Radio resource management - AbsoluteAstronomy.com

Radio resource management (RRM) is the system level control of co-channel interference

Co-channel interference

Co-channel interference or CCI is crosstalk from two different radio transmitters using the same frequency. There can be several causes of co-channel radio interference; four examples are listed here....

and other radio transmission characteristics in wireless communication systems, for example cellular network

Cellular network

A cellular network is a radio network distributed over land areas called cells, each served by at least one fixed-location transceiver known as a cell site or base station. When joined together these cells provide radio coverage over a wide geographic area...

s, wireless network

Wireless network

Wireless network refers to any type of computer network that is not connected by cables of any kind. It is a method by which homes, telecommunications networks and enterprise installations avoid the costly process of introducing cables into a building, or as a connection between various equipment...

s and broadcasting

Broadcasting

Broadcasting is the distribution of audio and video content to a dispersed audience via any audio visual medium. Receiving parties may include the general public or a relatively large subset of thereof...

systems. RRM involves strategies and algorithms for controlling parameters such as transmit power, channel allocation, data rates, handover criteria, modulation scheme, error coding scheme, etc. The objective is to utilize the limited radio spectrum resources and radio network infrastructure as efficiently as possible.

RRM concerns multi-user and multi-cell network capacity issues, rather than point-to-point channel capacity

Channel capacity

In electrical engineering, computer science and information theory, channel capacity is the tightest upper bound on the amount of information that can be reliably transmitted over a communications channel...

. Traditional telecommunications research and education often dwell upon channel coding and source coding

Source coding

In information theory, Shannon's source coding theorem establishes the limits to possible data compression, and the operational meaning of the Shannon entropy....

with a single user in mind, although it may not be possible to achieve the maximum channel capacity when several users and adjacent base stations share the same frequency channel. Efficient dynamic RRM schemes may increase the system capacity in an order of magnitude

Order of magnitude

An order of magnitude is the class of scale or magnitude of any amount, where each class contains values of a fixed ratio to the class preceding it. In its most common usage, the amount being scaled is 10 and the scale is the exponent being applied to this amount...

, which often is considerably more than what is possible by introducing advanced channel coding and source coding schemes. RRM is especially important in systems limited by co-channel interference rather than by noise, for example cellular systems and broadcast network

Broadcast network

A broadcast network is an organization, such as a corporation or other voluntary association, that provides live television or recorded content, such as movies, newscasts, sports, Public affairs programming, and other television programs for broadcast over a group of radio stations or television...

s homogeneously covering large areas, and wireless network

Wireless network

s consisting of many adjacent access points

Wireless access point

In computer networking, a wireless access point is a device that allows wireless devices to connect to a wired network using Wi-Fi, Bluetooth or related standards...

that may reuse the same channel frequencies.

The cost for deploying a wireless network is normally dominated by base station sites (real estate costs, planning, maintenance, distribution network, energy, etc) and sometimes also by frequency license fees. The objective of radio resource management is therefore typically to maximize the system spectral efficiency in bit/s/Hz/base station site or Erlang/MHz/site, under constraint that the grade of service

Grade of service

In telecommunication engineering, and in particular teletraffic engineering, the quality of voice service is specified by two measures: the grade of service and the quality of service ....

should be above a certain level. The latter involves covering a certain area and avoiding outage

Downtime

The term downtime is used to refer to periods when a system is unavailable.Downtime or outage duration refers to a period of time that a system fails to provide or perform its primary function...

due to co-channel interference

Co-channel interference

, noise

Noise

In common use, the word noise means any unwanted sound. In both analog and digital electronics, noise is random unwanted perturbation to a wanted signal; it is called noise as a generalisation of the acoustic noise heard when listening to a weak radio transmission with significant electrical noise...

, attenuation caused by long distances, fading

Fading

In wireless communications, fading is deviation of the attenuation that a carrier-modulated telecommunication signal experiences over certain propagation media. The fading may vary with time, geographical position and/or radio frequency, and is often modelled as a random process. A fading channel...

caused by shadowing and multipath

Multipath interference

Multipath interference is a phenomenon in the physics of waves whereby a wave from a source travels to a detector via two or more paths and, under the right condition, the two components of the wave interfere...

, Doppler shift and other forms of distortion

Distortion

A distortion is the alteration of the original shape of an object, image, sound, waveform or other form of information or representation. Distortion is usually unwanted, and often many methods are employed to minimize it in practice...

. The grade of service is also affected by blocking due to admission control, scheduling starvation or inability to guarantee quality of service

Quality of service

The quality of service refers to several related aspects of telephony and computer networks that allow the transport of traffic with special requirements...

that is requested by the users.

