Saudi Arabia is one of the largest consumer markets in the gulf region. The rising global oil prices and growing economy has increased the demand for telecommunication based services. There is a growing demand for online services offered by financial institutions, trade companies and travel industry. The telecommunication sector of Saudi Arabia witnessed privatization in the year 2002 and since then a large number of international telecom companies have shown interest in this sector. The UAE based Etisalat company entered the Saudi telecom market in the year 2004 with the brand name Mobily and latter this year a third telecom company a conglomerate of Saudi and Kuwait based investors entered the kingdom telecom sector with the brand name Zain. With a growing population the sector indicates a high business potential in the coming years.
Saudi Arabia predominantly has younger population. According to Middle East Economic Digest 2006, 60% of the population is under the age of 16. The growing economic reforms have impacted the telecom sector. Both the data and mobile markets have been liberalized, with the award of license in 2003 for Very Small Aperture Terminal (VSAT) services in August 2004 to provide mobile and data communications. The government also opened the fixed line sector to competition and licenses were auctioned in 2007 to compete with Saudi Telecom (STC). The second GSM mobile operator, an Etisalat-led consortium operating as Mobily, launched services in May 2005 and has rapidly acquired subscribers. An Integrated Dispatched Enhanced Network (IDEN) operator, Bravo, also launched services shortly afterwards. Mobily has wasted no time in building market share before the introduction of the third mobile operator. The impact of Mobily has been significant, with STC reducing tariffs numerous times both prior to Mobily's launch in May 2005 and soon afterwards. Despite fast growth, mobile penetration is still a little lower in Saudi Arabia compared to other countries in the region. This caused enormous media and telco interest in the third mobile licence.
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Internet penetration is comparatively low. Competition is allowed in the Internet Service Providers (ISP) market but all ISP's must be licensed. Broadband penetration is also low as cable broadband is non existent and ADSL is hampered by distance limitations. Internet access in Saudi Arabia has been available since 1994, but was restricted to state academic, medical, and research institutions until January 1999. In 2004 a resolution was passed transferring the regulation of Internet services from the King Abdulaziz City for Science and Technology (KACST) to the CITC. The CITC is responsible for the operation of the Saudi Network Information Centre (SaudiNIC), the management of the national top-level domain name (.sa) and Internet filtering services.
Widespread use of the Internet was initially curbed by excessive access rates and slow connection speeds but reductions in the price STC charges the KACST and reduced charges to ISPs by KACST from 2002 through to 2006 greatly helped. STC's price cut followed the launch of the two new data service providers - Bayanat and ITC. Bayanat was already offering international Internet bandwidth for 30% less cost than KACST.
Other factors in increasing Internet use have been the decreasing cost of laptops and PCs and the increasing number of websites in the Arabic language. PC penetration in Saudi households was around 34% in early 2007, according to a statement by the Minister for Communications and Information Technology.
Data service provider licenses
Licenses to provide data communications services in competition with incumbent STC were awarded in August 2004 to two Saudi companies, Bayanat Al-Oula for Network Services Consortium and Bayn Consortium (formerly Samawat Consortium), operating as Integrated Telecommunication Company (ITC). Bayant Al-Oula paid SAR120 million for the 25-year licence and promised to invest SAR 2 billion over five years in infrastructure development that will include a high-speed fibre optic network and wireless networks for main cities and remote areas. Bayn Consortium, operating as Integrated Telecommunication Company (ITC), was officially presented its license in March 2005, paying SAR300 million for the 25-year license. Eleven consortia were pre-qualified for the bidding. The two operators are licensed to install, operate and use wireless and fixed-line networks, including international calls, and provide Internet services. The data services include digital leased lines, broadband services, Virtual Private Networks (VPN), IP, Asynchronous Transfer Mode (ATM), frame relay, international data gateway services and international data traffic.
Implementing WiMax in Saudi Arabia:
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WiMAX technology has gained a lot of attention in recent years from the telecom industry. The technology was initially developed as a fixed wireless technology. Fixed WiMAX (IEEE 802.16-2004) has the potential to bring broadband Internet access to the millions of people worldwide who are not connected to a wired network infrastructure. However, due to the low penetration of copper and coax and their potential higher bit rates, Fixed WiMAX does not look attractive for the Saudi market. With the new IEEE 802.16e-2005 revision a new important feature is introduced: mobility. Mobile WiMAX could be a competitive technology next to UMTS and WiFi on the Saudi market.
Network & Equipment:
Mobile WiMAX typically uses a cellular approach, comparable to the exploitation of a GSM network. At the operator side, throughout the area that needs to be served, several sites or base stations (BS) have to be installed. An important feature of a WiMAX system is the use of advanced antenna techniques such as the built-in support of Multiple Input Multiple Output (MIMO) techniques and beam forming using smart antennas (also indicated with the term Adaptive Antenna System or AAS). Next to the above techniques, the capacity per base station can also be increased by installing several sectors on one site, each containing one (or more, in case of MIMO and/or AAS) sector antenna(s). One sector can then provide services to multiple simultaneous users. The antennas themselves are preferably placed at a certain altitude so that their signal is not being blocked by adjacent buildings.
