OPPORTUNISTIC INTERFERENCE ALIGNMENT

FOR RANDOM ACCESS NETWORKS

PHASE I PRESENTATION

DEPARTMENT OF ELECTRONICS AND COMMUNICATION ENGINEERING

ANNAI MATHAMMAL SHEELA ENGINEERING COLLEGE

PREPARED BY

V.LOGESWARAN

ME-APPLED ELECTRONICS

ABSTRACT:

An interference management problem among multiple overlapped random

access networks (RANs) is investigated, each of which operates with slotted

ALOHA protocol.

Assuming that access points and users have multiple antennas, a novel

opportunistic interference alignment (OIA) is proposed to mitigate interference

among overlapped RANs.

The proposed technique intelligently combines the transmit beam forming

technique at the physical layer and the opportunistic packet transmission at the

medium access control layer.

The transmit beam forming is based on interference alignment and the opportunistic

packet transmission is based on the generating interference of users to other RANs,

which can be regarded as a joint optimization of the physical layer and the medium

access control layer.

It is shown that the proposed OIA protocol significantly outperforms the

conventional schemes such as multi-packet reception and interference nulling.

INTRODUCTION:

IEEE 802.11:

IEEE 802.11 is a set of media access control (MAC) and physical layer (PHY)

specifications for implementing wireless local area network (WLAN) computer

communication in the 2.4, 3.6, 5, and 60 GHz frequency bands.

They are created and maintained by the IEEE LAN/MAN Standards Committee

(IEEE 802).

The base version of the standard was released in 1997, and has had subsequent

amendments.

The standard and amendments provide the basis for wireless network products

using the Wi-Fi brand.

While each amendment is officially revoked when it is incorporated in the latest

version of the standard, the corporate world tends to market to the revisions because

they concisely denote capabilities of their products

As a result, in the market place, each revision tends to become its own standard.

The 802.11 family consists of a series of half-duplex over-the-

air modulation techniques that use the same basic protocol.

802.11-1997 was the first wireless networking standard in the family, but 802.11b was the

first widely accepted one, followed by 802.11a, 802.11g, 802.11n,

and 802.11ac

Other standards in the family (c–f, h, j) are service amendments that are used to

extend the current scope of the existing standard, which may also include

corrections to a previous specification.

802.11b and 802.11g use the 2.4 GHz ISM band, operating in the United States

under Part 15 of the U.S. Federal Communications Commission Rules and

Regulations. Because of this choice of frequency band, 802.11b and g equipment

may occasionally suffer interference from microwave ovens, cordless telephones,

and Bluetooth devices.

802.11b and 802.11g control their interference and susceptibility to interference by

using direct-sequence spread spectrum (DSSS) and orthogonal frequency-division

multiplexing (OFDM) signaling methods, respectively.

802.11a uses the 5 GHz U-NII band, which, for much of the world, offers at least

23 non-overlapping channels rather than the 2.4 GHz ISM frequency band offering

only 3 non-overlapping channels, where other adjacent channels overlap — see list

of WLAN channels.

Better or worse performance with higher or lower frequencies (channels) may be

realized, depending on the environment.

RANDOM ACCESS NETWORK:

A radio access network (RAN) is part of a mobile telecommunication system. It implements a radio access technology

Conceptually, it resides between a device such as a mobile phone, a computer, or any remotely controlled machine and provides connection with its core network (CN).

Depending on the standard, mobile phones and other wireless connected devices are varyingly known as user equipment (UE), terminal equipment, mobile station (MS), etc.

RAN functionality is typically provided by a silicon chip residing in both the core network as well as the user equipment.

C-RAN (Cloud-RAN), sometimes referred to as Centralized-RAN, is a proposed architecture for future cellular networks.

It was first introduced by China Mobile Research Institute in April 2010 in Beijing, China.

Simply speaking, C-RAN is a centralized, cloud computing-based architecture for radio access networks that supports 2G, 3G, 4G and future wireless communication standards.

Base Station Architecture

In the 1G and 2G cellular networks, base stations had an all-in-one architecture.

