1 This firmware is only fit for F3v4.0 and its firmware version must be in V03.03.01.XX or more. Note: The hardware version marked at the label of devices as below: 2. Enhancedversion of Asus's router firmware (Asuswrt) (legacy code base) - asuswrt-merlin/ master · RMerl/asuswrt-merlin Vivoy91 ini sendiri adalah ponsel yang masih satu kelas dengan ponsel vivo lainnya seperti vivo v71 misalnya. Oleh karena itu dipostingan ini akan dipandu cara install twrp vivo y91. Ini Spesifikasi Dan Harga Terbaru Vivo Y53 Di 2019 Bukareview Jadi semua hp vivo seperti vivo v17,vivo y19,vivo y20,vivo y20s,vivo v19,vivo v19neo,vivo v9,vivo v20,vivo v20se, Perbedaanantara bandwidth dan kecepatan dapat diringkas dalam satu baris. Apakah 20 MHz lebih baik dari 40MHz? Di daerah ramai dengan banyak gangguan dan gangguan frekuensi, saluran tunggal 20MHz akan lebih stabil. Lebar saluran 40MHz memungkinkan kecepatan yang lebih besar dan kecepatan transfer yang lebih cepat tetapi Vay Tiền Nhanh Ggads. Improving and managing Wi-Fi performance is important to everyone, from home users to large enterprises. Channel width plays a big role in Wi-Fi performance. Selecting the right Wi-Fi channel widths can have a huge impact. Getting it right isn’t always straightforward, though. With multiple standards and a variety of tradeoffs, it can be hard to keep up with best wireless environment is different and you need to tailor your equipment to the conditions. With GHz, increasing your channel width often isn’t worth it, and you should stick with 20 MHz. Conversely, with 5 GHz, increasing channel width can improve performance, but there are tradeoffs. With 5 GHz, if you don’t have to worry about interference and all your client devices support it, go with the highest width course, there are plenty of “gotchas” and the rules of thumb above won’t always be best for you. Like most things in tech, the right answer to this question depends on context. Let’s explore the “why” behind these generalisations to help you gain a better understanding of the Wi-Fi BandsUnderstanding Wi-Fi bands is vital to understanding when to use 20 MHz versus 40 MHz versus 80 MHz channel widths. It’s also an important prerequisite to understanding WiFi channels and channel two main Wi-Fi bands are GHz and 5 GHz. These Wi-Fi bands are then split into channels for wireless devices to communicate GHz Wi-Fi BandThe GHz band covers a 100 MHz range of 2400 MHz to 2500 MHz equivalent to GHz to GHz. The GHz band is split into 14 discrete channels that are 20 MHz each more on other channel sizes in a bit.Note in the image above that there are 14 channels in the GHz band. Note that channels 1, 6, 11, and 14 do not you do a quick calculation, you’ll quickly see that 14 bands of 20 MHz equals 180 Mhz. This is greater than the 100 MHz size of the GHz band, which means that channels is important to understand because overlapping Wi-Fi channels can interfere with one another. With GHz Wi-Fi, there are four non-overlapping 20 MHz channels 1, 6, 11, and 14. Note that due to varying regulations, not all channels are available for use in all locations. For example, only 13 channels are available in Australia so we only have three non-overlapping GHz Wi-Fi BandThe 5 GHz Wi-Fi band up to Wi-Fi 6 covers a 150 MHz range from GHz to GHz. Wi-Fi 6E extends that band. However, an additional range of Unlicensed National Information Infrastructure UNII bands widens that range to 750 MHz. Using 20 MHz, there are 24 non-overlapping channels available within the 5 GHz band. Note that this is a generalisation and available channels vary depending on location and channel GHz vs 5 GHz Popularity, interference, throughput, and GHz is more popular than 5 GHz since many of the cheaper routers or industrial routers only support GHz, but both are widely used. GHz is cheaper to implement than its 5 GHz counterpart, so manufacturers leverage it to save costs. GHz has also been widely used for a longer period of time, so more GHz devices have been popularity does have a downside, though. The prevalence of GHz devices and limited number of non-overlapping channels with GHz can exacerbate network congestion consumer devices, such as cordless phones and microwaves, use GHz frequency bands. As a result, GHz bands are more likely to experience interference. The relative abundance of non-overlapping channels on 5 GHz Wi-Fi makes it less susceptible to GHz vs 5 GHz Which to Use?In most cases you should use GHz to optimize for distance and 5 GHz to optimize for speed. However, there is a tradeoff between increased performance and range of GHz is faster. 