5 G NETWORK

1. 5 G NETWORK Cross 11, Tapovan Enclave Nalapani Road, Dehradun 248001 Email: info@iskd.inContact : +918979066357, +919027669947

2. INDEX

3. What is 5 G ? 5G is the term used to describe the next-generation of mobile networks beyond the 4G LTE mobile networks of today. The vision of 5G is becoming clearer as we move closer to 2020. Most experts say 5G will feature network speeds that are blazingly fast at 20 G/bps or higher and have a latency that is mere milliseconds. The vision of 5G is becoming clearer as we move closer to 2020. Most experts say 5G will feature network speeds that are blazingly fast at 20 G/bps or higher and have a latency that is mere milliseconds. Not only will people be connected to each other but so will machines, automobiles, city infrastructure, public safety and more. 5G networks are also expected to have always-on capabilities and be energy efficient, all of which will likely require new protocols and access technologies.

4. Technical Requirement proposed by METIS to meet 5G goal are : • 10-100 times higher typical user data rate, where in a dense urban environment the typical user data rate will range from 1Gbit/s to 10Gbit/s; • 1,000 times more mobile data per area (per user), where the volume per area (per user) will be over 100 Gbps/km2; • Support for 10-100 times more connected devices; • 10 times longer battery life for low-power massive machine communications where machines such as sensors or pagers will have a battery life of a decade; • Support of ultra-fast application response times, where the end-to-end latency will be less than 5ms with high reliability; • Ability to fullfilthese requirements under a similar cost and energy dissipation per area as in today’s cellular systems.

8. 4G to 5G Migration/Evolution • If you just read all the 5G initial definition/requirement documents introduced in 5G Definition page. You may think "It is too good to be realized. It would be easy to say but almost impossible to implement." It would to true that we cannot realize all those requirement overnight in a single step. But as you look back the history of wireless communication (actually any technology), most of new technology start from what we have now and gradually evolve piece by piece and eventually realize what we thought would be impossible. •   5G would be realized in the similar fashion even though many of 5G document say '5G should take drastically different evolution path from the one we saw before'. We are already seeing some of the features regarded as very advanced feature in current technology (4G) but will become a kind of basic features in 5G. I think following illustration gives us pretty good idea of the evolution path. If you are interested in 5G technical details, but don't know what to do because there is no established standard/specification, following current 3GPP specification along the evolution path can be a good starting point.

9. 4G vs 5G • 5G will make communications so fast they become almost real-time, putting mobile inter 4G vs 5G mobile technology. 5G technology promises mobile data speeds that far outstrip the fastest home broadband network currently available in the UK. With speeds of up to 100 gigabits per second, 5G will be as much as 1,000 times faster than 4G, the latest iteration of mobile data technology. net services on a par with office services • It promises mobile data speeds that far outstrip the fastest home broadband network currently available to consumers. With speeds of up to 100 gigabits per second, 5G is set to be as much as 1,000 times faster than 4G. Low latency is a key differentiator between 4G and 5G. 5G will be able to fix bandwidth issues. • 5G has the potential to be 20 times faster than 4G, meaning you can download things 20 times faster or download more in less time. 5G has a peak speed of 20 Gb/s, while 4G's is only 1 Gb/s. However, things rarely work at peak speed, so it's important to take into consideration normal speeds as well.

10. Acronyms • There are so many Acronyms in 3GPP (probably in all other technologies) and these acronyms are defined in many different documents. In many cases I had to search through many different documents just to find the meaning (full words) for those acronyms. After repeating these open-look-close so many times, I decided to put all those terms in a single page for quick search.

15. Agreements  From RAN #84 meeting, a lot of detailed technical proposals start being documented and some of the items reaches the agreement. Most of technical items are yet to be determined, but I am trying to keep track of the agreed items in this page. There would be many items that are not listed here since I haven't gone through all the T Docs from the meeting. I am just putting those items that are closely related to my area. New Terminology Waveform/Modulation Numerology / FrameStructure / TTI Carrier Aggregation / Dual Connectivity Multiple Access MIMO Scheme (Codeword / Layer) Massive MIMO Beam Management Synchronization Signal/Process Initial Access / RACH Channel Coding Physical Layer Procedure (Scheduling / HARQ) Radio Interface Protocol Stack

