Original Link: https://www.anandtech.com/show/10878/extending-home-networks-a-comparison-of-ghn-homeplug-av2-and-wifi-mesh
Extending Home Networks - A Comparison of G.hn, HomePlug AV2 and Wi-Fi Mesh
by Ganesh T S on December 7, 2016 8:00 AM ESTOver the last decade or so, we have seen a rapid increase in the number of devices connecting to the home network. The popularity of IoT has meant that even devices that are not mobile require communication over the Internet, but, their placement might be far away from the primary router in the house. Given this situation, it is essential to find a reliable way to extend the reach of the home network. There have been many attempts to come up with a standardized way to do it, but consumers have been forced to use range extenders, powerline networking kits and the like to increase the reach of their home networks.
Given the multitude of available options to extend the reach of home networks, what underlying technology should consumers look for? Today's article provides a comprehensive overview of the available options as well as a quantitative comparison in one particular residential scenario - a 1800 sq. ft. single-level California house built in the 1970s.
Introduction
A discussion of the various ways to extend home networks must always be prefaced with a simple suggestion - if it is at all possible to wire up the major rooms in the house with Cat 6 cables, the reader should definitely go for it. Wi-Fi access can then be made available in remote locations with the use of access points that piggy-back on the Cat 6 backbone. This article tackles situations where wiring up the residence with Cat 6 cables is not a practical option.
Most residences have some sort of wired infrastructure going around - everyone has electrical wiring that is bound to be in every room. Some have telephone wires already present, while others have a coax cable network. In order to expand the reach of home networks, there are ways to use all of the above media. In addition to wired backhauls based on these, Wi-Fi itself can be used for this 'last feet' data transfer. Encompassing all these is the concept of hybrid networking - i.e., a way to get communication over different media to work together seamlessly in order to extend the network reach.
The industry recognized the need for hybrid networking around 5 years back and set up the IEEE P1905 working group. The approach, mainly spearheaded by Qualcomm Atheros, involved usage of HomePlug powerline chipsets as well as MoCA (Multimedia-over-Coax Alliance) chipsets in Wi-Fi routers to ensure a seamless connected digital home. However, the added price for the functionality led to the vendors largely giving this endeavor a miss. As of 2016, there are no known hybrid networking packages in the market. That said, there are many vendors who have range extenders that use a powerline backhaul (such as the TP-LINK AC1200 Wi-Fi Range Extender AV1200 Powerline Edition). Even though these products fulfill the basic requirement of extending the home network, they are not marketed as a unified solution with a primary router.
Netgear does have the Nighthawk DST (Dead Spot Terminator) kit hat combines a Nighthawk R7000 with a Broadcom-based HomePlug AV2-compliant PLC chipset. However, it is more of a limited release with the kit being sold only through Best Buy.
ITU's G.hn (G.9960) specification for home networks has been of interest due to its ability to operate over different media (telephone wiring, coax cables, and power lines). The technology had only been on paper for a long time, but, in early 2015, we saw some powerline networking products based on G.hn appear in the retail market. Marvell Semiconductors is a big proponent of G.hn. The current G.hn powerline adapters in the market are all based on their chipsets. Recognizing the need for hybrid networking, ARRIS has made an attempt to integrate proven 802.11ac Wi-Fi solutions with Marvell's G.hn platform. The resulting product portfolio has enabled consumers to seamlessly extend the reach of their home networks. Marketed under the RipCurrent moniker, these products include a primary Wi-Fi router and optional powerline extenders as well as a Wi-Fi range extender with a powerline backhaul. They target homes that end up with Wi-Fi dead spots when a single router is deployed.
