Channel allocation and Mobility management

1. Addis Ababa Science and Technology
University
College of Electrical and Mechanical Engineering
Department of Electrical and Computer Engineering
Group Assignment on
Wireless and Mobile Communication (ECEg 6111)
Resource Allocation and Mobility Management
Proposedby: Id No
1. MichaelTesfaye GSR 220/12
2. Shimelis Gebreab GSR 232/12
3. YeneneshW/senbet GSR 236/12
Submitted to:
Muluneh Mekonnen (Ph.D.)
December, 2019

2. I
Table of Contents
List of Figure...................................................................................................................................II
List of Acronyms ...........................................................................................................................III
1. Introduction............................................................................................................................. 1
1.2 Resource allocation in Wireless Communication System ........................................................ 2
1.2.1 Bandwidth Management .................................................................................................... 2
1.2.2 Transmission Power Management..................................................................................... 3
1.2.2.1 Performance Metric for Power Control ...................................................................... 3
1.2.3 Antenna Management ........................................................................................................ 4
1.2.4 Inter-cell Resource Management ....................................................................................... 4
1.3 Mobility Management............................................................................................................... 5
1.3.1 Location Management........................................................................................................ 5
1.3.2 Hand of Management......................................................................................................... 6
1.4 Importance of Mobility Management ....................................................................................... 7
Summery......................................................................................................................................... 7
References....................................................................................................................................... 8

3. II
List of Figure
Figure 1 System model for power control ...................................................................................... 3
Figure 2 Block diagram for Location management ........................................................................ 5
Figure 3 Block diagram for Handoff anagement ............................................................................ 6

4. III
List of Acronyms
CDMA Code Division Multiple Access
CINA Carrier to Interference and Noise Ratio
FDMA Frequency Division Multiple Access
Hz Hertz
ISI Inter symbol Interference
MIMO Multiple Input Multiple Output
MT Mobile Terminals
QOS Quality of Service
SDMA Space Division Multiple Access
SINR Signal to Interference and Noise Ratio
TDMA Time Division Multiple Access

5. 1
1. Introduction
Present wireless communication systems are required to support a variety of highspeed data
communication services for its users, such as video streaming and cloud-based services. As the
users’ demands for such services grow, more efficient wireless systems need to be designed that
can support high-speed data and, at the same time, serve the users in a fair manner. One method to
achieve this is by using efficient resource allocation schemes at the transmitters of wireless
communication systems. Here, the term “resources” refers to the fundamental physical and
network layer quantities that limit the amount of data that can be transmitted over a communication
link, such as available bandwidth and power [1,4]. Therefore, efficient resource allocation schemes
must be developed to exploit available resources in the best possible manner and provide
ubiquitous high-data-rate to all users in a fair manner.
Resource management in wireless communications refers to a series of processes that determine
the timing, ordering, procedures, and the amount of wireless resources to allocate to each user. The
wireless link tends to become a bottleneck, but wireless resource management aims at delivering
the required service quality of each user as far as possible. Resource management is necessary for
every wireless network, no matter what capability it may have. This is why wireless resource
management has attracted so much research interest [3]. For a resource management technique to
be effective, it is necessary to define certain factors. First, there is a set of available wireless
resources to share among the constituent users. Second, there is the information available at the
resource manager and the methods of information exchange among the users or protocol layers.
Third, there are the service requirements of each user, which may be differently determined
depending on the traffic characteristics and the performance metric. Fourth, there are the objectives
to optimize in relation to the performance metric of the service provider [1]. The importance of
resource management originates from the scarceness of wireless resources. The requirements
could be met simply if we had unlimited access to the three fundamental resources bandwidth,
transmission power, and antennas, but in practice there are various limitations.

6. 2
1.2 Resource allocationin Wireless CommunicationSystem
Wireless resource management is a series of processes needed to determine the timing and the
amount of relevant resources to allocate to each user. It is necessary to define first what types of
wireless resource are to be allocated, and then define the objectives that the resource management
tries to optimize and the constraints that restrict the degree of freedom in allocating resources. In
a transmitter–receiver pair equipped with multiple antennas, the information-theoretical capacity
C, which is the upper limit on the transmission rate supporting reliable information delivery, is
given by
𝐶 = 𝑾max
𝑄:𝑇𝑟( 𝑄)=1
log2[det(𝐼 𝑁 +
𝐸𝑠
𝑁𝑜
𝑸𝑯𝑯 𝐻
)](𝑏𝑖𝑡𝑠/𝑠𝑒𝑐) (1)
where W is the bandwidth, Q the covariance matrix of the transmitted signal, Es the symbol energy,
N0 the noise spectral density, and H the NR, NTchannel matrix for the channel with NT transmit and
NR receive antennas. According to this equation, there are three different kinds of wireless resource
bandwidth, transmission power, and antennas [2].
1.2.1 Bandwidth Management
Bandwidth is a fundamental wireless resource which refers to the range of frequencies occupied
by a transmitted signal. Since bandwidth determines the maximum symbol transmission rate, it
puts a fundamental limit on the channel access rate [4]. Broadly, bandwidth may be considered as
the transmission opportunity to access the wireless medium; that is, how often we can transmit
symbols over the wireless medium. If this transmission opportunity is shared by multiple users,
the scheduling that determines the order of user access over time becomes the essential part of
bandwidth management. Another important part of bandwidth is the admission control, which
determines the admissibility of a new connection in relation with QoS. Admission control may be
regarded as a long-term bandwidth management and is strongly related to scheduling.
A larger bandwidth means a greater chance to access the wireless channel during a given
time, and thus the transmission rate of a user increases in proportion to the bandwidth
allocated to it. This proportional property makes it relatively easy to estimate the
contribution of the bandwidth allocation to user performance. For example, the
transmission of a user would be doubled if the allocated bandwidth is doubled.

