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WO2009066986A2 - Augmentation de la capacité dans un réseau maillé wimax - Google Patents

Augmentation de la capacité dans un réseau maillé wimax Download PDF

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Publication number
WO2009066986A2
WO2009066986A2 PCT/MY2008/000152 MY2008000152W WO2009066986A2 WO 2009066986 A2 WO2009066986 A2 WO 2009066986A2 MY 2008000152 W MY2008000152 W MY 2008000152W WO 2009066986 A2 WO2009066986 A2 WO 2009066986A2
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WO
WIPO (PCT)
Prior art keywords
wimax
channel
nodes
mesh network
enhanced
Prior art date
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Ceased
Application number
PCT/MY2008/000152
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English (en)
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WO2009066986A3 (fr
Inventor
Abdelhaleem Saeed Rashid
Bin Mohd Ali Borhanuddin
Mohamad Hafizal
Chee Kyun Ng
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Universiti Putra Malaysia (UPM)
Mimos Bhd
Original Assignee
Universiti Putra Malaysia (UPM)
Mimos Bhd
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Universiti Putra Malaysia (UPM), Mimos Bhd filed Critical Universiti Putra Malaysia (UPM)
Publication of WO2009066986A2 publication Critical patent/WO2009066986A2/fr
Publication of WO2009066986A3 publication Critical patent/WO2009066986A3/fr
Anticipated expiration legal-status Critical
Ceased legal-status Critical Current

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Classifications

    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
    • H04L5/00—Arrangements affording multiple use of the transmission path
    • H04L5/003—Arrangements for allocating sub-channels of the transmission path
    • H04L5/0037—Inter-user or inter-terminal allocation
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04W—WIRELESS COMMUNICATION NETWORKS
    • H04W16/00—Network planning, e.g. coverage or traffic planning tools; Network deployment, e.g. resource partitioning or cells structures
    • H04W16/24—Cell structures
    • H04W16/28—Cell structures using beam steering
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04W—WIRELESS COMMUNICATION NETWORKS
    • H04W72/00—Local resource management
    • H04W72/04—Wireless resource allocation