Static radio resource management

Static RRM involves manual as well as computer aided fixed cell planning or radio network planning. Examples:

Frequency allocation
Frequency allocation
Use of radio frequency bands of the electromagnetic spectrum is regulated by governments in most countries, in a Spectrum management process known as frequency allocation or spectrum allocation. Radio propagation does not stop at national boundaries...

band plans decided by standardization bodies, by national frequency authorities and in frequency resource auctions.
Deployment of base station sites (or broadcasting transmitter site)
Antenna heights
Channel frequency plans
Sector antenna directions
Selection of modulation
Modulation
In electronics and telecommunications, modulation is the process of varying one or more properties of a high-frequency periodic waveform, called the carrier signal, with a modulating signal which typically contains information to be transmitted...

and channel coding parameters
Base station antenna space diversity, for example
- Receiver micro diversity using antenna combining
- Transmitter macro diversity such as OFDM single frequency networks (SFN)

Static RRM schemes are used in many traditional wireless systems, for example 1G

1G refers to the first-generation of wireless telephone technology, mobile telecommunications. These are the analog telecommunications standards that were introduced in the 1980s and continued until being replaced by 2G digital telecommunications...

and 2G

2G is short for second-generation wireless telephone technology. Second generation 2G cellular telecom networks were commercially launched on the GSM standard in Finland by Radiolinja in 1991...

cellular systems, in today's wireless local area networks and in non-cellular systems, for example broadcasting systems. Examples of static RRM schemes are:

Circuit mode communication using FDMA and TDMA
Time division multiple access
Time division multiple access is a channel access method for shared medium networks. It allows several users to share the same frequency channel by dividing the signal into different time slots. The users transmit in rapid succession, one after the other, each using its own time slot. This...

.
Fixed channel allocation (FCA)
Static handover criteria

Dynamic radio resource management

Dynamic RRM schemes adaptively adjust the radio network parameters to the traffic load, user positions, quality of service requirements, etc. Dynamic RRM schemes are considered in the design of wireless systems, in view to minimize expensive manual cell planning and achieve "tighter" frequency reuse patterns, resulting in improved system spectral efficiency.

Some schemes are centralized, where several base stations and access points are controlled by a Radio Network Controller

Radio Network Controller

The Radio Network Controller is a governing element in the UMTS radio access network and is responsible for controlling the Node Bs that are connected to it. The RNC carries out radio resource management, some of the mobility management functions and is the point where encryption is done before...

(RNC). Others are distributed, either autonomous algorithms in mobile station

Mobile Station

The mobile station comprises all user equipment and software needed for communication with a mobile network.The mobile station refers to global system connected to the mobile network, i.e. mobile phone or mobile computer connected using a mobile broadband adapter. This is the terminology of 2G...

s, base station

Base station

The term base station can be used in the context of land surveying and wireless communications.- Land surveying :In the context of external land surveying, a base station is a GPS receiver at an accurately-known fixed location which is used to derive correction information for nearby portable GPS...

s or wireless access points

Wireless access point

In computer networking, a wireless access point is a device that allows wireless devices to connect to a wired network using Wi-Fi, Bluetooth or related standards...

, or coordinated by exchanging information among these stations.

Examples of dynamic RRM schemes are:

Power control
Power control
Power control, broadly speaking, is the intelligent selection of transmit power in a communication system to achieve good performance within the system. The notion of "good performance" can depend on context and may include optimizing metrics such as link data rate, network capacity, geographic...

algorithms
Link adaptation
Link adaptation
Link adaptation, or adaptive coding and modulation , is a term used in wireless communications to denote the matching of the modulation, coding and other signal and protocol parameters to the conditions on the radio link Link adaptation, or adaptive coding and modulation (ACM), is a term used in...

algorithms
Dynamic Channel Allocation (DCA) or Dynamic Frequency Selection (DFS) algorithms, allowing "cell breathing"
Traffic adaptive handover
Handover
In cellular telecommunications, the term handover or handoff refers to the process of transferring an ongoing call or data session from one channel connected to the core network to another...

criteria, allowing "cell breathing
Cell breathing (telephony)
In CDMA-based mobile telephone systems, the effect of radio interference from other mobile transmitters in the same cell or coverage area is very marked and has a special name, cell breathing....

"
Re-use partitioning
Adaptive filter
Adaptive filter
An adaptive filter is a filter that self-adjusts its transfer function according to an optimization algorithm driven by an error signal. Because of the complexity of the optimization algorithms, most adaptive filters are digital filters. By way of contrast, a non-adaptive filter has a static...

ing
- Single Antenna Interference Cancellation
  Single Antenna Interference Cancellation
  Single Antenna Interference Cancellation is a promising technology to boost the capacity of GSM networks without any needed change in the network....
  