5 GHz Wi-Fi offers faster uploads and downloads than GHz. Additionally, 5 GHz benefits from more non-overlapping channels and less interference which can boost performance advantages. However, 5 GHz isn’t as good at going through instance, you should use 5 GHz when for bandwidth hungry use cases like online gaming when a wired connection isn’t possible or high-definition video streaming. But keep your gaming console close to the GHz goes further. The lower frequency of GHz is better at passing through solid objects and can cover a wider range than 5 GHz. For a comparison across different Wi-Fi standards, here’s a breakdown of different GHz vs 5 GHz speeds and instance, you should use GHz if your Wi-Fi clients and router/access point might be separated by multiple rooms. GHz will do a better job of penetrating walls and objects between your Wi-Fi can use both. It’s also worth keeping in mind that simultaneous dual band routers can broadcast GHz and 5 GHz at the same time. This allows you to use GHz for some devices and 5 GHz for others and can provide more flexibility. Additionally, if the GHz and 5 GHz networks use the same SSID service set identifier Wi-Fi network name, wireless devices can automatically connect to their preferred bandwidth. In short simultaneous dual band routers and modern smart devices can automatically do a lot of the work for is Wi-Fi Channel Width?When you’re making a decision among 20 MHz vs 40 MHz vs 80 MHz vs 160 MHz what you’re doing is picking a channel got an introduction to Wi-Fi channels above. We saw that the GHz Wi-Fi band is chopped up into smaller 20 MHz bands for use. These smaller bands are the channels that Wi-Fi devices communicate on. The channel width is simply the frequency range for the MHz and 40 MHz What’s the Difference?When dealing with Wi-Fi, channel widths are usually measured in megahertz MHz. 20 MHz was the norm and only option for channel width in and Wi-Fi more on the standards below. The standard introduced channel bonding, which enabled 40 MHz widths. further extended bonding to allow for 80 MHz and 160 MHz channels increases throughput, which can improve performance. Thus, the difference between 20 MHz and 40 MHz is throughput. 40 MHz has higher throughput than 20 MHz thanks to channel are downsides to channel bonding. While 40 Mhz might have higher throughput than 20 Mhz, it also reduces the number of non-overlapping channels. This increases the probability for interference. Additionally, not all Wi-Fi client devices support channels other than 20 MHz so compatibility can be a note on marketing lingo and tech talk 20 MHz Wi-Fi channels are generally referred to as “narrow channels” or “narrow widths”. 40, 80, and 160 MHz Wi-Fi channels are labeled “wide channels” or “wide widths”Understanding IEEE StandardsIf you are exploring router specs, studying for a Network+, or trying to determine Wi-Fi compatibility, has likely come up. IEEE develops the Wi-Fi standards, and these standards dictate what speeds and frequencies are is a quick rundown on the well-known IEEE standards was an early 5 GHz 54 Mbps Wi-Fi was a popular early GHz 11 Mbps version of increased GHz Wi-Fi speeds up to 54 “Wi-Fi 4″supports both GHz and 5 GHz Wi-Fi at speeds up to 450 “Wi-Fi 5” supports 5 GHz only and speeds of up to 1300 “Wi-Fi 6” is slated for final approvals in September and November of 2020. However, there is already Wi-Fi 6 technology on the market. V Even in 2019, vendors were releasing products based on earlier drafts. supports both GHz and 5 GHz and has a maximum speed of up to 10 and tend to be the most popular standards available today. You can expect to grow in popularity over the next few is important to