Mobile and Nomadic Communications Notes

Introduction

This section focuses on mobile and nomadic communications, covering 3G, 4G, 5G, and WiFi.
Mobile communication aims to replicate fixed-line capabilities without service interruption during movement.
Key challenge is to separate multiple transmissions and share resources among users in wireless networks.
Mobility requires seamless handover between access points; WiFi is considered nomadic due to limited seamless handover capabilities.
WiFi mesh networks allow limited mobility within a building, blurring the mobile/nomadic distinction.
Section 2 compares 3G, 4G, and 5G network structures and multiple access techniques.
Sections 3, 4, and 5 detail coding and transmission methods for 3G, 4G, and 5G to ensure data separation and delivery.
Section 6 briefly discusses WiFi technology.

Comparing Mobile Communication Networks

Each mobile communication generation improves upon the previous.
2G (GSM) was designed as a voice network; data facilities (GPRS/2.5G) were later added but were ill-suited for data traffic.
3G was designed for both voice and data; data demand exposed its inadequacies.
4G was conceived purely as a mobile data network.
5G continues the data-centered approach of 4G but caters to a wider range of use cases.
Mobile networks have core and access networks; access networks use wireless protocols incompatible with previous generations.
5G is close enough to 4G for dual-purpose access networks.
Core networks have evolved less radically, with some elements surviving across generations.

Core and Access Networks

Figure 2.1 shows a network operator's 3G and 4G networks.
Both networks are divided into core and access networks.
3G access network uses Node Bs (base stations); 4G uses eNode Bs.
3G and 4G core networks can interact for mobility management.
4G system is part of an IP network, allowing almost any element to communicate with any other.
3G network has a hierarchy of connections; each Node B cluster is controlled by a Radio Network Controller (RNC).
RNCs manage resource allocation and split voice and data traffic.
RNCs send voice traffic to the circuit-switched core network (same as 2G) and data traffic to the GPRS core network (2.5G).
SGSNs (serving GPRS support nodes) are analogous to local exchanges; GGSNs (gateway SGSNs) provide a gateway to other IP networks.
The mobile core network authenticates devices and records locations.
The 4G core network allows all main elements to communicate via IP.
The 4G network is flatter and less hierarchical due to lower costs of complex electronics.
4G base stations (eNode Bs) can perform more complex processes than earlier generations.
The 4G access network contains only eNode Bs; RNCs are eliminated, and eNode Bs communicate peer-to-peer.
RNC functions are transferred to eNode Bs or the core network.
4G does not offer native voice services; these are provided by the IP Multimedia Subsystem (IMS), using Voice over LTE (VoLTE), a form of VoIP.
4G phones can fall back to 3G or 2G for voice services if VoLTE is unavailable; 5G has a similar fall-back option to 4G or 3G.
Flattening the hierarchy in 4G reduces latency, a design objective.
Early 5G implementations (non-standalone, NSA) used the same core network as 4G.
Standalone (SA) 5G entails radical changes to the core network.

Multiple Access and Duplexing

Each digital mobile communication generation uses a different multiple access technology in the radio network.
Table 2.1 summarizes multiple access methods for different generations.
Each multiple access method is incompatible with the others.
Multi-standard user devices are equipped with more than one radio technology.
The wireless parts of 4G and 5G are similar enough for a base station to provide both services.
Successive mobile communication generations have used spectrum more efficiently and have delivered faster data rates due to the greater amount of spectrum used for the radio channel.
5G maximum radio channel width is 100 MHz, with wider channels (up to 400 MHz) available above 24 GHz.
Channel aggregation or bonding can increase spectrum available to a user.
FDMA allocates users to different frequency channels for simultaneous access.
OFDMA (4G and 5G) divides the radio channel into narrow slices allocated to users, achieving simultaneous access by separation in the frequency domain.
TDMA (2G) separates users in the time domain via rapid turn-taking.
Table 2.1 shows 2G using both FDMA and TDMA; each 200 kHz radio channel uses TDMA to serve up to eight users.
WCDMA (3G) and CDMA (some 2G systems) allow multiple users to access the same radio channel simultaneously using special codes.
Uplink vs. Downlink:
- Frequency division duplexing (FDD) uses different frequency bands for uplink and downlink.
- Time division duplexing (TDD) shares the same frequency, alternating between uplink and downlink.
Regulatory bodies allocate frequency bands for mobile networks as 'paired' (FDD) or 'unpaired' (TDD).
- Paired spectrum: the total spectrum is divided between lower and upper frequency bands.
- Example: $2 Imes 15$ MHz of 2.6 GHz means two bands, each with 15 MHz bandwidth, one in the lower, one in the upper 2.6 GHz band.