16. Antenna Ports • An antenna port is defined such that the channel over which a symbol on the antenna port is conveyed can be inferred from the channel over which another symbol on the same antenna port is conveyed. Each Antenna ports carries its own resource grid and a specific set of reference signal in the grid. The channel properties for RE(resource element) for the reference signal is assumed to be same (or very close to same) as the resource elements for other data channel. What is BeamForming ? • .Beam Forming is a technology to Form a beam. I would say it means 'electro magnetic waveradiation pattern (propagation pattern) for a set of antenna system'. Simply put, Beam Forming is a technic that construct the antenna radiation pattern. • Why we need beamforming ? It is simple. Let's look at the two illustrations as shown below. There are two antenna system and let's assume that the two antenna is transmitting the exactly same amount of total energy. In case 1, the antenna system is radiating the energy in almost same amount in all direction. The three UEs around the antenna would receive almost same amount of the energy but a large portions of energy not directed to those UEs is wasted.I n case 2, the signal strength of the radiation pattern ('beam') is specially 'formed' in such a way that the radiated energy in direction to UEs are much stronger than the other parts which is not directed to UEs.

18. How to 'Form' a beam ? The simplest way of forming a beam is to put multiple antenna in an array. There are many different ways of aligning those antenna elements, but one of the simplest way is to align the antenna along a line as shown in the following example. The intuitive idea you should see here is that you will get a sharper beam as you put more antenna elements in the array. Another way of arranging the elements in an array is align the elements in a two dimensional square as shown in the following examples. The intuitive idea you should see here is that you will get a sharper beam as you put more antenna elements in the array.

22. Technology for Beam Forming • Switched Array Antenna : This is the technique that change the beam pattern (radiation form) by switching on/off antenna selectively from the array of a antenna system. • DSP Based Phase Manipulation : This is the technique that change the beam pattern (radiation form) by changing the phase of the signal going through each antenna. Using DSP, you can change the signal phase for each antenna port differently to form a specific beam pattern that is best fit for one or multiple specific UEs. • Beam forming by Precoding: This is the technique that change the beam pattern (radiation form) by applying a specific precoding matrix. This is the technique used in LTE. In LTE, following transmission mode is implementing 'Beam Forming' implicitely • TM 6 - Closed loop spatial multiplexing using a single transmission layer. • TM 7 – Beam forming (Antenna port 5) • TM 8 - Dual Layer Beam forming (Antenna ports 7 and 8)

23. 5G/NR - Beam Management   Why we need Beam ? • Mostly by Nature of the wave (by Physics), when 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). Refer to Why Massive MIMO page for the details of this background.

25. Why Beam Management / Beam Control ? • Beam in high frequency deployment would be the matter of choice. It is a kind of 'MUST' implementation. In case of low / mid frequency region without using massive antenna array (as in (A) / (B)), a single transmission would cover a lot of UEs simultaneously. However, when the radiation become beam-shaped as (C), it is very difficult to cover multiple UEs in single transmission unless those multiple UEs are located in very close proximity. To handle this problem, we need a very sophisticated idea of managing/controlling the beam to cover the multiple devices scattered in all directions and the management/control mechanism should be different depending on the situations. All of these collection of idea would fall into the title of "Beam Management" in the specification.Beam Management/Control for each specific situation will be described in separate pages with relaventsituation (like Beam Management during Synchronization, Beam Management during Initial Attach, Beam Management in connected status etc). In this page, I would describe on general idea.

27. Beam Management/Control when a transmitter has no information on the location of the receiver • Now let's look into a more specific cases where the Beam Management/Control become crucial. As an example, let's think of following case. There is a Base Station with Massive MIMO operating at the very high frequency. There is a UE around the Base Station and you are just about to turning on the UE. 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.

29. 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 :). • Would the solution above be feasible, reasonable and effective ? The simple answer is NO (I would not explain why. You may easily guess why). • Then what can be another idea (possible solution) 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.

32. Then, the next question would be "how to reflect / implement this concept in the radio frame design ?". I would not go too much detail on this until this is explicatelydetermined in 3GPP TS (Technical Specification) document, but you can get the general ideas on various options /proposals from TDocs listed in Reference Section. • // Now that 3GPP Technical Specification on Beam Management has been released and I could write on this mechanism based on the formal specification. You may jump to NR Beam Management in a Nutshell section and read from there if you are interested in the formal specification.