Mesh Wi-Fi has emerged as one of the interesting approaches to residential Wi-Fi over the last 12 - 18 months. Even though it is being marketed as something revolutionary, the concepts have been around for a long time. In fact, Wi-Fi range extenders operate on almost the same principles, but, mesh Wi-Fi systems adopt a few strategies to make users think that they have a magical solution:
- By selling units in packs of 3, they guarantee that a vast majority of the homes can be completely blanketed with Wi-Fi
- By adopting an attractive industrial design, they ensure that users don't need to keep the networking equipment hidden away. This helps in minimizing the attenuation of the Wi-Fi signals
- The setup process and user experience are no longer bound by the traditional router configuration / usage interfaces. In a mobile-first world where the majority of the consumers prefer their experience to be dumbed down, many of the mesh Wi-Fi vendors have an app-based setup process and monitoring that focuses on basics and disregards advanced features. The ease of use has translated to popularity amongst consumers who are not tech-savvy.
The basic operation models for wireless range extenders and mesh Wi-Fi router units are similar. Some mesh systems such as the Netgear Orbi use a separate channel for the backhaul (communication between the member units). This ensures that there is no airtime wasted when there are active wireless clients.
Mesh Wi-Fi systems can either adopt a 'spokes' model, with a primary router and the satellites talking directly to it, or, a 'real mesh' model where a node can have one or more hops to reach the primary router. The effectiveness of either approach is dependent on the location of the primary router relative to the dead spots in the house, as well as the number of member nodes.
Most mesh Wi-Fi systems currently in the market are based on Qulacomm's Wi-Fi Self-Organizing-Networks (SON) solution. A detailed perusal of the technology makes it evident that it is the brains behind the marketing cloak of mesh Wi-Fi systems from Netgear, Google, Luma and eero.
Readers now have a broad understanding of the various options available to extend the reach of home networks. In the next section, we will take a look at the various kits that were evaluated and the approach under which each of them falls. The evaluation methodology is also spelt out in detail. A couple of sections looking at the performance numbers is followed by some concluding remarks.
Evaluation Methodology and Tested Configurations
The benchmarks processed for this article were aimed at determining the effectiveness of kits in extending the reach of the home networks. Therefore, it was an evaluation of the backhaul, rather than performance with client devices themselves.
The ARRIS RipCurrent product lineup is the most comprehensive suite in the market when it comes to hybrid networking. The following products were used in our evaluation:
- ARRIS SURFboard AC1900 Wi-Fi Router with RipCurrent using G.hn (SBR-AC1900P)
- ARRIS SURFboard AC1200 Wi-Fi Hotspot with RipCurrent using G.hn (SBX-AC1200P)
- ARRIS SURFboard Wired Network Extender with RipCurrent using G.hn (SBX-1000P)
Our review of the Comtrend G.hn powerline networking kit compared the first-generation Marvell G.hn chipset with various HomePlug chipsets from Qualcomm Atheros and Broadcom. The highest-end HomePlug AV2 chipset used in that review was the Qualcomm Atheros QCA7500 in the ZyXEL PLA5405 (AV1200-class). This chipset uses only the 0-65MHz band with MIMO, limiting the performance compared to what the HomePlug AV2 specifications allow. HomePlug contacted us with a suggestion to compare against an AV2 2000-class HomePlug AV2 product. D-Link provided us with the DHP-P701AV passthrough kit for this purpose.
In terms of testing wired backhauls using power lines, a comparison of the ARRIS SURFboard router and wired network extender (SBR-AC1900P + SBX-1000P) and the D-Link DHP-P701AV kit can show the effectiveness of G.hn and HomePlug AV2 for extending network reach.
In addition to the hardware made up of standard building blocks (Wi-Fi radios and router SOCs), Qualcomm Atheros's Wi-Fi SON is also a collection of software features. Different customers implement it differently. QCA told us that, as of Q4 2016, Netgear's Orbi is the best example because they use the whole package, while vendors like Luma, Google and eero all use some of the Wi-Fi SON features. Netgear provided us with the Orbi kit (RBK50-100NAS) to test out some of the features of Wi-Fi SON.
A comparison of the ARRIS SURFboard router and Wi-Fi hotspot (SBR-AC1900P + SBX-AC1200P) and the Netgear Orbi presents readers with data to make a decision between Wi-Fi and PLC as backhaul candidates for extending home network reach.