7. 3
1.2.2 Transmission Power Management
Transmission power management refers to techniques for determining the transmission power
level adequate to achieve system objectives in a given communication environment. The first
reason why transmission power needs to be managed properly is that the transmission of one user
is likely to interfere with the transmissions of other users. The power management performed for
such a purpose is called power control. In CDMA systems, especially in uplink channels, power
control is a key feature which dictates the system performance by regulating the interference level
generated by each constituent user.
1.2.2.1 Performance Metric for Power Control
A typical metric is the CINR, which is defined as the ratio of the received power of the desired
signal to the power of noise-plus-interference from other transmitters.
Figure 1 System model for power control
The CINR for k users
𝛾 𝑘 =
𝑔 𝑘𝑘 𝑝 𝑘
б 𝑘
2 +∑ 𝑔 𝑘𝑖 𝑝𝑖
𝑘
𝑖=1
(7)
Where Pk, σk
2 and gki are Transmission power, noise variance and the channel gain between the
transmitter of user i and the receiver of user k respectively. The CINR in may well describe the
link quality in FDMA or TDMA systems, but it cannot be used in CDMA systems where each
signal is spread by its own sequence. In this case, the SINR is applicable, which is defined as the
ratio of signal power to noise-plus-interference power after dispreading. If a spreading code Ck
with a spreading factor N is assigned to user k, the SINR is given by
Γk =
𝑔 𝑘𝑘 𝑝 𝑘 𝑐 𝑘
4
б 𝑘
2 𝑐 𝑘
2+∑ 𝑔 𝑘𝑖 𝑝𝑖 𝑐 𝑖 𝑐 𝑘
2𝑘
𝑖=1
(8)
Rx user 1
Rx user k
Tx user 1
Tx of user
k

8. 4
1.2.3 Antenna Management
Recently, antennas have become the most attractive wireless resource as they can contribute to
increasing the channel capacity without requiring additional bandwidth or transmission power.
However, as antennas need circuitry operating at radio frequency in the transmitting and receiving
devices, increasing the number of antennas implies an increased device cost. In addition, the
channel capacity heavily relies on the usage of antennas, and their optimal use varies depending
on the channel that connects the transmitter–receiver pair. This implies that, for an effective
operation of antennas, it is necessary to adopt an antenna management method adequate to the
current channel state. There are various MIMO technologies, including diversity transmission and
spatial multiplexing transmission. Also, there are multiuser MIMO transmission technologies,
such as SDMA and dirty paper coding.
Multiple-antenna technologies may be classified into. transmit diversity. And spatial
multiplexing. types. A diversity transmission scheme is a method to obtain spatial diversity on
fading channels by sending the same (or slightly modified) data on different antennas. A spatial-
multiplexing scheme transmits multiple streams of independent data from different antennas in
order to maximize the data rate.
1.2.4 Inter-cell Resource Management
A frequency-reuse scheme helps to mitigate inter-cell interference by reusing a common frequency
band only at base stations spaced far apart. This approach relies on the fact that the power of a
transmitted signal decreases rapidly as the signal propagates through space. A set of cells which
share the same channel set is called a co-channel set; the minimum distance among the members
of the co-channel set is called the reuse distance; and the number of channel sets that divides the
total bandwidth is called the reuse factor. There is a one-to-one correspondence between the reuse
factor and the reuse distance; that is, once the reuse factor is determined, the reuse distance is
calculated uniquely. So, two terms, reuse factor and reuse distance, can be used interchangeably.
In a sense, inter-cell interference management converges to the issue of determining the reuse
distance in consideration of the QoS requirement of the system, as the reuse distance dictates the
inter-cell interference level and the bandwidth used by each Base Station. Channel allocation refers