33. Beam Management/Control when the connection is already established • 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. Theoretically 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. • In case 1, UE and Network is connected through a single TRP (Tx/Rx Point) and a single beam. • In case 2, UE and Network is connected through multiple TRP (Tx/Rx Point) and a single beam for each TRP. • In case 3, UE and Network is connected through a single TRP (Tx/Rx Point) and multiple beams • In case 4, UE and Network is connected through multiple TRP (Tx/Rx Point) and multiple beams for each TRP

35. The general idea of the beam management during the connected states would be • i) Network transmit a specific reference signal for beam management • ii) UE detect the signal and perform some measurement and send feedback to Network • As you may notice, the general idea would be very similar to CSI report mechanism that are currently used in current LTE. However, a lot of details are yet to be determined.  For example, • i) Baseband Signal (Symbol) generation formula • ii) Resource Allocation mapping (How to allocate these reference symbols to which specific resource element) • iii) How often UE need to perform these measurement • iv) How UE report the measurement result ? (via RRC messages ? or via MAC / PHY layer transactions ?) • NOTE : Now that the technical specification on all of the questions listed above has been released and I wrote a few separate pages regarding this topic. Refer to CSI RS signal page and CSI Reportpage for further details based on 3GPP technical specification.

36. Where to point my beam ? We can think of this question in terms of two different cases : transmitting case and receiving case When transmitting • Now let's think of which direction a GNB or UE has to point its beam when they try to transmit the signal ? • The answer is simple.  They (GNB or UE) has to transmit the signal in the direction that can reach the receiver with the best signal quality'. When recieving • The answer is simple.  They (GNB or UE) has to tune their receiver in the direction in which they can receive the signal from the transmitter with best quality.

37. P1, P2, P3 - What is It ?As illustrated in Beam Management in a Nutshell, P1/P2/P3 are a set of processes that are designed for beam management while in connected state.P-1: is used to enable UE measurement on different TRP Tx beams to support selection of TRP Tx beams/UE Rx beam(s). For beam forming at TRP, it typically includes a intra/inter-TRP Tx beam sweep from a set of different beams. For beam forming at UE, it typically includes a UE Rx beam sweep from a set of different beams.

39. P-2: is used to enable UE measurement on different TRP Tx beams to possibly change inter/intra-TRP Tx beam(s). From a possibly smaller set of beams for beam refinement than in P-1. Note that P-2 can be a special case of P-1.

40. P-3: is used to enable UE measurement on the same TRP Tx beam to change UE Rxbeam in the case UE uses beam forming

41. 5G/NR Carrier Aggregation   Carrier Aggregation • The detailed mechanism of Carrier Aggregation in 5G/NR is not specified yet (as of Sep 2017), but I think overall mechanism will be similar to LTE Carrier Aggregation. However at least followings has been determined : • Carrier Aggregation is specified from the first specification of NR (i.e, Release 15) • Maximum number of Secondary Component Carrier in addition to Primary Carrier is 15 (38.211 - 4.5)

42. Definition of BWP Carrier Bandwidth Part is a contiguous set of physical resource blocks,selected from a contiguous subset of the common resource blocks for a given numerology(u) on a given carrier How BWP are defined ? • As mentioned in Carrier Bandwidth Part allocation for DL and UL, maximum 4 BWPs can be defined in DL and UL. Each of BWP are configured by RRC messages as described in RRC Parameters for BandwidthPart Configuration

43. Why BWP ? • When I first saw the descriptions on BWP, I asked myself 'why we need this ? We already has pretty flexible mechanism of changing Bandwidth dynamically. Just by changing the number of RBs and starting RB, we can change the operation bandwidth. Then, why we still need another mechanism of restricting bandwidth ?'. • The purpose of BWP is more for UE rather than for Network, especially for low end UEs which cannot afford to such a wideband operation. • In most case, NR would operate in very wideband and there wouldn't be any issues for the network (gNB) and high end UEs to handle the full operating band, but we cannot expect every types of UE to be able to work with this kind of wideband. So we need another special mechanism to tell some UEs 'Hey... we are operating in this wide band, but you don't need to worry about covering the full band. this is a fraction of spectrum you only need to care'. This is how (and why) we came out with the new concept called BWP. It would remind you of NarrowBand in LTE M1. (Refer to Ref[1] if you want to know more detailed stories on various alternatives on NR Wideband operation).