Definitions

  • the present invention relates to a capacity enhancement in WiMAX mesh network and more particularly the present invention relates to an enhanced WiMAX using a new channel allocation algorithm.
  • WiMAX or also known as Worldwide Interoperability for Microwave Access has been standardized as IEEE 802.16 standard which is initialized from a group called WiMAX Forum.
  • WiMAX Forum is an industry-led, non-profit corporation formed to promote and certify compatibility and interoperability of broadband wireless products based on IEEE 802.16 and ETSI HiperMAN wireless MAN standards.
  • WiMAX provide a broadband wireless access at high speed and a scalable solution for extension of a fiber-optic backbone.
  • WiMAX base stations can offer greater wireless coverage of about 5 miles, with line of sight (LOS) transmission within bandwidth of up to 70 Mbps.
  • LOS line of sight
  • WiMAX technology can be used for creating wide-area wireless backhaul network.
  • WiMAX mesh networks create connectivity over multiple wireless hops. It becomes an interesting alternative to wired access in metropolitan areas.
  • a narrower beam from smart antenna can spatially isolate the interference from other nodes besides in frequency domain.
  • the reuse of sub-channel for other nodes is possible as long as the interest nodes are not experiencing the co-channels from transmitting node.
  • Some constraints are imposed in this proposed algorithm.
  • the relay nodes must be in static mode in order to occupy the smart antenna as its beam forming system.
  • AU the nodes subscribed to the same node are assigned with different sub-channels.
  • these sub-channels can be reused in other tier nodes. There is a time that all the nodes in different tiers are transmitting in the same direction which will cause co-channel interference.
  • the present invention relates to a capacity enhancement in WiMAX mesh network to enhanced WiMAX.
  • the said WiMAX mesh network is enhanced by using a new channel allocation algorithm and a smart antenna.
  • the said smart antenna consists of an antenna array, combined with signal processing in both space and time.
  • a beam forming is performed at the radio frequency level by controlling the amplitudes and phases of the feeding currents through attenuators and phase shifters.
  • the smart antenna operates its beams in the baseband, thus the feeding currents of the antenna elements are directly proportional to the modulated baseband signals.
  • the smart antenna is capable to cancel co-channel interference and wherein co-channel interference in the transmitting mode is reduced by focusing a directive beam in the direction of the desired user, and nulls in the directions of other interfering users.
  • Each OFDM symbol is created by mapping the sequence of symbols on the sub-carriers.
  • the modulated symbols are mapped on to the sub-channels that have been allocated for the transmission of the data block.
  • the number and exact distribution of the subcarriers that constitute a sub-channel depend on the subcarrier permutation mode.
  • Each node is equipped with a smart antenna system and multiple beams generation is possible and wherein nodes in a WMN are either gateways or routers and wherein gateways are equipped with a base station interface and additionally offer connectivity to the wired internet network and wherein routers are equipped with base station and subscriber station interfaces which attributed to as relay station and wherein each relay station needs to have a connection to any gateway to be able to establish an internet link.
  • a task of channel allocation is to assign each communication link a channel on a given topology and wherein it is sufficient to allocate a channel between two nodes which is determined by base station interface of each node.
  • an algorithm is designed base on the topology information and interference values at each node.
  • Figure 1 shows a wireless communication system impairments.
  • Figure 2 shows a frequency domain representation of OFDM symbol.
  • Figure 3 shows a subcarriers permutation scheme.
  • Figure 4 shows a simple WMN topology construction.
  • Figure 5 shows a a direction of a node from origin.
  • Figure 6 shows different sub-channels are assigned to nodes in the same direction but different tiers.
  • the IEEE 802.16 Working Group is the IEEE group for wireless metropolitan area network (MAN).
  • the IEEE 802.16 standard published in April 2002 defines ⁇ the wireless MAN air interface.
  • the IEEE 802.16 designed to operate in the 10-66 GHz spectrum and it specifies the physical layer (PHY) and medium access control layer (MAC) of the broadband wireless access (BWA) air interface systems.
  • PHY physical layer
  • MAC medium access control layer
  • BWA broadband wireless access
  • the IEEE 802.16 standard provides the foundation for a wireless MAN industry.
  • the physical layer is not suitable for lower frequency applications where non- line-of-sight (NLOS) operation is required.
  • NLOS non-line-of-sight
  • the IEEE published 802.16a standard to accommodate NLOS requirement in April 2003.
  • the standard operates in licensed and unlicensed frequency between 2 GHz and 1 1 GHz and it is an extension of the IEEE 802.16 standard.
  • the IEEE 802.16a standard allows users to get broadband connectivity without needing direct LOS with the base station.
  • the IEEE 802.16a specifies three air interface specifications and these options provide vendors with the opportunity to customize their product for different types of deployments.
  • 802.16a are: a) Wireless MAN-SC: it uses a single carrier modulation format. b) Wireless MAN-OFDM: it use orthogonal frequency division multiplexing (OFDM) with 256 point Fast Fourier Transform (FFT). This modulation is mandatory' for license exempt bands. c) Wireless MAN-OFDMA: it uses orthogonal frequency division multiple access (OFDMA) with a 2048 point FFT. Multiple access is provided by addressing a subset of the multiple carriers to individual receivers.
