A Practical Performance Comparison Between 802.11n and 802.11ac Standards

Abstract

It is well known that the technological performance level of wireless communications in open frequency bands has increased considerably in the last years. Today, many devices that we use is based on wireless communications. This article aims to achieve a practical comparison between 802.11n and 802.11ac performance standards. Practical determinations were made through performance measurements in a wireless communications infrastructure, built by interconnecting pairs of wireless access point equipment, located in close proximity, to ensure maximum performance. The performances of IEEE 802.11ac and 802.11n standards were studied using the traffic measurement method, observing the necessary bandwidth and the response time for different sizes of data packets generated in the testbed communication infrastructure. An important aspect that was taken into consideration refers to the constant monitoring of resources load used for communication processes (CPU load from routers used in test process), to ensure that determinations were not compromised by hardware limitations of the equipment used.

Keywords: 80211n80211acwireless standardsperformance measurementsmonitoring resources

1.Introduction

The IEEE 802.11ac is nowadays the most advanced standard for data transmission over a wireless

environment. This communication standard can be briefly characterized by the following significant features:

• providing high-throughput communications, reaching Gbit/s speed level;

• proposing the migration to a cleaner 5GHz spectrum;

offering the opportunity for the implementations having mixed frequency bands for data

transmission, in the 2.4 GHz and 5GHz;

supports more performant MIMO (Multi-User Multiple-Input Multiple-Output) mode for

transmission antennas, that can be used to send information simultaneously to multiple clients, up

to four simultaneous MU-MIMO (Multi-User Multiple-Input Multiple-Output) downlink clients;

superior Modulation and Coding Schemes (MCS) with high signal modulations as QAM -

Quadrature amplitude modulation (QAM 256);

space multiplexing thought SDMA (Space Division Multiple Access), up to eight spatial streams

(compared with for in 802.11n MIMO);

commonly, the 802.11ac standard has 10 MCS (Andrew von Nagy, 2013).

Wireless technologies are widely implemented in the most diverse devices (IEEE, 2016). Wireless

chips are currently encountered on tablets, smartphones, TVs, game consoles, printers and the list could

continue. In parallel, to support the equipment growth, multiple wireless networks must be deployed in

various places, which include institutions, schools, shopping malls, universities and others. Wireless

hotspots with Internet access are also commonly installed in public areas, where any user can connect and

access resources it needs (Ong et al., 2011).

Lately, with the passing years, it is found that one of the trends of communications market

development is represented by the IT services migration into the cloud, to ease the use of resources. In the

early era of data communications, the first services were not very specific requirements on parameters, but

in our time, there are some services that require certain parameters to be within certain limits (delay, jitter,

packet loss) to function properly. In this sense, we can exemplify with the streaming video services, which

are very popular today (Park, 2011).

2.Purpose of the Study

The Wi-Fi standards have evolved over time, aiming to surmount the 802.3 Ethernet standard

performances, by providing the necessary resources and support to the current communication services.

(Punal, Escudero, & Gross, 2011; Cha et al., 2012; Bellalta et al.,2012).

This article is proposing a performance appraisal of IEEE 802.11ac, having the previous standard,

802.11n, as a reference (Dianu, Riihijarvi, & Petrova, 2014). Performance measurements regarding traffic

speeds, available bandwidth, volume of date packets sent or lost over data links having various physical

medium characteristics, such as frequency and channel bandwidth are presented in the following sections.

2.2.Generic Testbed

The first idea of this practical evaluation is to test the maximum transport capacity of the wireless

testbed system. For obtaining a ground reference, in the initial phase, an Ethernet cable was used between

laptops. The maximum transport capacity obtained was 720Mbit/s.

For a synthetic overview, in Figure 1 is presented a representative image of the evaluation

infrastructure used for practical determinations.

To generate packets between the two test laptops there was used the iperf utility (Tirumala, Qin,

Dugan, Ferguson, & Gibbs, 2016) a common Linux connections testing application, with five parallel

sessions.

The command used for starting the iperf server:

#iperf -s -i 1

For the client mode was used in the following form:

#iperf –c server_ip –i 1 –P 5 –t 60

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The second idea of the evaluation method is to determine the transport capacity, taking into

consideration the maximum number of packages that can be transported by the wireless link. For this

matter, another Linux utility was used the well-known ping tool. With this utility, the response time from

source to destination can determine and the packet loss where there are any. Considering that this model

of router has a MIPS processor at a frequency of 600 MHz, a special attention was focused on monitoring

resources (the processor load level), to ensure the no hardware limitations will affect the testing process.

In the following determination, there will be notices about the router’s processor load during the tests.

In conducted experiments, 802.11ac showed better results in terms of data traffic values, as

expected. What is important is to notice the reached performance level and the differences in other

standards. The general results are presented in Table 1 .

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As it could be observed, in terms of response time and packet loss we can pull some conclusions.

During the tests, there was obtained satisfactory results for the minimum package size (64 bytes). Our

practical determinations were stopped at the 10,000 PPS (packets per second) level, where the response

time parameter was presenting a good value (1-2 ms) and there were no losses.

The next sets of tests were made at the maximum level of package size parameter that can be

enforced with the ping utility (65,508 bytes). The results showed that the 802.11n in 20 MHz band did not

achieve satisfactory results, and were not included in those presented in this paper, as can be identified in

following tables (Tables 2 - 8 ) and graphically interpreted in Figures 3 - 6 :

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3.Results Interpretation

The general results from Table 1 can be graphically represented as in Figure 2 . It can be seen that the CPU load is increasing according to the growth of used bandwidth.

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4.Conclusions

In this paper, there are presented the results from an analysis study over the communication

performances provided by the IEEE 802.11ac standard. Although IEEE 802.11ac is an evolved wireless

standard, regarding IEEE 802.11a, as shown by the practical determinations from this paper, there are

considerable performance differences to pull through in the future implementations regarding the Ethernet

standard, which is being still the preferable solution for reliable data communications.

Given the order of the WiFi standards development, it is in the offing that the results to be better

for newer standards. Experiments showed in this article are made under real conditions and have shown

important practical differences between the widely and common used wireless standards, that can be taken

into consideration at the projecting and deployment of new wireless network infrastructures.

The article can be viewed as a basis for future similar comparative measurements when new waves

and generation of wireless standards will be available (802.11ax, 802.11ad, LiFi and others

communication standards that will be developed).

References

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