Multiple Access and Duplexing (Continued)

Lower band is usually used for the uplink due to better propagation characteristics.
3G and 4G standards allowed for FDD or TDD, although FDD has been more widely adopted.
In 3G networks, FDD and TDD used different access technologies, requiring dual-mode devices.
In 4G, LTE-FDD and LTE-TDD used the same access technology dependent on available spectrum.
TDD can operate in unpaired spectrum and suits environments with asymmetrical data rates.
In FDD, uplink and downlink use different frequency bands with no flexibility.
In TDD, TDD can dynamically assign time slots and is therefore better for asymmetry.
5G is expected to be data-intensive, making TDD an attractive option.
5G will use both TDD and FDD, with TDD as the default method above 1 GHz.
Dynamic TDD switches rapidly between uplink and downlink asymmetry.
Flexibility and efficient spectrum use are key strategies in 5G.
WiFi has always used TDD.

Scheduling

Multiple access can be achieved by sharing resources among users, such as frequency bands or time slots.
Allocations can be dynamic and vary among users.
Scheduling is the dynamic allocation and reallocation of communication resources based on needs and efficiency.
Scheduling includes modulation order and coding rate adjustments.
Operators use scheduling to maximize data throughput while providing reasonable service to all users.
Scheduling can cause temporary lack of data despite a good signal.

Third-Generation Mobile Communications

3G has been largely superseded by 4G and 5G for mobile data but is still used for mobile voice telephony.

Wideband Code Division Multiple Access (WCDMA)

3G uses wideband code division multiple access (WCDMA) as the radio access technology.
WCDMA is a development of CDMA, which was used by a few US-based operators for 2G voice communications.
WCDMA is 'wideband', using more spectrum than CDMA to provide a higher data rate and a more robust data service.
WCDMA allows multiple users in a cell to be served simultaneously on the same radio channel.
WCDMA uses channelisation codes and scrambling codes.
Channelisation codes are applied to data before scrambling codes.
At the receiver, the order of decoding is the reverse of the order of encoding.

Channelisation Codes

Downlink objective: enable each user device to extract its own data from a stream that carries data for every user in the cell.

At the Transmitter: Encoding

Each 1 and 0 of a user’s binary data in the downlink is replaced prior to transmission by several short ‘chips’.
Each chip has two possible states, represented as 1 and –1, rather than 1 and 0.
Chips taking values of 1 and –1 are said to be bipolar.
Several chips are used to represent a single bit.
A code for user A consists of chips 1, –1, 1, –1.
The chip pattern used to represent a binary 0 for user A is the inverse of that for a binary 1: –1, 1, –1, 1.
Each user’s data stream in the downlink is encoded with a unique channelisation code.
Codes are assigned to users’ equipment by the Node B.

At the Receiver: Decoding

The receiver needs to extract the appropriate data from a chip stream.
Each receiving device carries out a mathematical operation called correlation or in-phase correlation.
Receiver A multiplies each of the received chips by the corresponding chip in A’s channelisation code, stores the result, and then adds all those stored values together.