note that maximum theoretical speeds are NOT the same as real-world speeds. In other words With any given Wi-Fi version, you can expect slower actual speeds than the max speeds listed about 6 GHz and Wi-Fi 6E?In April of 2020, the FCC announced they will open up the 6 GHz band for Wi-Fi and other unlicensed use. The additional 1,200 MHz is the biggest addition of usable spectrum in decades. Wi-Fi 6 devices capable of using the 6 GHz bands will be known as “Wi-Fi 6E”. The “E” signifies the extension into the 6GHz 6E devices aren’t readily available today, but you can expect to see them on the market in late 2020 and early short Wi-Fi 6E will enable some big improvements, but it’ll be some time before it becomes the Dual Band Wi-Fi?Dual band refers to Wi-Fi routers that support both GHz and 5 GHz bands. Using a dual band router allows you to get the “best of both worlds”. Higher speeds and lower interference for 5 GHz devices, and wider range for GHz devices. It is very common for modern Wi-Fi routers to support dual band Ghz WiFi 20 MHz vs 40 MHz vs 80 MHzIf you’re using GHz, the answer is simple. The best bandwidth for Ghz is 20 the majority of cases, using wide widths on GHz isn’t performance tradeoffs from interference on overlapping channels will likely outweigh the throughput benefits. One possible exception to this rule is remote areas where there are not many other Wi-Fi networks or GHz Wi-Fi and 20 MHz channel widths offers the broadest range of client device support. If you need to support legacy devices and Wi-Fi standards like or you’ll need GHz and 20 Ghz Wi-Fi 20 MHz vs 40 MHz vs 80 MHzWith 5 GHZ, things get a bit less straightforward. There are valid use cases for multiple different Wi-Fi channel widths. The best bandwidth for 5 Ghz is 40 MHz. However, there are other considerations as Ghz Wi-Fi When to Use 20 MHzIf you have a 5 GHz router, consider using 20 MHz for maximizing the amount of non-overlapping channels. Regardless of using GHz or 5 GHz, 20 MHz leaves you with the largest amount of non-overlapping channels. 20 MHz makes sense for high-density deployments and areas where interference is a major Ghz Wi-Fi When to Use 40 MHzUse 40 MHz to strike a balance between minimizing interference and maximizing MHz offers more throughput than 20 MHz. It still leaves room for a dozen or so non-overlapping channels. This enables you to improve performance relative to 20 MHz, and without risking the interference associated with 80 Ghz Wi-Fi When to Use 80 MHzIf Wi-Fi clients are close to your router, your Wi-Fi devices support 80 MHz, interference isn’t a big issue, and you want to maximize throughput, consider 80 all your devices support it, and overlapping channels is not an issue, 80 MHz channels leave you with four or five non-overlapping channels. This increases the likelihood for interference. Additionally, clients often need to be very close < 15 feet to the Wi-Fi radio to get the most out of 80 are two common use cases for 80 MHz mesh backhaul and bridging. However, any application where distances are minimal and there isn’t too much congestion can make sense for 80 the takeaway here is that you must strike a balance between compatibility, throughput, and interference. While it seems intuitive that the right answer is always “up the width if you can”, it just isn’t that from overlapping channels can wreak havoc on network speeds, so you must account for it. This is particularly important in cities, industrial areas, and large businesses where high levels of wireless traffic are to Use 160 MHzAt this point, the use cases for 160 MHz are limited. However, as Wi-Fi 6 grows in popularity, we can expect to see use of 160 MHz widths grow as well. With 160 MHz, there is only one available non-overlapping channel, so there will be interference tradeoffs to consider with 160 course, the 6GHz band and Wi-Fi 6E will change this narrative in the near future. The additional spectrum in the 6 GHz band will allow for 14 more 80 MHz channels or 7 more 160 MHz to Automate Wi-Fi Channel and Width SelectionAs you can see, there’s quite a bit to selecting Wi-FI channel and width selection. However, there