Analog, digital, and power functions were housed in single cabinet as large as a

refrigerator.

Usually the base station cabinet was placed in a dedicated room along with all

necessary supporting facilitates such as power, backup battery, air conditioning,

environment surveillance, and backhaul transmission equipment.

The RF signal is generated by the base station RF unit and propagates through pairs

of RF cables up to the antennas on the top of a base station tower or other mounting

points

This all-in-one architecture was mostly found in macro cell deployments

Distributed Base Station:

For 3G, a distributed base station architecture was introduced by Nokia, Huawei

and other leading telecom equipment vendors.

In this architecture the radio function unit, also known as the remote radio head

(RRH), is separated from the digital function unit, or baseband unit (BBU) by fiber.

C-RAN(Cloud Random Access Network)

C-RAN architecture has the following characteristics that are distinct from other

cellular architectures.

Large scale centralized deployment: Allows hundreds of thousands of remote RRH

connect to a centralized BBU pool.

The maximum distance can be 20 km in fiber link for 4G (LTE/LTE-A) system,

even longer distance (40 km~80 km) for 3G (WCDMA/TD-SCDMA) and 2G

(GSM/CDMA) systems.

There are reports saying that some Asia operators have deployment C-RAN system

which centralized 1200 of RRH to one central office

APPLICATION:

CSMA/CD was used in now obsolete shared media Ethernet variants (10BASE5,

10BASE2) and in the early versions of twisted-pair Ethernet which used repeater

hubs

Modern Ethernet networks, built with switches and full-duplex connections, no

longer need to utilize CSMA/CD because each Ethernet segment, or collision

domain, is now isolated.

CSMA/CD is still supported for backwards compatibility and for half-duplex

connection.

IEEE Std 802.3, which defines all Ethernet variants, for historical reasons still bears

the title "Carrier sense multiple access with collision detection (CSMA/CD) access

method and physical layer specifications

FUNCTION OF MAC LAYER:

According to IEEE Std 802-2001 section 6.2.3 "MAC sublayer", the primary functions performed by the MAC layer are:[1].

Frame delimiting and recognition

Addressing of destination stations (both as individual stations and as groups of stations)

Conveyance of source-station addressing information

Transparent data transfer of LLC PDUs, or of equivalent information in the Ethernet sublayer.

Protection against errors, generally by means of generating and checking frame check sequences..

Control of access to the physical transmission medium.

In the case of Ethernet, according to 802.3-2002 section 4.1.4, the functions required of a MAC are:[2]

Receive/transmit normal frames

Half-duplex retransmission and backoff functions

Append/check FCS (frame check sequence)

Interframe gap enforcement

Discard malformed frames

EXISTING SYSTEM:

Interference management in random access networks has attracted a great interest.

For an example, the working group of IEEE 802.11, which is one of the most

successful standards in commercial wireless communication systems, is considering

performance improvement for overlapping basic service sets (OBSS) under the new

standardization called IEEE 802.11 high efficiency wireless local area network

(HEW).

PROPOSED SYSTEM:

The proposed IA algorithm in requires tight coordination among access points

(APs) in overlapped networks through wired backhaul and it does not consider

collisions among users even though the collision effect is the most important factor

to degrade the performance of RANs.

IA was applied to a fully distributed random access environment in like the

distributed coordinated function (DCF) of IEEE 802.11 standard.

CONCLUSION:

Interference management protocol called opportunistic interference alignment

(OIA) for overlapped random access networks operating with slotted ALOHA.

which intelligently combines the interference alignment based transmit beam

forming technqiue at the PHY layer and the opportunistic random access technique

at the MAC layer.

We also introduced a simple extension method of the conventional techniques for

interference-limited RANs: multipacket reception and interference nulling.

The proposed OIA protocol is shown to significantly outperform the conventional

schemes in terms of MAC layer throughput.

The proposed OIA protocol is expected to be applied to next-generation wireless

LANs such as IEEE 802.11 HEW without significant modifications.

Thank

You