Walsh Codes and High-Speed Codes

Channelisation codes are examples of orthogonal codes and come in sets.
A unique property of orthogonal codes is that correlation of any code in the set with any other code gives an answer of zero.
With Walsh codes, there are only as many different codes as there are chips in the code. So there are only four Walsh codes with four chips.
Channelisation codes can be long or short. Short codes might be 16 chips long, and long codes could have over 100 chips.
The chip rate in WCDMA is fixed at $3.84 Imes 10^6$ chips per second.
Short channelisation codes convey more bits per second than do long channelisation codes.
Modulation with QAM doubles the bit rate as, in effect, the I and Q phases carry independent chip streams.
Data encoded with short codes is less robust to interference than data encoded with long codes.
Short channelisation codes (16 chips) are used for high-speed data (called high speed packet access, or HSPA), whereas long channelisation codes are used for telephony.
Representing each bit of data with multiple chips increases the frequency bandwidth occupied by the data; this is called frequency spreading.
The degree of spreading, known as the spreading factor, is equal to the number of chips in the code.
In a typical, busy urban cell there might well be more than sixteen data users, so not everyone can have their own high-speed code, as there are only 16 such codes.
The codes are rationed among users for short periods through the process of scheduling.
In HSPA, users are often allocated several codes briefly, which increases the data throughput for that user.
Another implication of the limited number of high-speed codes is that they are re-used in adjacent cells.
In WCDMA, adjacent cells usually use the same radio channels as each other, so there is clearly a danger of interference and data corruption.

Scrambling Codes

Help to prevent code re-use problem of channelization codes: adjacent cells use different scrambling codes.
Scrambling codes also belong to a class of codes know as quasi-orthogonal codes which means they are not truly orthogonal.
They are also known as pseudo-random codes or pseudo-noise codes, meaning that after being encoded with a scrambling code the signal has a random-noise like appearance.
In the downlink, each Node B applies its own scrambling code to channelisation-encoded downlink data, allowing its data to be distinguished from that of neighboring cells, which use different scrambling codes.
In the uplink, each user has their own scrambling code, enabling their data to be distinguished from all the other users in the cell, and all the other users in neighboring cells.
Scrambling encoding is a chip-for-chip replacement of the channelisation encoded data.

Problems of WCDMA

Increasing the data rate means increasing the chip rate and, as a result, the bandwidth due to the spreading effect.
Unfortunately, the complexity of WCDMA increases markedly as the chip rate and bandwidth increase.
The implementation of power control is complex as devices in the cell are likely to be moving relative both to the Node B and to each other.

Fourth-Generation Mobile Communications (4G)

The wireless access part of 4G grew out of a project of a trade group known as the 3rd Generation Partnership Project (3GPP).
The project was entitled ‘long term evolution’, or LTE, and was eventually retitled 4G LTE when it became clear that what was being developed would be incompatible with what had preceded it.
Among the principal requirements for 4G LTE were greater spectral efficiency, lower latency and higher maximum data rates: 100 Mbit s−1 for a mobile user and 1 Gbit s−1 forastationary user.
Cells in the 4G LTE radio access network can use up to approximately 20 MHz of spectrum per channel.

Orthogonal Frequency Division Multiple Access (OFDMA)

The access method for the 4G LTE downlink was orthogonal frequency division multiple access (OFDMA).
Orthogonal frequency division multiplexing (OFDM) is used in WiFi, digital television, powerline communications, cable television and digital audio broadcasting (DAB).

Orthogonal Frequency Division Multiplexing (OFDM)

OFDM is a form of frequency division multiplexing (FDM).
In OFDM, it is usual for a single information stream to be distributed across multiple OFDM carriers.
OFDM is often described as a technique for ‘multicarrier modulation’.

Spectral Efficiency:

OFDM achieves a considerable saving of frequency bandwidth compared with FDM.
The carriers in OFDM are called subcarriers and the number and spacing of subcarriers in OFDM is unlike the typical number and spacing of carriers in FDM.
OFDM uses a large number of very closely packed subcarriers.
The subcarriers of OFDM are typically very closely packed in the frequency domain so bandwidth is conserved compared to FDM technique.
Provided the spacing of the subcarriers meets a precise specification, data can be recovered uncorrupted from the modulated subcarriers despite their overlapping spectra.

Orthogonality:

When the subcarrier spacing meets this specification, the subcarriers are said to be orthogonal – hence the ‘orthogonal’ in OFDM.
For a useful symbol period $T{us}$ on each subcarrier, orthogonality is achieved if adjacent subcarriers are separated in frequency by $\Delta f$ , where $\Delta f = frac{1}{T{us}}$ .
$\Delta f$ is typically very small in relation to the frequency of operation.