  (SAIC)
Dynamic diversity scheme
Diversity scheme
In telecommunications, a diversity scheme refers to a method for improving the reliability of a message signal by using two or more communication channels with different characteristics. Diversity plays an important role in combatting fading and co-channel interference and avoiding error bursts...

s, for example
- Soft handover
  Soft handover
  Soft handover or soft handoff refers to a feature used by the CDMA and WCDMA standards, where a cell phone is simultaneously connected to two or more cells during a call. If the sectors are from the same physical cell site , it is referred to as softer handoff...
- Dynamic Single Frequency Networks (DSFN)
- Phased array antenna with
  - beamforming
    Beamforming
    Beamforming is a signal processing technique used in sensor arrays for directional signal transmission or reception. This is achieved by combining elements in the array in a way where signals at particular angles experience constructive interference and while others experience destructive...
  - Multiple-input multiple-output communications (MIMO)
  - Space-time coding
Admission control
Dynamic bandwidth allocation
Dynamic bandwidth allocation
Dynamic bandwidth allocation is a technique by which traffic bandwidth in a shared telecommunications medium can be allocated on demand and fairly between different users of that bandwidth. This is a form of bandwidth management, and is essentially the same thing as statistical multiplexing...

using resource reservation multiple access schemes or statistical multiplexing
Statistical multiplexing
Statistical multiplexing is a type of communication link sharing, very similar to dynamic bandwidth allocation . In statistical multiplexing, a communication channel is divided into an arbitrary number of variable bit-rate digital channels or data streams. The link sharing is adapted to the...

, for example Spread spectrum
Spread spectrum
Spread-spectrum techniques are methods by which a signal generated in a particular bandwidth is deliberately spread in the frequency domain, resulting in a signal with a wider bandwidth...

and/or packet radio
Packet radio
Packet radio is a form of packet switching technology used to transmit digital data via radio or wireless communications links. It uses the same concepts of data transmission via Datagram that are fundamental to communications via the Internet, as opposed to the older techniques used by dedicated...
Channel-dependent scheduling, for instance
- Max-min fair scheduling using for example fair queuing
- Proportionally fair scheduling using for example weighted fair queuing
  Weighted fair queuing
  Weighted fair queuing is a data packet scheduling technique allowing different scheduling priorities to statistically multiplexed data flows.WFQ is a generalization of fair queuing . Both in WFQ and FQ, each data flow has a separate FIFO queue...
- Maximum throughput scheduling
  Maximum throughput scheduling
  Maximum throughput scheduling is a procedure for scheduling data packets in a packet-switched best-effort communications network, typically a wireless network, in view to maximize the total throughput of the network, or the system spectral efficiency in a wireless network...
  
  (gives low grade of service
  Grade of service
  In telecommunication engineering, and in particular teletraffic engineering, the quality of voice service is specified by two measures: the grade of service and the quality of service ....
  
  due to starvation)
- Dynamic packet assignment (DPA)
- Packet and Resource Plan Scheduling (PARPS) schemes
Mobile ad-hoc networks using multihop communication
Cognitive radio
Cognitive radio
A cognitive radio is a kind of two-way radio that automatically changes its transmission or reception parameters, in a way where the entire wireless communication network -- of which it is a node -- communicates efficiently, while avoiding interference with licensed or licensed exempt users...
Green communication
QoE-aware RRM
Femtocells

Inter-cell radio resource management

Future networks like the LTE standard defined by 3GPP are designed for a frequency reuse of one. In such networks neighbor cells are using the same frequency. Such standards can be highly efficient in terms of spectrum, but required close coordination between cells to avoid excessive inter-cell interference. Like in most cellular system deployments, the overall system capacity is not range limited or noise limited, but interference limited. Inter-cell radio resource management coordinates resource allocation between different cell sites. There are various means of Inter-cell Interference Coordination (ICIC) already defined in the standard. Dynamic single frequency networks, coordinated scheduling, multi-site MIMO or multi-site beam forming are other examples for inter-cell radio resource management.

For further reading

J. Zander, S-L Kim, M. Almgren (2001), Radio Resource Management for Wireless Networks, Artech House Publishers, ISBN 1580531466.
N. D. Tripathi, J. H. Reed, H. F. Vanlandingham (2001), Radio Resource Management in Cellular Systems, Springer, ISBN 079237374X http://books.google.com/books?id=xex6Z-DquTwC&dq=radio+resource+management
Introduction to International Radio Regulations; ICTP Lecture Notes 16; ISBN 92-95003-23-3 from public archives of Abdus Salam International Centre for Theoretical Physiscs

The source of this article is wikipedia, the free encyclopedia. The text of this article is licensed under the GFDL.

Static radio resource management

Dynamic radio resource management

Inter-cell radio resource management

See also

For further reading