Are There Limits On Data Transfer Through Wireless?

Theoritically channel capacity depends on various factors , mainly on bandwidth of the channel , signal to noise ratio. I cant recollect all the information, in practical scenarios nature of medium of transmission, fading effects such as (slow & fast fading effects), extent of noisy medium also determine the maxmimum limit of the channel.
Many attempts are currently under progress to improve the system, such as using multiple input and output antennas to increase the quality by creating redundant streams to increase the same channel capacity.

As always been mentioned, Shannon's laws describe the channel capapcity, where as Alomouti laws define the MIMO/SIMO nature of trasnmitters.

WIFI technology supports two types, one is called “infrastructure” other one is “Ad hoc” In ad hoc Wi-Fi network can be connected without central device known as router or access point Ad hoc mode is always preferred over infrastructure mode, however ad hoc networks have following issues Wi-Fi devices configure on Ad hoc mode offers nominal security against network intruders. Ad hock WiFi configured devices cannot disable SSID broadcast in contrast to infrastructure mode. Network attackers will not required much of effort to prevail in Ad hoc Network

Using Ad hoc mode signals issues can experienced where as using alternative infrastructure mode will provide full strength singles.Wi-Fi networking standard including 802.11g requires ad hoc mode of communication supports which 11Mbps bandwidth.Wi-Fi devices when configured to infrastructure mode can transfer data up to 54 Mbps, where as using ad hoc mode only 11 mbps can be achieved. Ad hoc mode is considered slower in comparison to infrastructure for this reason.

Security concerns
It is simple to set Wi-Fi network but keeping it secure takes much more effort, Access points of Wi-Fi do not deploy encryption methods. It is required to be done as network is enabled. Secure Wi-Fi network can be easily attacked by hackers to steal private information.
Guests who are not potentially harmful can still utilize the network resources and minimize the performance.

Interference from other devices
Wi-Fi transmits data at 2.4 GHz making susceptible to interfere Bluetooth enabled devices, mobile phones, cordless, Microwaves and other communication devices, closer the interfering devices are the poor communication will be and vice versa.

Lacking high-quality media streaming
Today’s fastest Wi-Fi standards are pushed beyond their limit when trying to view high end media.High definition video and audios cannot be viewed flawlessly because of lower transfer rate; things can be much more worst if other clients are accessing the same access points.
Even the fastest current Wi-Fi standards are pushed beyond their limit when trying to handle some of today's high-end media. High-definition audio and video files are timely-delivery-intensive, and typical wireless networks have neither the transfer speeds nor the consistency to transfer them flawlessly. This problem is further compounded if there are multiple devices connected to the same because the bandwidth must be divided between all of the equipment.

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At a job interview after college, I saw an electronic device in a box roughly 1'x2'x5" (30x60x13 cm). "What's that?" I asked. "A 9600 baud modem," my interviewer said. Now back in 1987, nobody had a 9600 baud modem. I had never heard of anything that fast.

But it was fun in the years after that to see off-the-shelf modem speeds catch up to that speed and then continually get faster and faster year after year. But somewhere around 57kbps, the progress suddenly stopped. AFAIK, modems for dialup phone lines never improve beyond that speed.

In that case, the limiting factor was the 64kbps sample rate of the digital telephone infrastructure and analog filtering. But every medium has a physical limit based on the things durga and Praveen-Kumar mentioned.

Personally, I hate wireless. I've run CAT5 ethernet cables throughout my house so I don't have to suffer wireless in my home. And I'm lucky enough to live where there is fiber internet service, so I don't have to suffer with wireless to my home.

Well as we are considering RF as a wireless also let me tell you that some RF Modules working on 2.4Ghz band provides you 2Mbps data rate for example RFM70.