LTE Example:

The useful symbol period in 4G LTE is $66.7 \mu s$ . $\Delta f = frac{1}{66.7 \times 10^{-6}s} = 15 kHz$ .
As a percentage of the operating frequency, a subcarrier separation of 15 kHz is: $frac{15 \times 10^3 Hz}{1.8 \times 10^9 Hz} \times 100 \% = 0.0008 \%$ .

Spectrum Usage:

Features of OFDM that could be expected to make it spectrally efficient are:
- The close spacing of subcarriers.
- The elimination of significant gaps between them.

Subchannels:

Associated with the subcarriers of OFDM are subchannels.
Each subchannel is centered on a subcarrier frequency, and is wide enough to enclose most of the power associated with a modulated subcarrier.
The width of the subchannels is the same as the subcarrier frequency separation.
All subchannels using the same modulation technique in a given OFDM implementation have the same bit rate.

Resource Allocation:

The ‘multiple access’ part of OFDMA is achieved by allocating particular subchannels to particular users for their exclusive use.
Blocks of subchannels called resource blocks are allocated to users.
OFDM is made feasible by digital signal processing in software, based on algorithms called the fast Fourier transform (FFT) and the inverse fast Fourier transform (IFFT).
There is a drawback associated with OFDM, namely the relatively high level of out-of-band signal power.
Agard band is needed sometimes between OFDM spectrum blocks and other radio bands.

OFDM vs. Single Carrier:

OFDM has a slow symbol rate compared with an equivalent single-carrier system.

OFDM vs. Single Carrier (Continued)

OFDM combines a slow symbol rate with a high data rate that is as high as could be achieved with a single-carrier system in the same amount of spectrum.
Figure represents a hypothetical single-carrier modulation scheme, which a succession of $n$ symbols in the time domain are transmitted, which are in a frequency band of width $W$ .
Each symbol has a period $\tau$ , so the total time taken to transmit the n symbols using conventional single-carrier modulation is $t= n\tau$ .(Ignoring any overheads that might extend the transmission time.)

Signal Processing:

The multicarrier approach slices the frequency domain into narrow bands (or subchannels) that contain the symbols. Whereas, the single-carrier appraoch the time domain is spread out with successions.
There is one symbol per subchannel.
Neither the single-carrier approach nor the multicarrier approach is inherently better than the other, and each can be as spectrally efficient as the other.
Shannon’s Theorem shows that the two approaches are equivalent from the point of view of channel capacity and spectrum use. $C = W log_2(1 + \frac{S}{N}).$ Where:
- $\,W$ is the channel width.
  * $\,S$ is the power of the signal.
- $\,N$ is the noise power.

Multicarrier Calculations:

In these calculations, the sub channels are assumed to have equivalent power distribution of frac{S}{100}: $C = 100 \times (\frac{W}{100} log2(1+ \frac{S}{N})) = W log2(1 + \frac{S}{N}).$

Inter-Symbol Interference

Inter-symbol interference is a type of noise or distortion caused by a symbol interfering with a following symbol.
A common cause is multipath propagation, in which a signal arrives at the destination having followed various paths.
The diverse routes introduce varying delays, causing the arrival of one symbol to coincide with the arrival of a different symbol that has travelled via a different route.
Inter-symbol interference therefore increases the error rate of wireless signals, because symbols interfere with one another.
Delay spread: the length of time that needs to elapse to encompass the arrival of all the delayed versions of a signal.
Symbol period much longer than the delay spread: inter-symbol interference can be reduced and possibly avoided.