The evaluation of the backhaul in different cases was carried out in a 1800 sq. ft. single-level detached California residence built in the 1970s. The rough floorplan of the house, along with the testing locations, is presented below.
The kits were configured in an isolated network. In the case of routers (the ARRIS SBR-AC1900P and the Netgear Orbi), the setup was quite straightforward with a NUC with an Intel NIC connected to one of the LAN ports. At the other end, we had another NUC with an Intel NIC connected to the wired port of the Wi-Fi hotspot / wired network extender (n the case of the ARRIS kit) or one of the LAN ports on the satellite (in the case of the Netgear Orbi). Since the routers were set up by default to act as DHCP servers, there was no special configuration needed to get IPs allocated to the NUCs at either endpoint. In the case of the D-Link DHP-P701AV, we configured the NUC connected to the adapter at the master location ('M' in red, in the above picture) to act as a DHCP server.
The location of the other endpoint was varied based on two factors - powerline adapter usage scenarios, and, electrical outlet locations that could be used to address typical Wi-Fi dead spots. Six different locations were tested (A - F in green in the picture above). All major rooms, including the garage, were covered.
The purpose of our benchmarking was not to tune the stream configuration for obtaining maximum possible bandwidth. Rather, we wanted to replay the same stream for multiple adapter sets in order to determine comparative performance. iperf with default parameters was used for benchmarking. On the 'server', we ran the following command:
TCP: iperf -s -B 10.1.1.2
UDP: iperf -s -u -B 10.1.1.2
The 'client' was connected to it using the following command:
TCP: iperf -c 10.1.1.2 -P ${num_parallel_streams} -t 30
UDP: iperf -c 10.1.1.2 -u -b ${curr_bw_to_test}m -t 30
The number of parallel streams were tested between 20 and 25 for the TCP case. The maximum obtained bandwidth was recorded. For the UDP case, we altered the bandwidth to test in order to arrive at the value that resulted in less than 1% packet loss during transmission. The roles of the server and client were then reversed, and the same benchmarks were processed.
PLC Performance: ARRIS SBX-1000P (G.hn) vs. D-Link DHP-P701AV (HomePlug AV2)
The ARRIS SBX-1000P is a wired network extender based on G.hn technology. It is meant to be used in conjunction with a RipCurrent router such as the SBR-AC1900P. The aspect that differentiates the SBR-AC1900P from other AC1900 routers is the integration of a G.hn PLC chipset inside the router itself. Otherwise the design is a standard Broadcom-based AC1900 router (Broadcom BCM4709A as the SoC and the Broadcom BCM4360 for the 3x3:3 an+ac / bgn 5 GHz and 2.4 GHz radios). The G.hn PLC chipset is from Marvell - the 88LX3142 for the digital baseband and the 88LX2718 for the analog front end.
The SBX-1000P is a simple PLC node with a single Ethernet port. It uses the same Marvell platform as the G.hn segment of the SBR-AC1900P. Similar to the Comtrend PG-9172 that we reviewed earlier, it comes with MIMO support and G.hn / HPAV co-existence technology.
The D-Link DHP-P701AV is an AV2 2000-class HomePlug AV2-compliant PLC kit. It uses the Broadcom BCM60500 chipset. It earns the AV2 2000 designation, thanks to its MIMO capabilities and the use of the full possible spectrum allowed by HomePlug AV2 - 2 to 86 MHz.
Note that this kit is meant to be used in conjunction with a regular router. There are products such as the Nighthawk DST in the market that combine the router and PLC chipset in a single unit (like the ARRIS kit we just discussed above). However, the Nighthawk DST uses a cheaper SISO version of the Broadcom chipset that is only AV750-class.
In any case, we are going to compared wired backhaul over power lines using the best possible products that G.hn and HomePlug AV2 currently have in the market. The graphs below shows the TCP and UDP downlink and uplink speeds across the six different locations in our test setup.