  • OFDM orthogonal frequency division multiplexing
  • FFT Fast Fourier Transform
  • IEEE 802.16 WiMAX provides mechanism for creating multi-hop mesh, which can be deployed as a high speed wide-area wireless network.
  • IEEE 802.16a standard defined the basic signaling flows and message formats to establish a mesh network connection. Subsequently, the mesh mode specifications were integrated into the TEEE 802.16-2004 revision.
  • single hop WiMAX provides high flexibility to attain QoS in terms of data throughput, achieving the same in multi-hop WiMAX mesh is challenging.
  • the major problem in WMN is dealing with the interference from transmission of the neighboring WiMAX nodes.
  • Cross-layer design and optimization is known to improve the performance of wireless communication and mobile networks.
  • Interference in wireless systems is one of the most significant factors that limit the network capacity and scalability of wireless mesh networks. Consideration of interference conditions during radio resource allocation and route formation processes impacts the design of concurrent transmission schemes with better spectral utilization while limiting the mutual interference.
  • Mesh networking allows data to hop from point to point, circumventing obstacles such as hills. Only a small amount of meshing is required to see a large improvement in the coverage of a single base station. If this group ' s proposal is accepted, they will become Task Force F and develop an 802.16f standard.
  • the 802.16-based WiMax mesh provides various advantages apart from increased range and higher bandwidth.
  • the time division multiple access (TDMA) based scheduling of channel access in WiMAX-based multi-hop relay system provides fine granularity radio resource control. This TDMA based scheduling mechanism allows centralized slot allocation, which provides overall efficient resource utilization suitable for fixed wireless backhau] network.
  • the interference remains a major issue in multi hop WMN.
  • an efficient algorithm for slot allocation is needed, so as to maximize the concurrent transmissions of data in the mesh.
  • the level of interference depends upon how the data is routed in the WMN.
  • the first and most fundamental challenge for broadband wireless comes from the transmission medium itself.
  • a physical connection such as a copper wire or fiber-optic cable, guides the signal from the transmitter to the receiver, but wireless communication systems rely on complex radio wave propagation mechanisms for traversing the intervening space.
  • Several large and small obstructions, terrain undulations, relative motion between the transmitter and the receiver, interference from other signals, noise, and various other complicating factors together weaken, delay, and distort the transmitted signal in an unpredictable and time-varying fashion. It is a challenge to design a digital communication system that performs well under these conditions, especially when the service requirements call for very high data rates and high-speed mobility.
  • the wireless channel for broadband communication introduces several major impairments such as multipath fading, delay-spread and co- channel interference, as shown in Figure 1.
  • Multipath fading is caused by the multiple traveling paths that the transmitted signal can take to arrive at the receiving antenna The signals from these paths add with different phases, resulting in a received signal amplitude and phase that vary with antenna location, direction, and polarization, as well as with some time delay for some movement in the environment.
  • synchronization would be very difficult to achieve between different users because very accurate timing synchronization at network level must be achieved, which is in general not easy.
  • three components are considered for a typical variation in the received signal level. The three components are mean path loss, slow fading (or lognormal fading), and fast fading (or Rayleigh fading). This increases the required average received signal power for a given BER.
  • each path has a different length such that the time of arrival (TOA) for each path is different.
  • TOA time of arrival
  • ISI inter-symbol interference
  • the delay spread exceeds about 10 percent of the symbol duration the significant inter-symbol interference (ISI) can occur. It will limit the maximum data rate of the system.
  • ISI inter-symbol interference
  • certain models are adapted to interpret the power level for each individual delay spread path. This power profile of each delay spread path is called power delay profile.
  • Co-channel interference where the main source of interference is coming from adjacent cells. Cellular systems divide the available frequency channels into channel sets, using one channel set per cell, with frequency reuse.
  • Smart antenna consists of an antenna array, combined with signal processing in both space and time. Beam forming is performed at the radio frequency (RF) level by controlling the amplitudes and phases of the feeding currents through attenuators and phase shifters. Hence, beam forming is sometimes referred to as spatial filtering, since some incoming signals from certain spatial directions are filtered out, while others are amplified. Smart antenna operates its beams in the baseband, thus the feeding currents of the antenna elements are directly proportional to the modulated baseband signals.
  • RF radio frequency
  • Co-channel interference is caused by radiation from cells that use th ⁇ same set of channel frequencies.
  • co-channel interference in the transmitting mode is reduced by focusing a directive beam in the direction of the desired user, and nulls in the directions of other interfering users.