Cyclic Prefix:

It occupies the initial part of each symbol, and has the same duration for each symbol.
Cyclic Prefix is longer than delay spread which allows inter-symbol interference to be eliminated entirely at a cost.
Arule of thumb which applies to delay spread and inter-symbol interference is that if no cyclic prefix is used (in which case the useful symbol period and the OFDM symbol period are the same), then provided the delay spread is not more than 10% of the symbol period, inter-symbol interference can be regarded as negligible.
Symbols per period = $CPp + T{us} = TOFDM$ , then $TCP = TOFDM - T_{us}$

Cyclic Prefixes and Symbol Rate for 4G LTE

Cyclic prefixes: they provide further safeguarding against inter-symbol interference can be used with single- carrier modulation or with OFDM. They provide a further safeguard in addition to the slow symbol rate that OFDM provides.
A cyclic prefix is a copy of the end section of a symbol, added to the front of the same symbol prior to transmission and has three periods:
* Useful Symbol
* Tus.
* ODFM symbol period TOFDM.

Cyclic Prefixes and Symbol Rate for 4G LTE Continued

The length of the cyclic prefix determines how much of inter-symbol interference is cancelled
The cyclic prefix effectively acts as a guard interval, however, it still transmits a signal, so its not truly a gap. Having power helps the signal transmit.
Cyclic prefixes are not always used in OFDM, but they are in 4G LTE devices
Cyclic prefixes also have an effect on DSL lines and cable lines as well
However, this is less obvious because there is no scope for multipath propogation because its within telecom lines not public spectrum broadcast. There are a few ways that ISI (Inter Symbol Interference) can arise and that can be from reflections in the wire causing multipath propogation which is an effect that can appear in DSL Broadband.

Equation

$ \Delta f = \frac{1}{T{us}}$ This simple equation of subcarrier separation will remain stable even with a cyclic prefix addition, and this is a good thing. Now it is time to look into the effect of symbols in terms of data rates, for symbol periods TOFDM which are the relevant term. Which gives a new equation and that equation is shown $\frac{1}{T{us}} x \text{bits per symbol} $
This means that as a result, it requires two cyclic prefix values to have certain stability to allow for better calculation

Data Rates vs Sub Channels

Data rates in cyclic prefixes need to be traded off against smaller subchannels given that too many errors could arise due to that problem. Now in many different ways, one can calculate what is being done and it might feel like information is being stretched to fulfill certain needs and this is all for balancing requirements in the technology that we are using.

OFDMA / LTE Resource Blocks

The most significant differnece between the two systems is that OFDMA does a better job by enabling a multitude of transmissions, such multiple transmissions can serve the purpose a multitude of users who can be served simulataneously. OFDMA shares in downlink by allocating groups of subchannels to users dynamically.
From practical speakly, resources are too small to be allocated at a micro level but it is important to allocate resources to each user for maxmimum communications. As a consequence of these constraints it is important to determine that within this range of operation how to manage those resources. Therefore, on a conceptual point of view, ressource management of an 4G LTE network has two dimensions, frequency and time. What are these time and frequency units based in? The resource element also factors in such, and from the axis it can be determined that these numbers can have varied units depending on need.
A resource element is used to define one symbol with one subcarrier. Because Resource allocatiosn is often conceived as 84 resource elements. The minimum numvber of resrouces to allocate a user at any given time is 2. (Due to short allocation duration being two slots or 1Ms.)
The allocation of units to users is reviewed at frequent intervals, typically every one ms on how to make it efficient.

A slot is always divided among cylic prefix and they can be either extended or standard
Slot timining of 0.5 MS with 7 symbol periods and standard clyic prefix.

Different Symbols Per Block:

There are two types of symboles to note

The first symbol will always have a slightly longer prefix
Standard prefix. All symbols in the block period have the same length.
However, when trying to apply a coding scheme there is a trade off since there are multiple trade off happening per channel!

4G LTE Upload

The wireless part of 4G grew out of project known as the third generation partnership project or long term elvolution which has two aims:

Spectral efficiency.
Low Latency.
However its also important to consider that with the low cost of electronics they need to account for Peak to average output. Now what the peak/average does it measure power consumption so in the most basci sense it relates peak power to average power and its easy to design because its a direct multicarrier design and single carrier modulation with power ratio.
A high PEAK to average power ratio design causes all sorts of issues, and as such, the downlink and upstream have changed the single carrier transmission. However when its set aside that helps better synrcnhonization, and flexibility.