In almost all cases (except for a few UDP ones), the HomePlug AV2 2000-class D-Link DHP-P701AV delivers better throughput. This is in contrast to the previous review of the Comtrend PG-9172, where the G.hn kit could hold its own against the AV2 1200 products. The upcoming generation of G.hn chipsets promises better performance - it remains to be seen if that makes G.hn achieve performance parity with HomePlug AV2 in our particular test setup.
Extending Wi-Fi Reach: ARRIS SBX-AC1200P (G.hn) vs. Netgear Orbi (Mesh Wi-Fi)
In the previous section, we looked at the performance of a G.hn device compared to one of the recent HomePlug AV2 products. Both products aimed at extending a wired network. Moving on to products that aim to improve Wi-Fi reach specifically, we again take a look at another G.hn device. For comparison of the performance of a wired power line backhaul against wireless backhaul, we go for a mesh Wi-Fi system with two nodes.
With respect to the PLC segment, the SBX-AC1200P is similar to the SBX-1000P that we saw in the previous section. However, the slightly larger footprint enables the integration of a 2x2 802.11ac/b/g/n simultaneous dual-band chipset. This chipset is again Broadcom-based, similar to the SBR-AC1900P. However, the actual SoC is the BCM47189 which integrates a 2x2:2 802.11ac (5 GHz) radio along with the CPU (ARM Cortex A7) and switch. The 2.4 GHz radio duties are handled by the BCM43217 SoC. With a G.hn node at the router end, the power line can act as a backhaul for the access point present in the SBX-AC1200P. A bit of work at the firmware level in both nodes can ensure that consumers/devices see only one SSID that gains strength in the vicinity of the location of the SBX-AC1200P.
The mesh Wi-Fi system that we will be comparing against is the Netgear Orbi. As mentioned in the introduction, the Netgear Orbi router and satellite kit operates in a hub-and-spoke model. For our evaluation, we only use one router and one satellite. For most households, this configuration is more than enough to blanket the whole house with Wi-Fi coverage compared to the packs of three sold by other vendors.
The reason that the Orbi is able to get away with just one router and one satellite is due to the effectiveness of the backhaul. While most mesh Wi-Fi systems in the market use the same radio for both clients as well as backhaul (a drawback depicted in the first section), Orbi uses a dedicated backhaul radio. In addition, most mesh Wi-Fi systems are currently more concerned with the user experience and external aspects, rather than performance under load with multiple clients. While the Wi-Fi reach aspect is solved to some extent (in a manner similar to range extenders), the usage of a single 2x2 radio severely hampers performance when it is used for the backhaul too. That said, some mesh Wi-Fi systems like eero do have a second 5 GHz radio, but, that is also a 2x2 configuration. Orbi's dedicated backhaul is a 4x4 configuration, and that results in some downright impressive throughput numbers, as we shall see further down in this section.
Netgear has adopted the Qulacomm Atheros IPQ4019 as the primary network processor SoC in the Orbi. This SoC supports Wi-Fi SON, and that handles a lot of the intelligence with respect to setup and ease of use. A detailed evaluation of the features of Wi-Fi SON is beyond the scope of this article, but, readers can easily recognize that most of the features offered by mesh Wi-Fi systems can trace their origin / concept to what is provided by Wi-Fi SON.
Our benchmarks involving these two kits help in comparing the performance of wired power line backhaul and Wi-Fi backhaul with a 4x4 802.11ac connection. The graphs below shows the TCP and UDP downlink and uplink speeds across the six different locations in our test setup.
The Wi-Fi backhaul turns out to be better than the wired G.hn backhaul in every tested scenario. Despite our UDP testing script not playing well with the Wi-Fi link. we find that the powerline backhaul is no match for the 4x4 802.11ac link between the Orbi router and satellite.
At all the tested nodes, the router and the satellite were able to maintain a successful link over the 5 GHz backhaul. Netgear indicated that in extreme cases, the router and satellite could also end up communicating over the 2.4 GHz band. However, we didn't encounter that case in our testing.
