The standard uses MIMO [26] and various new modulation and coding mechanisms to increase the data rates. The standard uses a fixed channel bandwidth of 20MHz, which is useful for backward compatibility with older standards. Data rates up to Mbps are achieved only with the maximum of four spatial streams using one 40 MHz-wide channel [25]. Frame Aggregation 2.
There is severe under utilization when the MAC frames are small. The frame aggregation technique enabled STAs to aggregate small frames into larger ones. To maximize efficiency, the maximum frame size is increased thereby allowing longer frames [27]. It defines enhancements to It includes data exchange between high-speed passenger vehicles and ambulances and the roadside infrastructure in the licensed ITS band of 5.
In this protocol, the vehicles send information about their traffic parameters like speed, distance from other vehicles etc. In this way each vehicle in the corresponding neighbourhood knows about the traffic status and acts accordingly. This standard provided fast roaming, even for vehicles in motion. It reduced the roaming delay between two basic service sets BSS to less than 50 ms. The standard also refined the mobile client transition process between APs by redefining the security key negotiation protocol, which permit negotiations and requests for wireless resources.
It defines how wireless devices can interconnect to create a WLAN mesh network, which may be used for static topologies as well as for ad-hoc networks [36]. Initially in , the It became a Task Group in In the following year i. After a series of eliminations and mergers, the proposals dwindled to two the "SEE-Mesh" and "Wi-Mesh" proposals , which became a joint proposal in fig. Network device which is based on the IEEE Mesh STAs form mesh links with each other, over which mesh paths can be established using a routing protocol fig.
But it still allows vendors to operate using alternate protocols. They can also collocate with Also, mesh STAs can collocate with an In both the cases, There are no defined roles in a mesh — no clients and servers, no initiators and also no responders. Security protocols used in a mesh must, therefore, be true peer- to-peer protocols where either side can initiate to the other or both sides can initiate simultaneously.
A key establishment protocol called "Simultaneous Authentication of Equals" SAE defines a secure password-based authentication technique. SAE is based on Diffie—Hellman key exchange using finite cyclic groups which can be a primary cyclic group or an elliptic curve. The problem on using Diffie—Hellman key exchange is that it does not have an authentication mechanism. Hence to solve the authentication problem, the resulting key is influenced by a pre-shared key as well as the MAC addresses of both peers [34].
SAE exchange takes place only when both the peers discover each other. On successful completion of SAE, each peer knows that the other party possesses the mesh password and, as a by-product of SAE exchange, the two peers establish a cryptographically strong key.
The key is then used with the "Authenticated Mesh Peering Exchange" AMPE to establish a secure peering and derive a session key to protect mesh traffic, including routing traffic [35].
However as on date, the standard has been cancelled from the IEEE project. This was achieved through network discovery and selection and QoS map distribution. The network discovery and selection may be provided in the following ways: 1. The discovery of suitable networks through the advertisement of access network type, roaming consortium and venue information. Nowadays, with mobile users whose devices can move between 3G and Wi-Fi networks at a low level using Actually, IEEE With the usage of external network authorization, the AP also provides service to the previously unknown STAs.
It introduces protected management frames with the help of mechanisms that enable data origin authenticity, data integrity and replay protection. To allow for this, the standard also adds three new concepts: 1.
DLS allows two stations to communicate directly with each other without the requirement of an AP. This standard basically provides direct-link setup enhancements to the IEEE The direct-link setup is made independent of the AP by tunnelling the protocol messages inside data frames.
It specification adds a "fast session transfer" feature, enabling the wireless devices to seamlessly make transition between the legacy 2. To operate with optimal performance and range criteria, the IEEE Many users in a dense deployment can all maintain top-speed performance, without interfering with each other or having to share bandwidth as with the legacy frequency bands [].
The likely enhancements to A protocol to communicate management frame prioritization policy is specified in this standard. This standard is expected to be published by the end of It is expected to provide a multi-station WLAN throughput of at least 1 Gbps and a single link throughput of at least Mbps [45].
This is achieved by extending the air interface concepts which are embraced by It will use cognitive radio technology to identify white spaces it can use. However, this cognitive technology will be based on an authorized geolocation database.
This database will provide information on which frequency, at what time and under what conditions networks may operate.
It will also enable devices based on the IEEE In addition it will provide improve coverage range which will allow new applications such as wide area based sensor networks, sensor backhaul systems and potential Wi-Fi off-loading functions to emerge [48]. This standard is currently under development and is predicted to be finalized by The amendment is also intended to maintain backward compatibility with This standard is scheduled to be finalized by the end of This creates opportunities to deliver new services, as the IEEE This information about services is to be made available prior to association by stations operating on IEEE This standard is scheduled to be published by Security One of the prime concerns in wireless networking is security.
As WLANs operate over the shared medium, eavesdropping by unauthorized people and critical information may be accessed with the use of malicious technologies. Although WPA and WPA2 are much more secure and provides good protection still it is not secure enough to be contend with. More complex encryption algorithms need to be implemented without decreasing the MAC layer throughput.