Single Carrier for 4G Upload

In Single Carrier transmissions all the subchannels allocated to the same receiver all effectively are treated the same since they use the entire spectrum. As such the symbol carrying is at a span of frequences in carrier transmissions. Its best to think of symbols in device being distrubited across subcarriers with better power efficency. Its important because mobile devices are allocated resources contorlled by the base stations that range from small slices such as 20 MHz to just a fraction of that. Otherwise all signal processing would be much different that which it has now, such a IFFT stage is useful.

Synchonization and Reference Signalings

Sychnronization
Channel Equalazion
Channel equalation refers to the signal processing in the transmitter and receiver. For example if it had a pilot signal sent out then anything that alters its phase is noted.The channel also goes to make a profile of what aplitude and phase charges it produces accrosss the fepqricny
Channel requalization requires sigals through channel but lesss room for data.
Adds a greater processing burden that battery devices need but there are also Physical Downlink.
There are ways to make things a bit simplare but data may get removed in many resource blocks but its mapped to resource blocks, its possible that higher level functions needs to manage this.

Channel Description

Phsycial Downlink Channel Shared. Transmits User Data.
Physical downlink COntorl charannel to transmit allocation allocation or some other sort of COntrol information.
Phsycial Control and Format Channel, in that the symbol is being mapped
There are various other down links. there will be pilot and signals on uplink and dowm linking in those signals.
The point of channels and signals is that they are a factor in how to make the process simpler. It is still important to consider the data usage and some functions may still not be aware on how theirdata maps to sources and elements

Fifth-Generation Mobile Communications (5G)

Evolving Standards and Use Cases

5G builds on 4G technology with key differences in standards and use cases.
ITU defined 5G requirements in IMT-2020; 3GPP outlined specifications starting with Release 15 in 2019.
Release 15 = 5G New Radio (5G NR);
Release 16 (2020) = Phase 2 (initial 5G specification).
Continued improvements in Release 17 (2021/2022).
5G NR uses OFDMA; is IP-based.
Key aim of 5G is building on existing 4G technology.
Deployment scenarios: operators continue to operate LTE + 5G in higher frequencies.
Two configuration types:
Non-standalone (NSA) 5G builds upon existing 4G networks; standalone (SA) 5G does not.
The full 5G core network is required to support services essential to 5G.

5G Core

It is designed from the outset to supportabroader number of use cases.
These different use cases, and the fact that 5G technologies are being designed to meet each of these from the outset, is a major departure from 4G.

5G Usage

It is not primarily for voice.
Instead its designed on high mobile broadbnad speeds and new types of traffics.
Typically, does not belong solely or wholly within one the three classes.
5G technologies are being designed to meet each of these.

Enhanced Mobile Broadband (eMBB)

eMBB is the closest use case to conventional mobile communications, technologically closer to LTE.
It emphasizes high throughput, enhanced spectral efficiency, and geographic range.
Targets peak rates of 10–20 Gbit s–1 (4G has peak rates of 1 Gbit s –1).

5G New Radio

Massive Machine-Type Communications (mMTC)

Supports the IoT Internet of Things.
Battery is central. Therefor lifetimes require long lives. Security and privacy protocols will be considered.

Wireless Communication classes

LTE Chat M1 bandwith 1.4.mhz data rate 300-400 kbuts -1 .
LTE Cat Mb1, low power broad brand - data rate 200 Khz band but data rates are around 30-50kbits
Main objective of these networks are the batter life, such can be a life time of an 10 year battery life.

Ultra-Reliable Low Latency Communications (URLLC)

*URLLC
* Connected/Driverless Car
* Smart Manufacturing
Remote Healthcare
Many experts few low latency a big challenge, for latency scheduling plays a central role given how limited bandwith must be allocated to each station, to better handle the reivew the source allocation as such a re-allocation of resources might not get what it seeks. To improve latency as needed. One of the innvoations is reduction of the time is for scalilng such changes that improove latenct for better communications

Innovation in 5G

Changes to scheduling to radio allocations.
Changes to core with Viatualizaiton tecnhieqs and treating different traffics differently.