  • Delay spread and multipath fading can also be reduced with employing smart antenna system that is capable of forming beams in certain directions and nulls in others, thereby cancelling some of the delayed arrivals.
  • the antenna focuses energy in the required direction, which helps to reduce multipath reflections and the delay spread.
  • each OFDM symbol is created by mapping the sequence of symbols on the subcarriers.
  • WiMAX has three classes of subcarriers.
  • IEEE 802.16e-2005 standard is a logical collection of subcarriers.
  • the number and exact distribution of the subcarriers that constitute a sub-channel depend on the subcarrier permutation mode as shown in Figure 3.
  • the number of sub-channels allocated for transmitting a data block depends on various parameters, such as the size of the data block, the modulation format, and the coding rate.
  • a burst profile refers to the combination of the chosen modulation format, code rate, and type of forward error correction (FEC): convolutional codes, turbo codes, and block codes.
  • FEC forward error correction
  • the subcarriers that constitute a subchannel can either be adjacent to each other or distributed throughout the frequency band, depending on the subcarrier permutation mode.
  • a distributed subcarrier permutation provides better frequency diversity, whereas an adjacent subcarrier distribution is more desirable for beam forming and allows the system to exploit multiuser diversity.
  • the task of topology construction is to connect the mesh nodes.
  • Each node is equipped with a smart antenna system and multiple beams generation is possible.
  • Nodes in a WMN are either gateways or routers. Gateways are equipped with a base station interface and additionally offer connectivity to the wired internet network. Routers ore 5 equipped with base station and subscriber station interfaces which attributed to as relay station (RS).
  • RS relay station
  • Each RS needs to have a connection to any gateway to be able to establish an internet link.
  • Figure 4 shows a simple WNfN topology construction.
  • the subscriber station interface of RS B subscribes to gateway A by using a channel determined from the base station interface of gateway A.
  • all LO other nodes, C. D and E subscribe to RS B with different channels given from the base station interface of RS B.
  • nodes can be in either static or mobile mode. Other nodes which are considered as RS worked in static mode where mobility is not available.
  • the task of channel allocation is to assign each communication link a channel on a given topology. In our WMN model, it is sufficient to allocate a channel between two nodes which is determined by base station interface of each node. To allocate the channels, an algorithm is designed base on the topology information and interference values at each node. Every node except the end subscriber nodes in WMN can become a host for other nodes. The host node is simply noted as PARENT node and the node joining the PARENT node is noted as CHILD node. Specifically, a CHILD node sends a REQUEST message to nearest PARENT node that willing to host it.
  • the PARENT node then stores the particular information especially IP address of the CHILD node for the routing purpose. After the connection is completed, the updated configuration files are stored in both PARENT and CHILD nodes.
  • the READY message from the PARENT node acts as a trigger on the CHILD node to set up the routing state. Once the routing state is set up. the CHILD node can start connect to the internet through its PARENT node. At the same time, the CHILD node also starts indicating its willingness to host other nodes in WMN.
  • the channel reuse is possible whenever there is full spatially separation.
  • the mesh direction among the nodes is in single direction.
  • different channels are allocated to the nodes along this mesh topology.
  • the nodes in WMN are located close to each other. In this case, much interference is experienced from either the sidelobes or the beams themselves. Hence, the different channels must also be assigned on these nodes.
  • a node makes a direction of a from origin ( ⁇ ) as shown in Figure 5. If there are n number of CHILD nodes in WMN that are closed to
  • a, [a i , ⁇ 2 , a, , a n ] ⁇ 10°
  • the different subchannel in OFDM band of WiMAX system shall be assigned to each CHILD node from its PARENT node to avoid interference.
  • nodes from different tiers of mesh are arranged in the same direction as shown in Figure 6.
  • different sub-channels are assigned among them.
  • Each PARENT node assigns the different sub-channels to theirs CHILD node using the channel assignment. Hence, in this case the isolation in frequency domain is more dominant than spatially separation.
  • the sub-channel assignment algorithm is designed such that the adjacent sub-channels are not assigned to the nodes that close to each other in order to avoid co-channel interference.
  • Table 1 the propagation zone is divided into 36 subzones with each size of 10o.
  • the subzones 1, 2, 3, ...., 36 are defined as in the Table 1.
  • the sub-channel assignment is then arranged in ascending manner (1, 2, 3, ...., 36).
  • sub-channels are also reused for the next tier of nodes in WMN with a condition that every tier cannot has the same sub-channel. And it is up to totally 36 tiers of hop. Therefore, in this scheduling table, the total nodes that can be accommodated are approximately 1296 (36 x 36) in one WMN system.
  • Table 1 Sub-channel assignment in WMN.
  • a novel channel allocation scheme using smart antenna system for improving the throughput of WMN exploits two separation techniques, both spatial and frequency domains to form a dominant co- channel cancellation algorithm.
  • ours proposed channel assignment allows more channel reusability which suit achieves higher throughput.