are ways to automate the example, some Wi-Fi routers enable automatic detection and use of a channel size based on network conditions. This is usually achieved by selecting “Auto 20/40” or similar option as your channel width. Similarly, with most routers and devices, channel selection can be negotiated automatically. If you’re not experiencing issues, and aren’t looking to optimize performance, sticking with these settings makes Can I Check for Wi-Fi Interference?If you are looking to optimise performance, a Wi-Fi network analyzer may help. Wireless network analyzers can help you identify interference on different channels and select the least noisy option. Alternatively, manually switching between channels and observing performance is a less scientific the Right Wi-Fi ChannelWhen it comes to selecting the right Wi-Fi channel width, every situation is different. By understanding the fundamentals, you can more effectively select a configuration that works best for you. While there is no one-size-fits all answer to the “20 MHz, 40 MHz, or 80 MHz?” question. However, understanding GHz vs 5 GHz frequencies and the tradeoffs between non-overlapping channels and speed goes a long us for your wireless networking needs. ICS Technologies is located in Brisbane, Australia with subcontractors across the country. Doubling the channel width slightly more than doubles the speeds of the PHY rates you can get. With 20MHz-wide channels on you can only get the or top PHY rates for 1-, 2-, and 3 spatial streams, respectively. Going to 40MHz-wide channels makes it 150, 300, and 450 Mbps, respectively. Of course this also cuts your available channels in half, so some enterprise Wi-Fi deployments choose to keep the narrow channels in order to crowd in more APs. 40- and 80- MHz-wide channels are fine in the spacious 5GHz band. But 40MHz-wide channels can cause problems in the relatively narrow band, where 40MHz wide channels take up half the band and don't leave enough room for Bluetooth and other technologies to work well. A largura de banda de 40 MHz permite uma maior transmissĂŁo de dados comparado com os 20 MHz, sĂł que alguns dispositivos podem nĂŁo conseguir conectar ao roteador de rede wi-fi e atĂ© pode ficar com uma rede wireless invisĂ­vel, caso opte pelos 40Mhz. Qual largura do canal usar no roteador? A largura do canal do roteador, ou a bandwidth, como tambĂ©m Ă© conhecida, pode ser de 20 MHz ou 40 MHz. A configuração depende de algumas especificaçÔes e dos dispositivos conectados, e pode ajudar a melhorar o desempenho e a velocidade do Wi-Fi. Qual o melhor canal para roteador wireless? Os melhores e principais canais disponĂ­veis sĂŁo o 01, 06 e 11 que nĂŁo sĂŁo sobrepostos por nenhum outro. Se na sua regiĂŁo algum desses trĂȘs estiver disponĂ­vel, use-o. Se nĂŁo for possĂ­vel, escolha algum outro canal que nĂŁo tenha outras redes sem fio ou nĂŁo tenha tantas redes quanto os outros canais. Qual a melhor largura de canal para Wi-fi? De modo geral, o mais indicado Ă© que – numa frequĂȘncia de 2,4 GHz, o bandwidth esteja em 20 MHz. E isso porque uma largura de 40 MHz pode causar transferĂȘncias, comprometendo o sinal da rede e fazendo com que a transmissĂŁo de dados fique muito fraca. Qual Canal do roteador vai mais longe? Geralmente, novos roteadores permitem que vocĂȘ escolha a frequĂȘncia da rede 2,4 GHz ou 5 GHz. A frequĂȘncia 2,4 GHz transfere dados mais lentamente, mas atinge maiores distĂąncias e atravessa melhor as paredes, enquanto a 5GHz Ă© indicada quando hĂĄ muitos aparelhos ligados Ă  mesma rede e vocĂȘ precisa de estabilidade. Como aumentar o alcance do sinal do roteador? 8 dicas para melhorar o sinal Wi-Fi da sua casa Mantenha seus aparelhos atualizados. 
 Escolha um local adequado para o seu roteador. 
 Proteja sua rede de ladrĂ”es de sinal. 
 Altere o canal de conexĂŁo. 
 Instale um repetidor para aumentar o alcance do sinal. 
 Fique atento aos aplicativos que sequestram sua banda. 
 Reinicie seu roteador com frequĂȘncia. Qual melhor modo de rede? Evite interferĂȘncias de sinal Uma dica importante para ampliar o sinal Ă© posicionar o roteador longe de geradores de interferĂȘncia. 