There was significant improvement in the data rates provided by the IEEE However, the 40 MHz channel required to support such data rates are not available in many countries. The more recent IEEE But this data rate is even still quite low as compared to the 10 GHz capacity of the wireline network standard Increasing the PHY layer data rate alone cannot solve the throughput problem; but the MAC layer also needs to be changed.
Two amendments IEEE In While IEEE Lost packets with overloaping channels. Lost packets with one channel of difference. Lost packets with two channels of difference. Lost packets with three channels of difference. Lost packets with four channels of difference Figure Lost packets with five channels of difference. This is mainly because IEEE Generally, in traditional wireless transmission the signal is affected by 20 reflections, causing self-degradation and therefore data loss.
MIMO takes advantage of physical phenomena such as 10 multipath propagation to increase the transmission rate and reduce the error rate. In IEEE Lost packets with non overlapping channel slight tendency to record fewer lost packets when the This average has been estimated taking into account the channel separation is an even number than when there is an measurements taken from all devices for each variant.
These losses can be approximated Fig. In particular, taking the measurements gathered, channel. As we can see, IEEE In order to test the performance of IEEE The first one was Cisco of 2.
This system does not there are three separation channels. Although in the 5GHz frequency band, devices could Fig. We can see that IEEE simultaneously, this device only allows us to work with 4 Then, we estimated the average The results are represented in fig. The IEEE Throughput and Bandwidth consumption measurements As it happens in lost packets measurements, there is a In order to measure the bandwidth offered by each trend in the bandwidth consumption that is related to the technology, we performed the following test.
First, 2 PCs separation of the working channels. The Net Meter captured the the number of separation channels is odd. The measures are Fig. As we can see, both The result of the average bandwidth consumed by each devices show a similar average bandwidth, with an average IEEE Average bandwidth with overloaping channels.
Average bandwidth with one channel of difference. Average bandwidth for two channel of difference. Average bandwidth for three channel of difference. Average bandwidth for four channel of difference. Average bandwidth for five channel of difference.
Average bandwidth when there are no overlapping channels in IEEE These values have been obtained by dividing the channels. Again, IEEE It provides us the and the IEEE In this devices were limited to this speed. The results of the case, IEEE The channel. In this They have In this case, IEEE Average throughput with overloaping channels. Average throughput with one channel of difference. Average throughput with two channels of difference.
Average throughput with three channels of difference. Average throughput with four channels of difference. Average throughput with five channels of difference 30 simulation that non-overlapping channels do not have interference. In fact, their tests were different from ours. Despite of this fact, the conclusions are 20 similar. As we have seen, the devices working at 2. We also see that the number of lost packets, maintaining 5 approximately the same value when there are 3 channels of separation Fig.
In the last two cases, the number of lost packets Cisco Aironet AG a Linksys WRTN a should be very low or zero, since the overlap between the spectral is virtually nonexistent. In this case, after having Figure Average throughput with non overlapping channels performed different tests, we state that there is a slight In general, we can see similar effects in all figures.
The tendency to register fewer lost packets when the channel IEEE In IEEE separation is an odd number. These measurements enabled That is, when the channel measures are shown in fig. This fact In this case it is clear that the interference highly affects corresponds to the values of lowest packet losses.
Therefore, the performance of the wireless network variant. IEEE although we have shown that non-overlapping channels does Some published papers define the throughput, as the VI. Throughout this work we have performed different test And others define the throughput as the channel benches in order to characterize the behavior of wireless performance. We have taken the second meaning of this signals in indoor environments.
These tests have allowed us concept. It relates the amount of information flowing through to check some statements realized by some papers related to the channel and the theoretical maximum capacity offered by this issue. We have also seen some other issues. Another factor that draws the attention of this Moreover, we analyzed the frequency spectrum between analysis is that despite of the packet losses registered in 2.
Because of their physical properties, we could performance is quite low. As we can see in [33] the think that if there is no overlap between channels, there theoretical maximum throughput and data rates for IEEE should not be any interference between them. But our results In [27], authors show in their with real throughput and data rates. Integrated circuits for WRTN Although this phenomenon has been seen in the 4 specific antenna has been used, with a particular sensitivity.
However, due to the results and In order to analyze this, first we have analyzed the hardware other previous tests we had made, we believe that the results characteristics of wireless device. In this case, WRTN obtained are a good sign of the technology behavior. Similar has 3 antennas, as shown in Fig. As those skilled in the art will recognize, other implementations of the present invention are possible, and the present invention is not limited to the example number of frequency rotations described above.
The selected set of parameters is chosen based on the specific number of subcarriers in the In other systems with different number of subcarriers and parsers, the principles of the present invention can be used while the specific rotation parameters can be different.
The present invention has been described in considerable detail with reference to certain preferred versions thereof; however, other versions are possible. Therefore, the spirit and scope of the appended claims should not be limited to the description of the preferred versions contained herein. A method of data communication in a wireless system, comprising the steps of: parsing a bit stream into multiple spatial data streams;.
