Making Sense of Home Wi-Fi Coverage Solutions

Transcription

1 Making Sense of Home Wi-Fi Coverage Solutions Phone: Lusk Blvd, Suite C102, San Diego, CA 92121

2 Introduction Wireless connectivity is so ingrained in our day-to-day lives that any loss or degradation of service is well beyond a nuisance. For most, Wi-Fi is the magical source of this untethered connection, especially in the home and work environments. Wi-Fi is cheap and embedded in an ever growing number of devices, in fact the Wi-Fi Alliance expects there to be more than 15B Wi-Fi enabled devices by the end of , making it the technology of choice for the foreseeable future. Wi-Fi works pretty well most of the time, but when it fails or behaves erratically it is very frustrating. There are a number of factors that cause Wi-Fi issues including congestion, reliability, and coverage. This paper focuses on demystifying coverage issues and the various solutions available to ensure service in every corner of your home. With coverage being a relatively common problem a number of different solutions are available. The challenge is figuring out what fits best for your environment and then setting it up properly. Thankfully equipment makers have realized that the setup should not be such a hassle and are providing a number of solutions (e.g. software to automate and/or simplify, more intuitive product design, etc.). As the setup becomes easier there are really only two major differences between the options. The first is topology do you have lots of low power access points (APs) or fewer high power APs? Frankly, this can be a bit of a philosophical debate without a clear winner. On one hand deploying more small power APs provides resilience and keeps the signal close to the devices. It also fits well for future requirements on the home network think complete home automation with many connected devices. On the other hand, fewer higher power APs are easier to setup, simplifies connectivity to the internet and is less likely to cause interference. The second difference is how the various APs gain access to the internet, often termed backhauling. In most homes there is not an Ethernet jack in every room so both wired and wireless options are provided for the additional APs. These two differences are not wholly independent. For example, if you have many low-power APs it makes it more important to have flexibility in how they are backhauled to the internet. The following sections focus on different backhaul techniques, their implications on topology and the benefits and drawbacks of each approach. 1 Wi-Fi device shipments to surpass 15 billion by end of 2016, Wi-Fi Alliance, 1

3 Multiple Independent APs The first approach is to simply have multiple Wi-Fi routers each with their own independent connection to the internet. In this configuration the individual APs are essentially independent of one another. Figure 1 illustrates the multiple independent AP solution. Channel in use Clients Internet 2.4GHz links/clients 5GHz links/clients Figure 1: Multiple Independent AP Architecture Benefits Deploying multiple independent APs is a simple approach. The user configures each AP and can place the APs where they need coverage. Most commercial APs are high-power as well so the choice of where to place is less complicated verses a wireless extender or mesh system. Additionally, each AP can choose its channel (i.e. portion of Wi-Fi spectrum) completely independent of the others. In alternatives that rely on a wireless connection back to the internet there are constraints imposed on the channel used to service clients based on how the secondary APs backhaul to the internet. By having the freedom to choose the best possible channel locally each AP has the potential to dramatically increase the capacity of the local wireless network and avoid interference from neighboring APs. Drawbacks The biggest challenge is having access to the internet in multiple locations throughout the home. Most homes are not equipped in this fashion and the configuration will require a switch be installed assuming a single broadband connection to the building. Additionally, while independent sounds simple it also means the system is completely uncoordinated which can cause multiple issues discussed in the conclusion of this paper. Summary In the end, the multiple independent AP architecture, though having a number of benefits, is highly unlikely based on the majority of home configurations and the complexity required to connect each AP independently to the local broadband connection. 2

4 Wired Extender An Extender is a secondary AP that connects back to your primary Wi-Fi router (a.k.a. Primary AP) delivering a local area of coverage. Extenders connect to the Primary AP using a wired or wireless connection. This section addresses the wired type. Multiple different wired connections are supported including Ethernet, powerline and coaxial (i.e. cable). Figure 2 illustrates the Wired Extender approach with Ethernet as the connection between the Extender and AP. Channel in use Primary AP Extender Ethernet Clients Internet 2.4GHz links/clients 5GHz links/clients Figure 2: Wired (Ethernet) Extender Architecture Benefits A Wired Extender provides similar location independence as the multiple independent AP option since it is not relying on a wireless signal to connect to the Primary AP. This means you can place the Extender anywhere there is a wired connection (i.e. Ethernet port, outlet, or cable drop depending on the type of Extender). For example, if your office is the dead zone because it is too far away from the Primary AP you would put the Wired Extender somewhere inside your office. If you re using a Wireless Extender, you ll need to find a mid-point between your office and the Primary AP so it can both connect to the Primary AP and reach to the dead zone. The second major benefit is that Wired Extenders enable the most efficient use of spectrum (i.e. wireless resources). This is true for two reasons. First, since the backhaul is wired the Extender is not using radio resources to connect back to the Primary AP. When wireless resources are used for backhaul there is less available for servicing devices. Second, when spectrum is used for backhaul it imposes constraints on what channels can be used for service. In a Wireless Extender the same channel is used to provide service to devices as is used for backhaul. In a Mesh System there is a potential for a wider variety of channels to be used across each node, but in the end there will be overlap. 3