The base stations are then connected to a WiMAX Access Controller through a backhaul
network. The WiMAX Access Controller, connected to the backbone network of the operator, is responsible for, among other things, the access control and accounting. It also guarantees the assignment of IP addresses to the users and mobility, by coordinating the handovers. This mobility is performed by using Mobile IP.
At the client side, the wireless signals are captured and interpreted by a subscriber station
(SS), also commonly known as Customer Premises Equipment (CPE). This CPE can be compared with a modem in DSL or cable broadband connections. However, it has to capture a wireless signal and it has thus an attached or integrated antenna. Since the wireless signals, which are transmitted to and from the base station, get severely degraded due to attenuation loss, best performance is reached by using a roof-mounted outdoor CPE. The signal is then brought to the end user computer using in-house Ethernet cabling or a WiFi access point. The end-user could also try to use an indoor CPE. This simplifies the installation process and no roof works are required, but comes at the cost of degraded network performance. If too many objects or walls are located between CPE and base station, communication can fail.
A lot of physical aspects of Mobile WiMAX are of importance to deploy a WiMAX network. The physical layer modulation of Mobile WiMAX is based on Scalable Orthogonal Frequency Division Multiple Access (SOFDMA). The channel bandwidth is divided into smaller sub carriers which are orthogonal with each other, generated by the Fast Fourier Transform (FFT) algorithm. There are three types of OFDM sub carriers: data sub carriers (for data transmission), pilot sub carriers (for various estimation and synchronization purposes) and null sub carriers (used as guard bands and DC subcarrier). Data and pilot sub carriers are divided into subsets of subcarriers, called subchannels. Subchannels are the smallest granularity for resource allocation and can be assigned to individual users. The physical layer is well adapted to the non-line-of-sight (NLOS) propagation environment in the 2-11 GHz frequency range and it is fundamentally different from the Code Division Multiple Access (CDMA) modulation used in the UMTS technologies. Another feature which improves performance is adaptive modulation, which is applied to each subscriber individually and can be dynamically adapted according to the radio channel capability. If the signal-to-noise ratio (SNR) is high enough, 64-QAM can be used, but with a decreasing SNR 16-QAM or QPSK is applied. WiMAX also provides flexibility in terms of carrier frequency and channel bandwidth.
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The installation of WiMAX base stations and especially the pylons is the determining cost factor in a WiMAX deployment. A lot of physical aspects have to be taken into account. The physical layer modulation of Mobile WiMAX is based on Scalable Orthogonal Frequency Division Multiple Access (SOFDMA). The channel bandwidth is divided into smaller subcarriers which are orthogonal with each other. Subsets of these subcarriers can be assigned to individual users. The physical layer is well adapted to the non-line-of-sight (NLOS) propagation environment in the 2 - 11 GHz frequency range and it is fundamentally different from the Code Division Multiple Access (CDMA) modulation used in the UMTS technologies. Another feature which improves performance is adaptive modulation, which is applied to each subscriber individually and can be dynamically adapted according to the radio channel capability.
In Europe, the 3.5 GHz licensed band and the 5.8 license free band are the most important ones at the moment. Also the 2.5 GHz band is investigated, but currently this one is reserved as extension to the UMTS band. Concerning the channel width, channels from 1.25 MHz to 20 MHz are possible. For Mobile WiMAX, channel bandwidths of 1.25 MHz, 5 MHz, 10 MHz en 20 MHz are specified. Mobile WiMAX uses Time Division Duplexing (TDD) as duplex mode, which means that downlink and uplink use the same frequency, but at a different time. Finally, an important feature of the WiMAX system is the use of advanced antenna techniques such as beam forming using smart antennas and the build in support of Multiple Input Multiple Output (MIMO) techniques.
In order to investigate the feasibility of a WiMAX rollout, one has to be able to asses the number of base stations that will be needed in a specific area, dependent on the offered services and the number of active users. To start with the calculation of the link budget, which indicates to what extent the signal may weaken. Then, a propagation model is proposed to determine the range, by taking into account the link budget. Based on this range, we illustrate the calculation of the cell coverage area. Further, we also calculate the bit rate per cell sector. Finally, the cell areas and bit rates are combined to estimate the required number of base stations to offer the desired services to the targeted users.
The link budget depends on several parameters such as base station profile, thermal noise, implementation loss and fade margins. For the current study we consider a base station with 2X2 MIMO. The various parameters for the base station required for the calculation of link budget are as follows:
Where DL and UL stands for downlink and uplink respectively, and Tx and Rx for transmitter and receiver.