The method of claim 1 wherein the number of frequency rotations for a spatial data stream is a function of the number of the total spatial data streams. The method of claim 1 wherein the steps of interleaving the bits in a spatial data stream includes the steps of performing a first interleaving permutation to ensure that adjacent coded bits are mapped onto nonadjacent subcarriers in one data stream for transmission, and a second permutation to ensure that coded bits are mapped alternately onto less and more significant bits of the constellation, and a third interleaving permutation providing the frequency rotation, varying on different spatial data streams to increase diversity of the wireless system.
The method of claim 1 , wherein the steps of interleaving the bits in a spatial data stream includes the steps of: a ensuring that adjacent coded bits are mapped onto nonadjacent sub-carriers, b ensuring that coded bits are mapped alternately onto less and more significant bits of the constellation whereby long runs of low reliability LSB bits are avoided, and c performing frequency rotation.
The method of claim 4 wherein each spatial data stream interleaver array includes N row rows and N column columns of bits, wherein: the steps a of ensuring that adjacent coded bits are mapped onto nonadjacent sub-carriers is according to relation:. The method of claim 4 further including the steps of receiving the transmitted bits of each spatial bit stream, and deinterleaving the received bits according to relations:. The method of claim 1 wherein the wireless system comprises a MIMO system.
The method of claim 1 wherein the steps of parsing the bit stream further includes the steps of bitwise or group-wise round robin parsing to increase spatial diversity.
The method of claim 9 wherein the steps of parsing the bit stream further includes the steps of bitwise round robin parsing such that one bit of the bit stream is parsed to one data stream each time. The method of claim 1 further including the steps of puncturing each spatial data stream after the step of parsing. The method of claim 11 wherein the step of puncturing for each spatial data stream is based on the channel condition.
A wireless communication system, comprising: a transmitter including: a parser that parses a bit stream into multiple spatial data streams;. The system claim 13 wherein an interleaver performs a first interleaving permutation to ensure that adjacent coded bits are mapped onto nonadjacent subcarriers in one data stream for transmission, and a second permutation to ensure that coded bits are mapped alternately onto less and more significant bits of the constellation, and a third interleaving permutation varying on different spatial data streams by performing different frequency rotation to increase diversity of the wireless system.
The system of claim 14 , wherein the interleaver performs interleaving the bits in each spatial data stream by: a ensuring that adjacent coded bits are mapped onto nonadjacent sub-carriers, b ensuring that coded bits are mapped alternately onto less and more significant bits of the constellation whereby long runs of low reliability LSB bits are avoided, and c performing frequency rotation.
The system of claim 15 wherein each spatial data stream interleaver array includes N row rows and N column columns of bits, wherein: ensuring that adjacent coded bits are mapped onto nonadjacent sub-carriers is according to relation:.
The system of claim 16 wherein the receiver includes a plurality of deinterleavers such that each deinterleaver deinterleaves the bits in a received spatial data stream. The system of claim 17 wherein each deinterleaver deinterleaves the received bits according to relations:. The system of claim 13 wherein the wireless system comprises a MIMO system. The system of claim 13 wherein the parser parses the bit stream by bitwise round robin parsing, to increase spatial diversity.
The system of claim 21 wherein the parser parses the bit stream by bitwise round robin parsing such that one bit of the bit stream is parsed to one data stream each time. USB2 en. EPB1 en. JPA en. KRB1 en. CNB en. WOA1 en. Interleaver design with multiple encoders for more than two transmit antennas in high throughput WLAN communication systems.
EPA1 en. Method and apparatus for coding and interleaving for very high throughput wireless communications. USB1 en. Method and apparatus for transmitting data in very high throughput wireless local area network system. Data stream interleaving with different rotation applied to changed bit streams for spatially diverse transmission. Compressed orthogonal frequency division multiplexing OFDM symbols in a wireless communication system. Method and apparatus for performing blind signal separation in an ofdm mimo system.
Address generating method and device for plurality of modes of interlacing and deinterlacing. Apparatuses and methods for wireless communications using a permutation sequence.
Method of transmitting data block in wireless communication system and transmitter. Apparatus for transmitting broadcast signals, apparatus for receiving broadcast signals, method for transmitting broadcast signals and method for receiving broadcast signals. Interleaving and deinterleaving method and device based on rotation of data cell blocks. A kind of three-dimensional Bit Interleave method and device based on space-time rotation. USA en. Method and apparatus for equalization and tracking of coded digital communications signals.
Method and system for utilizing space-time and space-frequency codes for multi-input multi-output frequency selective fading channels. Method and encoder for implementing a fully protected multidimensional linear block code.
This amendment describes protocols for IEEE The purpose of this amendment is to improve the IEEE It also incorporates Amendments 1 to 10 published in to A mechanism for prioritization of management frames is provided and a protocol to communicate management frame prioritization policy is specified in this amendment. Enhancements to the IEEE Modifications to both the IEEE Telecommunications and information exchange between systems - Local and metropolitan area networks?
The IEEE This amendment also defines modifications to the IEEE
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