Radio architecutre and Core network changes

More sophisticated architecture to enable more sophisticated usage.
Small Cells - To operate across shorter range of operation.

Challenges.

Negotiating building structure and access.Backhaul needs a way back to connect to network core.
To connect integrated access and back haul IAB links that support cells but are inside and out, and uses macro sites that use radio services to provide links to users. Also it provided wireless back hall support.

Spectrum for Different bands

5G can use bands with very differerent characterics

High Band - ablove 24 GHZ ( millimetre waves)
2.Mid Band- between (1GHZ and 7GHZ , to creep uo to 7.125 GHZ.
Low band-Below 1GHZ.
Official standards FR and FR bands is that all these changes are happening in different bands. FR1 in these lower bands and FR2 is the higher band but here are some broad types
mm waves that are useful due to lack of traffic but the characteristcs makes it so its only usefule over short distancbes. This due its poor porogration chracterstics.

Frequency and band charaterisicts

Mid Band A balance between propogation and coverage charactiersitcsc but offers similar fequenciuies that allows easy charctersitiocs.
There exists some refarmed bandwidth that used 2G and 3g networks that are intended for 5G network and allows all three clases eMMB and URLCC AND MMTC
LowBand
Also use 700MHx that was designed foer terrristtial TV broadcasts that allowed large amount that works in most buildings. Thereforre most freuqneires providew good poential and may even be used in IOT mntc.
along wide band and it meant contigisous spectrum means the band is large and allows better signal to ocuupy
20 mhz band to 11 hz however it is possible if one had enougn bandwith for the system as it standss 100mhz

Spectral usage

5g can also be used for non licensced spectrum. Therefroe as 5g standd now its has more and diffret ability than previous 4d

massive mimo beamforming andbeamstereing.

5G uses more multiple antenas at both the transmter receiver ends tp exploit multipath propogation, which takes several path for tranmsiosn and betetr snr that help massive mimo is arrays can come with more than one. Beam forming is used in many ways. As these signals may even reflect different type of surfaces. Another element is using element can be to form focus on more particular. By using more antenna the sigmal steangth be better and have much small interfernce. In those cases more antenna more power in certain directions in the MIMO system. To use beam forming you also need beam steering which means dymaically and chang the angle of propagation as required.

Scalabillity and Numeralogy and sub channel with.

With each increase in bandwidth the scalability can go from 2G or 3G, and 5G uses much greater.

5G wireless 5G new radio has scalable numeralogy or way to allow subcarrier spacing from multiple ranges
variable nature from 5G is that to cater data transfer, that are also practical than others with mm radio that it can shift and help. And that also happens too with signal range.
A set of spaced 5 GNR 15 Khz space from previous.
n is number and it might have other name or the numerology index.
The value of that is revealed that has high range which allgns effectivley that means you can do the next. Sub fram has data that for 1 micro second. It is for smaller data sets.
A key take away, its to figure and to make everything run at high speed

5GSynchronization

Synrchonziatton has been solved to give data to slot to reduce delays on data.
There a min slot which mean not has much data that reduces any delays with radio to radio.

Band Part and Frequent parts

As radio stations work to muplitple numerlogies they mus tbe assugned an exculisve radio used, by making a bandwidth band limited to specific numerolgies. Bandwith boundary has flexibility in band for resrouces.

Resource Grids and Resrrouce Blocks. Scheduling

Divides the channel in capacity. Theregular the more inits, the higher the allocated rate. The more resources allocated the stronger the data rate.
5gt NR builds based to provide greater functionality . The two dimensions are frequency in y axis, time in. x axis however units change depneding on numeralsogy. Resource element has a duration with symbol position. (One fotrrenth a sol)
As mentioned before the main take away about those signals that the time in a slot what what is going to drive a given rate and what should be happening on user devices. In those cases a good number of use cases for many more depolyment to happen a d and contribute to flexiblity.

Control and flexibility.

This is not something possibel due the the fact there would be more slots that have better range . this are all different features for making that transmission. Therefore with all the tools to ensure the correct the data at what could be more useful for people to engage those type of signals. Self contained slots is a