The thermal noise is dependent on the channel bandwidth and can be estimated as (in dBm): −174 + 10log10(_f), where _f is the bandwidth in hertz over which the noise is measured. As physical bandwidth (BW), there is a choice from 1.25 MHz, 5 MHz, 10 MHz and 20 MHz, where today 10 MHz is the most standard value. So the value of BW has to be multiplied by the ratio between the number of used sub carriers (NUsed) and the total number of OFDM sub carriers or FFT size (NFFT), and the sampling factor (n). For each bandwidth, the model contains different values for NFFT and NUsed. Since in the current study a BW of 10 is chosen the parameters for this bandwidth are as follows:
The sampling factor n determines the subcarrier spacing in conjunction with the bandwidth and used data subcarriers, and the useful symbol time. This value is set to 28/25 for channel bandwidths that are a multiple of any of 1.25, 1.5, 2 or 2.75 MHz.
So, the Thermal Noise = -174 + 10 Log( [10x10^6] x [ 28/25]x[841/1024])
= - 107.36 dB
The receiver SNR depends on the modulation scheme. As WiMAX adaptively selects the modulation scheme per user, the appropriate SNR value used in the link budget calculation is dynamically adapted. The modulation scheme also defines the number of data bits per symbol, but this parameter only influences the bit rate per sector. If we want to concentrate on covering specific small areas and providing more data bit per symbol because of the huge population density (for example Makkah) we will go for 64-QAM ¾, but if we want to concentrate in covering wide areas and providing reasonable data bit rate we can choose QPSK ½ or ¾. Since the objective is to cover large cities such as Riyadh, Jeddah and Dammam, we opt for QPSK ½ and the SNR= 5 dB.
The implementation loss includes non-ideal receiver effects such as channel estimation errors, tracking errors, quantization errors, and phase noise. The assumed value is 2 dB.
To calculate the link budget, we have to consider several margins, such as the fade margin, the interference margin and an urban correction factor. Fading covers the effect of the variation of the signal strength during the time on a fixed location. In contrast to shadowing this takes into account the variation of the signal strength between different locations on the same distance from the transmitter. The standard fade margin is 10 dB.
Due to co-channel interference (CCI) in frequency reuse deployments, users at the cell edge or the sector boundaries may suffer degradation in connection quality. The assumed interference margin is 2 dB for DL and 3 dB for UL respectively.
Buildings obstruct the transmitted electromagnetic signals. An extra correction on the link budget is added. The standard urban correction values are as follows:
The overall DL budget for Urban area = 35 dB + 16 dBi+0+0+0-(-107.36)-5dB-7dB-2dB-2dB-10dB-3dB = 129.36.
Range of Base Stations:
We can calculate the range of a base station by using an appropriate propagation or path loss model. Path loss (PL) is the reduction in power density of an electromagnetic wave as it propagates through space. We have used the Erceg-Greenstein model, which is also applied by the IEEE 802.16 working group.
To calculate the range distance d, we have to determine the other parameters and to equate the PL with the link budget from. The wavelength λ depends on the carrier frequency. The parameters a, b and c are constants, depending on the terrain type and specified as standard values mentioned in the table below. The shadowing effect s follows a lognormal distribution with mean 0, and a standard deviation depending on the terrain type, which is also specified in the Table. The various terrain scenarios are:
- Type A: hilly, moderate tree
- Type B: intermediate
- Type C: flat, light tree
The model is valid for a base station height hb between 10 m and 80 m. In Saudi Arabia, the current GSM pylons e.g. have a height between 30 m.
A = 20 Log ( 4 d0 / λ )
λ =( 3 x 10^8) / ( 2.5 x 10^9) = 0.12 m
3x10^8 is the speed of light, 2.5x10^9 is the frequency used here is 2.5 GHz.
→ A = 20 log ( 4 (100) / 0.12) = 80.40 dB
10γ Log (d/do)
γ = a - bh + c/h
The constant parameters a, b & c are dependent on the terrain type , for example in Makkah we could choose Type A because of hilly , moderate tree and for Jeddah we can say Type B , for Riyadh we can say either Type A or Type B, but for Dmmam it can go for Type C. For uniformity purpose and looking at the future growth of high rising buildings all over the cities of Saudi Arabia, Type A is considered to be ideal. The parameters for Type A are as follows:
S0, γ= (4.6) - (30*0.0075) + (12.6/30) = 4.795
→ 10γ Log (d/do) = 10 (4.795) log (d/100)
For S as we assume a case of 90% probability of shadowing , so for Type A we can see from the table it is 10.6 dB
ΔPLf and ΔPLh , the above formula is only valid for frequencies close to 2GHz and for receiver antenna heights close to 2 m.
The value of f is on MHz , so f= 2500 MHz
→ ∆Plf= 6log(2500/2000) = 0.972 dB
∆Plh= -10.8 log(h/2)
For the value of h for receiver terminal we will assume it as 2m so ∆Plh = 0.8786.
So the PL value can be calculated as:
PL = 80.40 dB + 10(4.795) Log (d/100) + 10.6 + 0.972 + 0.8786.
PL= 92.8506 + 47.95 Log(d/100)
In the next step we try to equate the Link Budget (DL) and the Range (PL) for urban scenario, which is as follows:
129.36 = 92.8506 + 47.95 Log (d/100)
Log (d/100) = 11.4406. There d = 1140.