 AtĂ© mesmo micro-ondas sĂŁo capazes de interferir na rede, e quanto mais longe o roteador estiver desses aparelhos, melhor serĂĄ o sinal. Como deve ficar a antena do roteador? Normalmente, o melhor jeito de posicionar a antena externa Ă© deixando-a reta para cima, o que farĂĄ com que o sinal se espalhe de forma horizontal. Mas se o objetivo Ă© fazer com que o Wi-Fi chegue em diferentes andares, o ideal Ă© deixar a antena deitada – assim, as ondas serĂŁo disseminadas verticalmente. O que pode atrapalhar o sinal do roteador? Certos aparelhos e objetos podem atrapalhar significativamente o desempenho dos roteadores. “AquĂĄrios, espelhos, telas LCD, telefones sem fio, equipamentos que emitem sinais de rĂĄdio, estruturas metĂĄlicas e paredes muito espessas podem causar interferĂȘncias e prejudicar a instabilidade do sinal“, aponta. O que pode interferir no sinal do roteador? Telefones sem fio, fornos microondas, babĂĄs eletrĂŽnicas, brinquedo de controle remoto e outros dispositivos que funcionem sem fio podem atrapalhar o sinal do Wi-Fi quando utilizados ao mesmo tempo e prĂłximos ao modem. O que pode interferir no Wi-fi? Podem ser alto-falantes sem fio, monitores de bebĂȘs, controles de portas de garagem, etc. Alguns outros dispositivos sem fio que operam no espectro de 2,4 GHz ou 5 GHz, incluindo transmissores de micro-ondas e cĂąmeras sem fio, tambĂ©m podem contribuir para a interferĂȘncia na rede sem fio. Como reduzir a interferĂȘncia do Wi-fi? Como reduzir a interferĂȘncia sem fio Aproxime o dispositivo Wi-Fi do roteador Wi-Fi. 
 Evite usar os dispositivos sem fio prĂłximos a fontes comuns de interferĂȘncia, como cabos de alimentação, fornos de micro-ondas, lĂąmpadas fluorescentes, cĂąmeras de vĂ­deo sem fio e telefones sem fio. O que fazer se sua internet estiver ruim? Como lidar com uma conexĂŁo lenta Ă  Internet em 10 passos Sinal da operadora. 
 Verifique falhas no hardware. 
 Posicione bem seu roteador/modem. 
 Cuidado com repetidores. 
 Roteadores mesh. 
 Use um canal de transmissĂŁo liberado. 
 Verifique quantos aparelhos estĂŁo conectados. 
 Experimente um servidor DNS diferente. O que pode diminuir a velocidade da internet? 7 fatores que podem estar prejudicando a velocidade da internet Equipamentos antigos e obsoletos. Algo que pode diminuir a velocidade da internet, assim como a capacidade de segurança, sĂŁo os equipamentos ultrapassados. 
 Tecnologias sem qualidade. 
 Problemas de software. 
 Malware, spyware e vĂ­rus. 
 Recursos do computador. 
 Alcance do Wi-Fi. 
 Uso comum do sinal. Porque roteador diminui a velocidade da internet? Roteador mal posicionado Isso acontece porque o sinal Wi-Fi Ă© uma onda de rĂĄdio que sofre mudanças em sua intensidade conforme a distĂąncia entre o roteador emissor e os dispositivos conectados a ele receptores. Quanto mais distante, menor a intensidade de banda emitida, ou seja, menor a velocidade disponĂ­vel. Como saber se a internet foi reduzida? O site SpeedTest oferece gratuitamente a medição online da velocidade da sua conexĂŁo para download e tambĂ©m para upload. Basta entrar no site e clicar no botĂŁo “Já” e o teste se inicia automaticamente, trazendo os resultados em apenas alguns segundos. Como aumentar a velocidade da internet a cabo? Cinco dicas para aproveitar a mĂĄxima velocidade da sua Internet Troque seu servidor DNS. Mude o canal do seu roteador. Utilize a banda correta no roteador. Compre um roteador mais moderno. Utilize um cabo Ethernet. Como se chama o aparelho que distribui internet? O modem Ă© responsĂĄvel por decodificar a internet que chega do provedor para a sua casa, enquanto o roteador Ă© responsĂĄvel por distribuir a internet para dois ou mais dispositivos. Mas, as diferenças nĂŁo param por aĂ­! Abaixo, vocĂȘ pode conferir o que fazem e quais as principais diferenças entre o modem e o roteador! O que Ă© um dispositivo PLC? Ele transmite dados em banda larga utilizando cabo Ethernet, que se conecta ao roteador. Como mencionado anteriormente, o nome vem de Power Line Communication PLC, que significa “comunicação via rede elĂ©trica”, em tradução livre. O que Ă© repetidor de sinal de internet? Gente, o repetidor de sinal Wi-Fi Ă© um aparelhinho que aumenta o alcance da internet sem fio em casa ou no escritĂłrio. 