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  • Engineering & Computer Science (AREA)
  • Signal Processing (AREA)
  • Computer Networks & Wireless Communication (AREA)
  • Mobile Radio Communication Systems (AREA)

Abstract

La présente invention concerne la capacité dans des réseaux maillés WiMAX (WMN) qui est devenue de première importance en raison de la demande sans cesse croissante de services multimédia et de la possibilité d'offrir un Internet haut débit sans fil. Le principal facteur limitant la capacité dans de tels systèmes est l'interférence provenant des nœuds adjacents, à savoir l'interférence dans le même canal. La présente invention consiste généralement en une analyse d'interférence dans le même canal pour une configuration WMN efficace de manière spectrale. Un nouvel algorithme d'attribution de canal est proposé en utilisant un système d'antennes intelligentes afin d'éliminer l'interférence dans le même canal. Cet algorithme considère le nombre de sous-canaux dans le spectre OFDM de manière à augmenter la capacité du système. Le nouvel algorithme est désigné pour éviter que le même sous-canal de spectre OFDM soit attribué à des nœuds adjacents. La capacité du système peut être augmentée lorsque l'interférence dans le même canal est réduite.
PCT/MY2008/000152 2007-11-22 2008-11-24 Augmentation de la capacité dans un réseau maillé wimax Ceased WO2009066986A2 (fr)

Applications Claiming Priority (2)

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MYPI20072066 2007-11-22
MYPI20072066A MY147158A (en) 2007-11-22 2007-11-22 Capacity enhancement in wimax mesh network

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Cited By (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US9237529B2 (en) 2012-03-30 2016-01-12 Blinq Wireless Inc. Method and apparatus for managing interference in wireless backhaul networks through power control with a one-power-zone constraint
US9338753B2 (en) 2011-05-06 2016-05-10 Blinq Wireless Inc. Method and apparatus for performance management in wireless backhaul networks via power control
US9338672B2 (en) 2010-09-13 2016-05-10 Blinq Wireless Inc. System and method for coordinating hub-beam selection in fixed wireless backhaul networks
US9345032B2 (en) 2010-09-13 2016-05-17 Blinq Wireless Inc. Method and apparatus for determining network clusters for wireless backhaul networks
WO2019162351A1 (fr) * 2018-02-25 2019-08-29 Bluwireless Technology Limited Réseaux de communication sans fil

Family Cites Families (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US7538740B2 (en) * 2006-03-06 2009-05-26 Alcatel-Lucent Usa Inc. Multiple-element antenna array for communication network

Cited By (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US9338672B2 (en) 2010-09-13 2016-05-10 Blinq Wireless Inc. System and method for coordinating hub-beam selection in fixed wireless backhaul networks
US9345032B2 (en) 2010-09-13 2016-05-17 Blinq Wireless Inc. Method and apparatus for determining network clusters for wireless backhaul networks
US9338753B2 (en) 2011-05-06 2016-05-10 Blinq Wireless Inc. Method and apparatus for performance management in wireless backhaul networks via power control
US9237529B2 (en) 2012-03-30 2016-01-12 Blinq Wireless Inc. Method and apparatus for managing interference in wireless backhaul networks through power control with a one-power-zone constraint
WO2019162351A1 (fr) * 2018-02-25 2019-08-29 Bluwireless Technology Limited Réseaux de communication sans fil
US11330601B2 (en) 2018-02-25 2022-05-10 Bluwireless Technology Limited Wireless communications networks

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Publication number Publication date
MY147158A (en) 2012-11-14
WO2009066986A3 (fr) 2009-08-13

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