In-home Wi-Fi Networks: Today, Tomorrow, and Beyond
July 22, 2014
Do you have broadband Internet service? If yes, most likely you also have a Wi-Fi Access Point (AP) for wireless connectivity in the home. Today, in-home Wi-Fi is almost ubiquitous in the countries with developed economies, and the penetration is only growing. A new iGR study forecasts that almost 98 percent of broadband data use in U.S. households will be on Wi-Fi devices by 2018.
Emergence of Operator Managed In-home Wi-Fi
The demands on home networks have increased over time. In the past customers would connect a few computers directly to a cable modem using Ethernet or USB. Then customers wanted the convenience of receiving wireless data at their laptop so they could read E-mail or surf the web. Customers achieved this by going to a retail outlet and purchasing a Wi-Fi access point, which they would plug into the cable modem. Now broadband service providers are taking on the responsibility of providing and installing the access point. This raises the customer’s expectation. An additional complication is that customers want to stream videos to their smart phones, laptops, and tablet computers.
Recent Wi-Fi Technology Improvements
Over the last decade Wi-Fi performance has also improved significantly. The latest Wi-Fi standard – 802.11ac – promises support for more than 1 Gbps of speed. Many Wi-Fi products support Multiple Input Multiple Output (MIMO) and Transmit Beamforming. These technologies promise greater reliability and better performance.
For instance, as shown in the chart below, 802.11ac delivers higher throughput than 802.11n as a result of the support for 256 QAM. 802.11n supports up to 64QAM only.
Factors Impacting In-home Wi-Fi Performance
While Wi-Fi, in most cases, works as expected, in-home Wi-Fi network performance is highly dependent on a number of variables, including materials used for house construction, distance between AP and Client, level and type of interference, Multiple Input Multiple Output (MIMO) configuration, Transmit Beamforming (TxBF), antenna orientation, RF spectrum, background traffic, and device capabilities.
Additionally, Wi-Fi utilizes unlicensed spectrum that is not solely under the control of operators. Numerous devices (e.g. microwave, cordless phones) with a variety of technologies may utilize the spectrum. As a result, Wi-Fi may be subject to radio disturbances that may be immitigable.
Considerations for In-home Wi-Fi Deployment
Interference can be a significant issue and AP location and channelization should be set to avoid it. Not only co-channel, but adjacent channel and alternate channel interference can also be significant issues. Intelligent tools such as Automatic Channel Selection, Radio Resource Management (RRM), and Self Organizing Networks (SON) should be considered to help with interference mitigation.
The 5 GHz band offers more channels and is less crowded than the 2.4 GHz band and should be considered for in-home Wi-Fi deployments. Dual Band Dual Concurrent (DBDC) APs, which allow use of both bands simultaneously, are also available and should also be considered for in-home Wi-Fi deployments.
Support for Wireless Multimedia (WMM) and airtime fairness is recommended for in-home Wi-Fi networks in order to prioritize real-time application over background traffic and prevent slower clients (e.g. legacy) from dominating the airtime. Currently, Airtime Fairness is not part of Wi-Fi standards.
Although the 2.4 GHz band offers better distance coverage, Wi-Fi signals in the 5 GHz band provide excellent coverage as well in homes with drywall panel walls. Analysis shows that three HD video streams can be successfully transmitted to three Wi-Fi clients up to 80 feet from the AP in a home with drywall construction. Wi-Fi signals in the 5 GHz band offer more limited coverage in houses with brick walls (or concrete floors). In these houses, HD video streaming is possible if there is only one wall between the AP and clients. Wi-Fi signal attenuation is too high for two or more brick walls to reliably support HD video streaming. In cases where a single Wi-Fi AP is not sufficient to provide whole house coverage and required performance, there are multiple options for the consumer and operators to improve Wi-Fi coverage and performance. A few examples of these include:
- Multimedia over Coax (MoCA) to Wi-Fi extenders
- Power Line Communications (PLC) to Wi-Fi extenders
- Wi-Fi mesh (e.g. 802.11s)
- Wi-Fi repeater
- Or a combination of the options above
Transmit Beamforming (TxBF) and spatial division multiplexing improve wireless system performance. Increasing the number of spatial streams increases the Wi-Fi system throughput; however, the relative gain in throughput is diminished as the number of spatial streams increases. TxBF is not standardized in 802.11n, resulting in a lack of interoperability. On the other hand TxBF is standardized in 802.11ac.
Additionally, Optimum placement of the AP in the customer house can make a significant difference in Wi-Fi signal coverage and performance. Recommendations and guidelines for in-home Wi-Fi installation will be covered in detail in a future blog post.
Demands on in-home Wi-Fi networks are only growing. There are many factors influencing the performance of in-home Wi-Fi networks. Proper deployment and management of In-home Wi-Fi networks can help improve customer experience.
As of this writing, home networks and in-home Wi-Fi topics are active areas of research within CableLabs. If you are a supplier and want to get involved, please see the information here on how to engage. We plan to write additional blogs on this topic in the near future.
Also, CableLabs released a vendor RFI (on July 20, 2014) to the vendor community with an objective of soliciting information about current and future generation vendor products, architectures and technologies related to home networks and also to gauge vendor participation in the Future Home Networks project. The vendor RFI is available here.
Vikas Sarawat is a member of the wireless group at CableLabs. He leads several initiatives related to home networks and wireless networks.