 Quando usar pra começar, vocĂȘ sabe que tĂĄ precisando de um repetidor de sinal Wi-Fi se a internet geralmente fica fraquinha nos cĂŽmodos mais distantes de onde o roteador fica. O que Ă© roteador Wi-fi no celular? Muitos dispositivos com Android dĂŁo nomes diferentes para essa função. Alguns chamam de “Roteador Wi–Fi”, outros chamam de “Hotspot Wi–Fi”, “Ponto de acesso mĂłvel” e vocĂȘ pode atĂ© encontrar o nome “ancoragem” ou “roteamento” perto de algum desses tĂ­tulos. NĂŁo se confunda o princĂ­pio Ă© exatamente o mesmo. Para que serve um roteador em um celular? Qualquer smartphone com planos de dados pode se transformar em um roteador e compartilhar Wi-Fi para outros dispositivos, como tablets, computadores e celulares. Dessa forma, se a sua internet ou de algum amigo acabar, Ă© possĂ­vel fazer o compartilhamento. Como Ă© possĂ­vel configurar um link sem fio sem saber muito sobre os vĂĄrios parĂąmetros avançados que um deve permitir, muitos usuĂĄrios enfrentam problemas quando os links ficam submetidos a interferĂȘncia. Uma das perguntas que recebo Ă© muito, o que obviamente Ă© uma conseqĂŒĂȘncia direta do pouco conhecimento que a maioria dos usuĂĄrios do espectro de freqĂŒĂȘncia de 5GHz tem, qual largura de canal Ă© melhor usar? Tendo em mente que ser um bom engenheiro de rede nĂŁo faz necessariamente um bom engenheiro sem fio, tentarei explicar o uso das larguras de canal de 20MHz ,40MHz e 80MHz . Curso Completo Mikrotik Largura do canal 20MHz A largura do canal de 20MHz nos rĂĄdios Mikrotik 5GHz estabelece ponto a ponto ou aponta para conexĂ”es multiponto em um espectro mais estreito. O que isto significa Ă© que, na largura do canal de 20MHz, vocĂȘ terĂĄ um sinal muito melhor, menos interferĂȘncia, mas com menor throughput. Devido a isso, a velocidade do link serĂĄ mais lenta em comparação com um link de 40MHz, sendo todas as coisas o espectro Ă© estreito, as chances de o rĂĄdio da estação pegar outros SSIDs na mesma freqĂŒĂȘncia serĂŁo menores. O sinal do AP Ă© capaz de ir longe e Ă© captado com melhor qualidade de conexĂŁo do cliente CCQ pelo s rĂĄdio s da estação. No entanto, a velocidade Ă© reduzida por causa do espectro estreito. A largura do canal de 20MHz Ă© recomendada para conexĂ”es de longa distĂąncia . Largura do canal de 40MHz A largura do canal turbo de 40MHz ou 40MHz, transmite em amplo espectro de frequĂȘncia, dando espaço para velocidade, mas com uma grande possibilidade de flutuaçÔes de sinal causadas por interferĂȘncia. Com o espectro de 40MHz cobrindo um espectro mais amplo, o sinal transmitido pelo AP cobre menos distĂąncias, enquanto a estação, tambĂ©m em 40MHz, pega os SSIDs na mesma freqĂŒĂȘncia que o AP ao qual estĂĄ conectado. Isso resulta em interferĂȘncia de sinal. A largura do canal de 40MHz Ă© adequada para links implantados em distĂąncias curtas com alta demanda de largura de conclusĂŁo, use a largura do canal de 40MHz para links que cubram a curta distĂąncia com alta demanda de largura de banda, enquanto a largura dos canais de 20MHz deve ser usada para links sem fio de maior distĂąncia. Curso Consultor Projetista de Redes Ópticas Observe que a largura do canal configurada no AP tambĂ©m deve ser configurada na estação para que o link seja estabelecido. Largura do canal de 80MHz A largura do canal de 80MHz nos rĂĄdios Mikrotik , estĂĄ disponĂ­vel apartir do protocolo e oferece um canal ainda mais amplo e, como tal, maior largura de banda. No entanto, isso torna ainda mais suscetĂ­vel a interferĂȘncia co-canal . Desta forma, os canais de 80 MHz sĂŁo melhor utilizados com base no melhor esforço, mas somente quando o alcance total do canal Ă© claro. Se vocĂȘ tiver alguma dĂșvida sobre qual Largura de Banda do Canal vocĂȘ deve usar em sua rede, por favor, comente abaixo.

perbedaan bandwidth 20mhz dan 40mhz