5 Drawbacks The primary challenge with Wired Extenders is having the wired connection in the location where you need better coverage. In most cases, consumer Wired Extenders either use powerline or Ethernet. Power provides the greatest flexibility, but still outlets can be limited and/or in bad locations leading to difficulty in placing the Extender. Beyond placement flexibility, a Wired Extender installation can become complex or not even possible if the home is larger requiring more than one Extender to deliver coverage. Most Wired Extender solutions are designed for one Primary AP and one Extender limiting the footprint that can be covered. Summary Wired Extenders provide a simple and flexible way to improve coverage in most homes. They only utilize radio resources for providing service which enables a larger increase in capacity and limits likelihood of radio resource contention. From a retail perspective the biggest drawback is the one-to-one ratio with the Primary AP. However, many operators are considering solutions which enable a one-to-many relationship removing this limitation, while maintaining all the benefits of wired backhaul. 4

6 Wireless Extender Similar to the Wired Extender in most ways the Wireless Extender differs in that it uses Wi-Fi spectrum to connect to the Primary AP. Figure 3 illustrates the Wireless Extender approach. Extender-1 Channel in use Primary AP 2.4GHz links/clients 5GHz links/clients Internet Extender-2 Figure 3: Wireless Extender Architecture For the wireless backhaul, Wireless Extenders have the flexibility to use both 2.4 GHz and 5 GHz spectrum. Currently, 5 GHz spectrum is lightly used so many systems choose this band. However, the usage of 5 GHz will continue to increase and 5 GHz signals do not travel as far, which means the Extender needs to be placed close to the Primary AP. Since, most Wireless Extenders only have one or two radios (i.e. either 2.4 GHz only or both 2.4 GHz and 5 GHz) the Extender uses the same channel for backhaul as it does service. Benefits Wireless Extenders and Mesh Systems for that matter provide the most flexibility in where the Extender can be placed once the right general location is identified. All they require is a power outlet to be in that location. Additionally, multiple Wireless Extenders can work with one Primary AP. Each Extender is another Wi-Fi client device in the eyes of the Primary AP. This is a nice expandable architecture for most homes. Consider a two story home with a basement and the Primary AP on the first floor. It is possible to put a Wireless Extender on the 2nd floor and one in the basement providing a blanket of coverage across the whole footprint. 5

7 Drawbacks The main drawback of a Wireless Extender is the source of its primary benefit wireless backhaul. The usage of the same airwaves for backhaul as service further congests the Wi-Fi spectrum. This can create contention and bring down performance especially if your neighbor ends up using that same channels for their system. As most of these devices choose a channel at boot-up and rarely change interference and congestion issues can result over time especially in suburban and urban environments. Additionally, the usage of wireless backhaul halves the bandwidth. The Wireless Extender receives the signal and then rebroadcasts it and does this in both directions from the Primary AP to the device and vice versa. For many homes the issue is speed within the home and not the speed of their broadband link. Halving the wireless bandwidth reduces performance especially for streaming applications. Summary A Wireless Extender is a solid solution especially if your home is larger, lacks the necessary wiring, and/or flexibility with placement is important (i.e. wiring is there but not where you want / need it). If the intent is to connect many devices all over the house the usage of wireless backhaul can become a capacity limiting factor especially if neighbors are reasonably close by with similar network demands. 6

8 Mesh System Until recently Extenders were the primary coverage solution offered via retail channels. However, in the last year multiple mesh solutions have emerged. This includes products from startups (e.g. Eero, Luma, etc.) and established players (e.g. Netgear). In a mesh solution architecture all APs connect to one another via wireless links. This differs from a Wireless Extender where each Extender connects wirelessly only to the Primary AP. Instead of a Primary AP, the main Wi-Fi router acts as a Gateway providing access to the internet. Traffic to every AP ultimately passes through the Gateway from the internet and vice versa. Best-path forwarding is used to send data packets out from any given Mesh AP. In this regard, the Mesh APs and the Gateway act as routing peers. Traffic can traverse multiple Mesh APs on route to and from the Gateway. Figure 4 illustrates a Mesh System. Mesh Node-1 Mesh Node-3 Mesh Node-2 Gateway Router Internet 2.4GHz links/clients 5GHz links/clients Figure 4: Mesh Architecture 7