9. 5
to the design task of determining which channels are to be used by which cells, and in what reuse
distance to attain maximal frequency-reuse efficiency. Among a large number of schemes
proposed to date the following are the main
i. fixed channel allocation: for which the channels assigned to each cell are fixed during
the run time;
ii. dynamic channel allocation: it assigns channels dynamically to each cell while
employing an explicit homogeneous reuse distance;
iii. channel allocation based on SINR: measurement that dynamically decides the
reusability of the channels based on SINR measurement;
iv. channel allocation with inter-cell power control: that permits each cell to control its
power allocated to each channel continuously.
1.3 Mobility Management
Mobility management enables mobile wireless networks to locate roaming terminals for call
delivery and to maintain connections as the terminal is moving into a new service area. Thus,
mobility management supports mobile terminals (MTs), allowing users to roam while
simultaneously offering them incoming calls and supporting calls in progress [2]. Mobility
management contains two components: location management and handoff (or handover)
management.
1.3.1 Location Management
It enables the system to track the attachment points of MTs between consecutive communications.
Figure 2 Block diagram for Location management
Location
Management
Data
Base
Queries
Terminal
Paging
Call
Delivery
Location
Registration
Update
Data
Base
Update
Authentication

10. 6
Location registration/update: Terminal informs network about its current access point
New Call/Session/Data delivery
 When a new Call/Session/Data arrives to terminal’s home network
 Network requested to find the terminal location, either by querying location databases
1.3.2 Hand of Management
Handoff management enables the network to maintain a user’s connection as the MT continues to
move and change its access point to the network.
It maintains terminal connection/routes when terminal moves
Figure 3 Block diagram for Handoff management
Initiation: need for handoff identified
New connection/route generation
 Resources found for the handoff connection
 In Network-Controlled Handoff (NCHO) the network finds the resources
 In Mobile-Controlled Handoff (MCHO) terminal finds resources, network approves
 Routing operations performed
Data-flow control: delivery of data from old to new paths, maintaining QoS
Moreover, when a user is in the coverage area of multiple wireless networks, for example, in
heterogeneous wireless environments, handoff management provides always best connectivity to
the user by connecting the user to the best available network.
Hand off
management
New connection
generation
Data flow
control
Initiation
Buffering
Sequencing
Resource
allocation
User
movement
Multicast
Connection
Routing
Network
movement

11. 7
In next-generation wireless systems, there are two types of mobility for MTs: intra-system (intra-
domain) and inter-system (inter-domain) mobility. Intra-system mobility refers to mobility
between different cells of the same system. Intra-system mobility management techniques are
based on similar network interfaces and protocols. Inter-system mobility refers to mobility
between different backbones, protocols, technologies, or service providers.
1.4 Importance of Mobility Management
Mobility in wireless networks can take different forms, such as:
 Terminal mobility: the ability for a user terminal to continue to access the network when
the terminal moves;
 User mobility: the ability for a user to continue to access network services from different
terminals under the same user identity when the user moves;
 Service mobility: the ability for a user to access the same services regardless of where the
user is.
In addition, a terminal or a user may be considered by a network to have “moved” even if the
terminal or the user has not changed its physical location. Mobility management is the fundamental
technology to enable the seamless access to next-generation wireless networks and mobile
services.
Summery
Generally, efficient resource allocation schemes must be developed to exploit available resources
in the best possible manner and provide ubiquitous high-data-rate to all users in a fair manner. So
the available wireless resources optimally resource management can lead to a significant
improvement in transmission rate without using more resource. In addition, it can make the system
flexible enough to operate in adaptation to the channel characteristics and QoS requirements,
thereby permitting a flexible service architecture for integrating various different services in a
single air-interface. The above resource allocation and management issues can be taken as an
umbrella for recent researches on different algorithms and schemes in optimization of QOS for
wireless network.

12. 8
References
[1]. Byeong Gi Lee,Daeyoung Park and Hanbyul Seo, Wireless Communication Resource
Management, Singapore: John Wiley & Sons (Asia) Pte Ltd, 2009.
[2]. M. Selim Demir*, "Unified Resource Allocation and Mobility Management Technique Using
Particle Swarm Optimization for VLC Networks," IEEE Photonics , vol. 2, no. Resource
Allocation and Mobility Management, pp. 2-3, 2018.
[3]. Yun Meng* and Xinyi Liu, "Resource allocation and interference management for multi-
layer wireless in heterogeneous cognitive," Meng and Liu EURASIP Journal on Wireless
Communications and Networking, vol. 4, no. Review, pp. 2-6, 2019.
[4]. Faramarz Nikjoo, Abbas Mirzaei & Amin Mohajer, "A Novel Approach to Efficient Resource
Allocation in NOMA Heterogeneous Networks: Multi-Criteria," Applied Artificial
Intelligence An International Journal, vol. 5, pp. 2-7, 2018.