The worst case TCP throughput in the Orbi case was slightly more than 600 Mbps. Under impractical 'ideal' conditions (the router and satellite being placed in adjacent rooms and just separated by a drywall), the TCP throughput came out to be close to 800 Mbps. It can also be seen that the link rate doesn't degrade much between locations, since most of them are within the same radius. That is another advantage of the wireless link strategy being adopted by the Wi-Fi mesh vendors. Mileage is bound to vary based on a number of environmental factors such as sources of Wi-Fi interferences, placement of circuit breakers etc. Therefore, it is important to note that our comments on the performance are based on results from the testing done in a Wi-Fi-friendly building structure
Concluding Remarks
In drawing this investigation to a close, we once again wish to reiterate that the best way to extend the reach of a home network is to wire up the house with Cat 6 and have a few judiciously placed enterprise access points. Mesh Wi-Fi systems such as the Netgear Orbi are a more consumer-friendly alternative for the latter part. Wi-Fi devices can easily outnumber wired clients in a typical home network. Therefore, depending on the size of the house, multiple access points may be needed.
Consumers with minimal number of wired clients should just opt for the Netgear Orbi. With 3x3 clients being quite uncommon, the 2x2 client-side configuration of the routers and satellites is not a big deal. The important aspect is the 4x4 backhaul that emerges as the best performer in our evaluation. In our opinion, Netgear's Orbi combines the best of both worlds - interesting mesh Wi-Fi features to address the current hot topic in the Wi-Fi market, along with effective performance and reach for covering large areas and a large number of simultaneously active wireless clients.
The Netgear Orbi kit (one router and one satellite) is currently available for $380.
The benchmarks processed as part of this article gave us a chance to compare the performance of G.hn against AV2 2000-class HomePlug AV2. The D-Link DHP-P701AV managed to outscore the ARRIS SBX-1000P in most locations. However, with AV2 2000, HomePlug is already at the frequency limits as mandated by the specifications (85 MHz). Marvell indicated that they have the second-generation G.hn kits currently under trial with several service providers, and delivering a good jump in performance. However, if one is shopping for the best performing powerline networking kit in the market, we have to recommend AV2 2000-class adapters such as the D-Link DHP-P701AV ($129 for a kit of 2).
Beyond the traditional problem of Wi-Fi dead spots, some consumers also need to support multiple rooms with multiple wired clients. In such cases, a mesh Wi-Fi system doesn't fit the bill. Short of a fully wired network, the best bet is a powerline network with wired extenders in each room with a wired client. Certain nodes can be powerline-backed wireless access points. This market niche is very effectively targeted by the ARRIS SURFboard lineup with RipCurrent (G.hn) technology. The lineup includes multiple routers and a wired network extender (SBX-1000P) as well as a wireless access point backed by a power line backhaul (SBX-AC1200P).
It is likely that standalone range extenders or powerline kits can yield better performance compared to the current ARRIS SURFboard lineup. However, the main selling point is the integration and ease of use of the whole package, with additional extenders being added in a seamless manner to the network. The kit used in this review currently retails on Amazon for $330 (SBR-AC1900P ($180), SBX-1000P ($60), and the SBX-AC1200P ($90)). For the price, it is arguably more versatile in terms of delivering wired nodes to more rooms compared to mesh Wi-Fi systems.
Our investigation of various backhauls for extending home networks have led us to conclude that the mesh Wi-Fi scheme (as implemented by the Netgear Orbi) emerges as the best bet. However, note that this was in a single-level detached California residence (no brick walls or concrete). It is possible that a different scenario could prove detrimental to Wi-Fi signals and make powerline backhauls more efficient. It must also be noted that different consumers have different needs when it comes to extending the reach of home networks. There is no single solution that fits every scenario, and it definitely helps to have different approaches in the market such as the G.hn solution offered by ARRIS.