Good morning, ladies and gentlemen. On behalf of Comba Telecom Systems Holdings Limited, I would like to welcome all of you joining the 2022 annual results investor presentation today. Today, there will be a presentation followed by Q&A session. The senior management who are joining us today are: the Chairman, Mr. Fok Tung Ling [Foreign language] . The Executive Director and President of the Group, Mr. Xu Huijun [Foreign language]. The Executive Director and Group CFO, Mr. Ken Chang[Foreign language]. The Executive Director and Senior Vice President of the Group, Miss Huo Xinru [Foreign language]. Now may I invite Mr. Ken Chang, Executive Director and Group CFO, to present the financial highlights and review of 2022. [Foreign language]
Good morning, everyone. I'm here to brief the financial part of the 2022 annual result. Revenue is HKD 6.36 billion, which is up by 8.4% YoY. Revenue up by about 8% is because we have remarkable success in our antenna section in the Mainland China segment, as well as in international market. Gross profit has increased by 31.7% to HKD 1.8 billion. Gross profit margin has increased significantly from about 24%- 29.4%. Gross profit margin up significantly because of three reason. One, we actually have better margin product mix. Second, is because of our R&D efforts since the design phase has been quite effective. Thirdly, is because our production efficiency. On the other hand, operating expenses have come down quite.
substantially by about 25.5%. This is due to our cautious cost control. Profit and loss before tax is a profit of close to HKD 300 million, which is a sharp contrast of a loss of about HKD 656 million of losses a year ago. Income tax has gone up significantly at about HKD 153 million. This is because of adjustment of a deferred tax asset. The net profit to shareholder is HKD 190 million, which is again, a sharp contrast of a net loss of close to HKD 600 million a year ago. Net profit margin at 3%. This year, because we have a profit, we'll resume the dividend paying policy, and the payout ratio is about 30%.
Dividend per share for the whole year is HKD 0.021. As mentioned, operating expenses have come down substantially in absolute term and also in relative terms. In relative terms, a year ago, the operating expenses is about 39.1%, and it has come down dramatically to 31%. Basically, besides finance cost and income tax, all other major category of operating expenses have come down in relative term and also in absolute term. Admin expense, selling expense have come down by about 17.9% and 5.8% respectively. This is due to our operating efficiency, and also cautious cost control as well. R&D expenses as a percentage of revenue is still 8.1%. It's still within the range of our targeted R&D spends.
We believe that we continue to boost the competitiveness and as well, we increase the efficiency of our R&D output. Finance cost has come up by about 38%. This is mainly because of the macro inflation environment where the interest rate has gone up. On the other hand, actually because of our excess cash position, the interest income has also gone up for our group. Actually the net effect is actually not so harmful for us. Income tax has gone up dramatically, this is because of the changes in the deferred tax asset. If you look at our balance sheet, I think we still have a net cash position at roughly about HKD 781 million. Total asset, total liability side have come down roughly by about 8% and 9.8% respectively.
Net asset is HKD 3.7 billion, which is about the same as a year ago. NAV per share is HKD 1.34. If you gauge our financial ratios, I would say that most of the indicator still shows that we are operating healthy. Inventory turnover day is 140 days, has gone up slightly by about six days. Account receivable turnover days is 229 days, has down by about 28 days from a year ago. Account payable days is 349 days. Cash conversion cycle is still kind of breakeven, so it actually means that it's not really occupying our working capital. Operating cash flow is actually healthy at around HKD 500 million.
Even a year ago, we still have operating, positive operating cash flow of about HKD 375 million. This year we have higher operating cash flow. Gross gearing ratio, a measure of our interest bearing debt divided by our total asset, is still at a healthy level at about 12.7%. About the same a year ago. Debt to asset ratio, 62.4%. The ROE for our company is 5.1% for the year. If we look at our debt situation over the last five years, we can actually see our gross gearing ratio has come down from 17.7% - 12.7%. 5% decrease over the last five years.
Also the interest bearing debt absolute amount coming down from HKD 2 billion to roughly about HKD 1.3 billion in this year, in 2022. Also, you actually have seen that the net cash position has gradually built up. This is actually a pretty good preparation for us to face the current inflationary environment where interest rates gone up, where we actually try to avoid paying more tax, paying more interest expenses. Over the last 10 years, except for one back in 2020, we always have the positive operating cash flow. Again, even in 2021 we have HKD +1, and this year we generate even more operating cash flow. Let's look at our business by segment.
Basically the, in China, the three major operators account for roughly about 46% of the total revenue. The three combined together YoY is 13.6% up. It's also worth noting that China Unicom revenue is up by more than 100%. China Tower roughly down by about 5%. Our international segment, which is up by 9.3%. It's worth noting that European countries is up by close to 100%. Middle East also 100%. OEM segment, which also up very strongly by about 38%. The others is mainly our ETL, which is our 51% owned Laos operators. The revenue in the local currency term is up by 5%.
Of course, the local currency depreciated by roughly 30% last year, so in the HKD term, the revenue has come down. In local currency term, it has gone up. If we look at the business by segment, as mentioned, the main driver is antenna business. In fact, the antenna business is basically record-breaking for us over the last 20 years. You know, antenna actually reached a new high for us. It's up by 25.8% YoY. It's both strong in domestic China market as well as international market, which are both up by around 25% and 26%-27% respectively. The network system, which is down by 15.9%. This is mainly due to, number one, the delay in small cell deployment, and also because of the COVID situation.
Secondly is we voluntarily give up the low margin projects. The management is very positive in the prospect in 2023 and beyond. Services is up by 3.1%. The wireless transmission business, which is around 5.6% of total revenue, is up by 21.7%. This mark the end of the financial part. I will pass my time to Mr. Xu Huijun, our President of the group. Thank you.
Thank you thank you Mr. Ken. May I now invite Mr. Xu Huijun, Executive Director and President of the group, to present the industry development and company outlook. [Foreign language]
[Foreign language]