As future internet speed most likely will exceed 1 Gbps. This reduces the risk of malicious firmware gets downloaded to your modem. Meaning the time it takes for data to travel from its source to its destination is shorter. This improves voice quality in VoIP calls and the online gaming experience.
Because it might take so long time that the one you buy now will be too old. It allowed for programming by users, which was not easily implemented beforehand. This gives you a bigger pool of devices to choose from when picking the modem for your home.
Allowing you to pick a device with the features and benefits that you want. It will also be less secure and have higher latency. Making it easier to get malicious firmware on your device. As well as giving you a worse experience playing online games. One should note, however, that it might take a long time before this comes to fruition.
Therefore, it is often seen as an investment for the future to get a 3. It is a good feature on a modem that will give you unmatched speeds. You will get excellent speeds and usage from 3. It is also cheaper, making it a more realistic option for a lot of people. With each generation bringing something new to the table.
Top-tier data plans offer eight downstream and four upstream QAM channels. That way, even if only a little data can get through each channel, bonding them together will allow you to push that data through multiple pipes at one time and thus work around that congestion. First Name required. Last Name required. Your Company required. Your Email required. Powered by WordPress Popup. In previous DOCSIS releases, the lower part of the spectrum had been dedicated to upstream while the higher portion was dedicated to downstream.
The spectrum sharing of full duplex is accomplished through the use of self-interference cancellation and intelligent scheduling. The boost in upstream capacity is the real breakthrough for full duplex. Visit Deploying and Maintaining the Advanced HFC Upstream to understand the benefits and challenges with advancements related to the upstream path.
The spectrum sharing of Full Duplex is accomplished through the use of self-interference cancellation and intelligent scheduling. The boost in upstream capacity is the real breakthrough for Full Duplex.
If there was a problem within a carrier, the modulation was reduced to keep data moving—not just for that carrier, but for all carriers in a plant. This means that modulations were optimized for the worst part of a plant.
Within these boundaries, OFDM can run as many as subcarriers running at 25 kHz or 50 kHz over the entire bandwidth. All subcarriers are time synchronized across the bandwidth and communicate together to form symbols. These symbols carry codewords and are spread across multiple subcarriers and time slots.
The main takeaway is that symbols are no longer tied to specific frequencies, but instead, are allocated across different frequencies over the entire bandwidth. This creates some unique opportunities. Now, if a particular subcarrier is experiencing a problem, OFDM can simply exclude it by bridging the adjacent subcarriers together.
This allows symbols to continue to travel over the entire bandwidth at optimal performance levels. Since OFDM is modulated for a set period, the technology can shape subcarriers by controlling their phase relationship. If one subcarrier has a peak, the adjacent subcarrier can be shaped to have a null. This reduces interference and provides an opportunity for higher modulations.
Modulations are where OFDM makes significant improvements in network performance. Instead of using one modulation for the entire plant, OFDM can allow different modulations for each subcarrier. Profiles can be created that define what modulation is used on each subcarrier and multiple profiles can be created for this purpose. Now, expand what is happening on this one subcarrier to cover all subcarriers. Each profile controls every subcarrier to maximize the performance on a particular subcarrier at a specific moment in time.
As mentioned before, all subcarriers are linked with each other to form symbols and those symbols carry codewords. The subcarriers are allocated to codewords on each symbol and their modulation is controlled by a profile.
Each profile is assigned a letter for example, A, B, C, and D. Not only is each subcarrier optimized for performance, all the other subcarriers know what each subcarrier is doing. Instead of modulations being optimized for the worst part of the plant, they can now be optimized for the best part of the plant at any given moment.
The advances made by OFDM would not be possible without some form of error correction. Since OFDM spreads the data across multiple subcarriers and potentially different subcarriers on every symbol, BER no longer makes sense.
LDPC can see across the entire bandwidth and looks for codeword errors instead of bit errors. If codeword errors are correctable, LDPC will automatically adjust correct the codeword so that higher modulations can be obtained. This greatly reduces the need for retries and keeps subcarriers working at optimal levels.
LDPC is designed to allow data to be transmitted at its theoretical limits. But LDPC does have one downside. As LDPC makes real-time adjustments, it can reach its limits regarding power levels and modulation error ratio MER while trying to correct codewords.
This means that LDPC gives less warning of impending failure. If LDPC goes over this edge, codewords can become uncorrectable and customer quality of experience QoE begins to decline. To keep this from happening, testing becomes even more important. For accurate testing to happen, it is important to understand the building blocks that make up OFDM.
One level up is the next codeword pointer NCP that tells the modem which codewords are present and which profile to use on each codeword. Next is profile A. Once this is complete, profiles B and above can be used to reach higher QAMs and more efficiency. Figure 3: Profiles — a basic conceptualization. For simplicity, assume that the profiles use the same modulation for all subcarriers.
If there are lost messages at this point, there will be retries, or even worse, no communications at all. These lower modulation rates can operate at lower MER and power levels. Just like the two building blocks before it, profile A must be locked and have no uncorrectable CWE. Profile A can run at higher modulations but will start to experience correctable CWE.
This is okay if they do not become uncorrectable CWE. One mistake technicians can make is to test the power level across the entire MHz carrier. Keep in mind that the total power of an OFDM carrier is equal to the total power of a 6 MHz carrier plus the channel bandwidth. To make accurate power level adjustments, the power levels must be measured and referenced in comparison to the power in a 6 MHz carrier.
There are also a few unique characteristics to OFDM. This becomes important when using a standard meter or when looking at the power within individual 6 MHz blocks of OFDM. In addition, the PLC carrier will be approximately 0. Figure 4: Profiles — a realistic conceptualization.
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