Connected world: a changing wireless paradigm
Inherently we the humans always want to get connected by phone, email, social media, Television, radio with the rest of the world. Things are changing fast now it’s about connected devices, appliances, automobiles, transport systems and even the plants. Anything can be connected will be connected. Anything can have a chipset will have a chipset.
When we talk about the connectivity, wireless comes to our minds.
In wireless land scape there are several technologies having different set of advantages and disadvantages. Broadly the wireless technologies divided into WAN, MAN, LAN, PAN. We have a distance Vs throughput with application comparison chart located below.
Traditionally 3GPP standard based technologies dominate in the WAN and MAN technology landscape. In MAN segment, WiMAX is used to some extent, which is an IEEE standard (IEEE802.16 *) based technology. It did not get traction world-wide. In the wireless LAN and PAN segment IEEE standards based technologies are very common. Bluetooth which started from Ericsson initially was accepted by IEEE and incorporated IEEE802.15.4 features. Zigbee is very popular in sensor networks, connected homes and smartgrid home area network segment. It is built on IEEE802.15.4.
We are all familiar to home wireless network, popularly known as Wi-Fi. There are several IEEE standards approved by Wi-Fi alliance. It started in late 1990s with IEEE802.11. 802.11 has two PHY layers one is DSSS (Direct Sequence Spread Spectrum) and FHSS (Frequency Hopping Spread Spectrum). Both provided maximum throughput of 2 Mbps. Due to inherent advantages such as multiple channel reuse capability, DSSS gained momentum and FHSS slowly died. In early 2000 DHSS 802.11b became standard and it supported 11 Mbps, 5Mbps, 2 Mbps and 1 Mbps.
Human need for speed (throughput and bandwidth) did not stop there. IEEE published 802.11 g standard in 2005. This supported maximum throughput of 54 Mbps, 22 Mbps, 11 Mbps, and all other bandwidth supported by 802.11b. 802.11g was fully compatible with 802.11b. This means all existing Wi-Fi devices (clients) would work perfectly with 802.11g Access Points (APs). 802.11 g is OFDM (Orthogonal Frequency Division Multiplexing) modulation scheme. Although another competing technology PBCC (Packet Binary Convolution Coding) led by TI (Texas Instruments) tried their best to make it 802.11g standard, it did not succeed. Finally OFDM PHY layer won the battle and became 802.11g standard. Manufacturers started selling 802.11g products under Wi-Fi certified product by year 2006. Interestingly year 2007 onwards mobile phones were shipped with Wi-Fi chipset. One of the reasons was accessing corporate mails with Blackberry “smart phones”, secondly T-Mobile USA launched UMA (Unlicensed Mobile Access) service where the users can make a call on T-Mobile hotspot locations nation-wide or they can make a call from any Wi-Fi network as long as they know the password for the network. (T-Mobile hotspot does not need password for UMA calls, it authenticates based on MSISDN (actual mobile phone number).
IEEE 802.11a standard was ratified in 1999 and operates on 5 GHz UNII band. It uses OFDM modulation and provided maximum throughput upto 54 Mbps. Although 5GHz band is much less interfered than 2.4 GHz, due to lack of devices it was not popular like 802.11 b/g until recently. All the smart phones and majority of the feature phones come with Wi-Fi chipset which is 802.11b/g.
As usual we always crave for more and more throughput, less latency and less jitter we needed wireless fat pipes. IEEE 802.11 n draft standard was released around mid2007 and vendors started shipping devices with n draft standard. By End of 2008, 802.11n became a full standard. 802.11 n has capability of aggregating two contiguous channels of 20 MHz and capable of MIMO (Multiple Input Multiple Output). Maximum theoretical throughput is upto 300 Mbps. 802.11n can operate in 2.4 GHz ISM band or 5 HGz UNII band. It is also OFDM based technology and completely back ward compatible. If it’s with 5GHz radio then it is backward compatible to 802.11a. If its 2.4 GHz radio it will be backward compatible to 802.11 g/b. Right now majority of the Wi-Fi Access Points available in the market are 802.11n. It may have dual band radio which is actually two radios placed in the same device to communicate with 2.4 GHz devices as well as 5GHz devices.
As IEEE standards evolved within last decade, 3GPP (Third Generation Partnership Project), which started from ETSI (European Telecommunication Standards Institute) based technologies also evolved from GSM to GPRS to WCDMA to LTE. The next step is LTE advanced. 3GPP release 8 incorporates HNBs (Home node B) popularly known as “Femto cell”. LTE Advanced would provide up to 1 Gbps bandwidth over 100 MHz bandwidth. It can work over 8 x 8 MIMO. All the mobile phones will come with a LTE advanced radio. We see from the market trend for computers and tablets, some of them come with LTE (or WiMAX) radio along with WiFi radios. We may wonder, going forward in five years, if the computers and tablets coming with LTE chip inside, and LTE has a coverage either from macro network or Femto Access Point at home, why someone would buy a WiFi chipset in a tablet, computer or even in a phone. There will be one less radio chip inside the phone, which can reduce the complexity of the device. Probably LTE home access points would be sold in stores for everyone to buy and use as a home Access Point like WiFi. Well, the threat is real. There is a fair chance that it may happen. That triggers IEEE to work really hard to push new standards which would keep LTE out of Home networking segment. As always all IEEE future standards would be backward compatible so that the user does not have to replace any existing device and can migrate to newer high throughput devices smoothly.
IEEE is aggressively working to come up with 802.11ac standard. This would operate upto 160 MHz of contiguous bandwidth and can support 8×8 MIMO. It will operate in 5GHz band. 802.11ac has multi user MIMO capabilities therefore these radios can support 1 Gbps multi station throughput. And 500 Mbps single station throughput.
Simultaneously IEEE is also working on 802.11ad standard. 802.11ad would operate on 60 GHz along with 2.4 GHz and 5 GHz. This can support 10*10 MIMO provide up to 7 Gbps. Although distance of operation would be less than 15 feet, it can be used for uncompressed video. We can visualize, we don’t have to connect TV with Cable set top boxes or with Blue Ray Disc player. Open the box, connect to power, push a disc and watch on the TV, no wires no clutter in the living room. 802.11 ad certification would be done under Wi-Gig alliance, sister concern of Wi-Fi alliance.
Future of wireless is really interesting, stay tuned! Since so many radios working inside one small smart phone, the battery utilization increasing tremendously. Next time we will discuss about the battery life of mobile devices.