9 Benefits Similar to a Wireless Extender, a Mesh System provides flexibility on where to place each AP. Once the Gateway Router is connected to the broadband connection other Mesh APs can be placed where they are needed. The only caveat is that the first hop (i.e. AP closest to the Gateway) needs to be within a good signal range to the Gateway AP. Additionally, Mesh APs are often designed to be lower power with the intention of deploying multiple across the footprint of the home. This decreases the potential for channel contention across APs and provides a better signal to devices by having APs closer to the clients they are servicing. Finally, a mesh system provides both expandability and resiliency. Any number of mesh APs can be added over time ensuring coverage across the entire footprint. Generally, the coverage areas for mesh APs overlap so if one of the APs happens to fail then service is maintained. Drawbacks The first issue with mesh systems is its cost. They require more hardware and higher complexity software. The system must be self-configuring or only a select few consumers would be able to set it up. Each AP requires additional compute power to handle the routing functions as well as multiple radios increasing the hardware cost per AP. The need to install three or more to get the full benefit even further increases expense. Secondly mesh systems are less efficient in their use of wireless spectrum. Despite claims that infer infinite flexibility in what channels are used for communication between mesh AP, there is re-use of spectrum for both service and backhaul which is amplified in a mesh system. In a typical three AP configuration a single data packet could conceivable use the same wireless spectrum resource four times before getting to its destination. With ever increasingly congested airwaves this inefficiency has the potential to be a problem especially in locations where homes are clustered closer together. Summary Mesh systems provide flexibility and resiliency, but at a very high cost. Both monetarily and from a spectrum perspective. They tend to be a good fit for larger homes without too many neighbors nearby essentially where the system can dominate the usage of Wi-Fi airwaves. In moderate homes both Wireless and Wired Extenders are sufficient. 8

10 Summary & Other Considerations Like most things there is no one size fits all solution when it comes to Wi-Fi coverage. From a technical perspective it depends on the size of your house, the wiring, and the strain you and your neighbors will be putting on the Wi-Fi airwaves. From a practical perspective cost and simplicity are paramount. Table 1 summarizes benefits of each approach. Independent APs Wired Extender Wireless Extender Mesh System Spectrum Efficiency X X Flexible Placement X X Location Independence X X Expandable Coverage X X Network Resiliency X Cost Medium Low Low High Table 1: Coverage Option Comparison In summary, systems that use wired backhaul (e.g. Independent APs and Wired Extenders) provide coverage without impacting capacity. Systems that use wireless backhaul provide flexibility and expandability, but use up wireless capacity to deliver the flexibility. Mesh systems in particular maximize the flexibility and expandability, but at a prohibitive cost for many. Regardless of how the systems are setup they all can suffer from a few key issues if they lack features that enable intelligent coverage. The first of these is roaming (i.e. moving from one AP to another) across different APs or lack thereof. If roaming decision are left to devices, then service issues will occur. Wi-Fi clients tend to be sticky, they stay with whatever AP they first connect to as long as possible even if there is another AP close by that can provide a much better service. Have you noticed when you leave home your phone takes way too long to let go of Wi-Fi? Imagine if this happens when you go from downstairs to upstairs in your house. Similarly, since the devices have no idea how much of an APs capacity is already in use they will attach to whichever is closer. This can lead to a situation where one AP is overloaded, despite there being a lightly loaded AP nearby, bringing down performance to all connected devices unnecessarily. The second common challenge is lack of coordination which can leave the APs to interfere with one another or other neighboring APs outside the home degrading service. Smart algorithms need to be in place that enable the best use of radio resources and mitigates potential interference especially in systems that backhaul traffic wirelessly. Finally, as soon as your setting up a second AP the complexity of managing the network increases. The configuration and troubleshooting should be automated and intuitive. While a number of individuals will relish the opportunity to figure out the right coverage architecture for their home, go through the process of setup and the on-going management of the new network the majority of people have no interest. This is where Internet Service Providers (ISPs) have the opportunity to deliver a managed home Wi-Fi service. From a simplified ordering process that identifies the right setup (i.e. number of APs) to installation and on-going assurance ensuring the system delivers reliable high-performance wireless internet access. Phone: sales@xcellair.com 6540 Lusk Blvd, Suite C102, San Diego, CA 92121