for reporting. A 4G connection can be used to report the optimal set of directions to gNB, ao that the UE does not need to wait for and additional beam seeping from gNB. This manifesto will connect the RF Engineers globally to address the needs of the revolutionizing world of Telecommunications.
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Home Articles Radio Tech Members. Radio Tech. Simply said, beam management is nothing but a procedure with a set of Phases like, Beam Sweeping: It refers to covering a spatial area with a set of beams transmitted and received according to pre-defined intervals and direction Beam Measurement: It relates to the evaluation of the quality of the received signal at the gNB or at the UE end.
Beam Determination: It is the selection of a suitable beam or beams either at the gNB or at the UE, according to the measurement results obtained during the beam measurement procedure. Tags Beamforming. Share on Twitter. Share on Linkedin. Leave a reply Cancel reply.Signing up for our Online Anytime 12 month Package will give you:. It is dedicated to promoting the professional development of members through Professional Registration, training, mentoring and qualifications.
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5G: How To Control Beamforming